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D'Antò V, Rongo R, Casaburo SD, Martina S, Petrucci P, Keraj K, Valletta R. Predictability of tooth rotations in patients treated with clear aligners. Sci Rep 2024; 14:11348. [PMID: 38762583 PMCID: PMC11102536 DOI: 10.1038/s41598-024-61594-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2023] [Accepted: 05/07/2024] [Indexed: 05/20/2024] Open
Abstract
Clear aligners are employed daily for the treatment of several malocclusions. Previous clinical studies indicated low accuracy for the correction of tooth rotations. The aim of this study was to evaluate the predictability of tooth rotations with clear aligners. The sample comprised 390 teeth (190 mandibular; 200 maxillary), measured from the virtual models of 45 participants (21 men, 24 women; mean age: 29.2 ± 6.6 years old). For each patient, pre-treatment (T0) digital dental models (STL files), virtual plan (T1) and post-treatment digital dental models (T2) of both the mandibular and maxillary arches were imported onto Geomagic Control X, a 3D metrology software which allows angular measurements. Rotations were calculated by defining reproducible vectors for all teeth in each STL file and superimposing both T0 with T1 to determine the prescribed rotation, and T0 with T2 to determine the achieved rotation. Prescribed and achieved rotations were compared to assess movement's accuracy. The Wilcoxon signed-rank test and paired t-test were used to assess differences between the prescribed and achieved movements (P < 0.05). The overall predictability of rotational movement was 78.6% for the mandibular arch and 75.0% for the maxillary arch. Second molar accuracy was the lowest in both arches. Clear aligners were not able to achieve 100% of the planned movements.
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Affiliation(s)
- Vincenzo D'Antò
- Department of Neurosciences, Reproductive Sciences and Oral Sciences, School of Orthodontics, University of Naples Federico II, Via Pansini, 5, 80131, Naples, Italy.
| | - Roberto Rongo
- Department of Neurosciences, Reproductive Sciences and Oral Sciences, School of Orthodontics, University of Naples Federico II, Via Pansini, 5, 80131, Naples, Italy
| | - Sossio Dario Casaburo
- Department of Neurosciences, Reproductive Sciences and Oral Sciences, School of Orthodontics, University of Naples Federico II, Via Pansini, 5, 80131, Naples, Italy
| | - Stefano Martina
- Department of Medicine, Surgery and Dentistry "Scuola Medica Salernitana", University of Salerno, Via Al-Lende, 84081, Baronissi, Italy
| | - Paolo Petrucci
- Department of Neurosciences, Reproductive Sciences and Oral Sciences, School of Orthodontics, University of Naples Federico II, Via Pansini, 5, 80131, Naples, Italy
| | - Kreshnik Keraj
- Department of Prosthodontic, Faculty of Dental Medicine, University of Medicine, Rruga e "Dibrës", AL1005, Tirana, Albania
| | - Rosa Valletta
- Department of Neurosciences, Reproductive Sciences and Oral Sciences, School of Orthodontics, University of Naples Federico II, Via Pansini, 5, 80131, Naples, Italy
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Fausto da Veiga Jardim A, Curado de Freitas J, Estrela C. Surface wear and adhesive failure of resin attachments used in clear aligner orthodontic treatment. J Orofac Orthop 2024; 85:52-62. [PMID: 37314488 DOI: 10.1007/s00056-023-00471-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Accepted: 04/02/2023] [Indexed: 06/15/2023]
Abstract
PURPOSE This study evaluated adhesive and cohesive failures and the surface wear of attachments employed in clear aligner treatment (CAT) using three-dimensional (3D) superimposition. METHODS In all, 3D models of 150 teeth were obtained from intraoral scans from patients undergoing CAT with at least 4 months between each scan. Of the initial sample, 25 teeth were discarded, and 125 teeth were included in the study. Superimpositions of each individual tooth at the first and second time points were made using computer-aided design (CAD) software (Meshmixer; Autodesk, Mill Valley, CA, USA). Analyses were performed to compare surface wear and failures related to type of attachment (optimized/conventional), dental group (molars/premolars/anterior teeth), and arch (mandibular/maxillary). Mann-Whitney and Kruskal-Wallis statistical tests were applied with significance set at 5%. RESULTS More surface wear was observed in conventional attachments, mandibular and anterior teeth with statistical significance for surface wear on the distal surface of conventional attachments (p < 0.05). Cohesive failure was observed in 10% of attachments, occurring most frequently on optimized attachments and molar teeth. Adhesive failure was observed in 10% of the samples, more frequently on conventional attachments and posterior teeth. CONCLUSION Attachment type (conventional vs. optimized) was significantly correlated with surface wear on the distal surface of the attachment. Arch (mandibular or maxillary) and group of teeth (anterior or posterior) showed no correlation with surface wear. Failure, both adhesive and cohesive, correlated with attachment type and group of teeth, but not with the arch in which they were located.
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Affiliation(s)
- Alexandre Fausto da Veiga Jardim
- Department of Stomatologic Sciences, Federal University of Goiás, Av. Universitária, s/n-Setor Leste Universitário, 74605-020, Goiânia, Brazil.
| | - Jairo Curado de Freitas
- Department of Stomatologic Sciences, Federal University of Goiás, Av. Universitária, s/n-Setor Leste Universitário, 74605-020, Goiânia, Brazil
| | - Carlos Estrela
- Department of Stomatologic Sciences, Federal University of Goiás, Av. Universitária, s/n-Setor Leste Universitário, 74605-020, Goiânia, Brazil
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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] [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] [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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Ardila CM, Arrubla-Escobar DE, Vivares-Builes AM. Efficacy of microchips and 3D sensors for orthodontic force measurement: A systematic review of in vitro studies. Orthod Craniofac Res 2024. [PMID: 38372469 DOI: 10.1111/ocr.12768] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2023] [Revised: 01/28/2024] [Accepted: 02/03/2024] [Indexed: 02/20/2024]
Abstract
OBJECTIVE To evaluate the efficacy of microchips and 3D microsensors in the measurement of orthodontic forces. METHODS Through September 2023, comprehensive searches were conducted on PubMed/MEDLINE, SCOPUS and SCIELO without restrictions. RESULTS After removing duplicate entries and applying the eligibility criteria, 23 studies were included for analysis. All the studies were conducted in vitro, and slightly more than half of them were centred on evaluating orthodontic forces exerted by aligners. Eight utilized microchips as measurement tools, while the remaining studies made use of 3D microsensors for their assessments. In the context of fixed appliances, key findings included a high level of agreement in 3-dimensional orthodontic force detection between simulation results and actual applied forces. Incorporating critical force-moment combinations during smart bracket calibration reduced measurement errors for most components. Translational tooth movement revealed a moment-to-force ratio, aligning with the bracket's centre of resistance. The primary findings in relation to aligners revealed several significant factors affecting the forces exerted by them. Notably, the foil thickness and staging were found to have a considerable impact on these forces, with optimal force transmission occurring at a layer height of 150 μm. Furthermore, the type of material used in 3D-printing aligners influenced the force levels, with attachments proving effective in generating extrusive forces. Deliberate adjustments in aligner thickness were observed to alter the forces and moments generated. CONCLUSIONS Microchips and 3D sensors provide precise and quantitative measurements of orthodontic forces in in vitro studies, enabling accurate monitoring and control of tooth movement.
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Affiliation(s)
- Carlos M Ardila
- School of Dentistry, University of Antioquia, Medellín, Colombia
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Khursheed Alam M, Hajeer MY, Shqaidef A, Alswairki HJ, Alfawzan AA, Shrivastava D, Chandan Srivastava K, Cicciù M, Minervini G. Impact of various aligner auxiliaries on orthodontic activity: A systematic review and network meta-analysis. Saudi Dent J 2024; 36:199-207. [PMID: 38419986 PMCID: PMC10897539 DOI: 10.1016/j.sdentj.2023.10.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Revised: 10/18/2023] [Accepted: 10/24/2023] [Indexed: 03/02/2024] Open
Abstract
Background It is imperative to analyze the forces and moments produced by various auxiliaries in order to select the optimal attachments and, eventually, to maximize the efficacy and efficiency of orthodontic therapy. Through this investigation, we aimed to highlight the impact of various aligner auxiliaries on orthodontic activity in patients undergoing orthodontic treatment on a pre/post treatment protocol basis. Methods After a thorough search of the online journals, a total of 482 documents were found using keywords such as "Orthodontic Treatment", "Aligner Auxiliaries", "Elastic Ligatures" and "Tooth Movement." The database research, elimination of duplicate studies, data extraction and risk of bias were performed by the authors independently. This systematic review and network meta-analysis included prospective studies and clinical trials to evaluate research that had looked at the impact of various aligner auxiliaries on orthodontic activity in patients undergoing orthodontic treatment. Results Eight investigations of varying designs were selected for this review. The majority of investigations revealed that aligner auxiliaries significantly improve anterior root torque, rotation, and mesio-distal (M-D) movement, as well as posterior anchoring. They also significantly improved anterior root rotation. However, few studies have presented inconsistent or non-statistically significant findings. Conclusion Auxiliaries for aligners also appear to improve extrusion and other orthodontic movements, but there is insufficient evidence to support these claims. No research has examined posterior bucco-lingual expansion or tilting. Clarification of the effect of attachments and their related variables requires additional clinical investigations.
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Affiliation(s)
- Mohammad Khursheed Alam
- Orthodontic Division, Preventive Dentistry Department, College of Dentistry, Jouf University, Sakaka 72345, Saudi Arabia
- Department of Dental Research Cell, Saveetha Dental College and Hospitals, Saveetha Institute of Medical and Technical Sciences, Chennai, India
- Department of Public Health, Faculty of Allied Health Sciences, Daffodil International University, Dhaka, Bangladesh
| | - Mohammad Younis Hajeer
- Department of Orthodontics, University of Damascus Faculty of Dentistry, Damascus, Syria
| | - Abedalrahman Shqaidef
- Department of Clinical Sciences, Center of Medical and Bio-Allied Health Sciences Research, College of Dentistry, Ajman University, Ajman, United Arab Emirates
| | | | - Ahmed Ali Alfawzan
- Department of Preventive Dentistry, College of Dentistry in Ar Rass, Qassim University, Ar Rass 52571, Saudi Arabia
| | - Deepti Shrivastava
- Periodontics Division, Preventive Dentistry Department, College of Dentistry, Jouf University, Sakaka 72345, Saudi Arabia
| | - Kumar Chandan Srivastava
- Department of Oral & Maxillofacial Surgery & Diagnostic Sciences, College of Dentistry, Jouf University, Sakaka 72345, Saudi Arabia
- Department of Oral Medicine and Radiology, Saveetha Dental College, Saveetha Institute of Medical and Technical Sciences, Saveetha University, Chennai 602105, India
| | - Marco Cicciù
- Department of Biomedical and Surgical and Biomedical Sciences, Catania University, 95123 Catania, Italy
| | - Giuseppe Minervini
- Saveetha Dental College & Hospitals, Saveetha Institute of Medical & Technical Sciences, Saveetha University, Chennai 600 077, India
- Multidisciplinary Department of Medical-Surgical and Dental Specialties, University of Campania, Luigi Vanvitelli, 80138 Naples, Italy
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Spanier C, Schwahn C, Krey KF, Ratzmann A. Fused filament fabrication (FFF): influence of layer height on forces and moments delivered by aligners-an in vitro study. Clin Oral Investig 2023; 27:2163-2173. [PMID: 36790628 PMCID: PMC10159977 DOI: 10.1007/s00784-023-04912-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Accepted: 02/03/2023] [Indexed: 02/16/2023]
Abstract
OBJECTIVES To investigate the effect of layer height of FFF-printed models on aligner force transmission to a second maxillary premolar during buccal torquing, distalization, extrusion, and rotation using differing foil thicknesses. MATERIALS AND METHODS Utilizing OnyxCeph3™ Lab (Image Instruments GmbH, Chemnitz, Germany, Release Version 3.2.185), the following movements were programmed for the second premolar: buccal torque (0.1-0.5 mm), distalization (0.1-0.4 mm), extrusion (0.1-0.4 mm), rotation (0.1-0.5 mm), and staging 0.1 mm. Via FFF, 91 maxillary models were printed for each staging at different layer heights (100 µm, 150 µm, 200 µm, 250 µm, 300 µm). Hence, 182 aligners, made of polyethylene terephthalate glycol (PET-G) with two thicknesses (0.5 mm and 0.75 mm), were prepared. The test setup comprised an acrylic maxillary model with the second premolar separated and mounted on a sensor, measuring initial forces and moments exerted by the aligners. A generalized linear model for the gamma distribution was applied, evaluating the significance of the factors layer height, type of movement, aligner thickness, and staging on aligner force transmission. RESULTS Foil thickness and staging were found to have a significant influence on forces delivered by aligners, whereas no significance was determined for layer height and type of movement. Nevertheless, at a layer height of 150 µm, the most appropriate force transmission was observed. CONCLUSIONS Printing aligner models at particularly low layer heights leads to uneconomically high print time without perceptible better force delivery properties, whereas higher layer heights provoke higher unpredictability of forces due to scattering. A z-resolution of 150 µm appears ideal for in-office aligner production combining advantages of economic print time and optimal force transmission.
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Affiliation(s)
- Claudia Spanier
- Department of Orthodontics and Craniofacial Orthopedics, University Medicine Greifswald, 17475, Greifswald, Germany
| | - Christian Schwahn
- Department for Prosthodontics, Gerostomatology and Biomaterials, University Medicine Greifswald, Greifswald, Germany
| | - Karl-Friedrich Krey
- Department of Orthodontics and Craniofacial Orthopedics, University Medicine Greifswald, 17475, Greifswald, Germany.
| | - Anja Ratzmann
- Department of Orthodontics and Craniofacial Orthopedics, University Medicine Greifswald, 17475, Greifswald, 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] [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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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] [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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Wang Q, Dai D, Wang J, Chen Y, Zhang C. Biomechanical analysis of effective mandibular en-masse retraction using Class II elastics with a clear aligner: a finite element study. Prog Orthod 2022; 23:23. [PMID: 35811318 PMCID: PMC9271451 DOI: 10.1186/s40510-022-00417-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Accepted: 05/05/2022] [Indexed: 11/13/2022] Open
Abstract
Background This study aimed to evaluate the displacement and stress distribution of mandibular dentition by various positions of the Class II elastics during en-masse retraction in clear aligner therapy. Methods Models including a mandibular dentition (without first premolars), periodontal ligament (PDL), mandible, as well as attachments, aligners and buttons were constructed and imported into Ansys Workbench 2019 (ANSYS, USA) to generate the three-dimensional (3D) finite element model. Six combinations were created: (1) aligner alone (control), (2)-(5) Class II elastics with buttons placed on the mesiobuccal (MB), distobuccal (DB), mesiolingual (ML) and distolingual (DL) surface of the mandibular first molar, and (6) Class II elastics with a button on the aligner corresponding to the mesiobuccal surface of the mandibular first molar (AMB). The elastic force was set to 2 N for simulations. Results The central incisors appeared lingual tipping in the six models. The lingual crown movement of the central incisors was 0.039 mm, 0.034 mm, 0.034 mm, 0.042 mm, 0.041 mm, and 0.034 mm for control model, MB model, DB model, ML model, DL model, and AMB model, respectively. The first molars showed mesial tipping in the six models. The mesial movement of the mesiobuccal cusps of the first molars was 0.045 mm, 0.060 mm, 0.063 mm, 0.048 mm, 0.051 mm, and 0.055 mm for control model, MB model, DB model, ML model, DL model, and AMB model, respectively. Conclusions Class II elastics reduced lingual tipping of anterior teeth but aggravated mesial tipping of posterior teeth. Mesiolingual elastics developed minimum mesial tipping of the posterior teeth. When Class II elastics are required, attaching elastics on the mesiolingual surface of the mandibular first molar is recommended to prevent mandibular anchorage loss.
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Nowak CM, Othman A, Ströbele DA, von See C. Comparative mechanical testing for different orthodontic aligner materials over time - in vitro study. J Clin Exp Dent 2022; 14:e457-e463. [PMID: 35765355 PMCID: PMC9233917 DOI: 10.4317/jced.59569] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Accepted: 04/11/2022] [Indexed: 11/08/2022] Open
Abstract
Background The purpose of the present study is to mechanically evaluate and compare the forces over 12 hours on different orthodontic aligners manufactured by Polyethylene terephthalate glycol (PETG).
Material and Methods Twelve orthodontic aligner specimens will be produced by a thermoforming laboratory vacuum machine. All specimens will be divided into two equal groups, group A representing Duran (Scheu Dental GmbH, Iserlohn, Germany) and group B representing Erkodur (Erkodent, Pfalzgrafenweiler, Germany). These specimens will be fabricated via CAD/CAM technology by scanning a Frasaco model (Henry Schein Dental, Gallin, Germany) using D 800 (3Shape, Copenhagen, Denmark) and printed via a Varseo S machine using Varseo ModelWax material (BEGO, Bremen, Germany). Group A specimens are manufactured by a Twinster thermoforming machine (Scheu Dental GmbH, Iserlohn, Germany) while group B is produced using Erkoform thermoforming machine (Erkodent, Pfalzgrafenweiler, Germany). Afterwards, a tooth will be removed from the printed model and replaced by an ivory tooth (Henry Schein Dental, Gallin, Germany) to apply forces at a predicted measured centre of resistance. The universal testing machine Z010 (ZwickRoell, Ulm, Germany) will be used for mechanical testing with 0.3 mm displacement over 12 hours. Statistical analysis was performed using Sigmaplot 13.0 (Systat Software GmbH, Erkrath, Germany). Behaviours over time were analysed using R2-regression analysis (SPSS 26.0, IBM SPSS Statistics, Armonk, USA).
Results There is no statistically significant difference in the maximum force between both groups (p=0.071). The mechanical testing over 12 hours showed cubic properties.
Conclusions The PETG material has no influence on the produced mechanical forces regardless of the manufacturing company. The forces over time showed no tendency towards a lower boundary of force. Key words:Mechanical testing, CAD/CAM, orthodontics, thermoplastic aligner materials.
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Affiliation(s)
- Clara-Marie Nowak
- Researcher in the digital technologies in dentistry and CAD/CAM department- Danube Private University- Austria
| | - Ahmed Othman
- Assistant Professor, Research Center for Digital Technologies in Dentistry and CAD/CAM, Department of Dentistry, Faculty of Medicine and Dentistry, Danube Private University, 3500 Krems, Austria
| | - Dragan-Alexander Ströbele
- Researcher in the digital technologies in dentistry and CAD/CAM department- Danube Private University- Austria
| | - Constantin von See
- Professor and Director of Research Center for Digital Technologies in Dentistry and CAD/CAM, Department of Dentistry, Faculty of Medicine and Dentistry, Danube Private University, 3500 Krems, Austria
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12
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Ferlias N, Dalstra M, Cornelis MA, Cattaneo PM. In Vitro Comparison of Different Invisalign® and 3Shape® Attachment Shapes to Control Premolar Rotation. Front Bioeng Biotechnol 2022; 10:840622. [PMID: 35372304 PMCID: PMC8966893 DOI: 10.3389/fbioe.2022.840622] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Accepted: 02/02/2022] [Indexed: 11/13/2022] Open
Abstract
Aim: To evaluate in vitro the differences of various Invisalign® attachments in their effectiveness during derotation of an upper second premolar in terms of forces and moments created and compare them to the 3Shape® box attachment as well as to no attachment at all.Materials and Methods: A Force System Identification (FSI) machine, comprising two load sensors, was used in this study. Sensor 1 was connected to the test tooth (i.e. upper second premolar) carrying a different attachment design, and the fixed sensor (Sensor 2) was connected to the base model. Once the corresponding aligner was passively seated on the teeth, 12 different setups (i.e. 11 different attachments and one setup with no attachment at all) were tested by rotating the test tooth 4.5° mesially and 4.5° distally, in increments of 0.45°.Results: The vertical rectangular attachments were able to generate the highest derotational moment on both mesial and distal rotations but also received the most side effects (intrusive force, torque, and tipping). The no-attachment setup performed least favorably in terms of derotational ability but exhibited the least side effects. In the y-axis, all attachments received a buccal root torque with a lingual force during disto-rotation and a lingual root torque with a buccal force during mesio-rotation.Conclusion: Attachments are necessary for derotating an upper second premolar. An aligner incremental change of more than 1° derotation can generate high moments. The vertical rectangular attachments perform best in derotations; however, they exhibit the most side effects. Finally, despite presenting the least side effects, derotation of a premolar with no attachment is not as efficient.
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Affiliation(s)
- Nikolaos Ferlias
- Section of Orthodontics, Department of Dentistry and Oral Health, Aarhus University, Aarhus, Denmark
- *Correspondence: Nikolaos Ferlias,
| | - Michel Dalstra
- Section of Orthodontics, Department of Dentistry and Oral Health, Aarhus University, Aarhus, Denmark
| | - Marie A. Cornelis
- Melbourne Dental School, Faculty of Medicine, Dentistry and Health Sciences, The University of Melbourne, Melbourne, VIC, Australia
| | - Paolo M. Cattaneo
- Melbourne Dental School, Faculty of Medicine, Dentistry and Health Sciences, The University of Melbourne, Melbourne, VIC, Australia
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13
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Performance of Rigid and Soft Transfer Templates Using Viscous and Fluid Resin-Based Composites in the Attachment Bonding Process of Clear Aligners. Int J Dent 2022; 2022:1637594. [PMID: 35190741 PMCID: PMC8858075 DOI: 10.1155/2022/1637594] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2021] [Revised: 01/09/2022] [Accepted: 01/17/2022] [Indexed: 12/17/2022] Open
Abstract
Objectives The study aims at assessing the accuracy of the process of attachment bonding in aligner treatments. The analysis leads to the error estimation in the faithful reproduction of master model attachments using two types of transfer templates and two light-curing resin-based composites usually used in orthodontics. Methods The authors have used two transfer templates made of two different materials. The first, named Leone-biocompatible thermoforming material hard/soft, has a lower Young's modulus and is labelled as soft, while the other, named Leone-biocompatible thermoforming material, is marked as rigid. The resin-based composites possess different mechanical and rheological properties. Specifically, Transbond™ XT Light Cure Paste Adhesive, 3M has a higher viscosity than the TetricEvoflow, Ivoclar Vivadent, a flowable nanohybrid composite. The authors attempt to estimate the performance ranking between the four possible couples obtained by combining the two light-curing resin-based composites and transfer templates. Each combination was repeated in six models and compared with twelve master models, resulting in 36 total samples. A 3-D laser scanner is used to generate a digital model of each model. The comparison between digital models is the base for a comparative assessment in terms of relative and absolute error. The relative error is estimated using scalar performance indicators ranging from 0 to 1, where 1 indicates the optimum matching. The absolute error estimated from the mean square error between the coordinates of each digital model yields the reproduction accuracy in micrometer. Furthermore, the authors attempted to assess the error distribution by evaluating the point-by-point difference between the digital models. Results This analysis aims at localizing the sources of error in the considered models. The use of Transbond™ XT Light Cure Paste Adhesive, 3M with a rigid transfer template is always associated with significant accuracy and minor dispersion. However, in a few instances, using the soft template or the flowable resin-based composite can lead to bad performances. Significance. The data processing bestowed the following performance ranking from the first with lower reproduction error to the last characterized by the worst performance: (1) attachments bonding with rigid template and Transbond™ XT Light Cure Paste Adhesive, 3M, (2) attachments bonding with soft template and Transbond™ XT Light Cure Paste Adhesive, 3M, (3) attachments bonding with rigid template and TetricEvoflow, Ivoclar Vivadent, and (4) attachments bonding with soft template and TetricEvoflow, Ivoclar Vivadent.
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14
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Nucera R, Dolci C, Bellocchio AM, Costa S, Barbera S, Rustico L, Farronato M, Militi A, Portelli M. Effects of Composite Attachments on Orthodontic Clear Aligners Therapy: A Systematic Review. MATERIALS 2022; 15:ma15020533. [PMID: 35057250 PMCID: PMC8778413 DOI: 10.3390/ma15020533] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/16/2021] [Revised: 12/20/2021] [Accepted: 01/04/2022] [Indexed: 12/26/2022]
Abstract
This systematic review aims to highlight the differences between different clear aligner therapies that differ in the presence of attachments or in attachment configuration. Eight electronic databases were searched up to March 2020. Two authors independently proceeded to study selection, data extraction, and risk of bias assessment. The analysis of the results was carried out examining six groups of movements (mesio-distal tipping/bodily movement; anterior bucco-lingual tipping/root torque; posterior bucco-lingual tipping/expansion; intrusion; extrusion; rotation). Five clinical trials were selected and all of them showed a medium risk of bias. Literature showed that attachments mostly increase the effectiveness of orthodontic treatment with clear aligners, improving anterior root torque, rotation, and mesio-distal (M-D) movement; they are also important to increase posterior anchorage. However, some articles showed contradictory or not statistically significant results. Attachments also seem to improve intrusion, but the evidence about this movement, as well as extrusion, is lacking. No studies evaluated posterior bucco-lingual tipping/expansion. Further clinical trials are strongly suggested to clarify the influence of attachments and their number, size, shape, and position on each orthodontic movement.
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Affiliation(s)
- Riccardo Nucera
- Department of Biomedical and Dental Sciences and Morphofunctional Imaging, Section of Orthodontics, University of Messina, 98125 Messina, Italy; (R.N.); (A.M.B.); (S.C.); (S.B.); (L.R.); (A.M.)
| | - Carolina Dolci
- Department of Biomedical, Surgical and Dental Sciences, Fondazione IRCCS Cà Granda—Ospedale Maggiore Policlinico, University of Milan, 20122 Milan, Italy; (C.D.); (M.F.)
| | - Angela Mirea Bellocchio
- Department of Biomedical and Dental Sciences and Morphofunctional Imaging, Section of Orthodontics, University of Messina, 98125 Messina, Italy; (R.N.); (A.M.B.); (S.C.); (S.B.); (L.R.); (A.M.)
| | - Stefania Costa
- Department of Biomedical and Dental Sciences and Morphofunctional Imaging, Section of Orthodontics, University of Messina, 98125 Messina, Italy; (R.N.); (A.M.B.); (S.C.); (S.B.); (L.R.); (A.M.)
| | - Serena Barbera
- Department of Biomedical and Dental Sciences and Morphofunctional Imaging, Section of Orthodontics, University of Messina, 98125 Messina, Italy; (R.N.); (A.M.B.); (S.C.); (S.B.); (L.R.); (A.M.)
| | - Lorenzo Rustico
- Department of Biomedical and Dental Sciences and Morphofunctional Imaging, Section of Orthodontics, University of Messina, 98125 Messina, Italy; (R.N.); (A.M.B.); (S.C.); (S.B.); (L.R.); (A.M.)
| | - Marco Farronato
- Department of Biomedical, Surgical and Dental Sciences, Fondazione IRCCS Cà Granda—Ospedale Maggiore Policlinico, University of Milan, 20122 Milan, Italy; (C.D.); (M.F.)
| | - Angela Militi
- Department of Biomedical and Dental Sciences and Morphofunctional Imaging, Section of Orthodontics, University of Messina, 98125 Messina, Italy; (R.N.); (A.M.B.); (S.C.); (S.B.); (L.R.); (A.M.)
| | - Marco Portelli
- Department of Biomedical and Dental Sciences and Morphofunctional Imaging, Section of Orthodontics, University of Messina, 98125 Messina, Italy; (R.N.); (A.M.B.); (S.C.); (S.B.); (L.R.); (A.M.)
- Correspondence: ; Tel.: +39-0902216905
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15
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Koletsi D, Iliadi A, Eliades T. Predictability of rotational tooth movement with orthodontic aligners comparing software-based and achieved data: A systematic review and meta-analysis of observational studies. J Orthod 2021; 48:277-287. [PMID: 34176358 PMCID: PMC8385585 DOI: 10.1177/14653125211027266] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
OBJECTIVE To evaluate all available evidence on the prediction of rotational tooth movements with aligners. DATA SOURCES Seven databases of published and unpublished literature were searched up to 4 August 2020 for eligible studies. DATA SELECTION Studies were deemed eligible if they included evaluation of rotational tooth movement with any type of aligner, through the comparison of software-based and actually achieved data after patient treatment. DATA EXTRACTION AND DATA SYNTHESIS Data extraction was done independently and in duplicate and risk of bias assessment was performed with the use of the QUADAS-2 tool. Random effects meta-analyses with effect sizes and their 95% confidence intervals (CIs) were performed and the quality of the evidence was assessed through GRADE. RESULTS Seven articles were included in the qualitative synthesis, of which three contributed to meta-analyses. Overall results revealed a non-accurate prediction of the outcome for the software-based data, irrespective of the use of attachments or interproximal enamel reduction (IPR). Maxillary canines demonstrated the lowest percentage accuracy for rotational tooth movement (three studies: effect size = 47.9%; 95% CI = 27.2-69.5; P < 0.001), although high levels of heterogeneity were identified (I2: 86.9%; P < 0.001). Contrary, mandibular incisors presented the highest percentage accuracy for predicted rotational movement (two studies: effect size = 70.7%; 95% CI = 58.9-82.5; P < 0.001; I2: 0.0%; P = 0.48). Risk of bias was unclear to low overall, while quality of the evidence ranged from low to moderate. CONCLUSION Allowing for all identified caveats, prediction of rotational tooth movements with aligner treatment does not appear accurate, especially for canines. Careful selection of patients and malocclusions for aligner treatment decisions remain challenging.
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Affiliation(s)
- Despina Koletsi
- Clinic of Orthodontics and Pediatric Dentistry, Center of Dental Medicine, University of Zurich, Zurich, Switzerland
| | - Anna Iliadi
- Department of Dental Biomaterials, School of Dentistry, National and Kapodistrian University of Athens, Attica, Greece
| | - Theodore Eliades
- Clinic of Orthodontics and Pediatric Dentistry, Center of Dental Medicine, University of Zurich, Zurich, Switzerland
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Lin S, Huang L, Li J, Wen J, Mei L, Xu H, Zhang L, Li H. Assessment of preparation time and 1-year Invisalign aligner attachment survival using flowable and packable composites. Angle Orthod 2021; 91:583-589. [PMID: 33848325 DOI: 10.2319/063020-598.1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Accepted: 12/01/2020] [Indexed: 11/23/2022] Open
Abstract
OBJECTIVES To compare preparation time and 1-year Invisalign aligner attachment survival between a flowable composite (FC) and a packable composite (PC). MATERIALS AND METHODS Fifty-five participants (13 men and 42 women, mean age ± SD: 24.2 ± 5.9 years) were included in the study. Ipsilateral quadrants (ie, maxillary and mandibular right, or vice versa) of attachments were randomly assigned to the FC group (Filtek Z350XT Flowable Restorative) and the PC group (Filtek Z350XT Universal Restorative) by tossing a coin. The primary outcome was preparation time. The secondary outcome was time to the first damage of an attachment. Preparation times were compared using the paired t-test, and the survival data were analyzed by the Cox proportional hazards model with a shared frailty term, with α = .05. RESULTS The preparation times were significantly shorter with the FC (6.22 ± 0.22 seconds per attachment) than with the PC (32.83 ± 2.16 seconds per attachment; P < .001). The attachment damage rates were 14.79% for the FC and 9.70% for the PC. According to the Cox models, attachment damage was not significantly affected by the attachment material, sex, arch, tooth location, attachment type, presence of overbite, or occurrence of tooth extraction. CONCLUSIONS The use of a FC may save time as compared with the use of a PC. With regard to attachment survival, there was no significant difference between the two composites. None of the covariates of attachment materials (sex, arch, tooth location, attachment type, presence of overbite, oir occurrence of tooth extraction) affected attachment damage.
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