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Seide M, Kruse T, Graf I, Bourauel C, Lapatki BG, Jäger R, Braumann B. Inadvertent side effects of fixed lingual retainers : An in vitro study. J Orofac Orthop 2024; 85:223-232. [PMID: 36369385 PMCID: PMC11035406 DOI: 10.1007/s00056-022-00432-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Accepted: 09/10/2022] [Indexed: 11/13/2022]
Abstract
PURPOSE To better understand the side effects of fixed lingual retainers by means of an in vitro study in a two-tooth model determining the three-dimensional (3D) force-moment components acting at adjacent teeth combined with different composite-wire interfaces. METHODS Triple-stranded round retainer wires were embedded in cured disks of flowable composite. At one side the composite-wire interface was untreated and checked to be absolutely fix. At the other side the composite-wire interface was configured as either an isolated compound with (1) petroleum jelly coating, or an adhered compound with (2) no manipulation, (3) ethanol degreasing or (4) ethanol degreasing and rectangular bending of the wire ends. The 3D force-moment components were registered, while the intertooth distance was increased in steps of 0.01 mm leading to increasing tension of the wire. Measurements were repeated after artificially aging the specimens. RESULTS Retainer wire specimens with adhered compound (2, 3, 4) showed negative vestibulo-oral moments ranging maximally each between -0.3 and -0.9 Nmm in opposite direction to positive moments of 1.9 Nmm for specimens with isolated compound 1. Significant tipping moments occurred in the group with isolated compound at lower forces than in those groups with adhered compound. Similar effects were observed after artificial aging. CONCLUSION Side effects emerge under specific circumstances: an altered adhesive compound combined with the presence of oral forces. Compounds with lost adhesion at the composite-wire interface showed rotational moments in the direction of the wire windings even during low tensile forces similar to those that may occur in clinical settings. Opposite rotational moments leading to unwinding of the wire may occur in cases with adhered compounds at higher tensile forces. Utilization of round triple-stranded retainer wires without bent ends are of higher risk to induce inadvertent side effects.
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Affiliation(s)
- Marlen Seide
- Faculty of Medicine and University Hospital Cologne, Department for Orthodontics, University of Cologne, Kerpener Street 32, 50931, Cologne, Germany
| | - Teresa Kruse
- Faculty of Medicine and University Hospital Cologne, Department for Orthodontics, University of Cologne, Kerpener Street 32, 50931, Cologne, Germany.
| | - Isabelle Graf
- Faculty of Medicine and University Hospital Cologne, Department for Orthodontics, University of Cologne, Kerpener Street 32, 50931, Cologne, Germany
| | - Christoph Bourauel
- Oral Technology, University Hospital Bonn, Welschnonnenstraße 17, 53111, Bonn, Germany
| | - Bernd G Lapatki
- Department of Orthodontics, Center of Dentistry, University of Ulm, Albert-Einstein-Allee 11, 89081, Ulm, Germany
| | - Rudolf Jäger
- Department of Orthodontics, Center of Dentistry, University of Ulm, Albert-Einstein-Allee 11, 89081, Ulm, Germany
| | - Bert Braumann
- Faculty of Medicine and University Hospital Cologne, Department for Orthodontics, University of Cologne, Kerpener Street 32, 50931, Cologne, Germany
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Elshazly TM, Keilig L, Nang D, Golkhani B, Weber A, Elattar H, Talaat S, Bourauel C. Effect of thermomechanical aging on force system of orthodontic aligners made of different thermoformed materials : An in vitro study. J Orofac Orthop 2024:10.1007/s00056-024-00527-0. [PMID: 38653792 DOI: 10.1007/s00056-024-00527-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Accepted: 02/23/2024] [Indexed: 04/25/2024]
Abstract
PURPOSE The aim was to investigate the effect of aging by thermocycling and mechanical loading on forces and moments generated by orthodontic clear aligners made from different thermoplastic materials. METHODS A total of 25 thermoformed aligners made from 5 different materials, i.e., Essix ACE® and Essix® PLUS™ (Dentsply Sirona, Bensheim, Germany), Invisalign® (Align Technology, San Jose, CA, USA), Duran®+ (Iserlohn, Germany), Zendura™ (Fremont, CA, USA), underwent a 14-day aging protocol involving mechanical loading (a 0.2 mm vestibular malalignment of the upper left second premolar [tooth 25]) and thermocycling in deionized water (temperature range 5-55 °C). The 3D forces/moments exerted on tooth 25 of a resin model were measured at three time points: before aging (day 0), after 2 days and after 14 days of aging. RESULTS Before aging, extrusion-intrusion forces were 0.6-3.0 N, orovestibular forces were 1.7-2.3 N, and moments as mesiodistal rotation were 0.3-42.1 Nmm. In all directions, multilayer Invisalign® exhibited the lowest force/moment magnitudes. After aging, all materials showed a significant force/moment decay within the first 2 days, except Invisalign® for orovestibular and vertical translation. However, following thermomechanical aging, Duran®+ and Zendura™ aligners had equivalent or even higher vestibular forces (direction of mechanical load). CONCLUSION Thermomechanical aging significantly reduced forces and moments during the first 48 h. Multilayer aligner materials exhibit lower initial forces and moments than single-layer ones, and were less influenced by aging. Material hardening was observed after subjecting some of the aligner materials to mechanical loading. Thus, orthodontists should be aware of possible deterioration of orthodontic aligners over time. This work also sheds light on how material selection impacts the mechanical behavior of aligners and may provide valuable guidance regarding optimal timing for the aligner changing protocol.
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Affiliation(s)
- Tarek M Elshazly
- Oral Technology Department, Dental School, University Hospital Bonn, Bonn, Germany.
- Oral Technology, University Hospital Bonn, Welschnonnenstr. 17, 53111, Bonn, Germany.
| | - Ludger Keilig
- Oral Technology Department, Dental School, University Hospital Bonn, Bonn, Germany
- Department of Dental Prosthetics, Propaedeutics and Materials Science, Dental School, University Hospital Bonn, Bonn, Germany
| | - Diva Nang
- Oral Technology Department, Dental School, University Hospital Bonn, Bonn, Germany
| | - Bijan Golkhani
- Oral Technology Department, Dental School, University Hospital Bonn, Bonn, Germany
| | - Anna Weber
- Oral Technology Department, Dental School, University Hospital Bonn, Bonn, Germany
| | - Hanaa Elattar
- Orthodontic Department, Faculty of Dentistry, Umm Al-Qura University, Makkah, Saudi Arabia
- Orthodontic Department, Faculty of Dentistry, Suez Canal University, Ismailia, Egypt
| | - Sameh Talaat
- Oral Technology Department, Dental School, University Hospital Bonn, Bonn, Germany
- Orthodontic Department, Future University in Egypt, Cairo, Egypt
| | - Christoph Bourauel
- Oral Technology Department, Dental School, University Hospital Bonn, Bonn, Germany
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Elshazly TM, Bourauel C, Ismail A, Ghoraba O, Aldesoki M, Salvatori D, Elattar H, Alhotan A, Alkabani Y. Effect of material composition and thickness of orthodontic aligners on the transmission and distribution of forces: an in vitro study. Clin Oral Investig 2024; 28:258. [PMID: 38637429 PMCID: PMC11026231 DOI: 10.1007/s00784-024-05662-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2024] [Accepted: 04/12/2024] [Indexed: 04/20/2024]
Abstract
OBJECTIVES To investigate the effects of material type and thickness on force generation and distribution by aligners. MATERIALS AND METHODS Sixty aligners were divided into six groups (n = 10): one group with a thickness of 0.89 mm using Zendura Viva (Multi-layer), four groups with a thickness of 0.75 mm using Zendura FLX (Multi-layer), CA Pro (Multi-layer), Zendura (Single-layer), and Duran (Single-layer) sheets, and one group with a thickness of 0.50 mm using Duran sheets. Force measurements were conducted using Fuji® pressure-sensitive films. RESULTS The lowest force values, both active and passive, were recorded for the multi-layered sheets: CA Pro (83.1 N, 50.5 N), Zendura FLX (88.9 N, 60.7 N), and Zendura Viva (92.5 N, 68.5 N). Conversely, the highest values were recorded for the single-layered sheets: Duran (131.9 N, 71.8 N) and Zendura (149.7 N, 89.8 N). The highest force was recorded at the middle third of the aligner, followed by the incisal third, and then the cervical third. The net force between the incisal and cervical thirds (FI-FC) showed insignificant difference across different materials. However, when comparing the incisal and middle thirds, the net force (FI-FM) was higher with single-layered materials. Both overall force and net force (FI-FM) were significantly higher with 0.75 mm compared to those with a thickness of 0.50 mm. CONCLUSIONS Multi-layered aligner materials exert lower forces compared to their single-layered counterparts. Additionally, increased thickness in aligners results in enhanced retention and greater force generation. For effective bodily tooth movement, thicker and single-layered rigid materials are preferred. CLINICAL RELEVANCE This research provides valuable insights into the biomechanics of orthodontic aligners, which could have significant clinical implications for orthodontists. Orthodontists might use this information to more effectively tailor aligner treatments, considering the specific tooth movement required for each individual patient. In light of these findings, an exchangeable protocol for aligner treatment is suggested, which however needs to be proven clinically. This protocol proposes alternating between multi-layered and single-layered materials within the same treatment phase. This strategy is suggested to optimize treatment outcomes, particularly when planning for a bodily tooth movement.
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Affiliation(s)
- Tarek M Elshazly
- Oral Technology, Dental School, University Hospital Bonn, Welschnonnenstr. 17, Bonn, 53111, Germany.
| | - Christoph Bourauel
- Oral Technology, Dental School, University Hospital Bonn, Welschnonnenstr. 17, Bonn, 53111, Germany
| | - Ahmed Ismail
- Oral Technology, Dental School, University Hospital Bonn, Welschnonnenstr. 17, Bonn, 53111, Germany
- Biomaterials Department, Faculty of Dentistry, Ain Shams University, Cairo, Egypt
| | - Omar Ghoraba
- Oral Technology, Dental School, University Hospital Bonn, Welschnonnenstr. 17, Bonn, 53111, Germany
| | - Mostafa Aldesoki
- Oral Technology, Dental School, University Hospital Bonn, Welschnonnenstr. 17, Bonn, 53111, Germany
| | | | - Hanaa Elattar
- Orthodontic Department, Faculty of Dentistry, Suez Canal University, Ismailia, Egypt
| | - Abdulaziz Alhotan
- Department of Dental Health, College of Applied Medical Sciences, King Saud University, Riyadh, Saudi Arabia
| | - Yasmine Alkabani
- Oral and Dental Research Institute, National Research Centre, Giza, Egypt
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Keilig L, Fittgen A, Schneider H, Sifa R, Schwarze J, Bourauel C, Konermann A. Accuracy of Digital Orthodontic Treatment Planning: Assessing Aligner-Directed Tooth Movements and Exploring Inherent Intramaxillary Side Effects. J Clin Med 2024; 13:2298. [PMID: 38673571 PMCID: PMC11051260 DOI: 10.3390/jcm13082298] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2024] [Revised: 04/03/2024] [Accepted: 04/11/2024] [Indexed: 04/28/2024] Open
Abstract
Background: The attainment of precise posterior occlusion alignment necessitates a deeper understanding of the clinical efficacy of aligner therapy. This study aims to determine whether the treatment goals defined in the virtual planning of aligner therapy are effectively implemented in clinical practice, with a particular focus on the influence of distalization distances on potential vertical side effects. Methods: In this retrospective, non-interventional investigation, a cohort of 20 individuals undergoing Invisalign® treatment was examined. Pre- and post-treatment maxillary clinical and ClinCheck® casts were superimposed utilizing a surface-surface matching algorithm on palatal folds, median palatine raphe, and unmoved teeth as the stable references. The effectivity of planned versus clinical movements was evaluated. Groupings were based on distalization distances, planned vertical movements, and Class II elastic prescription. Statistics were performed with a two-sample t-test and p-value < 0.05. Results: Clinically achieved distalization was significantly lower than virtually planned distalization, regardless of additional vertical movements, where a lack of implementation was contingent upon the extent of distalization, with no mitigating effects observed with the application of Class II elastics. Intriguingly, no adverse vertical side effects were noted; however, the intended intrusions or extrusions, as per the therapeutic plans, remained unattainable regardless of the magnitude of distalization. Conclusions: These findings underscore the imperative for future investigations to delve deeper into the intricacies surrounding translational mesio-distal and vertical movements, thereby enhancing predictability within orthodontic practice. To facilitate successful clinical implementation of vertical and translational movements via aligners, the incorporation of sliders emerges as a promising strategy for bolstering anchorage reinforcement.
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Affiliation(s)
- Ludger Keilig
- Oral Technology, University Hospital Bonn, 53111 Bonn, Germany
- Department of Prosthodontics, University Hospital Bonn, 53111 Bonn, Germany
| | - Anna Fittgen
- Department of Orthodontics, University Hospital Bonn, 53111 Bonn, Germany
| | - Helen Schneider
- Fraunhofer-Institute for Intelligent Analysis- and Informationsystems IAIS, 53757 Sankt Augustin, Germany
| | - Rafet Sifa
- Bonn-Aachen International Center for Information Technology (B-IT), LAMARR Institute for Machine Learning and Artificial Intelligence, University of Bonn, 53115 Bonn, Germany
| | | | | | - Anna Konermann
- Department of Orthodontics, University Hospital Bonn, 53111 Bonn, Germany
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Aboelfadl A, Keilig L, Ebeid K, Ahmed MAM, Nouh I, Refaie A, Bourauel C. Biomechanical behavior of implant retained prostheses in the posterior maxilla using different materials: a finite element study. BMC Oral Health 2024; 24:455. [PMID: 38622680 PMCID: PMC11020654 DOI: 10.1186/s12903-024-04142-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2024] [Accepted: 03/13/2024] [Indexed: 04/17/2024] Open
Abstract
BACKGROUND The aim of this study is to evaluate the biomechanical behavior of the mesial and distal off-axial extensions of implant-retained prostheses in the posterior maxilla with different prosthetic materials using finite element analysis (FEA). METHODS Three dimensional (3D) finite element models with three implant configurations and prosthetic designs (fixed-fixed, mesial cantilever, and distal cantilever) were designed and modelled depending upon cone beam computed tomography (CBCT) images of an intact maxilla of an anonymous patient. Implant prostheses with two materials; Monolithic zirconia (Zr) and polyetherketoneketone (PEKK) were also modeled .The 3D modeling software Mimics Innovation Suite (Mimics 14.0 / 3-matic 7.01; Materialise, Leuven, Belgium) was used. All the models were imported into the FE package Marc/Mentat (ver. 2015; MSC Software, Los Angeles, Calif). Then, individual models were subjected to separate axial loads of 300 N. Von mises stress values were computed for the prostheses, implants, and bone under axial loading. RESULTS The highest von Mises stresses in implant (111.6 MPa) and bone (100.0 MPa) were recorded in distal cantilever model with PEKK material, while the lowest values in implant (48.9 MPa) and bone (19.6 MPa) were displayed in fixed fixed model with zirconia material. The distal cantilever model with zirconia material yielded the most elevated levels of von Mises stresses within the prosthesis (105 MPa), while the least stresses in prosthesis (35.4 MPa) were recorded in fixed fixed models with PEKK material. CONCLUSIONS In the light of this study, the combination of fixed fixed implant prosthesis without cantilever using a rigid zirconia material exhibits better biomechanical behavior and stress distribution around bone and implants. As a prosthetic material, low elastic modulus PEKK transmitted more stress to implants and surrounding bone especially with distal cantilever.
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Affiliation(s)
- Ahmad Aboelfadl
- Department of Fixed Prosthodontics, Faculty of Dentistry, Ain Shams University, Cairo, Egypt.
- Oral Technology, Dental School, University Hospital Bonn, Bonn, Germany.
| | - Ludger Keilig
- Oral Technology, Dental School, University Hospital Bonn, Bonn, Germany
- Department of Dental Prosthetics, Propaedeutics and Material Science, Dental School, University Hospital Bonn, Bonn, Germany
| | - Kamal Ebeid
- Department of Fixed Prosthodontics, Faculty of Dentistry, Ain Shams University, Cairo, Egypt
| | | | - Ingy Nouh
- Department of Fixed Prosthodontics, Faculty of Dentistry, Ain Shams University, Cairo, Egypt
| | - Ashraf Refaie
- Oral Technology, Dental School, University Hospital Bonn, Bonn, Germany
- Department of Fixed Prosthodontics, Fayoum University, Fayoum, Egypt
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Elshazly TM, Bourauel C, Chavanne P, Elattar H, Keilig L. Numerical biomechanical finite element analysis of different trimming line designs of orthodontic aligners: An in silico study. J World Fed Orthod 2024; 13:65-71. [PMID: 38395726 DOI: 10.1016/j.ejwf.2024.01.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Revised: 12/23/2023] [Accepted: 01/03/2024] [Indexed: 02/25/2024]
Abstract
BACKGROUND A finite element model was used to investigate the effect of different designs and thicknesses of orthodontic aligner margins on their biomechanical behavior. METHODS A three-dimensional data set of an upper jaw was imported into the 3-matic software. The upper right central incisor tooth (Tooth 11) was separated from the remaining model, and its periodontal ligament and surrounding bone were designed. Aligners were designed with four different trimming lines (scalloped, straight, scalloped extended, straight extended), each with four different thicknesses (0.3, 0.4, 0.5, and 0.6 mm). The models were imported into a finite element package (Marc/Mentat). A linear elastic constitutive material model was applied. A facial 0.2 mm bodily malalignment of tooth 11 was simulated. RESULTS The maximum resultant force was in the range of 1.0 N to 2.2 N. The straight trimming designs deliver higher resultant forces compared with scalloped trimming designs. Increasing the aligner thickness and/or extending the aligner edge beyond the gingival line leads to an increase in the resultant force. All designs showed an uneven distribution of the normal contact forces over the tooth surface with a predominant concentration toward the cervical third and distal third, particularly with the extended trimming designs. All designs showed uncontrolled tipping of the tooth. CONCLUSIONS Based on the current model outcomes, the use of a straight extended trimming line design for aligners is favored because of its positive impact on force distribution and, consequently, the control of tooth movement. CLINICAL RELEVANCE These findings provide aligner companies and orthodontists a valuable biomechanical evidence and guidance to enhance control over tooth movement and therefore optimize treatment outcomes. This can be achieved by trimming the edges of aligners with a straight extended design and selecting the appropriate aligner thickness.
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Affiliation(s)
- Tarek M Elshazly
- Oral Technology, Dental School, University Hospital Bonn, Bonn, Germany.
| | | | | | - Hanaa Elattar
- Orthodontic Department, Faculty of Dentistry, Suez Canal University, Ismailia, Egypt
| | - Ludger Keilig
- Oral Technology, Dental School, University Hospital Bonn, Bonn, Germany; Department of Dental Prosthetics, Propaedeutics and Materials Science, Dental School, University Hospital Bonn, Bonn, Germany
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Elshazly TM, Bourauel C, Aldesoki M, Salvatori D, Alhotan A, Keilig L, Ghoneima A. Effect of attachment configuration and trim line design on the force system of orthodontic aligners: A finite element study on the upper central incisor. Orthod Craniofac Res 2024. [PMID: 38459802 DOI: 10.1111/ocr.12779] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/01/2024] [Indexed: 03/10/2024]
Abstract
OBJECTIVES To use the finite element method (FEM) to investigate the effect of various attachment configurations and trimming line designs of orthodontic aligners on their biomechanical performance. METHOD A 3D upper jaw model was imported into 3D design software. The upper right central incisor tooth (Tooth 11) was made mobile, and its periodontal ligament (PDL) and bone structures were designed. Aligners were modelled with three distinct attachment configurations: No attachment, rectangular horizontal, rectangular vertical, and two trimming line designs; scalloped and straight extended, with a homogeneous thickness of 0.6 mm. These models were then imported into an FE software. Simulations were conducted for three different movements, including facial translation, distalization, and extrusion. RESULTS Forces were recorded at 1.3-2.6 N during facial translation, 1.4-5.9 N in distalization, and 0.0-2.0 N in extrusion. The straight extended trimming line consistently generated higher forces than the scalloped design. Attachments had no significant impact on force components during facial translation but were more effective in distalization and extrusion. The combination of a straight extended trimming line with horizontal attachments exhibited the least stresses at the apical third during distalization, and the highest stresses during extrusion, suggesting superior retention. CONCLUSIONS Rectangular attachments offer limited benefits in facial translation, but horizontal rectangular attachments can intensify load in distalization and are crucial for force generation in extrusion. Horizontal attachments are preferred over vertical options. Additionally, the straight extended trim line enhances control of tooth movement and can replace attachments in certain cases. CLINICAL RELEVANCE These findings provide biomechanical evidence and an optimal protocol to guide clinical practice in planning diverse teeth movements. The emphasis is on the influence of attachment utilization and the specific design of aligner trimming lines to enhance control over tooth movement.
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Affiliation(s)
- Tarek M Elshazly
- Oral Technology, Dental School, University Hospital Bonn, Bonn, Germany
- Department of Orthodontics and Pediatric Dentistry, Hamdan Bin Mohammed College of Dental Medicine (HBMCDM), Mohammed Bin Rashid University of Medicine and Health Sciences (MBRU), Dubai, United Arab Emirates
| | | | - Mostafa Aldesoki
- Oral Technology, Dental School, University Hospital Bonn, Bonn, Germany
| | | | - Abdulaziz Alhotan
- Department of Dental Health, College of Applied Medical Sciences, King Saud University, Riyadh, Saudi Arabia
| | - Ludger Keilig
- Oral Technology, Dental School, University Hospital Bonn, Bonn, Germany
- Department of Dental Prosthetics, Propaedeutics and Materials Science, Dental School, University Hospital Bonn, Bonn, Germany
| | - Ahmed Ghoneima
- Department of Orthodontics and Pediatric Dentistry, Hamdan Bin Mohammed College of Dental Medicine (HBMCDM), Mohammed Bin Rashid University of Medicine and Health Sciences (MBRU), Dubai, United Arab Emirates
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Keilig L, Brieskorn L, Schwarze J, Schupp W, Bourauel C, Konermann A. Treatment Efficiency of Maxillary and Mandibular Orovestibular Tooth Expansion and Compression Movements with the Invisalign ® System in Adolescents and Adults. J Clin Med 2024; 13:1267. [PMID: 38592077 PMCID: PMC10932250 DOI: 10.3390/jcm13051267] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2024] [Revised: 02/16/2024] [Accepted: 02/19/2024] [Indexed: 04/10/2024] Open
Abstract
OBJECTIVES Aligners are an effective and esthetic orthodontic treatment option for permanent and mixed dentition. There are only a few studies dealing with the effectiveness of orovestibular tooth movement using aligners and applying adequate examination methods. In the present retrospective study, the aligner efficiency of orovestibular movements for the entire dentition was systematically evaluated using 3D superimposition, taking into account the influence of jaw, tooth type and Invisalign® system. METHODS Group 1 (n = 18 adults, Invisalign®) and Group 2 (n = 17 adolescents, Invisalign® Teen) were treated with Invisalign® Ex30 aligner material and Invisalign® specific auxiliary means. In this non-interventional retrospective study, pre- and post-treatment maxillary and mandibular plaster cast models were scanned and superimposed with ClinChecks® via Surface-Surface Matching Algorithm on unmoved teeth providing stable references. Effectivity of planned versus clinically realized movements was evaluated for each tooth. Statistics were performed with a t-test and Bonferroni-Holm correction (α = 0.05). RESULTS Orovestibular movement efficiency was excellent without statistical significance regarding jaw, tooth type or Invisalign® system. Mandibular translational tooth movements were highly effective, and outstanding for premolars (91-98%). Maxillary translational tooth movements were successful for incisors and premolars, but less effective for canines and molars. Almost all teeth were moderately or very effectively corrected by crown tipping, performing better for mandibular (70-92%) than maxillary (22-31%) canines as much as for adolescent upper front teeth (81-85%) and lower canines (92%). CONCLUSIONS Aligners are able to effectively implement translational orovestibular movements, supported by tilting the crowns for even more efficient implementation of the movements. This phenomenon was observed in our studies for all teeth in both jaws, regardless of the Invisalign® system used. Treatment planning should nevertheless take into account the individual patient parameters with regard to the movements to be performed in order to make the aligner therapy as successful as possible in terms of realizing the desired therapeutic goal.
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Affiliation(s)
- Ludger Keilig
- Oral Technology, University Hospital Bonn, 53111 Bonn, Germany
- Department of Prosthodontics, University Hospital Bonn, 53127 Bonn, Germany
| | - Lena Brieskorn
- Oral Technology, University Hospital Bonn, 53111 Bonn, Germany
| | | | | | | | - Anna Konermann
- Department of Orthodontics, University Hospital Bonn, University of Bonn, Welschnonnenstr. 17, 53111 Bonn, Germany
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Atta I, Bourauel C, Alkabani Y, Mohamed N, Kimbe H, Alhotan A, Ghoneima A, Elshazly T. Physiochemical and mechanical characterisation of orthodontic 3D printed aligner material made of shape memory polymers (4D aligner material). J Mech Behav Biomed Mater 2024; 150:106337. [PMID: 38154364 DOI: 10.1016/j.jmbbm.2023.106337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2023] [Revised: 12/14/2023] [Accepted: 12/16/2023] [Indexed: 12/30/2023]
Abstract
OBJECTIVES To conduct a physiochemical and mechanical material analysis on 3D printed shape-memory aligners in comparison to thermoformed aligners. MATERIALS AND METHODS Four materials were examined, including three thermoformed materials: CA Pro (CP), Zendura A (ZA), Zendura FLX (ZF), and one 3D printed material: Tera Harz (TC-85). Rectangular strips measuring 50 × 10 × 0.5 mm were produced from each material. Five tests were conducted, including differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), shape recovery tests, three-points bending (3 PB), and Vickers surface microhardness (VH). RESULTS DSC recorded glass transition temperatures (Tg) at 79.9 °C for CP, 92.2 °C for ZA, 107.1 °C for ZF, and 42.3 °C for TC-85. In DMA analysis at 20-45 °C, a prominent decrease in storage modulus was observed, exclusively for TC-85, as the temperature increased. Notably, within the temperature range of 30-45 °C, TC-85 exhibited substantial shape recovery after 10 min, reaching up to 86.1 %, while thermoformed materials showed minimal recovery (1.5-2.9 %). In 3 PB test (at 30, 37, 45 °C), ZA demonstrated the highest force at 2 mm bending, while TC-85 exhibited the lowest. Regarding VH at room temperature, there was a significant decrease for both ZA and ZF after thermoforming. ZA had the highest hardness, followed by ZF and TC-85, with CP showing the lowest values. CONCLUSIONS TC-85 demonstrates exceptional shape memory at oral temperature, improving adaptation, reducing force decay, and enabling, together with its higher flexibility, extensive tooth movement per step. Additionally, it maintains microhardness similar to thermoformed sheets, ensuring the durability and effectiveness of dental aligners. CLINICAL RELEVANCE The 3D printed aligner material with shape memory characteristics (4D aligner) has revolutionized the orthodontic aligner field. It showed mechanical properties more suitable for orthodontic treatment than thermoforming materials. Additionally, it offers enhanced control over aligner design and thickness, while optimizing the overall workflow. It also minimizes material wastage, and reduces production expenses.
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Affiliation(s)
- Islam Atta
- Oral Technology, Dental School, University Hospital Bonn, Bonn, Germany
| | | | - Yasmine Alkabani
- Restorative and Dental Materials Department, National Research Centre, Giza, Egypt
| | | | - Hoon Kimbe
- Research Institute of Agriculture and Life Sciences, College of Agriculture and Life Sciences, Seoul National University, Seoul, Republic of Korea
| | - Abdulaziz Alhotan
- Department of Dental Health, College of Applied Medical Sciences, King Saud University, Riyadh, Saudi Arabia
| | - Ahmed Ghoneima
- Department of Orthodontics and Pediatric Dentistry, Hamdan Bin Mohammed College of Dental Medicine (HBMCDM), Mohammed Bin Rashid University of Medicine and Health Sciences (MBRU), Dubai, United Arab Emirates
| | - Tarek Elshazly
- Oral Technology, Dental School, University Hospital Bonn, Bonn, Germany; Department of Orthodontics and Pediatric Dentistry, Hamdan Bin Mohammed College of Dental Medicine (HBMCDM), Mohammed Bin Rashid University of Medicine and Health Sciences (MBRU), Dubai, United Arab Emirates.
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Youssef E, Jungbluth H, Jepsen S, Gruener M, Bourauel C. Comparing Cyclic Fatigue Resistance and Free Recovery Transformation Temperature of NiTi Endodontic Single-File Systems Using a Novel Testing Setup. Materials (Basel) 2024; 17:566. [PMID: 38591373 PMCID: PMC10856488 DOI: 10.3390/ma17030566] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Revised: 01/05/2024] [Accepted: 01/22/2024] [Indexed: 04/10/2024]
Abstract
The aim of this study was to assess the effect of body temperature (37 °C) on the cyclic fatigue resistance of three endodontic single-file systems using a new testing setup. One Shape® new generation (OS), WaveOne™ (WO) and WaveOne® GOLD (WOG), which are made from different NiTi alloys and operated in different motions (rotation/reciprocation), were evaluated. The study design included four groups. Each group comprised 30 files, 10 files of each of the three file systems, tested at 20 ± 2 °C (group 1 and 3) and at 37 ± 1 °C (group 2 and 4). All files were tested in a custom-made metal block with artificial canals of 60° angle, and a 5 mm and 3 mm radius of curvature, respectively. A heating element was attached to replicate a temperature of 37 °C. Files were introduced 18 mm into the canals and operated until failure. Transformation temperatures of five samples of each of the tested file systems were determined via the bend and free recovery (BFR) method. With the exception of WOG in canals with a 3 mm radius of curvature (p = 0.075), all the tested file systems showed statistically significantly less time needed to fracture when operated at 37 ± 1 °C compared to at 20 ± 2 °C in canals with a 5 mm and 3 mm radius of curvature using Mann-Whitney U test (p < 0.05). All file systems showed transformation temperatures below the body temperature. We concluded that body temperature directly affects the cyclic fatigue resistance of all tested file systems. Bend and free recovery can be suitable for the determination of austenite finish temperatures (Af) of endodontic instruments as it allows testing a longer portion of the instrument.
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Affiliation(s)
- Emad Youssef
- Department of Periodontology, Operative and Preventive Dentistry, University of Bonn, 53111 Bonn, Germany
- Department of Oral Technology, Faculty of Medicine, University of Bonn, 53111 Bonn, Germany
| | - Holger Jungbluth
- Department of Periodontology, Operative and Preventive Dentistry, University of Bonn, 53111 Bonn, Germany
| | - Søren Jepsen
- Department of Periodontology, Operative and Preventive Dentistry, University of Bonn, 53111 Bonn, Germany
| | - Manfred Gruener
- Department of Oral Technology, Faculty of Medicine, University of Bonn, 53111 Bonn, Germany
| | - Christoph Bourauel
- Department of Oral Technology, Faculty of Medicine, University of Bonn, 53111 Bonn, Germany
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Aldesoki M, Bourauel C, Elshazly TM, Schkommodau E, Keilig L. Evaluation of micromotion in multirooted root analogue implants embedded in synthetic bone blocks: an in vitro study. BMC Oral Health 2024; 24:99. [PMID: 38233794 PMCID: PMC10792929 DOI: 10.1186/s12903-024-03854-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Accepted: 01/03/2024] [Indexed: 01/19/2024] Open
Abstract
BACKGROUND While conventional threaded implants (TI) have proven to be effective for replacing missing teeth, they have certain limitations in terms of diameter, length, and emergence profile when compared to customised root analogue implants (RAI). To further investigate the potential benefits of RAIs, the aim of this study was to experimentally evaluate the micromotion of RAIs compared to TIs. METHODS A 3D model of tooth 47 (mandibular right second molar) was segmented from an existing cone beam computed tomography (CBCT), and a RAI was designed based on this model. Four RAI subgroups were fabricated as follows: 3D-printed titanium (PT), 3D-printed zirconia (PZ), milled titanium (MT), milled zirconia (MZ), each with a sample size of n = 5. Additionally, two TI subgroups (B11 and C11) were used as control, each with a sample size of n = 5. All samples were embedded in polyurethane foam artificial bone blocks and subjected to load application using a self-developed biomechanical Hexapod Measurement System. Micromotion was quantified by analysing the load/displacement curves. RESULTS There were no statistically significant differences in displacement in Z-axis (the loading direction) between the RAI group and the TI group. However, within the RAI subgroups, PZ exhibited significantly higher displacement values compared to the other subgroups (p < 0.05). In terms of the overall total displacement, the RAI group showed a statistically significant higher displacement than the TI group, with mean displacement values of 96.5 µm and 55.8 µm for the RAI and TI groups, respectively. CONCLUSIONS The RAI demonstrated promising biomechanical behaviour, with micromotion values falling within the physiological limits. However, their performance is less predictable due to varying anatomical designs.
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Affiliation(s)
- Mostafa Aldesoki
- Dental School, Oral Technology, University Hospital Bonn, Welschnonnenstr.17, 53111, Bonn, Germany.
| | - Christoph Bourauel
- Dental School, Oral Technology, University Hospital Bonn, Welschnonnenstr.17, 53111, Bonn, Germany
| | - Tarek M Elshazly
- Dental School, Oral Technology, University Hospital Bonn, Welschnonnenstr.17, 53111, Bonn, Germany
| | - Erik Schkommodau
- Institute for Medical Engineering and Medical Informatics, University of Applied Sciences and Arts Northwestern Switzerland, Muttenz, Switzerland
| | - Ludger Keilig
- Dental School, Oral Technology, University Hospital Bonn, Welschnonnenstr.17, 53111, Bonn, Germany
- Department of Prosthodontics, Dental School, University Hospital Bonn, Bonn, Germany
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12
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Singer L, Bourauel C. Herbalism and glass-based materials in dentistry: review of the current state of the art. J Mater Sci Mater Med 2023; 34:60. [PMID: 37962680 PMCID: PMC10645656 DOI: 10.1007/s10856-023-06764-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Accepted: 10/26/2023] [Indexed: 11/15/2023]
Abstract
Half a million different plant species are occurring worldwide, of which only 1% has been phytochemically considered. Thus, there is great potential for discovering novel bioactive compounds. In dentistry, herbal extracts have been used as antimicrobial agents, analgesics, and intracanal medicaments. Glass-ionomer cement (GIC) and bioactive glass (BAG) are attractive materials in dentistry due to their bioactivity, adhesion, and remineralisation capabilities. Thus, this review summarizes the evidence around the use of phytotherapeutics in dental glass-based materials. This review article covers the structure, properties, and clinical uses of GIC and BAG materials within dentistry, with an emphasis on all the attempts that have been made in the last 20 years to enhance their properties naturally using the wisdom of traditional medicines. An extensive electronic search was performed across four databases to include published articles in the last 20 years and the search was concerned only with the English language publications. Publications that involved the use of plant extracts, and their active compounds for the green synthesis of nanoparticles and the modification of GIC and BAG were included up to May 2023. Plant extracts are a potential and effective candidate for modification of different properties of GIC and BAG, particularly their antimicrobial activities. Moreover, natural plant extracts have shown to be very effective in the green synthesis of metal ion nanoparticles in an ecological, and easy way with the additional advantage of a synergistic effect between metal ions and the phytotherapeutic agents. Medicinal plants are considered an abundant, cheap source of biologically active compounds and many of these phytotherapeutics have been the base for the development of new lead pharmaceuticals. Further research is required to assess the safety and the importance of regulation of phytotherapeutics to expand their use in medicine.
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Affiliation(s)
- Lamia Singer
- Oral Technology, University Hospital Bonn, 53111, Bonn, North Rhine-Westphalia, Germany.
- Department of Orthodontics, University Hospital Bonn, 53111, Bonn, North Rhine-Westphalia, Germany.
| | - Christoph Bourauel
- Oral Technology, University Hospital Bonn, 53111, Bonn, North Rhine-Westphalia, Germany
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Singer L, Karacic S, Szekat C, Bierbaum G, Bourauel C. Biological properties of experimental dental alginate modified for self-disinfection using green nanotechnology. Clin Oral Investig 2023; 27:6677-6688. [PMID: 37775587 PMCID: PMC10630233 DOI: 10.1007/s00784-023-05277-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Accepted: 09/23/2023] [Indexed: 10/01/2023]
Abstract
OBJECTIVES Disinfection of alginate impression materials is a mandatory step to prevent cross-infection in dental clinics. However, alginate disinfection methods are time-consuming and exert a negative impact on accuracy and mechanical properties. Thus, this study aimed to prepare disinfecting agents (CHX and AgNO3) and silver nanoparticles reduced by a natural plant extract to produce a self-disinfecting dental alginate. METHODS Conventional alginate impression material was used in this study. Silver nitrate (0.2% AgNO3 group) and chlorohexidine (0.2% CHX group) solutions were prepared using distilled water, and these solutions were later employed for alginate preparation. Moreover, a 90% aqueous plant extract was prepared from Boswellia sacra (BS) oleoresin and used to reduce silver nitrate to form silver nanoparticles that were incorporated in the dental alginate preparation (BS+AgNPs group). The plant extract was characterized by gas chromatography/mass spectrometry (GC/MS) analysis while green-synthesized silver nanoparticles (AgNPs) were characterized by UV-visible (UV-vis) spectroscopy and scanning electron microscopy (SEM). An agar disc diffusion assay was used to test the antimicrobial activity against Candida albicans, Streptococcus mutans, Escherichia coli, methicillin-resistant and susceptible Staphylococcus aureus strains, and Micrococcus luteus. Agar plates were incubated at 37 ± 1 °C for 24 h to allow microbial growth. Diameters of the circular inhibition zones formed around each specimen were measured digitally by using ImageJ software. RESULTS Chemical analysis of the plant extract revealed the presence of 41 volatile and semi-volatile active compounds. UV-Vis spectrophotometry, SEM, and EDX confirmed the formation of spherical silver nanoparticles using the BS extract. CHX, AgNO3, and the BS+AgNPs modified groups showed significantly larger inhibition zones than the control group against all tested strains. BS+AgNPs and CHX groups showed comparable efficacy against all tested strains except for Staphylococcus aureus, where the CHX-modified alginate had a significantly higher effect. CONCLUSIONS AND CLINICAL RELEVANCE CHX, silver nitrate, and biosynthesized silver nanoparticles could be promising inexpensive potential candidates for the preparation of a self-disinfecting alginate impression material without affecting its performance. Green synthesis of metal nanoparticles using Boswellia sacra extract could be a very safe, efficient, and nontoxic way with the additional advantage of a synergistic action between metal ions and the phytotherapeutic agents of the plant extract.
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Affiliation(s)
- Lamia Singer
- Oral Technology, Medical Faculty, University Hospital Bonn, Bonn, Germany.
- Department of Orthodontics, Medical Faculty, University Hospital Bonn, Bonn, Germany.
| | - Sabina Karacic
- Institute of Medical Microbiology, Immunology, and Parasitology, Medical Faculty, University Hospital Bonn, 53127, Bonn, North Rhine-Westphalia, Germany
| | - Christiane Szekat
- Institute of Medical Microbiology, Immunology, and Parasitology, Medical Faculty, University Hospital Bonn, 53127, Bonn, North Rhine-Westphalia, Germany
| | - Gabriele Bierbaum
- Institute of Medical Microbiology, Immunology, and Parasitology, Medical Faculty, University Hospital Bonn, 53127, Bonn, North Rhine-Westphalia, Germany
| | - Christoph Bourauel
- Oral Technology, Medical Faculty, University Hospital Bonn, Bonn, Germany
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Fouda AM, Stawarczyk B, Özcan M, Singer L, Bourauel C. Impact of glazing on wear, fracture load, and optical properties of a new fully crystallized lithium disilicate ceramic material. J Mech Behav Biomed Mater 2023; 146:106102. [PMID: 37660448 DOI: 10.1016/j.jmbbm.2023.106102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Revised: 08/28/2023] [Accepted: 08/29/2023] [Indexed: 09/05/2023]
Abstract
OBJECTIVES Lithium disilicate (LDS) based glass ceramics are indispensable materials in the field of prosthetic dentistry due to their strength and excellent esthetics. Recently, novel fully crystallized LDS for the milling process have been introduced to the market, requiring only chairside polishing before delivery. Since limited data is available about subjecting this material to glazing, this study aimed to evaluate the wear properties, fracture resistance, and optical properties of the newly introduced fully crystallized LDS after glazing. METHODS Lithium disilicate glass-ceramics (fully crystallized (LiSiCAD) and partially crystallized types (EmaxCAD), of shade A3, were used in the present study. The fully crystallized specimens were subjected to a glazing firing cycle in a furnace (LiSiCAD-G) and compared to a polished fully crystallized counterpart (LiSiCAD-P, negative control) and a glazed partially crystallized LDS (EmaxCAD, positive control). Rectangular-shaped ceramic specimens (n = 10, 12 × 6.5 × 1.5 mm) and enamel antagonists were used to test the wear resistance in a specially designed wear machine built at the Department of Oral Technology, University of Bonn, Germany. The volumetric enamel loss of antagonists was measured by means of overlapping virtual 3D models derived from micro-CT scans for the teeth before and after the wear test. The weight loss of ceramic specimens in milligrams was measured after 100,000 and 200,000 wear cycles. A spectrophotometer was used to calculate the CIELAB color parameters of the ceramic specimens against black and white backgrounds to measure the translucency. Fracture resistance was also assessed after thermodynamic fatigue using a universal testing machine until fracture at a 1 mm/min crosshead speed. Statistical analysis was performed using one-way ANOVA and the significance level was set at α = 0.05. RESULTS EmaxCAD and LisiCAD-G groups showed significantly higher mean ceramic weight loss after 100,000 cycles (2 ± 0.3 mg and 1.93 ± 0.2 mg, respectively) than LisiCAD-P group (0.78 ± 0.19 mg). Glazed LiSiCAD specimens demonstrated significantly higher ΔE values from shade A3 compared to polished LiSiCAD. There was no significant difference in ΔE between LiSiCAD-G and EmaxCAD. For fracture resistance, no significant difference was observed between LiSiCAD-G and LiSiCAD-P before or after aging. CONCLUSIONS The glazed fully crystallized LDS was superior to the partially crystallized one with regard to wear resistance but showed more color changes than the polished fully crystallized one. Furthermore, polishing of fully crystallized LDS could still be considered a better option than glazing when aesthetics is a primary prerequisite.
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Affiliation(s)
- Ahmed Mahmoud Fouda
- Department of Oral Technology, Medical Faculty, University Hospital Bonn, 53111, Bonn, North Rhine-Westphalia, Germany; Department of Fixed Prosthodontics, Suez Canal University, Ismailia, Egypt.
| | - Bogna Stawarczyk
- Department of Prosthetic Dentistry, University Hospital, LMU Munich, Munich, Germany
| | - Mutlu Özcan
- University of Zurich, Center for Dental Medicine, Clinic of Chewing Function Disturbances and Dental Biomaterials, Zurich, Switzerland
| | - Lamia Singer
- Department of Oral Technology, Medical Faculty, University Hospital Bonn, 53111, Bonn, North Rhine-Westphalia, Germany; Department of Orthodontics, Medical Faculty, University Hospital Bonn, 53111, Bonn, North Rhine-Westphalia, Germany
| | - Christoph Bourauel
- Department of Oral Technology, Medical Faculty, University Hospital Bonn, 53111, Bonn, North Rhine-Westphalia, Germany
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15
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Refaie A, Bourauel C, Fouda AM, Keilig L, Singer L. The effect of cyclic loading on the fracture resistance of 3D-printed and CAD/CAM milled zirconia crowns-an in vitro study. Clin Oral Investig 2023; 27:6125-6133. [PMID: 37615777 PMCID: PMC10560138 DOI: 10.1007/s00784-023-05229-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Accepted: 08/17/2023] [Indexed: 08/25/2023]
Abstract
OBJECTIVES The aim of this study was to evaluate the effect of cyclic mechanical loading on the fracture resistance of 3D-printed zirconia crowns in comparison to milled zirconia crowns. MATERIALS AND METHODS Monolithic zirconia crowns (n = 30) were manufactured using subtractive milling (group M) and 3D additive printing (group P). Nine samples of each group were fractured under one-time loading while the other 6 samples were subjected to cyclic loading for 1.2 million cycles before being subjected to one-time loading until fracture. Scanning electron microscope (SEM) fractographic analysis was carried out on fractured fragments of representative samples. RESULTS The mean for fracture resistance of group M was 1890 N without cyclic loading and 1642 N after being subjected to cyclic loading, and they were significantly higher than that of group P (1658 N and 1224 N respectively). CONCLUSIONS The fabrication technique and cyclic loading affect the fracture resistance of zirconia crowns. Although the fracture resistance values for the 3D-printed crowns were lower than those of the milled, still they are higher than the masticatory forces and thus could be considered being clinically acceptable. CLINICAL RELEVANCE Concerning fracture resistance, 3D-printed crowns can withstand the masticatory forces for the long term without any cracks or failure.
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Affiliation(s)
- Ashraf Refaie
- Oral Technology, Dental School, Medical Faculty, University Hospital of Bonn, Welschnonnenstr. 17, 53111, Bonn, North Rhine-Westphalia, Germany.
- Department of Fixed Prosthodontics, Faculty of Dentistry, Fayoum University, Faiyum, Egypt.
| | - Christoph Bourauel
- Oral Technology, Dental School, Medical Faculty, University Hospital of Bonn, Welschnonnenstr. 17, 53111, Bonn, North Rhine-Westphalia, Germany
| | - Ahmed Mahmoud Fouda
- Oral Technology, Dental School, Medical Faculty, University Hospital of Bonn, Welschnonnenstr. 17, 53111, Bonn, North Rhine-Westphalia, Germany
- Suez Canal University, Ismailia, Egypt
| | - Ludger Keilig
- Oral Technology, Dental School, Medical Faculty, University Hospital of Bonn, Welschnonnenstr. 17, 53111, Bonn, North Rhine-Westphalia, Germany
- Department of Prosthodontics, Preclinical Education and Dental Materials Science, Dental School, Medical Faculty, University Hospital of Bonn, 53111, Bonn, North Rhine-Westphalia, Germany
| | - Lamia Singer
- Oral Technology, Dental School, Medical Faculty, University Hospital of Bonn, Welschnonnenstr. 17, 53111, Bonn, North Rhine-Westphalia, Germany
- Department of Orthodontic, Dental School, Medical Faculty, University Hospital of Bonn, 53111, Bonn, North Rhine-Westphalia, Germany
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Youssef A, El-Bialy T, Bourauel C. Comparative assessment of frictional forces between differently designed esthetic brackets during simulated canine retraction. J Orofac Orthop 2023; 84:222-230. [PMID: 36441190 DOI: 10.1007/s00056-022-00433-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Accepted: 10/06/2022] [Indexed: 11/30/2022]
Abstract
OBJECTIVES To evaluate force loss due to friction (FR) with an emphasis on esthetic brackets and their design differences during simulated canine retraction. MATERIALS AND METHODS The tested brackets were round and sharp-cornered conventional-ligating brackets and round-cornered self-ligating brackets. The tested archwires were stainless steel (0.018 × 0.025″ and 0.019 × 0.025″, and 0.018″) archwires. A total of 90 bracket-archwire combinations in 9 equally-sized groups (n = 10) were analyzed. Canine retraction was experimentally simulated in a biomechanical set-up utilizing the custom-made orthodontic measurement and simulation system (OMSS) using a NiTi coil spring that delivered a constant force of 1 N. The simulated retraction path was up to 4 mm. FR was compared among groups using the Welch t‑test. Significance level (α) was set to 0.05. RESULTS The round-cornered conventional-ligating bracket exhibited the least FR (28.6 ± 5.4%), while there were no significant differences in FR between the round-cornered conventional-ligating bracket and the round-cornered self-ligating bracket with 0.018″ stainless steel wires. However, the round-cornered self-ligating bracket exhibited the least FR (34.9 ± 5.1% and 39.3 ± 4.6%) with 0.018 × 0.025″ and 0.019 × 0.025″ stainless steel archwires, respectively. The sharp-cornered conventional-ligating bracket showed the highest FR of 72.4 ± 3.0% among the bracket systems tested in this study. CONCLUSIONS The round-cornered conventional-ligating bracket showed less FR when compared to sharp-cornered conventional-ligating bracket. Conversely, the round-cornered conventional-ligating bracket exhibited greater FR when compared to the round-cornered self-ligating bracket, with an exception with respect to the 0.018″ wire. In general, FR increased with increased wire dimension.
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Affiliation(s)
- Ahmed Youssef
- Department of Orthodontics, School of Dentistry, Marquette University, Milwaukee, WI, USA.
| | - Tarek El-Bialy
- Department of Orthodontics, School of Dentistry, University of Alberta, Edmonton, Canada
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Gholami M, Ahrari F, Sedigh HS, Bourauel C. Micro-computed tomography analysis of mineral attachment to the implants augmented by three types of bone grafts: An experimental study in dogs. Dent Res J (Isfahan) 2023; 20:100. [PMID: 38020252 PMCID: PMC10630541] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2022] [Revised: 07/22/2023] [Accepted: 07/26/2023] [Indexed: 12/01/2023] Open
Abstract
Background This study compared the effect of various grafting materials on the area and volume of minerals attached to dental implants. Materials and Methods In this animal study, 13 dogs were divided into three groups according to the time of sacrificing (2 months, 4 months, or 6 months). The implants were placed in oversized osteotomies, and the residual defects were filled with autograft, bovine bone graft (Cerabone), or a synthetic substitute (Osteon II). At the designated intervals, the dogs were sacrificed and the segmented implants underwent micro-computed tomography analysis. The bone-implant area (BIA) and bone-implant volume (BIV) of bone and graft material were calculated in the region of interest around the implant. The data were analyzed by two-way analysis of variance (ANOVA) at P < 0.05. Results There was no significant difference in BIA and BIV between the healing intervals for any of the grafting materials (P > 0.05). ANOVA exhibited comparable BIA and BIV between the grafting materials at 2 and 4 months after surgery (P > 0.05), although a significant difference was observed after 6 months (P < 0.05). Pairwise comparisons revealed that BIA was significantly greater in the autograft-stabilized than the synthetic-grafted sites (P = 0.035). The samples augmented with autograft also showed significantly higher BIV than those treated by the xenogenic (P = 0.017) or synthetic (P = 0.002) particles. Conclusion All graft materials showed comparable performance in providing mineral support for implants up to 4 months after surgery. At the long-term (6-month) interval, autogenous bone demonstrated significant superiority over xenogenic and synthetic substitutes concerning the bone area and volume around the implant.
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Affiliation(s)
- Mahdi Gholami
- Oral and Maxillofacial Disease Research Center, School of Dentistry, Mashhad University of Medical Sciences, Mashhad, Iran
- Department of Oral Technology, School of Dentistry, University Hospital of Bonn, Bonn, Germany
| | - Farzaneh Ahrari
- Dental Research Center, School of Dentistry, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Hamideh Salari Sedigh
- Department of Clinical Sciences, School of Veterinary Medicine, Ferdowsi University of Mashhad, Mashhad, Iran
| | - Christoph Bourauel
- Department of Oral Technology, School of Dentistry, University Hospital of Bonn, Bonn, Germany
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Mando M, Talaat S, Bourauel C. The efficacy of chewing gum in the reduction of orthodontic pain at its peak intensity: a systematic review and meta-analysis. Angle Orthod 2023; 93:580-590. [PMID: 37043773 PMCID: PMC10575647 DOI: 10.2319/110622-760.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Accepted: 02/01/2023] [Indexed: 04/14/2023] Open
Abstract
OBJECTIVES To evaluate the efficacy of chewing gum on the intensity of pain in patients undergoing orthodontic treatment. MATERIALS AND METHODS A search strategy that included both a manual search and a search of electronic databases was implemented; the electronic databases included PubMed, Cochrane Central Register of Controlled Trials (CENTRAL), ScienceDirect, Scopus, and EBSCO. Only randomized controlled trials were included in this study. All of the studies were assessed independently and in duplicate in accordance with the exclusion and inclusion criteria. The Cochrane risk of bias tool was used to evaluate the risk of bias within the included studies, and the GRADE approach was used to evaluate the certainty of evidence. RESULTS Sixteen RCTs were included in the final analysis. The meta-analysis revealed that chewing gum significantly reduced pain intensity in comparison to pharmacologic agents (mean difference [MD] -0.50 [95% confidence interval {CI} -0.90 to -0.10], P = .01). When compared with a placebo, chewing gum significantly reduced pain intensity (MD -0.60 [95% CI -1.06 to -0.13], P = .01), while bite wafer and chewing gum groups had the same levels of reduction in pain intensity (MD -0.15 [95% CI -0.56 to 0.26], P = .48). CONCLUSIONS In patients undergoing fixed orthodontic treatment, chewing gum was significantly more effective than both pharmacologic agents and placebo in reducing orthodontic pain 24 hours after the initial placement of the archwire.
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Affiliation(s)
- Mahmoud Mando
- Corresponding author: Dr Mahmoud Mando, Department of Oral Technology, University of Bonn, Bonn 53127, Germany (e-mail: )
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Klemeit A, Weber A, Bourauel C, Welle K, Burger C, Schildberg FA, Deborre C. The Influence of Sagittal Pin Angulation on the Stiffness and Pull-Out Strength of a Monolateral Fixator Construct. Bioengineering (Basel) 2023; 10:982. [PMID: 37627867 PMCID: PMC10451265 DOI: 10.3390/bioengineering10080982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2023] [Revised: 08/03/2023] [Accepted: 08/18/2023] [Indexed: 08/27/2023] Open
Abstract
Monolateral pin-to-bar-clamp fixators are commonly used to stabilize acute extremity injuries. Certain rules regarding frame geometry have been established that affect construct stability. The influence of sagittal pin angulation on construct stiffness and strength has not been investigated. The purpose of this biomechanical study was to demonstrate the effect of a pin angulation in the monolateral fixator using a composite cylinder model. Three groups of composite cylinder models with a fracture gap were loaded with different mounting variants of monolateral pin-to-bar-clamp fixators. In the first group, the pins were set parallel to each other and perpendicular to the specimen. In the second group, both pins were set convergent each in an angle of 15° to the specimen. In the third group, the pins were set each 15° divergent. The strength of the constructions was tested using a mechanical testing machine. This was followed by a cyclic loading test to produce pin loosening. A pull-out test was then performed to evaluate the strength of each construct at the pin-bone interface. Initial stiffness analyses showed that the converging configuration was the stiffest, while the diverging configuration was the least stiff. The parallel mounting showed an intermediate stiffness. There was a significantly higher resistance to pull-out force in the diverging pin configuration compared to the converging pin configuration. There was no significant difference in the pull-out strength of the parallel pins compared to the angled pin pairs. Convergent mounting of pin pairs increases the stiffness of a monolateral fixator, whereas a divergent mounting weakens it. Regarding the strength of the pin-bone interface, the divergent pin configuration appears to provide greater resistance to pull-out force than the convergent one. The results of this pilot study should be important for the doctrine of fixator mounting as well as for fixator component design.
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Affiliation(s)
- Axel Klemeit
- Department of Orthopedics and Trauma Surgery, University Hospital Bonn, 53127 Bonn, Germany
| | - Anna Weber
- Oral Technology, Dental School, Medical Faculty, University Hospital Bonn, 53111 Bonn, Germany
| | - Christoph Bourauel
- Oral Technology, Dental School, Medical Faculty, University Hospital Bonn, 53111 Bonn, Germany
| | - Kristian Welle
- Department of Orthopedics and Trauma Surgery, University Hospital Bonn, 53127 Bonn, Germany
| | - Christof Burger
- Department of Orthopedics and Trauma Surgery, University Hospital Bonn, 53127 Bonn, Germany
| | - Frank A. Schildberg
- Department of Orthopedics and Trauma Surgery, University Hospital Bonn, 53127 Bonn, Germany
| | - Christoph Deborre
- Clinic for Orthopedics and Trauma Surgery, Bethlehem Health Center Stolberg, 52222 Stolberg, Germany
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Hüfner M, David S, Brunello G, Kerberger R, Rauch N, Busch CV, Drescher D, Bourauel C, Becker K. Autoclaving-induced dimensional changes of three-dimensional printed surgical guides: An in vitro study. Clin Oral Implants Res 2023. [PMID: 37565539 DOI: 10.1111/clr.14158] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Revised: 07/20/2023] [Accepted: 07/26/2023] [Indexed: 08/12/2023]
Abstract
OBJECTIVES Surgical guides are frequently used for dental implant placement. The aim of this study was to evaluate the impact of the 3D printing process itself and subsequent steam autoclaving on the dimensional stability of five different resin/printer combinations (RPCs). MATERIALS AND METHODS Fifty identical surgical guides (10 per group) were produced consisting of five RPCs. Half of the guides (5 per group) were steam autoclaved with cycle 1 (121°C, 1 bar, 20.5 min) and the other half with cycle 2 (134°C, 2 bar, 5.5 min). All guides were scanned with a structured-light (SL) 3D scanner before (T0) and after (T1) autoclaving. Linear measurements along the x-, y-, and z-axes were performed at landmarks on the original STL file and on SL scans at T0 and T1, respectively. Wilcoxon signed-rank test, Kruskal-Wallis test, and linear mixed-effects models were performed, depending on the analysis. RESULTS Three-dimensional printing was associated with significant dimensional alterations for all RPCs. Steam autoclaving using cycle 1 was associated with significant shrinkage in x- (1 RPC), y- (2 RPCs), and z-direction (2 RPCs), while cycle 2 was also associated with shrinkage in x- (2 RPCs), y- (1 RPC), and z-direction (1 RPC). One resin did not present any dimensional changes independently of the cycle. CONCLUSIONS The majority of the guides presented minor but significant shrinkage due to 3D printing itself and both steam autoclaving cycles, the extent varied between different RPCs. Whether these changes compromise implant placement accuracy remains to be investigated.
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Affiliation(s)
- Mira Hüfner
- Department of Orthodontics, University Hospital of Düsseldorf, Düsseldorf, Germany
| | - Samuel David
- Department of Orthodontics, University Hospital of Düsseldorf, Düsseldorf, Germany
| | - Giulia Brunello
- Department of Oral Surgery, University Hospital of Düsseldorf, Düsseldorf, Germany
- Department of Neurosciences, University of Padua, Padua, Italy
| | - Robert Kerberger
- Department of Orthodontics, University Hospital of Düsseldorf, Düsseldorf, Germany
| | - Nicole Rauch
- Department of Oral Surgery, University Hospital of Düsseldorf, Düsseldorf, Germany
| | - Caroline Viola Busch
- Department of Oral Surgery, University Hospital of Düsseldorf, Düsseldorf, Germany
| | - Dieter Drescher
- Department of Orthodontics, University Hospital of Düsseldorf, Düsseldorf, Germany
| | | | - Kathrin Becker
- Department of Orthodontics, University Hospital of Düsseldorf, Düsseldorf, Germany
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21
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Refaie A, Fouda A, Bourauel C, Singer L. Marginal gap and internal fit of 3D printed versus milled monolithic zirconia crowns. BMC Oral Health 2023; 23:448. [PMID: 37403169 DOI: 10.1186/s12903-023-03184-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Accepted: 06/28/2023] [Indexed: 07/06/2023] Open
Abstract
BACKGROUND This study aimed to evaluate and compare the marginal gap using two different methods and the internal fit of 3D printed and zirconia crowns. METHODS 3Y-TZP zirconia crowns (n = 20) were manufactured using subtractive milling (group M) and 3D printed (group P). The marginal gap was measured at 60 points using vertical marginal gap technique (VMGT). On the other hand, the silicone replica technique (SRT) was used to evaluate the internal fit and was divided into 4 groups: marginal gap, cervical gap, axial gap, and occlusal gap where the thickness of light impression was measured at 16 references. The numerical data was tested for normality using Shapiro-Wilk's test. They were found to be normally distributed and were analyzed using an independent t-test. RESULTS Using VMGT, group P had significantly higher mean marginal gap values of 80 ± 30 µm compared to group M = 60 ± 20 µm (p < 0.001). Also, with the SRT, the marginal gap of group P (100 ± 10 µm) had significantly higher values compared to group M (60 ± 10 µm). The internal fit showed significant difference between the tested groups except for Axial Gap. CONCLUSIONS Although milled crowns showed better results. The 3D printed zirconia crowns offer clinically acceptable results in terms of marginal adaptation and internal fit. Both VMGT and SRT are reliable methods for the assessment of the marginal gap.
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Affiliation(s)
- Ashraf Refaie
- Oral Medicine Technology, University Hospital Bonn, Bonn, Germany.
- Department of Fixed Prosthodontics, Faculty of Dentistry, Fayoum University, Faiyum, Egypt.
- Faculty of Oral and Dental Medicine, British University in Egypt, Cairo, Egypt.
| | - Ahmed Fouda
- Oral Medicine Technology, University Hospital Bonn, Bonn, Germany
| | | | - Lamia Singer
- Oral Medicine Technology, University Hospital Bonn, Bonn, Germany
- Department of Orthodontics, University Hospital Bonn, Bonn, Germany
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22
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Elshazly TM, Nang D, Golkhani B, Elattar H, Keilig L, Bourauel C. Effect of thermomechanical aging of orthodontic aligners on force and torque generation: An in vitro study. J Mech Behav Biomed Mater 2023; 143:105911. [PMID: 37207526 DOI: 10.1016/j.jmbbm.2023.105911] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Revised: 05/10/2023] [Accepted: 05/14/2023] [Indexed: 05/21/2023]
Abstract
The aim of the study is to investigate the effects of artificial aging by thermocycling and mechanical loading on force/torque delivery by thermoplastic orthodontic aligners. Ten thermoformed aligners, made of Zendura™ thermoplastic polyurethane sheets, were aged over two weeks in deionized water by thermocycling alone (n = 5) and by both thermocycling and mechanical loading (n = 5). The force/torque generated on upper second premolar (Tooth 25) of a plastic model was measured before aging (as control), and after 2, 4, 6, 10, and 14 days of aging, using a biomechanical set-up. Before aging, the extrusion-intrusion forces were in the range of 2.4-3.0 N, the oro-vestibular forces were 1.8-2.0 N, and the torques on mesio-distal rotation were 13.6-40.0 Nmm. Pure thermocycling had no significant effect on the force decay of the aligners. However, there was a significant decrease in force/torque after 2 days of aging for both thermocycling and mechanical loading aging group, which is no longer significant over 14 days of aging. In conclusion, artificial aging of aligners in deionized water with both thermocycling and mechanical loading results in a significant decrease in force/torque generation. However, mechanical loading of aligners has a greater impact than pure thermocycling.
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Affiliation(s)
- Tarek M Elshazly
- Oral Technology Department, Dental School, University Hospital Bonn, Bonn, Germany.
| | - Diva Nang
- Oral Technology Department, Dental School, University Hospital Bonn, Bonn, Germany
| | - Bijan Golkhani
- Oral Technology Department, Dental School, University Hospital Bonn, Bonn, Germany
| | - Hanaa Elattar
- Orthodontic Department, Faculty of Dentistry, Umm Al-Qura University, Makkah, Saudi Arabia; Orthodontic Department, Faculty of Dentistry, Suez Canal University, Ismailia, Egypt
| | - Ludger Keilig
- Oral Technology Department, Dental School, University Hospital Bonn, Bonn, Germany; Department of Dental Prosthetics, Propaedeutics and Materials Science, Dental School, University Hospital Bonn, Bonn, Germany
| | - Christoph Bourauel
- Oral Technology Department, Dental School, University Hospital Bonn, Bonn, Germany
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Fritz F, Daratsianos N, Bourauel C, Papageorgiou SN, Jäger A. Changes in the distribution of occlusal forces in the course of the orthodontic retention phase : A prospective cohort study. J Orofac Orthop 2023:10.1007/s00056-023-00480-4. [PMID: 37382657 DOI: 10.1007/s00056-023-00480-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2023] [Accepted: 04/17/2023] [Indexed: 06/30/2023]
Abstract
PURPOSE Aim of the present study was to assess the relative distribution of occlusal forces after orthodontic treatment and during the first 3 months of the retention phase using a computerized occlusal analysis system (T-Scan, Tekscan Inc., Norwood, MA, USA). MATERIALS AND METHODS A total of 52 patients were included in this prospective cohort study and underwent analysis of occlusal forces on the level of tooth, jaw-half, and -quadrant during a 3-month period. Furthermore, differences between three retention protocols (group I: removable appliances in both jaws; group II: fixed 3-3 lingual retainers in both jaws; group III: removable appliance in the maxilla and fixed 3-3 lingual retainer in mandible) were assessed with Wilcoxon signed-rank tests at 5%. RESULTS Directly after debonding, measured forces distribution were similar to published references for untreated samples. In the following, no significant difference was found between retention protocols II and III with regard to the asymmetry of the anterior occlusal forces. Both groups maintained an asymmetric force distribution in the anterior segment during the study period. There was also no difference between groups II and III in the distribution of occlusal forces for the posterior segments. Both retention concepts kept the symmetrical distribution of occlusal forces stable over the observation period. The retention concept of group I demonstrated a symmetrical distribution of occlusal forces in the anterior segment after debonding and this remained stable during the 3‑month period. In the posterior segment, no improvement of the initially asymmetric masticatory force distribution could be observed. CONCLUSIONS All three studied retention protocols showed stability in retaining their original symmetrical or asymmetrical occlusal force distribution posteriorly/anteriorly during the 3‑month observation period. Therefore, an even distribution of occlusal forces should be the aim of the finishing phase, as no relative benefit of any single retention scheme in terms of post-debond improvement during the retention phase was seen.
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Affiliation(s)
- F Fritz
- Department of Orthodontics, University of Bonn, Welschnonnenstr. 17, 53111, Bonn, Germany
| | - N Daratsianos
- Department of Orthodontics, University of Bonn, Welschnonnenstr. 17, 53111, Bonn, Germany
| | - C Bourauel
- Department of Oral Technology, University of Bonn, Welschnonnenstr. 17, 53111, Bonn, Germany
| | - Spyridon N Papageorgiou
- Clinic of Orthodontics and Pediatric Dentistry, Center of Dental Medicine, University Zurich, Plattenstrasse 11, 8032, Zurich, Switzerland
| | - A Jäger
- Department of Orthodontics, University of Bonn, Welschnonnenstr. 17, 53111, Bonn, Germany.
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Grosch K, Meister J, Raval SD, Fouda AM, Bourauel C. Comparative evaluation of different debonding and reconditioning methods for orthodontic ceramic brackets regarding effectiveness for reuse : An in vitro study. J Orofac Orthop 2023:10.1007/s00056-023-00469-z. [PMID: 37318554 DOI: 10.1007/s00056-023-00469-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2023] [Accepted: 04/02/2023] [Indexed: 06/16/2023]
Abstract
PURPOSE To investigate the reusability of ceramic brackets in terms of shear bond strength, friction behavior, slot dimension, fracture strength, and color stability. METHODS A total of 90 conventionally debonded and 30 by an Er:YAG laser debonded ceramic brackets were collected. All the used brackets were inspected under a stereomicroscope at 18 × magnification and sorted according to their adhesive remnant index (ARI). Five groups were formed (n = 10): (1) new brackets as a control group, (2) flamed and sandblasted, (3) flamed and acid bathed, (4) laser-reconditioned, and (5) laser-debonded brackets. The bracket groups were tested regarding different properties such as shear bond strength, friction behavior, slot size, fracture strength, and color stability. Analysis of variance (ANOVA) and nonparametric Kruskal-Wallis tests were used for statistical analysis (significance level: p < 0.05). RESULTS Shear bond strength values of the acid reconditioned brackets were significantly lower (8.0 ± 3.1 MPa) compared to the control group (12.9 ± 2.9 MPa). Laser-reconditioned (32.8 ± 2.7%) and laser-debonded (30.9 ± 2.4%) brackets showed the lowest force loss due to friction (control group 38.3 ± 3.0%). No significant differences were observed between groups regarding slot size and fracture strength. All groups had color differences of [Formula: see text]< 10. Scanning electron microscope images and ARI scores indicated that most of the residues on the bracket bases were removed. CONCLUSION All reconditioning methods yielded adequate results regarding bracket properties. Yet, focusing on the need to protect the enamel and the bracket base, laser debonding seems to be the most suitable method for reconditioning ceramic brackets.
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Affiliation(s)
- Katharina Grosch
- Department of Oral Technology, Center of Dentomaxillofacial Medicine, University Hospital Bonn, Bonn, Germany.
| | - Jörg Meister
- Department of Periodontology, Operative and Preventive Dentistry, Center of Dentomaxillofacial Medicine, University Hospital Bonn, Bonn, Germany
- Center of Applied Medical Laser Research and Biomedical Optics (AMLaReBO), University Hospital Bonn, Bonn, Germany
| | | | - Ahmed Mahmoud Fouda
- Department of Oral Technology, Center of Dentomaxillofacial Medicine, University Hospital Bonn, Bonn, Germany
| | - Christoph Bourauel
- Department of Oral Technology, Center of Dentomaxillofacial Medicine, University Hospital Bonn, Bonn, Germany
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25
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Fouda AM, Atta O, Özcan M, Stawarczyk B, Glaum R, Bourauel C. An investigation on fatigue, fracture resistance, and color properties of aesthetic CAD/CAM monolithic ceramics. Clin Oral Investig 2023; 27:2653-2665. [PMID: 36574045 PMCID: PMC10264477 DOI: 10.1007/s00784-022-04833-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2022] [Accepted: 12/18/2022] [Indexed: 12/28/2022]
Abstract
OBJECTIVES To evaluate and compare fracture resistance, translucency, and color reproducibility, as well as the effect of aging on the fracture load and color stability of novel monolithic CAD/CAM ceramics. MATERIALS AND METHODS One hundred crowns of uniform thickness were milled from five ceramic blocks (n = 20): partially crystallized lithium disilicate (PLD) and fully crystallized lithium disilicate (FLD), lithium metasilicate (LMS), 4Y-TZP (SMZ), and 5Y-TZP (UMZ) monolithic zirconia. PLD crowns were glazed, LMS was fired, and FLD was polished. SMZ and UMZ crowns were sintered and polished. Crowns were adhesively cemented to epoxy dies. Half of the crowns (n = 10) were subjected to 1.200.000 load cycles with thermal cycling. Color space values L, a, b defined by the Commission Internationale de l´Eclairage (CIELAB) were measured before and after aging, and (∆E) was calculated. Both aged and non-aged specimens were loaded until fracture in a universal testing machine and the fracture load was recorded. X-ray diffraction (XRD) and scanning electron microscope (SEM) fractographic analysis were carried out on fractured fragments of representative samples. For translucency and color reproducibility, 50 rectangular-shaped specimens were fabricated and processed as described previously. Color values were measured over black and white backgrounds, and the translucency parameter (TP) was computed. Using the shade verification mode, (∆E) to shade A3 was calculated. Data were statistically analyzed using one-way and two-way ANOVA, and t-test. RESULTS Aging did not affect fracture resistance significantly (p > 0.05). The highest mean fracture load was obtained for the SMZ and UMZ. A significant color change was observed after aging in all groups. The highest TP was noted for FLD. SMZ and UMZ had the best shade match. CONCLUSIONS Zirconia showed higher fracture resistance and color stability than lithium silicate ceramics. Lithium silicate ceramics were more translucent. The experimental FLD demonstrated high translucency. CLINICAL RELEVANCE Tested ceramics showed sufficient stability to withstand masticatory forces. Characterization of final restorations might be mandatory for better color match.
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Affiliation(s)
- Ahmed Mahmoud Fouda
- Department of Oral Technology, University Hospital Bonn, Bonn University, Welschnonnenstr. 17, 53111, Bonn, Germany.
- Department of Fixed Prosthodontics, Suez Canal University, Ismailia, Egypt.
| | - Osama Atta
- Department of Fixed Prosthodontics, Suez Canal University, Ismailia, Egypt
| | - Mutlu Özcan
- Division of Dental Biomaterials, Center for Dental Medicine, Clinic for Reconstructive Dentistry, University of Zurich, Zurich, Switzerland
| | - Bogna Stawarczyk
- Department of Prosthetic Dentistry, University Hospital, LMU Munich, Munich, Germany
| | - Robert Glaum
- Institute of Inorganic Chemistry, Bonn University, Bonn, Germany
| | - Christoph Bourauel
- Department of Oral Technology, University Hospital Bonn, Bonn University, Welschnonnenstr. 17, 53111, Bonn, Germany
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26
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Hodecker LD, Scheurer M, Scharf S, Roser CJ, Fouda AM, Bourauel C, Lux CJ, Bauer CAJ. Influence of Individual Bracket Base Design on the Shear Bond Strength of In-Office 3D Printed Brackets-An In Vitro Study. J Funct Biomater 2023; 14:289. [PMID: 37367253 DOI: 10.3390/jfb14060289] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Revised: 05/19/2023] [Accepted: 05/22/2023] [Indexed: 06/28/2023] Open
Abstract
(1) Background: Novel high-performance polymers for medical 3D printing enable in-office manufacturing of fully customized brackets. Previous studies have investigated clinically relevant parameters such as manufacturing precision, torque transmission, and fracture stability. The aim of this study is to evaluate different design options of the bracket base concerning the adhesive bond between the bracket and tooth, measured as the shear bond strength (SBS) and maximum force (Fmax) according to DIN 13990. (2) Methods: Three different designs for printed bracket bases were compared with a conventional metal bracket (C). The following configurations were chosen for the base design: Matching of the base to the anatomy of the tooth surface, size of the cross-sectional area corresponding to the control group (C), and a micro- (A) and macro- (B) retentive design of the base surface. In addition, a group with a micro-retentive base (D) matched to the tooth surface and an increased size was studied. The groups were analyzed for SBS, Fmax, and adhesive remnant index (ARI). The Kruskal-Wallis test with a post hoc test (Dunn-Bonferroni) and Mann-Whitney U test were used for statistical analysis (significance level: p < 0.05). (3) Results: The values for SBS and Fmax were highest in C (SBS: 12.0 ± 3.8 MPa; Fmax: 115.7 ± 36.6 N). For the printed brackets, there were significant differences between A and B (A: SBS 8.8 ± 2.3 MPa, Fmax 84.7 ± 21.8 N; B: SBS 12.0 ± 2.1 MPa, Fmax 106.5 ± 20.7 N). Fmax was significantly different for A and D (D: Fmax 118.5 ± 22.8 N). The ARI score was highest for A and lowest for C. (4) Conclusions: This study shows that conventional brackets form a more stable bond with the tooth than the 3D-printed brackets. However, for successful clinical use, the shear bond strength of the printed brackets can be increased with a macro-retentive design and/or enlargement of the base.
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Affiliation(s)
- Lutz D Hodecker
- Department of Orthodontics and Dentofacial Orthopedics, University of Heidelberg, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany
| | - Mats Scheurer
- Department of Oral and Maxillofacial Surgery, University of Heidelberg, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany
| | - Sven Scharf
- Private Practice of Orthodontics, 50933 Cologne, Germany
| | - Christoph J Roser
- Department of Orthodontics and Dentofacial Orthopedics, University of Heidelberg, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany
| | - Ahmed M Fouda
- Oral Technology, Dental School, Medical Faculty, University Hospital of Bonn, Welschnonnenstr 17, 53111 Bonn, Germany
| | - Christoph Bourauel
- Oral Technology, Dental School, Medical Faculty, University Hospital of Bonn, Welschnonnenstr 17, 53111 Bonn, Germany
| | - Christopher J Lux
- Department of Orthodontics and Dentofacial Orthopedics, University of Heidelberg, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany
| | - Carolien A J Bauer
- Department of Orthodontics and Dentofacial Orthopedics, University of Heidelberg, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany
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27
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Singer L, Bourauel C. Mechanical and Physical Properties of an Experimental Chemically and Green-Nano Improved Dental Alginate after Proven Antimicrobial Potentials. Gels 2023; 9:gels9050429. [PMID: 37233020 DOI: 10.3390/gels9050429] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Revised: 05/19/2023] [Accepted: 05/20/2023] [Indexed: 05/27/2023] Open
Abstract
OBJECTIVES Impression materials could be a source of cross-contamination due to the presence of microorganisms from blood and saliva inside the oral cavity. Nevertheless, routinely performed post-setting disinfection could compromise the dimensional accuracy and other mechanical properties of alginates. Thus, this study aimed to evaluate detail reproduction, dimensional accuracy, tear strength, and elastic recovery of new experimentally prepared self-disinfecting dental alginates. METHODS Two antimicrobial-modified dental alginate groups were prepared by mixing alginate powder with 0.2% silver nitrate (AgNO3 group) and a 0.2% chlorohexidine solution (CHX group) instead of pure water. Moreover, a third modified group was examined by the extraction of Boswellia sacra (BS) oleoresin using water. The extract was used to reduce silver nitrate to form silver nanoparticles (AgNPs), and the mixture was used as well in dental alginate preparation (BS + AgNP group). Dimensional accuracy and detail reproduction were examined as per the ISO 1563 standard guidelines. Specimens were prepared using a metallic mold engraved with three parallel vertical lines 20, 50, and 75 µm wide. Detail reproduction was evaluated by checking the reproducibility of the 50 µm line using a light microscope. Dimensional accuracy was assessed by measuring the change in length between defined reference points. Elastic recovery was measured according to ISO 1563:1990, in which specimens were gradually loaded and then the load was released to allow for recovery from the deformation. Tear strength was evaluated using a material testing machine until failure at a crosshead speed of 500 mm/min. RESULTS The recorded dimensional changes between all tested groups were insignificantly different and within the reported acceptable values (between 0.037-0.067 mm). For tear strength, there were statistically significant differences between all tested groups. Groups modified with CHX (1.17 ± 0.26 N/mm) and BS + AgNPs (1.11 ± 0.24 N/mm) showed higher tear strength values compared to the control (0.86 ± 0.23 N/mm) but were insignificant from AgNO3 (0.94 ± 0.17 N/mm). All tested groups showed elastic recovery values that met both the ISO standard and ADA specifications for elastic impression materials and tear strength values within the acceptable documented ranges. DISCUSSION The CHX, silver nitrate, and green-synthesized silver nanoparticles could be promising, inexpensive alternatives for the preparation of a self-disinfecting alginate impression material without affecting its performance. Green synthesis of metal nanoparticles could be a very safe, efficient, and nontoxic method, with the advantage of having a synergistic effect between metal ions and active chemical constituents of plant extracts.
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Affiliation(s)
- Lamia Singer
- Oral Technology, Dental School, Medical Faculty, University Hospital Bonn, 53111 Bonn, Germany
- Department of Orthodontics, Dental School, Medical Faculty, University Hospital Bonn, 53111 Bonn, Germany
| | - Christoph Bourauel
- Oral Technology, Dental School, Medical Faculty, University Hospital Bonn, 53111 Bonn, Germany
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28
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Nagi N, Fouda AM, Bourauel C. Comparative evaluation of internal fit and marginal gap of endocrowns using lithium disilicate and polyether ether ketone materials - an in vitro study. BMC Oral Health 2023; 23:207. [PMID: 37029396 PMCID: PMC10082505 DOI: 10.1186/s12903-023-02857-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Accepted: 03/06/2023] [Indexed: 04/09/2023] Open
Abstract
BACKGROUND The aim of the study was to investigate the effect of material and occlusal preparation design on the internal fit and marginal gap of endocrowns made of Polyether ether ketone (PEEK) and lithium disilicate. METHODS 32 endocrowns were fabricated on prepared mandibular molars and divided into two groups (n = 16) according to the material. Group L: lithium disilicate and Group P: PEEK. Each group was further subdivided into two subgroups (n = 8) according to the occlusal preparation design: full occlusal coverage (LF and PF) and partial occlusal coverage (LP and PP). Samples were analyzed using microcomputed tomography (µCT) with a voxel size of 6 μm to evaluate internal fit, and an optical microscope was used to evaluate the marginal gap. Data were collected, tabulated, and statistically analyzed. Numerical data were described as mean and standard deviation and compared using the ANOVA test. The level of significance was set at α P ≤ 0.05. RESULTS All groups' internal fit and marginal gaps values were within the acceptable clinical range. However, the lithium disilicates group recorded statistically significantly higher mean internal gap values than the PEEK groups. Regardless of the material, the difference between the two occlusal designs was not statistically significant in both internal fit and marginal gap records. CONCLUSION Within the limitations of this study, PEEK endocrown restorations revealed better internal fit and marginal gap than lithium disilicate endocrown restorations. The marginal and internal fit of both lithium disilicate and PEEK endocrown restorations were within the clinically acceptable range. The occlusal preparation design had no influence on the internal fit and marginal gap of the endocrown restoration.
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Affiliation(s)
- Nermeen Nagi
- Bonn University, Bonn, Germany.
- Faculty of Dentistry, Galala University, Suez, Egypt.
- Faculty of Dentistry, Fayoum University, Fayoum, Egypt.
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29
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Singer L, Keilig L, Fichte M, Bourauel C. Evaluation of the properties of a new super quick-setting (2 min) polyether impression material. Clin Oral Investig 2023:10.1007/s00784-023-04982-8. [PMID: 37017760 DOI: 10.1007/s00784-023-04982-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Accepted: 03/28/2023] [Indexed: 04/06/2023]
Abstract
OBJECTIVES Although a new super-quick setting polyether impression material has been commercially recently introduced, its properties have not been yet reported. Thus, it was the aim of this study to assess the dimensional stability, tear strength, and elastic recovery of the new material and to compare it with another commonly used polyether and polyvinyl siloxane. MATERIALS AND METHODS A new super-quick set polyether, a regular set polyether and a polyvinylsiloxane (PVS) impression material have been used in the study. Dimensional changes were measured using a modified mold as per ISO 4823:2000 after 1 h and 7 days. Tear strength was evaluated by subjecting specimens to tension until failure with a crosshead speed of 250 mm/min. Elastic recovery was measured by deforming specimens using a materials testing machine to a height of 16 mm (20% strain). The change in length (ΔL) was measured afterwards and elastic recovery was calculated in percentages. RESULTS Dimensional changes of the super quick and regular set polyether were comparable in both the vertical and horizontal dimensions after 24 h and 7 days. All the tested materials showed dimensional change values far below the maximum accepted ISO requirement (1.5%). The super quick setting polyether showed significantly improved tear strength (4.9 N/mm) in comparison to the regular set polyether (3.5 N/mm) and similar to PVS (5.2 N/mm). The elastic recovery of PVS (99.6%) was the highest among all the groups. CONCLUSIONS AND CLINICAL RELEVANCE The newly available super-fast set polyether offers a great potential for a reduced chair side time and comfort for both, the patient and the dentist. Super quick polyether showed as well improved tear strength, which is considered one of the shortcomings of the regular set polyether. In addition, the new polyether was as accurate as the regular set polyether and with good elastic recovery.
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Affiliation(s)
- Lamia Singer
- Oral Technology, Dental School, Medical Faculty, University Hospital of Bonn, Welschnonnenstr. 17, 53111, North Rhine-Westphalia, Bonn, Germany.
- Department of Orthodontic, Dental School, Medical Faculty, University Hospital of Bonn, 53111, North Rhine-Westphalia, Bonn, Germany.
| | - Ludger Keilig
- Oral Technology, Dental School, Medical Faculty, University Hospital of Bonn, Welschnonnenstr. 17, 53111, North Rhine-Westphalia, Bonn, Germany
- Department of Prosthodontics, Preclinical Education and Dental Materials Science, Dental School, Medical Faculty, University Hospital of Bonn, 53111, North Rhine-Westphalia, Bonn, Germany
| | - Michèle Fichte
- Department of Prosthodontics, Preclinical Education and Dental Materials Science, Dental School, Medical Faculty, University Hospital of Bonn, 53111, North Rhine-Westphalia, Bonn, Germany
| | - Christoph Bourauel
- Oral Technology, Dental School, Medical Faculty, University Hospital of Bonn, Welschnonnenstr. 17, 53111, North Rhine-Westphalia, Bonn, Germany
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Elshazly TM, Salvatori D, Elattar H, Bourauel C, Keilig L. Effect of trimming line design and edge extension of orthodontic aligners on force transmission: A 3D finite element study. J Mech Behav Biomed Mater 2023; 140:105741. [PMID: 36857974 DOI: 10.1016/j.jmbbm.2023.105741] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Revised: 02/20/2023] [Accepted: 02/21/2023] [Indexed: 02/27/2023]
Abstract
OBJECTIVES To investigate in a numerical study the effect of the geometry and the extension of orthodontic aligner edges and the aligner thickness on force transmission to upper right central incisor tooth (Tooth 11). METHODS A three-dimensional (3D) digital model, obtained from a 3D data set of a complete dentulous maxilla, was imported into 3-matic software. Aligners with four different trimming line designs (scalloped, straight, scalloped extended, straight extended) were designed, each with four different thicknesses (0.3, 0.4, 0.5, and 0.6 mm). The models were exported to a finite element (FE) software (Marc/Mentat). A facial 0.2 mm bodily malposition of tooth 11 was simulated. RESULTS The maximum resultant force was in the range of (7.5 - 55.2) N. The straight trimming designs had higher resultant force than the scalloped designs. The resultant force increases with increasing the edge extension of the aligner. The normal contact forces were unevenly distributed over the entire surface and were concentrated in six areas: Incisal, Mesio-Incisal, Disto-Incisal, Middle, Mesio-Cervical, and Disto-Cervical. The resultant force increases super linearly with increasing thickness. CONCLUSIONS The design of the trimming line, the edge extension, and the thickness of the aligner affect significantly the magnitude of the resultant force and the distribution of normal contact force. The straight extended trimming design exhibited better force distribution that may favor a bodily tooth movement. CLINICAL RELEVANCE A straight extended trimming design of an orthodontic aligner may improve the clinical outcomes. In addition, the manufacturing procedures of the straight design are much simpler compared to the scalloped design.
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Affiliation(s)
- Tarek M Elshazly
- Oral Technology, Dental School, University Hospital Bonn, Bonn, Germany.
| | | | - Hanaa Elattar
- Orthodontic Department, Faculty of Dentistry, Umm Al-Qura University, Makkah, Saudi Arabia; Orthodontic Department, Faculty of Dentistry, Suez Canal University, Ismailia, Egypt
| | | | - Ludger Keilig
- Oral Technology, Dental School, University Hospital Bonn, Bonn, Germany; Department of Dental Prosthetics, Propaedeutics and Materials Science, Dental School, University Hospital Bonn, Bonn, Germany
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Roulias P, Mylonopoulou IM, Sifakakis I, Bourauel C, Eliades T. Thermo-mechanical properties in bending of a multizone nickel-titanium archwire: A retrieval analysis. Korean J Orthod 2023; 53:89-98. [PMID: 36746751 PMCID: PMC10040288 DOI: 10.4041/kjod22.183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Revised: 11/08/2022] [Accepted: 11/16/2022] [Indexed: 02/08/2023] Open
Abstract
Objective This study aimed to compare the mechanical and thermal properties in the anterior and posterior segments of new and retrieved specimens of a commercially available multizone superelastic nickel-titanium (NiTi) archwire. Methods The following groups of 0.016 × 0.022-inch Bioforce NiTi archwires were compared: a) anterior and b) posterior segments of new specimens and c) anterior and d) posterior segments of retrieved specimens. Six specimens were evaluated in each group, by three-point bending and bend and free recovery tests. Bending moduli (Eb) were calculated. Furthermore, the new specimens were evaluated with scanning electron microscopy/energy-dispersive X-ray spectrometry. A multiple linear regression model with a random intercept at the wire level was applied for data analysis. Results The forces in the posterior segments or new specimens were higher than those recorded in the anterior segments or retrieved specimens, respectively. Accordingly, Eb also varied. Higher austenite start and austenite finish (Af) temperatures were recorded in the anterior segments. No statistically significant differences were found for these temperatures between retrieved and new wires. The mean elemental composition was (weight percentage): Ni, 52.6 ± 0.5; Ti, 47.4 ± 0.5. Conclusions The existence of multiple force zones was confirmed in new and retrieved Bioforce archwires. The retrieved archwires demonstrated lower forces during the initial stages of deactivation in three-point bending tests, compared with new specimens. The Af temperature of these archwires may lie higher than the regular intraoral temperature. Even at 2 mm deflections, the forces recorded from these archwires may lie beyond biologically safe limits.
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Affiliation(s)
- Panagiotis Roulias
- Department of Orthodontics, School of Dentistry, National and Kapodistrian University of Athens, Athens, Greece
| | - Ioulia-Maria Mylonopoulou
- Department of Orthodontics, School of Dentistry, National and Kapodistrian University of Athens, Athens, Greece
| | - Iosif Sifakakis
- Department of Orthodontics, School of Dentistry, National and Kapodistrian University of Athens, Athens, Greece
| | - Christoph Bourauel
- Department of Oral Technology, School of Dentistry, University Hospital Bonn, Bonn, Germany
| | - Theodore Eliades
- Clinic of Orthodontics and Paediatric Dentistry, Center of Dental Medicine, University of Zurich, Zurich, Switzerland
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Heim N, Warwas FB, Singer L, Kramer FJ, Bourauel C, Götz W. Differences in the Osseous Ultrastructure in 2 Differing Etiologies of Eagle Syndrome. A Micro-CT Study. J Craniofac Surg 2023:00001665-990000000-00646. [PMID: 36941242 DOI: 10.1097/scs.0000000000009296] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Accepted: 12/27/2022] [Indexed: 03/23/2023] Open
Abstract
OBJECTIVES Eagle syndrome is a rare disease caused by an elongated styloid process (type I) or ossified stylohyoid ligament (type II) and causes a heterogeneous symptom complex, ranging from pain in the throat and neck to neurological symptoms and neurovascular entrapment. The 2 different types present differing shapes and ultrastructures and cause different symptoms. This study aimed to distinguish the 2 types by investigating the structures by micro-computed tomography. METHODS Micro-computed tomography was performed and evaluated in n=10 resected styloid processes from patients diagnosed with Eagle syndrome. The tissues were measured for their shape, ratio of soft tissue and bone amounts, bone volume, and ultrastructure, and compared within the groups. RESULTS The shapes of the different types were different and the ultrastructure differed between the 2 groups, with an absence of trabecular architecture in type II. The area of bone to nonbone tissues in type I samples was significantly higher compared with type II (P=0.007). Alike these results, the bone volume and bone-to-soft tissue ratio were significantly higher in type I compared with type II (P=0.009). CONCLUSIONS The findings suggest that both the popular theories (hyperplasia and metaplasia) may be probable but each solely valid for 1 type of Eagle. Type I may derive from bone hyperplasia with cancellous bone formation and rather high bone density in the elongated styloid process. Type II most likely originates from ligament metaplasia into bone without a compact structure.
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Affiliation(s)
- Nils Heim
- Deparment of Oral & Cranio-Maxillo and Facial Plastic Surgery, University Clinic Bonn
| | - Felix B Warwas
- Deparment of Oral & Cranio-Maxillo and Facial Plastic Surgery, University Clinic Bonn
| | - Lamia Singer
- Oral Technology Medical Faculty, Dental School, University of Bonn
| | - Franz-Josef Kramer
- Deparment of Oral & Cranio-Maxillo and Facial Plastic Surgery, University Clinic Bonn
| | | | - Werner Götz
- Department of Orthodontics, Dental Hospital of the University of Bonn, Bonn, Germany
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Zhang Y, Keilig L, Dörsam I, Bourauel C. Numerical investigation of the biomechanical effects of orthodontic intermaxillary elastics on the temporomandibular joint. J Mech Behav Biomed Mater 2023; 141:105764. [PMID: 36965216 DOI: 10.1016/j.jmbbm.2023.105764] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Revised: 03/03/2023] [Accepted: 03/06/2023] [Indexed: 03/14/2023]
Abstract
Temporomandibular joint disorder (TMD) often coincides with malocclusion, and in some cases TMDs are reported after orthodontic treatment. Intermaxillary elastics (also known as orthodontic elastics, OE) are a common way to apply force during orthodontic treatment, and they might cause mechanical effects on the temporomandibular joint (TMJ), thereby lead to joint remodeling. It is still a controversial topic whether the adapted remodeling of the TMJ or of the alveolar bone is the main cause for the alteration of occlusion after treatment with OEs. It was the aim of this study to analyze whether variations of OEs would develop harmful effects on the healthy TMJ. A TMJ model with a masticatory system based on Hill-type muscle actuators was established. Mouth opening and closure with and without OEs were simulated, and maximum principal stresses in the disc and condylar cartilage as well as the displacement of the mandible were analyzed. We found no considerably difference in the mandibular movement without and with symmetrical OEs during mouth opening and closing. At full mouth opening, stresses in the disc and condylar cartilage of some models with OEs were much smaller than without OEs, but we did not find consistency in the results from the left and right sides of the same model (e.g. the lowest compressive stress on the left side of disc from the model with Class II OEs is much smaller than without OEs, -17.3 MPa compared with -28.2, while on the right side, there was no obvious difference). Hence, we could not conclude that OEs would develop deleterious effects on the healthy TMJ.
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Affiliation(s)
- Yaqiu Zhang
- Oral Technology, Dental School, University Hospital Bonn, Bonn, Germany.
| | - Ludger Keilig
- Oral Technology, Dental School, University Hospital Bonn, Bonn, Germany; Department of Dental Prosthetics, Propaedeutics and Materials Science, Dental School, University Hospital Bonn, Bonn, Germany
| | - Istabrak Dörsam
- Department of Dental Prosthetics, Propaedeutics and Materials Science, Dental School, University Hospital Bonn, Bonn, Germany
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Bauer CAJ, Scheurer M, Bourauel C, Kretzer JP, Roser CJ, Lux CJ, Hodecker LD. Precision of slot widths and torque transmission of in-office 3D printed brackets : An in vitro study. J Orofac Orthop 2023:10.1007/s00056-023-00460-8. [PMID: 36862188 DOI: 10.1007/s00056-023-00460-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Accepted: 12/29/2022] [Indexed: 03/03/2023]
Abstract
PURPOSE To investigate a novel in-office three-dimensionally (3D) printed polymer bracket regarding slot precision and torque transmission. METHODS Based on a 0.022″ bracket system, stereolithography was used to manufacture brackets (N = 30) from a high-performance polymer that met Medical Device Regulation (MDR) IIa requirements. Conventional metal and ceramic brackets were used for comparison. Slot precision was determined using calibrated plug gages. Torque transmission was measured after artificial aging. Palatal and vestibular crown torques were measured from 0 to 20° using titanium-molybdenum (T) and stainless steel (S) wires (0.019″ × 0.025″) in a biomechanical experimental setup. The Kruskal-Wallis test with post hoc test (Dunn-Bonferroni) was used for statistical analyses (significance level p < 0.05). RESULTS The slot sizes of all three bracket groups were within the tolerance range according to DIN 13996 (ceramic [C]: 0.581 ± 0.003 mm; metal [M]: 0.6 ± 0.005 mm; polymer [P]: 0.581 ± 0.010 mm). The maximum torque values of all bracket-arch combinations were above the clinically relevant range of 5-20 Nmm (PS: 30 ± 8.6 Nmm; PT: 27.8 ± 14.2 Nmm; CS: 24 ± 5.6 Nmm; CT: 19.9 ± 3.8 Nmm; MS: 21.4 ± 6.7 Nmm; MT: 16.7 ± 4.6 Nmm). CONCLUSIONS The novel, in-office manufactured polymer bracket showed comparable results to established bracket materials regarding slot precision and torque transmission. Given its high individualization possibilities as well as enabling an entire in-house supply chain, the novel polymer brackets bear high potential of future usage for orthodontic appliances.
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Affiliation(s)
- Carolien A J Bauer
- Poliklinik für Kieferorthopädie, Universitätsklinikum Heidelberg, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany.
| | - Mats Scheurer
- Klinik und Poliklinik für Mund‑, Kiefer‑, Gesichtschirurgie, Universitätsklinikum Heidelberg, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany
| | - Christoph Bourauel
- Oralmedizinische Technologie, Zentrum für Zahn‑, Mund- und Kieferheilkunde, Universitätsklinikum Bonn, Welschnonnenstr. 17, 53111, Bonn, Germany
| | - J Philippe Kretzer
- Labor für Biomechanik und Implantatforschung, Klinik für Orthopädie, Universitätsklinikum Heidelberg, Schlierbacher Landstraße 200a, 69118, Heidelberg, Germany
| | - Christoph J Roser
- Poliklinik für Kieferorthopädie, Universitätsklinikum Heidelberg, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany
| | - Christopher J Lux
- Poliklinik für Kieferorthopädie, Universitätsklinikum Heidelberg, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany
| | - Lutz D Hodecker
- Poliklinik für Kieferorthopädie, Universitätsklinikum Heidelberg, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany
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Aldesoki M, Keilig L, Dörsam I, Evers-Dietze B, Elshazly TM, Bourauel C. Trueness and precision of milled and 3D printed root-analogue implants: A comparative in vitro study. J Dent 2023; 130:104425. [PMID: 36646269 DOI: 10.1016/j.jdent.2023.104425] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Revised: 12/03/2022] [Accepted: 01/10/2023] [Indexed: 01/15/2023] Open
Abstract
OBJECTIVES The present study aimed to evaluate the accuracy (trueness and precision) of titanium and zirconia multi-rooted root analogue implants (RAIs) manufactured by milling and 3D-printing. METHODS A multi-rooted RAI was designed based on a mandibular second molar segmented from cone-beam computed tomography (CBCT). The manufactured RAIs were divided into four groups: 3D-printed titanium (PT) and 3D-printed zirconia (PZ) (n=10 each), as well as milled titanium (MT) and milled zirconia (MZ) (n=5 each). The specimens were scanned with a high-precision scanner, and the scanned data were imported into 3D-measurement software to evaluate the precision and trueness of each group. Root mean square (RMS) deviations were measured and statistically analysed (One-way ANOVA, Tukey's, p≤0.05). RESULTS PZ showed the highest precision with RMS value of 21±6 µm. Nevertheless, there was no statistically significant difference in precision among the other groups. Regarding trueness, MZ showed the highest trueness with RMS value of 66±3 µm, whereas MT showed the lowest trueness result. Inspection sections showed that MT had significantly high RMS deviation in the furcation area (612±64 µm), whereas PZ showed significantly high RMS deviation at the apical area (197±17 µm). CONCLUSIONS The manufacturing process significantly influenced the RAI accuracy. PZ exhibited the highest precision, whereas MZ exhibited the highest trueness, followed by PT. Finally, our results suggest that 3D-printing can reproduce concave surfaces and less accessible areas better than milling. CLINICAL SIGNIFICANCE Milled and 3D-printed RAIs showed promising results in terms of precision and trueness. However, further clinical research is needed to advocate their use as immediate implants. Additionally, the inherent volumetric changes of the various materials during manufacturing should be considered.
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Affiliation(s)
- Mostafa Aldesoki
- Oral Technology, Dental School, University Hospital Bonn, Bonn, Germany.
| | - Ludger Keilig
- Oral Technology, Dental School, University Hospital Bonn, Bonn, Germany; Department of Prosthodontics, Dental School, University Hospital Bonn, Bonn, Germany
| | - Istabrak Dörsam
- Oral Technology, Dental School, University Hospital Bonn, Bonn, Germany; Department of Prosthodontics, Dental School, University Hospital Bonn, Bonn, Germany
| | - Bernd Evers-Dietze
- Department of Electrical Engineering, Mechanical Engineering and Technical Journalism (EMT), Bonn-Rhein-Sieg University of Applied Sciences, Sankt Augustin, Germany
| | - Tarek M Elshazly
- Oral Technology, Dental School, University Hospital Bonn, Bonn, Germany
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Wagner C, Herberg S, Bourauel C, Stark H, Dörsam I. Biomechanical analysis of different fixed dental restorations on short implants: a finite element study. BIOMED ENG-BIOMED TE 2023:bmt-2022-0414. [PMID: 36795430 DOI: 10.1515/bmt-2022-0414] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2022] [Accepted: 02/02/2023] [Indexed: 02/17/2023]
Abstract
OBJECTIVES Although the use of short implants is becoming more common for patients with atrophic alveolar ridges, their use is still quite limited. This is due to the lack of data of long-term survival compared to standard-length implants. The aim of this study was to determine the load in the bone and implant system with different superstructures. METHODS Three kinds of prosthetic restorations were created on short implants based on CT-Data. Two short implants with different macro-geometries were used. The implants were inserted in idealised posterior lower mandibular segments and afterwards restored with a crown, a double splinted crown, and a bridge. RESULTS The analysis was performed under load of 300 N either divided between a mesial and distal point or as a point load on the pontic/mesial crown. The different design of the implant systems had a noticeable influence on the stress in the cortical bone, in the implant system, and the displacement of the superstructure as well. CONCLUSIONS Compared with implants of standard length, higher stresses were observed, which can lead early failure of the implant during the healing period or a late cervical bone resorption. Precise indications are essential for short implants to avoid the failure of short implants.
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Affiliation(s)
- Christian Wagner
- Department of Prosthetic Dentistry, Preclinical Education and Materials Science, Dental School, University of Bonn Bonn, Germany
| | - Samira Herberg
- Department of Prosthetic Dentistry, Preclinical Education and Materials Science, Dental School, University of Bonn Bonn, Germany
| | | | - Helmut Stark
- Department of Prosthetic Dentistry, Preclinical Education and Materials Science, Dental School, University of Bonn Bonn, Germany
| | - Istabrak Dörsam
- Department of Prosthetic Dentistry, Preclinical Education and Materials Science, Dental School, University of Bonn Bonn, Germany.,Oral Technology, University of Bonn Bonn, Germany
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Singer L, Fouda A, Bourauel C. Biomimetic approaches and materials in restorative and regenerative dentistry: review article. BMC Oral Health 2023; 23:105. [PMID: 36797710 PMCID: PMC9936671 DOI: 10.1186/s12903-023-02808-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2022] [Accepted: 02/10/2023] [Indexed: 02/18/2023] Open
Abstract
Biomimetics is a branch of science that explores the technical beauty of nature. The concept of biomimetics has been brilliantly applied in famous applications such as the design of the Eiffel Tower that has been inspired from the trabecular structure of bone. In dentistry, the purpose of using biomimetic concepts and protocols is to conserve tooth structure and vitality, increase the longevity of restorative dental treatments, and eliminate future retreatment cycles. Biomimetic dental materials are inherently biocompatible with excellent physico-chemical properties. They have been successfully applied in different dental fields with the advantages of enhanced strength, sealing, regenerative and antibacterial abilities. Moreover, many biomimetic materials were proven to overcome significant limitations of earlier available generation counterpart. Therefore, this review aims to spot the light on some recent developments in the emerging field of biomimetics especially in restorative and regenerative dentistry. Different approaches of restoration, remineralisation and regeneration of teeth are also discussed in this review. In addition, various biomimetic dental restorative materials and tissue engineering materials are discussed.
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Affiliation(s)
- Lamia Singer
- Oral Technology, University Hospital Bonn, 53111, Bonn, North Rhine-Westphalia, Germany. .,Department of Orthodontics, University Hospital Bonn, 53111, Bonn, North Rhine-Westphalia, Germany.
| | - Ahmed Fouda
- grid.15090.3d0000 0000 8786 803XOral Technology, University Hospital Bonn, 53111 Bonn, North Rhine-Westphalia Germany ,grid.33003.330000 0000 9889 5690Department of Fixed Prosthodontics, Suez Canal University, Ismailia, Egypt
| | - Christoph Bourauel
- grid.15090.3d0000 0000 8786 803XOral Technology, University Hospital Bonn, 53111 Bonn, North Rhine-Westphalia Germany
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Meister J, Kaschuba N, Romer M, Bourauel C. Influence of Cementation on the Aesthetical Appearance of Full-Ceramic Restorations. Materials (Basel) 2023; 16:1236. [PMID: 36770241 PMCID: PMC9919653 DOI: 10.3390/ma16031236] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 12/23/2022] [Accepted: 01/28/2023] [Indexed: 06/18/2023]
Abstract
The use of dental ceramics as restorative materials requires corresponding luting materials (cements) that, in turn, influence the visual appearance of the restoration. Due to the high light transmission through the ceramics, the cements can affect the color perception of the dental restoration. This study aims to investigate the optical effects of various cements on the visual appearance of full-ceramic restorations. Three fixing polymer resins (Bifix SE (VOCO GmbH, Cuxhafen, Germany), BreezeTM (Pentron Clinical, West Collins Orange, CA, USA), and PanaviaTM F. 2.0 (Kuraray, Noritake, Osaka, Japan)), with layer thicknesses of 50, 100, 200, and 250 µm, were applied onto a ceramic base model (0.4 mm thick), and irradiated with laser light of wavelengths 532, 632.8, and 1064 nm. Light intensities and scattering effects of light of various wavelengths were angle-dependent, analyzed using a goniophotometer with perpendicular light incidence on the sample specimen (base model plus luting material). In addition, the transmitted power of the light through the sample specimen was determined as a function of the layer thickness. With increasing layer thickness, power losses of respectively 30% for Bifix SE and BreezeTM in the visible spectral range were comparable, whereas PanaviaTM F. 2.0 showed a power loss of ca. 44% here. For the near-infrared range, the power losses for all cements were 25%. This could be confirmed by the interpretation of the line widths. Moreover, the line widths for thin cement layer thicknesses (50 and 100 µm) in the visible spectral range displayed only a redistribution of light by scattering, which does not affect color perception at all. In addition, at 200 and 250 µm, absorption occurred which causes a change in color perception. Within the scope of this study, it could be shown that for thin-layer thicknesses of the cement applied here, there is no adverse optical effect on the aesthetic visual appearance of the restoration.
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Affiliation(s)
- Jörg Meister
- Department of Periodontology, Operative and Preventive Dentistry, Bonn University, 53111 Bonn, Germany
- Center of Applied Medical Laser Research and Biomedical Optics (AMLaReBO), Bonn University, 53111 Bonn, Germany
- Laser Application in Medical Sciences Research Center, Shahid Beheshti University of Medical Sciences, Tehran 19839 69411, Iran
| | | | | | - Christoph Bourauel
- Center of Applied Medical Laser Research and Biomedical Optics (AMLaReBO), Bonn University, 53111 Bonn, Germany
- Oral Technology, Bonn University, 53111 Bonn, Germany
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Jepsen K, Jervøe-Storm PM, Henrichs I, Lensing I, Müller AL, Cosgarea R, Keilig L, Bourauel C, Jepsen S. Biomechanical properties of periodontal tissues in non-periodontitis and periodontitis patients assessed with an intraoral computerized electronic measurement device. Clin Oral Investig 2023; 27:797-805. [PMID: 36625961 PMCID: PMC9889448 DOI: 10.1007/s00784-023-04859-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Accepted: 12/28/2022] [Indexed: 01/11/2023]
Abstract
OBJECTIVE To identify tooth mobility (TM) by time-dependent tooth displacement using an electronic intra-oral loading device (ILD) in periodontally healthy and periodontally compromised patients. MATERIALS AND METHODS Twenty-eight untreated periodontitis and 20 periodontally healthy patients [25 female and 26 male; ages: 20-81 years], contributing with 68 teeth (periodontitis: nteeth = 28; non-periodontitis: nteeth = 40), participated in the study. TM was measured in vivo by displacing central or lateral incisors to a maximum of 0.2 mm orally over durations of 0.5 s, 1 s, and 10 s with the ILD. The maximum force (Fmax) was extracted from the measured force/deflection curves for every single measurement. RESULTS Differences in TM-ILD values were found for periodontitis as compared to non-periodontitis patients derived from the same loading durations (differences of 3.9 (0.5 s), 3.1 (1 s), 2.8 (10 s), (95% CI for 0.5 s (1.2-6.7), p = 0.024; 1 s (1.4-6.0), p = 0.067; 10 s (0.2-5.3), p = 0.001), rejecting the null hypothesis of no difference (T-test) for durations of 0.5 and 10 s. There was a significant correlation of TM-ILD (Fmax) with BOP at 0.5 s (- 0.52) and with attachment loss at all time durations (- 0.47 at 0.5 s; - 0.57 at 1 s; - 0.47 at 10 s). CONCLUSIONS This clinical investigation could demonstrate that time-dependent tooth displacements using a new computerized electronic device were associated with attachment loss and bleeding on probing. CLINICAL RELEVANCE ILD can improve the monitoring of tooth mobility, as TM-ILD values reflect qualitative (inflammatory status interpreted by BOP) and quantitative parameters (interpreted as the amount of CAL loss) of periodontal disease.
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Affiliation(s)
- Karin Jepsen
- Department of Periodontology, Operative and Preventive Dentistry, University Hospital Bonn, Welschnonnenstrasse 17, 53111, Bonn, Germany.
| | - Pia-Merete Jervøe-Storm
- Department of Periodontology, Operative and Preventive Dentistry, University Hospital Bonn, Welschnonnenstrasse 17, 53111, Bonn, Germany
| | - Isabel Henrichs
- Department of Periodontology, Operative and Preventive Dentistry, University Hospital Bonn, Welschnonnenstrasse 17, 53111, Bonn, Germany
| | - Ina Lensing
- Department of Periodontology, Operative and Preventive Dentistry, University Hospital Bonn, Welschnonnenstrasse 17, 53111, Bonn, Germany
| | - Alja Larissa Müller
- Department of Periodontology, Operative and Preventive Dentistry, University Hospital Bonn, Welschnonnenstrasse 17, 53111, Bonn, Germany
| | - Raluca Cosgarea
- Department of Periodontology, Operative and Preventive Dentistry, University Hospital Bonn, Welschnonnenstrasse 17, 53111, Bonn, Germany
- Clinic for Periodontology and Peri-Implant Diseases, Philipps University Marburg, Marburg, Germany
- Clinic of Prosthodontics, Iuliu Hatieganu University Cluj-Napoca, Cluj-Napoca-Napoca, Romania
| | - Ludger Keilig
- Oral Technology, University Hospital Bonn, Bonn, Germany
- Department of Dental Prosthetics, Propaedeutics and Materials Science, University Hospital Bonn, Bonn, Germany
| | | | - Søren Jepsen
- Department of Periodontology, Operative and Preventive Dentistry, University Hospital Bonn, Welschnonnenstrasse 17, 53111, Bonn, Germany
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Söntgen S, Keilig L, Kabir K, Weber A, Reimann S, Welle K, Bourauel C. Mechanical and numerical investigations of biodegradable magnesium alloy screws for fracture treatment. J Biomed Mater Res B Appl Biomater 2023; 111:7-15. [PMID: 35796311 DOI: 10.1002/jbm.b.35127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 06/20/2022] [Accepted: 06/22/2022] [Indexed: 11/11/2022]
Abstract
Small fracture treatment includes the use of so-called "Herbert screws". In the past years, novel resorbable materials were introduced as an alternative to the classical titanium implants. The purpose of this study was to evaluate the influence of ongoing resorption/corrosion processes on the mechanical stability screws made from the magnesium alloy MgYREZr®. Our samples consisted of two partly resorbed screws, explanted due to medical reasons after 6 and 12 weeks, respectively, and five unused reference screws. We performed three-point bending tests to determine the stability of all screws. Additionally, with FE-models of the screws based on μCT-scans, we investigated whether any differences in the bending behavior of the screws can be attributed to the reduction of the material volume due to resorption alone. Both partly resorbed screws failed at a lower force than the reference screws (178.6 ± 5.5 N for the reference screws, 72.5 N and 74.5 N for the screw explanted after 6 and 12 weeks, respectively). FE simulations performed with the three different geometries and original material parameters (Young's modulus Enew = 45 GPa, yield limit σnew = 235 MPa) showed that the early fracture could not be attributed to the changed geometry alone. Material parameters for the partly resorbed screws were determined by fitting the numerical to the experimental force-displacement curves (E6week = 15 GPa, σ6week = 135 MPa and E12week = 8 GPa, σ12week = 135 MPa, respectively). Our results showed that both geometry of the screws and different material properties contribute to the overall stability. Understanding and controlling these two factors throughout the resorption process could enhance treatment options.
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Affiliation(s)
- Sabrina Söntgen
- Oral Technology, Medical Faculty, University of Bonn, Bonn, Germany
| | - Ludger Keilig
- Department of Prosthetic Dentistry, Preclinical Education and Materials Science, Medical Faculty, University of Bonn, Bonn, Germany
| | - Koroush Kabir
- Department of Orthopedic and Trauma Surgery, Medical Faculty, University of Bonn, Bonn, Germany
| | - Anna Weber
- Oral Technology, Medical Faculty, University of Bonn, Bonn, Germany
| | - Susanne Reimann
- Oral Technology, Medical Faculty, University of Bonn, Bonn, Germany
| | - Kristian Welle
- Department of Orthopedic and Trauma Surgery, Medical Faculty, University of Bonn, Bonn, Germany
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Elshazly TM, Bourauel C, Aldesoki M, Ghoneima A, Abuzayda M, Talaat W, Talaat S, Keilig L. Computer-aided finite element model for biomechanical analysis of orthodontic aligners. Clin Oral Investig 2023; 27:115-124. [PMID: 35989373 DOI: 10.1007/s00784-022-04692-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Accepted: 08/15/2022] [Indexed: 02/01/2023]
Abstract
OBJECTIVES To design a finite element (FE) model that might facilitate understanding of the complex mechanical behavior of orthodontic aligners. The designed model was validated by comparing the generated forces - during 0.2-mm facio-lingual translation of upper left central incisor (Tooth 21) - with the values reported by experimental studies in literature. MATERIALS AND METHODS A 3D digital model, obtained from scanning of a typodont of upper jaw, was imported into 3-matic software for designing of aligners with different thicknesses: 0.4, 0.5, 0.6, 0.7 mm. The model was exported to Marc/Mentat FE software. Suitable parameters for FE simulation were selected after a series of sensitivity analyses. Different element classes of the model and different rigidity values of the aligner were also investigated. RESULTS The resultant maximum forces generated on facio-lingual translation of Tooth 21 were within the range of 1.3-18.3 N. The force was direction-dependent, where lingual translation transmitted higher forces than facial translation. The force increases with increasing the thickness of the aligner, but not linearly. We found that the generated forces were almost directly proportional to the rigidity of the aligner. The contact normal stress map showed an uneven but almost repeatable distribution of stresses all over the facial surface and concentration of stresses at specific points. CONCLUSIONS A validated FE model could reveal a lot about mechanical behavior of orthodontic aligners. CLINICAL RELEVANCE Understanding the force systems of clear aligner by means of FE will facilitate better treatment planning and getting optimal outcomes.
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Affiliation(s)
- Tarek M Elshazly
- Oral Technology Department, Dental School, University Hospital Bonn, Welschnonnenstr. 17, 53111, Bonn, Germany.
| | - Christoph Bourauel
- Oral Technology Department, Dental School, University Hospital Bonn, Welschnonnenstr. 17, 53111, Bonn, Germany
| | - Mostafa Aldesoki
- Oral Technology Department, Dental School, University Hospital Bonn, Welschnonnenstr. 17, 53111, Bonn, Germany
| | - Ahmed Ghoneima
- Department of Orthodontics, College of Dental Medicine, MBRU, Dubai, United Arab Emirates
| | - Moosa Abuzayda
- Department of Prosthodontics, College of Dental Medicine, MBRU, Dubai, United Arab Emirates
| | - Wael Talaat
- Department of Oral and Craniofacial Health Sciences, College of Dental Medicine, University of Sharjah, Sharjah, United Arab Emirates.,Department of Oral and Maxillofacial Surgery, Faculty of Dentistry, Suez Canal University, Ismailia, Egypt
| | - Sameh Talaat
- Oral Technology Department, Dental School, University Hospital Bonn, Welschnonnenstr. 17, 53111, Bonn, Germany.,Department of Orthodontics, Future University in Egypt, Cairo, Egypt
| | - Ludger Keilig
- Oral Technology Department, Dental School, University Hospital Bonn, Welschnonnenstr. 17, 53111, Bonn, Germany.,Department of Dental Prosthetics, Propaedeutics and Materials Science, Dental School, University Hospital Bonn, Bonn, Germany
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Singer L, Habib SI, Shalaby HEA, Saniour SH, Bourauel C. Digital assessment of properties of the three different generations of dental elastomeric impression materials. BMC Oral Health 2022; 22:379. [PMID: 36064393 PMCID: PMC9442984 DOI: 10.1186/s12903-022-02419-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Accepted: 08/29/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND This study aimed to compare the dimensional accuracy, hydrophilicity and detail reproduction of the hybrid vinylsiloxnether with polyether and polyvinylsiloxane parent elastomers using modified digital techniques and software. This was done in an attempt to aid in solving the conflict between the different studies published by competitive manufacturers using different common manual approaches. METHODS A polyether, polyvinylsiloxanes and vinyl polyether silicone hybrid elastomeric impression materials were used in the study. Dimensional accuracy was evaluated through taking impressions of a metallic mold with four posts representing a partially edentulous maxillary arch, that were then poured with stone. Accuracy was calculated from the mean of measurements taken between fixed points on the casts using digital single-lens reflex camera to produce high-resolution digital pictures for all the casts with magnification up to 35×. Hydrophilicity was assessed by contact angle measurements using AutoCAD software. The detail reproduction was measured under dry conditions according to ANSI/ADA Standard No. 19 and under wet conditions as per ISO 4823. A metallic mold was used with three V shaped grooves of 20, 50, and 75 µm width. Specimens were prepared and examination was made immediately after setting using digital images at a magnification of 16×. RESULTS The hybrid impression (0.035 mm) material showed significantly higher dimensional accuracy compared to the polyether (0.051 mm) but was not as accurate as the polyvinyl siloxane impression material (0.024 mm). The contact angles of the hybrid material before and after setting was significantly lower than the parent materials. With regard to the detail reproduction, the three tested materials were able precisely to reproduce the three grooves of the mold under dry conditions. Whereas, under wet conditions, the hybrid material showed higher prevalence of well-defined reproduction of details same as polyether but higher than polyvinylsiloxane that showed prevalence of details with loss of sharpness and continuity. CONCLUSIONS The digital technique used could be a more reliable and an easier method for assessment of impression materials properties. The hybridization of polyvinyl siloxane and polyether yielded a promising material that combines the good merits of both materials and overcomes some of their drawbacks.
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Affiliation(s)
- Lamia Singer
- Oral Technology, Medical Faculty, Dental School, University Hospital of Bonn, North Rhine-Westphalia, 53111, Bonn, Germany. .,Department of Orthodontics, Medical Faculty, Dental School, University Hospital of Bonn, North Rhine-Westphalia, 53111, Bonn, Germany.
| | - Shaymaa I Habib
- Dental Biomaterials Department, Faculty of Oral and Dental Medicine, Cairo University, Cairo, Egypt
| | - Heba El-Amin Shalaby
- Dental Biomaterials Department, Faculty of Dentistry, October University for Modern Sciences and Arts, Cairo, Egypt
| | - Sayed H Saniour
- Dental Biomaterials Department, Faculty of Oral and Dental Medicine, Cairo University, Cairo, Egypt.,Dental Biomaterials Department, Faculty of Oral and Dental Medicine, British University in Egypt, Cairo, Egypt
| | - Christoph Bourauel
- Oral Technology, Medical Faculty, Dental School, University Hospital of Bonn, North Rhine-Westphalia, 53111, Bonn, Germany
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Elshazly TM, Keilig L, Salvatori D, Chavanne P, Aldesoki M, Bourauel C. Effect of Trimming Line Design and Edge Extension of Orthodontic Aligners on Force Transmission: An in vitro Study. J Dent 2022; 125:104276. [PMID: 36055460 DOI: 10.1016/j.jdent.2022.104276] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Revised: 08/26/2022] [Accepted: 08/29/2022] [Indexed: 11/29/2022] Open
Abstract
OBJECTIVES To investigate how the stress distribution and forces transmitted from orthodontic aligners to the tooth surface are affected by the geometry and extension of the trimming line. MATERIALS AND METHODS Thirty-six aligners were thermoformed from Zendura FLX sheets (0.75 mm thick) and divided into four groups based on the design of the trimming line: Scalloped, Scalloped extended, Straight and Straight extended. Fuji pressure-sensitive films were used for pressure measurement. The pressurized films were scanned and evaluated. Pressures and forces were measured over the entire facial surface of an upper right central incisor (Tooth 11) and at 7 different locations [cervical, middle, incisal, mesio-incisal, mesio-cervical, disto-cervical, and disto-cervical]. In addition, the thickness of the aligners at these 7 sites was measured with a digital caliper. RESULTS The active force ranged from (2.2 - 6.9) N, and the average pressure was (1.6 - 2.7) MPa. The highest values were recorded for the (straight extended) design, while the lowest values were recorded for the scalloped design. The forces and stresses were not uniformly distributed over the surface. When the values in each area were compared separately, significant differences were found between the different designs in the cervical area, with the scalloped design transmitting the lowest cervical forces. Aligner thickness was drastically reduced (60-75% thinning) over the entire tooth surface after thermoforming. CONCLUSIONS The straight extended design of aligner's trimming line exhibited more uniform force transfer and stress distribution across the surface than the other designs. CLINICAL RELEVANCE The trimming line design could have a significant impact on the clinical outcome of orthodontic aligner treatment.
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Affiliation(s)
- Tarek M Elshazly
- Oral Technology, Dental School, University Hospital Bonn, Bonn, Germany.
| | - Ludger Keilig
- Oral Technology, Dental School, University Hospital Bonn, Bonn, Germany; Department of Dental Prosthetics, Propaedeutics and Materials Science, Dental School, University Hospital Bonn, Bonn, Germany
| | | | | | - Mostafa Aldesoki
- Oral Technology, Dental School, University Hospital Bonn, Bonn, Germany
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Montasser MA, Keilig L, Bourauel C. Change in crown inclination accompanying initial tooth alignment with round archwires. Dental Press J Orthod 2022; 27:e2220489. [PMID: 35792791 PMCID: PMC9255984 DOI: 10.1590/2177-6709.27.3.e2220489.oar] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Accepted: 02/18/2021] [Indexed: 11/22/2022] Open
Abstract
OBJECTIVE To evaluate, in-vitro, the change in crown inclination that occurs during orthodontic leveling and alignment using different archwire-bracket-ligation combinations. MATERIALS AND METHODS Four archwire types were tested: (1) 0.012-in stainless steel and (2) 0.0155-in stainless steel multi-stranded, (3) 0.012-in nitinol Orthonol® and (4) 0.012-in nitinol Thermalloy®. Combinations with five types of 0.022-in slot orthodontic brackets were tested: SmartClipTM and Time3® self-ligating brackets, Mini-Taurus® and Victory SeriesTM conventional brackets, and Synergy® conventional-low friction bracket. Conventional brackets were ligated with both stainless steel and elastomeric ligatures. The simulated malocclusion comprised 2.0mm gingival and 2.0mm labial displacements of a maxillary right central incisor. Rotation around the Y-axis (representing labio-palatal inclination) was measured for the different archwire-bracket-ligation combinations. RESULTS The largest rotation was measured whith Orthonol® and Thermalloy® wires when combined with SmartClipTM brackets (8.07±0.24º and 8.06±0.26º, respectively) and with Synergy® brackets ligated with stainless steel ligatures (8.03±0.49º and 8.0±0.37º, respectively). The lower rotation was recorded when Thermalloy®, multi-stranded, and Orthonol® wires were ligated with elastomeric rings to Mini-Taurus® brackets (1.53±0.18º, 1.65± 0.23º and 1.70±0.28º, respectively) and to Victory SeriesTM brackets (1.68± 0.78º, 2.92± 1.40º and 1.74±0.46º, respectively). CONCLUSIONS All archwire-bracket-ligation combinations produced lingual crown inclination; however, lower changes were observed when the conventional brackets were ligated with elastomeric rings. The multi-stranded archwire produced less rotation with nearly every bracket-ligation combination, compared to the other archwires. The effect of the archwire-bracket-ligation combination on tooth inclination during leveling and alignment should be considered during planning treatment mechanics.
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Affiliation(s)
- Mona A Montasser
- Mansoura University, Faculty of Dentistry, Orthodontic Department (Mansoura/Egypt)
| | - Ludger Keilig
- University of Bonn, Department of Oral Technology, School of Dentistry (Bonn/Germany)
| | - Christoph Bourauel
- University of Bonn, Department of Oral Technology, School of Dentistry (Bonn/Germany)
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Singer L, Bourauel C, Habib SI, Shalaby HEA, Saniour SH. Tear strength and elastic recovery of new generation hybrid elastomeric impression material: A comparative study. BMC Res Notes 2022; 15:224. [PMID: 35761301 PMCID: PMC9235106 DOI: 10.1186/s13104-022-06110-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Accepted: 06/15/2022] [Indexed: 11/16/2022] Open
Abstract
Objective Since there is no material in the market met all the ideal requirements of an impression material, thus in an attempt to find one, hybridization between the two most commonly used impression materials were done. The aim of the hybridization was to obtain a new material combining the good merits of both and eliminate their shortcomings. Thus, this study aimed to assess the impact of hybridization between polyether with addition silicone on tear strength and elastic recovery of the new material and compare such effect with regard to parent materials. Results A polyether (PE), polyvinyl siloxanse (PVS) and vinyl polyether silicone (VPES) hybrid elastomers were used in the present study. Tear strength was measured one hour after setting time of each material according to the manufacturer and the three materials showed statistically comparable tear strength in N/mm. Elastic recovery was evaluated one minute after the setting time recommended by the manufacturer. The three materials were statistically insignificant from each other, and all met the ISO4823 requirement of having greater than 96.5% recovery.
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Affiliation(s)
- Lamia Singer
- Oral Medicine Technology, Dental School, Medical Faculty, University of Bonn, 53111, Bonn, North Rhine-Westphalia, Germany.
| | - Christoph Bourauel
- Oral Medicine Technology, Dental School, Medical Faculty, University of Bonn, 53111, Bonn, North Rhine-Westphalia, Germany
| | - Shaymaa I Habib
- Dental Biomaterials Department, Faculty of Oral and Dental Medicine, Cairo University, Cairo, Egypt
| | - Heba El-Amin Shalaby
- Dental Biomaterials Department, Faculty of Dentistry, October University for Modern Sciences and Arts, Cairo, Egypt
| | - Sayed H Saniour
- Dental Biomaterials Department, Faculty of Oral and Dental Medicine, Cairo University, Cairo, Egypt.,Dental Biomaterials Department, Faculty of Oral and Dental Medicine, British University in Egypt, Cairo, Egypt
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Aldesoki M, Bourauel C, Morsi T, El-Anwar MI, Aboelfadl AK, Elshazly TM. Biomechanical behavior of endodontically treated premolars restored with different endocrown designs: Finite element study. J Mech Behav Biomed Mater 2022; 133:105309. [DOI: 10.1016/j.jmbbm.2022.105309] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Revised: 05/31/2022] [Accepted: 06/02/2022] [Indexed: 10/18/2022]
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Begand S, Spintzyk S, Geis-Gerstorfer J, Bourauel C, Keilig L, Lohbauer U, Worpenberg C, Greuling A, Adjiski R, Jandt KD, Lümkemann N, Stawarczyk B, Güllmar A, Kailer A, Oberle N, Stephan M. Fracture toughness of 3Y-TZP ceramic measured by the Chevron-Notch Beam method: A round-robin study. Dent Mater 2022; 38:1128-1139. [PMID: 35618552 DOI: 10.1016/j.dental.2022.05.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 05/03/2022] [Accepted: 05/03/2022] [Indexed: 11/28/2022]
Abstract
OBJECTIVE This interlaboratory round robin test investigated the robustness of the Chevron-Notch Beam (CNB) test method and the effect of the processing and testing variations on the fracture toughness of a dental 3Y-TZP ceramic. METHODS The round robin test was performed precisely following the procedures recommended in ISO 24370:2005 and applied on a commercial 3Y-TZP ceramic (product information). A total of 335 test specimens with dimensions 3×4 x 45 mm³ was equally distributed among 10 participating laboratories of varying experience in fracture toughness testing. A standard operating procedure was defined with either narrow processing tolerances or alternative (wider) processing tolerances (as proposed in ISO 24370). Fracture toughness data (series 2) was analyzed using one way ANOVA followed by post hoc Tukey HSD test and 95% Confidence Intervals (CI) were computed (p < 0.05). A further, preceding round-robin (series 1) test was conducted with - more possible variations of test conditions regarding CNB notch processing and storage conditions. Those results are summarized in the supplement and discussed with the actual ISO 24370 test. RESULTS Fracture toughness of the 3Y-TZP ceramic material, summarized over all laboratories was measured to KIc = 4.48 ± 0.11 MPam0.5 for the standard processing tolerance and KIc = 4.55 ± 0.31 MPam0.5 for the alternative tolerance. The results revealed a significant influence of cutting offset and notch geometry on KIc when using CNB method. The test medium also has a significant influence on KIc in terms of reduced fracture toughness under the influence of water. With defined testing conditions the number of valid tests and reduced standard deviation increased. In case of strictly following such standard operation procedures, KIc can be determined with high reliability. There is no difference between the involved laboratories, but significant influence of cutting offset on KIC was observed. SIGNIFICANCE The CNB method is suitable method for determination of KIc on fine-grained ceramics such as 3Y-TZP ceramic. By using tighter tolerances for processing and testing, i.e. closely following the ISO 24370 procedure, a highly-precise evaluation of fracture toughness with low data variation is achievable. The information of the storage medium should always be reported along with the data. CNB fracture toughness testing is an alternative method compared to Single-edge V-notch beam (SEVNB), especially for fine-grained ceramics.
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Affiliation(s)
- Sabine Begand
- Fraunhofer Institute for Ceramics Technologies and Systems IKTS, Michael-Faraday-Str. 1, 07629 Hermsdorf, Germany.
| | - Sebastian Spintzyk
- University Hospital Tübingen, Section "Medical Materials Science & Technology", Osianderstr. 2-8, 72076 Tuebingen, Germany
| | - Jürgen Geis-Gerstorfer
- University Hospital Tübingen, Section "Medical Materials Science & Technology", Osianderstr. 2-8, 72076 Tuebingen, Germany
| | - Christoph Bourauel
- University Hospital Bonn, Oral Technology, School of Dentistry, University of Bonn, Welschnonnenstr. 17, 53111 Bonn, Germany
| | - Ludger Keilig
- University Hospital Bonn, Oral Technology, School of Dentistry, University of Bonn, Welschnonnenstr. 17, 53111 Bonn, Germany
| | - Ulrich Lohbauer
- University of Erlangen-Nuremberg, Dental Clinic 1 - Operative Dentistry and Periodontology, Glueckstrasse 11, 91054 Erlangen, Germany
| | - Christin Worpenberg
- Hannover Medical School, Clinic for Dental Prosthetics, Carl-Neuberg-Straße 1, 30625 Hannover, Germany
| | - Andreas Greuling
- Hannover Medical School, Clinic for Dental Prosthetics, Carl-Neuberg-Straße 1, 30625 Hannover, Germany
| | - Ranko Adjiski
- Otto Schott Institute of Materials Research, Friedrich Schiller University Jena, Löbdergraben 32, 07743 Jena, Germany
| | - Klaus D Jandt
- Otto Schott Institute of Materials Research, Friedrich Schiller University Jena, Löbdergraben 32, 07743 Jena, Germany
| | - Nina Lümkemann
- Department of Prosthetic Dentistry, University Hospital, Dental School, Ludwig-Maximilians-University Munich, Goethestraße 70, 80336 Munich, Germany
| | - Bogna Stawarczyk
- Department of Prosthetic Dentistry, University Hospital, Dental School, Ludwig-Maximilians-University Munich, Goethestraße 70, 80336 Munich, Germany
| | - André Güllmar
- University Hospital Jena, Polyclinic for Conservative Dentistry, An der Alten Post, 407743 Jena, Germany
| | - Andreas Kailer
- Fraunhofer IWM, Freiburg, Wöhlerstraße 11, 79108 Freiburg im Breisgau, Germany
| | - Natalie Oberle
- Fraunhofer IWM, Freiburg, Wöhlerstraße 11, 79108 Freiburg im Breisgau, Germany
| | - Marc Stephan
- Materials Competence Center bei Institut Straumann AG, Peter-Merian-Weg 12, CH-4002 Basel, Switzerland
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Bojko J, Khoury M, Masson W, Weber A, Hilgers C, Bourauel C, Steinmetz M, Welle K, Schildberg FA, Kabir K. Erratum: Impact of Long-term, High-fat, and High-calorie Diet on Murine Vertebrae Bones. Z Orthop Unfall 2022; 160:e1. [PMID: 35235974 DOI: 10.1055/a-1770-7268] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- Jessica Bojko
- Clinic for Orthopedics and Trauma Surgery, University Hospital Bonn
| | - Mona Khoury
- Clinic for Orthopedics and Trauma Surgery, University Hospital Bonn
| | - Werner Masson
- Clinic for Orthopedics and Trauma Surgery, University Hospital Bonn
| | - Anna Weber
- Oral Technology, School of Dentistry, University of Bonn
| | - Cäcilia Hilgers
- Clinic for Orthopedics and Trauma Surgery, University Hospital Bonn
| | | | - Martin Steinmetz
- Department of Cardiology, Heart Center Bonn, University Hospital Bonn
| | - Kristian Welle
- Clinic for Orthopedics and Trauma Surgery, University Hospital Bonn
| | | | - Koroush Kabir
- Clinic for Orthopedics and Trauma Surgery, University Hospital Bonn
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Hodecker L, Bourauel C, Braumann B, Kruse T, Christ H, Scharf S. Comparative in vitro analysis of the sliding resistance of a modern 3D-printed polymer bracket in combination with different archwire types. Clin Oral Investig 2022; 26:4049-4057. [PMID: 35092503 PMCID: PMC9072478 DOI: 10.1007/s00784-022-04373-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Accepted: 01/03/2022] [Indexed: 11/10/2022]
Abstract
Objectives To analyse the sliding resistance of a modern 3D-printed polymer bracket combined with different archwire types and to compare the results with conventionally used polymeric, ceramic and metal brackets. It was of further interest which bracket-archwire combination could be best qualified for clinical use. Materials and methods The sliding behaviour was tested using an orthodontic measurement and simulation system (OMSS) for the use of two bracket types of the polymer, ceramic and metal group in combination with a 0.016 inch × 0.022 inch and 0.017 inch × 0.025 inch archwire of nickel-titanium (NiTi), titanium-molybdenum alloy (TMA) and stainless steel. Six bracket types were combined with six different archwire types and compared to each other. Results The sliding resistance showed significant differences between various the bracket-archwire complexes. The combination of 3D-printed polymer brackets with both steel archwire cross-sections showed the least values of sliding resistance (average 23–29%), while the combination of ceramic brackets with TMA archwires presented the highest (average 47%). Conclusions The present study could show that modern 3D-printed bracket materials can have similar or even better mechanical properties than conventional ones regarding sliding resistance. Although the combination of bracket and archwire material is decisive for low sliding resistance values, the selection of the bracket material seems to have a greater influence than the selection of the archwire material or its cross section. Clinical relevance It might be possible in future to combine aesthetic and biomechanical requirements for aesthetic brackets by using 3D-printing technology.
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Johal A, Bourauel C, Moghanchi S, Dickerson T, Gaudin P, Elliott EL. The Tip and Torque adjustable bracket as a new concept in design:. Angle Orthod 2022; 92:380-387. [DOI: 10.2319/061421-474.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Accepted: 11/01/2021] [Indexed: 11/23/2022] Open
Abstract
ABSTRACT
Objectives
To test a new concept in bracket design—the tip and torque adjustable bracket (TTAB)—to identify its integral ability to change both tip and torque.
Materials and Methods
The newly designed TTAB underwent independent testing using the orthodontic measurement and simulation system. The TTAB incorporated Roth tip and torque prescription values, with the unique quality of the bracket to enhance or reduce the innate prescribed values of tip (by either +10° or −10°) and torque (by either +7.5° or −7.5°). The TTAB was tested using both the incorporated standard Roth prescription on the rate of canine retraction (sliding mechanics), using 0.018-inch stainless-steel (SS) arch wire, and with alteration of tip values (−10° and +10°). Similarly, frictional measurements and torque evaluations using 0.019 × 0.025-inch SS arch wire were undertaken with the standard prescription and altered torque (+7.5° and −7.5°). In addition, a number of control investigations were performed. Differences were analyzed using analysis of variance.
Results
The rate of observed tooth movement for the TTAB with its prescribed baseline values was comparable to that of the control brackets. Importantly, the alteration of TTAB tip to −10° and +10° significantly (P < .001) increased and reduced, respectively, the rates of canine retraction. In the alteration of torque, at +7.5° and −7.5°, the bracket delivered a moment of +9.3 (2.8) Nmm and −11.9 (3.8) Nmm, respectively, to the lateral incisor (P < .001).
Conclusions
This in vitro study demonstrates a new concept in preadjusted edgewise bracket design, offering adjustable tip and torque, with the potential for expanded clinical scope.
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