Novel porcelain laminate preparation approach driven by a diagnostic mock-up

A hybrid workflow for fabricating diagnostic trial restorations using a two-piece additively manufactured index

The accuracy of diagnostic trial restorations depends on the rigidity of the restoration index. However, as the index becomes stiffer, its removal from the mouth without the detachment of the underlying trial restoration can be challenging, especially in patients where a diagnostic trial restoration is required for a complete arch rehabilitation. The present manuscript describes a step-by-step hybrid technique to transfer the virtual diagnostic waxing into the patient's mouth by using a 2-piece index. An additively manufactured custom tray relined on a diagnostically waxed cast using polyvinyl siloxane material is used to fabricate a silicone index. The presented technique provides an index with higher rigidity and uniformity compared with conventional methods, enabling sequential removal after the polymerization of the resin interim material.

Comparisons of analog and digital methods to produce an accurate trial restoration

STATEMENT OF PROBLEM

A trial restoration is an important diagnostic tool that can be fabricated through analog or digital pathways. Digital workflows may have improved accuracy, but this is yet to be demonstrated conclusively.

PURPOSE

The purpose of this in vitro study was to compare the dimensional accuracy of trial restorations produced by different analog (molded) and digital (milled and 3D printed) methods. Parameters studied included fabrication methods, Shore-A hardness of silicone putty indices, length of span, and labial tooth levels.

MATERIAL AND METHODS

Digital additive trial restorations were designed on a single virtual cast from maxillary right to left lateral incisor teeth (4 teeth) and from maxillary right to left first premolar teeth (8 teeth). Both designs were identical on the 4 anterior teeth. Each digital trial restoration was 3-dimensionally (3D) printed to produce reference casts. The original cast was 3D printed to produce 44 replica casts. There were 8 experimental groups (4 analog and 4 digital) with 10 specimens each. For the analog groups, 20 silicone indices per reference cast were made: 10 from standard silicone putty (63 to 70 Shore-A hardness) and 10 from hard silicone putty (90 Shore-A hardness). The analog trial restorations were molded on replica casts with silicone indices and bis-acryl resin. The digital trial restorations were either milled or 3D printed and adapted onto replica casts. Each trial restoration was scanned and digitally superimposed onto respective scanned reference casts. Measurements were recorded at 3 levels: cervical, middle, and incisal. The independent samples Kruskal-Wallis, 2-sample Mann-Whitney, and Bonferroni tests were used to compare the distribution of accuracy among all groups (α=.05).

RESULTS

The dimensional accuracy of the different trial restoration fabrication methods was comparable in terms of median values of trueness (how close the readings were to the reference), and no statistically significant difference was found among them (P>.05). When the dimensional accuracy in terms of precision (how close the readings were to each other) were analyzed, the hard putty groups demonstrated a statistically significant better outcome, whereas standard putty consistently showed the poorest result. The incisal level displayed the most significant deviation (P=.005) when all groups were compared. The incisal discrepancy values of the short-span standard putty trial restoration varied by as much as 0.84 mm in some specimens.

CONCLUSIONS

Milled and 3D printed trial restoration fabrication techniques showed dimensional accuracy comparable with that of the analog groups. However, the choice of silicone putty was shown to affect the dimensional accuracy of an analog molded trial restoration. A high Shore-A hardness silicone putty produced the best precision and should be used when fabricating an analog molded trial restoration.

A completely digital workflow to fabricate a double-layered template for anterior esthetic veneers

In the esthetic restoration of anterior teeth, trial restorations are an efficient way of communicating among patients, doctors, and dental laboratory technicians. Although the development of digital technologies has made it popular to design digital diagnostic waxing in a software program, problems such as the polymerization inhibition of silicone materials and time-consuming trimming remain. The silicone mold based on a 3-dimensionally printed resin cast still has to be transferred to the digital diagnostic waxing and to the patient's mouth to generate a trial restoration. A digital workflow is proposed to fabricate a double-layer guide to reproduce the digital diagnostic waxing in the patient's mouth. This technique is suitable for esthetic restorations of anterior teeth.

A fully digital workflow involving 3D printed tooth reduction guides and injection resin-indexes to restore an impacted canine

OBJECTIVE

The present clinical report describes a long-term temporary restorative approach using injectable composite to reshape a canine into a central incisor, within the context of an ongoing orthodontic treatment. This treatment protocol describes a fully-digital workflow, incorporating digital designed and 3D printed diagnostic wax up, reduction guides and resin-injection index.

CLINICAL CONSIDERATIONS

Effective planning is important when aiming to deliver a comprehensive and multidisciplinary workflow, and digital tools serve as invaluable aids.

CONCLUSION

The use of a fully digital workflow in a comprehensive dental treatment resulted in a predictable and successful outcome for a restoration of a canine that was transformed into a central incisor.

CLINICAL SIGNIFICANCE

This approach highlights the efficacy of digital technology in achieving precise and successful dental restorations, emphasizing its significance in modern dental practice.

Three Dimensional-Printed Gingivectomy and Tooth Reduction Guides Prior Ceramic Restorations: A Case Report

Computer-aided design and computer-aided manufacturing (CAD/CAM) dentistry have significantly changed workflows in recent years. Restorations and devices can now be digitally designed and 3D-printed for dental care purposes. This clinical case report provides straightforward protocols for the digital design and 3D manufacture of gingivectomy and tooth preparation guides. These types of guides improved the gingival architecture of the anterior teeth and provided controllable tooth preparations prior to labial ceramic veneers. Thoughtful clinical evaluation started with listening to the patient's chief complaint and extra- and intra-oral evaluations. Then a digital wax-up was performed, followed by an intra-oral mock-up, to evaluate the shape of the proposed restorations. After patient acceptance, the clinical procedure started with the gingivectomy and tooth preparation. Hand-crafted porcelain veneers were bonded under rubber dam isolation to avoid any contamination and maximize the bonding protocol. The esthetic and functional demands were fully satisfied. Predictable outcomes can be obtained whenever a meticulous evaluation and execution of all the steps are performed. Three dimensional printing technology allows the fabrication of devices such as gingivectomy and tooth reduction guides that help accomplish the desired results.

Freehand vs. depth-gauge rotary instruments for veneer preparation: A controlled randomized simulator study

PURPOSE

To investigate whether depth-gauge burs in veneer preparations influence preparation depth in a randomized, controlled, single-blinded trial and whether inexperienced operators can perform adequate veneer preparations.

METHODS

Participants were 20 undergraduate dental students with no prior veneer preparation experience. The instruments used were the "Laminate Veneer System" (LVS), "Keramik-Veneers. de" (KVD), and a "Freehand" group (FH) for reference. All participants prepared three educational acrylic resin maxillae and three mandibular central incisors mounted in typodonts in patient simulators. The objectives were to achieve a preparation depth of 0.6 mm (tooth 11) and 0.4 mm (tooth 31). The sequences of the instruments used and prepared teeth were randomized. The measurements were performed using a laser triangulation coordinate-measuring machine. The data were stratified according to tooth location.

RESULTS

The preparation depths of both depth-gauge-instrument-groups LVS and KVD achieved the objectives significantly better than did the instruments from the "Freehand" group (P < 0.001). The differences between the depth gauge groups were insignificant, although the maximum preparation depths were smaller in the KVD group. Regarding the prepared teeth, the preparation depths in the mandibular incisors were lower, and the differences were smaller.

CONCLUSIONS

The use of special depth-gauge burs for initial veneer preparation leads to significantly lower preparation depths than "Freehand" preparations. The tapered instruments resulted in a lower incidence of extreme preparation depths. The inexperienced operators performed veneer preparation remarkably well.

Esthetic integration area concept in digitally guided veneer rehabilitation: A dental technique

Computer-aided design and computer-aided manufacturing (CAD-CAM) technologies have been integrated into the dental digital workflow. However, pretreatment virtual veneer preparations and the digital design and manufacturing of guided preparation and cementation templates has not yet been incorporated into the clinical routine. This article presents a novel protocol for digitally guided veneer rehabilitation by following the esthetic integration area concept, facilitating precise control over tooth structure removal and obviating the need for interim restorations.

Digitally designed and additively manufactured tooth reduction guides for porcelain laminate veneer preparations: A clinical report

Porcelain laminate veneers are a conservative treatment to enhance esthetics, tooth shape, color, and contours. Enamel preservation during tooth preparation is essential for the long-term success of these micromechanically retained partial coverage restorations. Different methods have been described to clinically assess tooth preparation relative to definitive restorative contours. This clinical report describes a digital workflow to fabricate 3-dimensionally (3D) printed tooth reduction guides based on digital esthetic planning. These 3D printed reduction guides help clinicians visualize and gauge tooth preparations relative to the desired restorative contours, aid in enamel preservation, and overcome some of the limitations associated with conventionally fabricated tooth reduction guides.

A comparative study of the use of digital technology in the anterior smile experience

OBJECTIVES

this study aims to compare the clinical outcomes of traditional and digital crown extension guides in the aesthetic restoration of anterior teeth. Additionally, the study will analyze the differences in the results of various digital crown extension guides in anterior aesthetic restorations.

METHODS

Sixty-two patients who required aesthetic restoration of their anterior teeth were selected for this study. The patients had a total of 230 anterior teeth and were randomly divided into three groups: a control group of 22 cases who received diagnostic wax-up with pressure film, an experimental group 1 of 20 cases who received 3D printed digital models with pressure film, and an experimental group 2 of 20 patients who received digital dual-positioning guides. The control group had a total of 84 anterior teeth, experimental group 1 had 72 anterior teeth, and experimental group 2 had 74 anterior teeth. The study compared three methods for fabricating crown extension guides: the control group used the diagnostic wax-up plus compression film method, while experimental group 1 used compression film on 3D printed models and experimental group 2 used 3D printed digital dual-positioning crown extension guides. After the crown lengthening surgery, the control group patients wore DMG resin temporary crown material for gingival contouring, while the experimental group patients wore 3D printed resin temporary crowns for the same purpose. The patients were followed up in the outpatient clinic after wearing temporary crowns for 1 month, 3 months, and 6 months, respectively. The clinical results were evaluated in terms of marginal fit, red aesthetic index, and white aesthetic index.

RESULTS

Based on the statistical analysis, the experimental group required significantly fewer follow-up visits and less time for guide design and fabrication compared to the control group. Additionally, the surgical time for the experimental group was significantly shorter than that of the control group. During the postoperative period between the 1st and 3rd month, the PES index scores for the marginal gingival level, proximal, and distal mesiodistal gingival papillae of the experimental group showed a trend of superiority over those of the control group. By the 6th month, the marginal gingival level exhibited a significant difference between the experimental and control groups. The experimental group demonstrated superior results to the control group in terms of shape, contour, and volume of the teeth, color, surface texture, and transparency of the restorations, and features during the 1st and 3rd postoperative months. In the 6th month, the comparative results indicated that the experimental group continued to exhibit superior outcomes to the control group in terms of the shape, color, surface texture, and transparency of the restorations, as well as the characteristics of the teeth. Additionally, the experimental group demonstrated significantly fewer gingival alterations than the control group at 1 month, 3 months, and 6 months post-procedure, with this difference being statistically significant. Furthermore, the combination of 3D printing technology and restorative techniques was utilized, resulting in consistent patient satisfaction.

CONCLUSION

Digitalisation plays an important role in anterior aesthetic restorations. The use of digital technology to manage the entire process of anterior cosmetic restorations can improve restorative results, reduce the number of follow-up appointments, shorten consultation time, and achieve better patient satisfaction.

Digital intraoperative evaluation of restorative space and nontemplate-guided tooth preparation when replacing failed anterior restorations: A dental technique

Assessing the correlation between the current restorative space and the target restorative space is important in determining whether additional tooth preparation is required when replacing failed prostheses. However, existing techniques are not always accurate or efficient. This article describes a digital workflow for the accurate chairside evaluation of the current restorative space and nontemplate-guided tooth preparation. Reference data was obtained from an initial scan of the existing restoration with an intraoral scanner. After removing the existing restoration, a second scan of the tooth was made and compared with the reference data to evaluate the current restorative space. Subsequently, the abutment tooth was prepared and rescanned, with the restorative space being re-evaluated until it met the requirements. This workflow enables the immediate and accurate evaluation of the restorative space, facilitating accurate chairside tooth preparation without the need for silicone indices or other templates, thereby saving time and cost.

Digital guided veneer preparation: A dental technique

This article describes a digital workflow for ceramic veneer preparation using computer-aided design and computer-aided manufacturing technology. A digital waxing was planned on the exocad software program to reestablish esthetic and functional parameters. Then, the digital guides for veneer preparation were designed by using the Meshmixer design software program to control the tooth structure removed during preparation to the minimal thickness necessary for the definitive restorations. The digital guides were printed in an additively manufactured clear resin and used in the preparation appointment, allowing a more conservative and controlled preparation.

Preparation of ultrathin translucent zirconia laminate veneers using 3D printing reduction guides

Minimizing and controlling the amount of tooth reduction during the preparation of ultrathin laminate veneers is a challenge for minimally invasive dentistry. The use of reduction guides is advised to reach the optimal space required for the definitive restoration without excessive reduction. The digital production of a reduction guide used to control tooth preparation for ultrathin laminate veneers is described.

Ceramic veneer shade evaluation using a multicolored 3D-printed model-A case report

OBJECTIVE

This article demonstrates the use of a multicolored 3D-printed model for laboratory shade evaluation of ceramic veneers.

CLINICAL CONSIDERATIONS

A young female patient presented with peg lateral incisors and diastemata between her maxillary incisors. Four ceramic veneers for her maxillary incisors were fabricated using a digital workflow. A multicolored 3D-printed model was manufactured using material jetting technology. The multicolored model and try-in pastes were used to evaluate and adjust the shade of the veneers. Clinically acceptable color matching was achieved, the veneers were delivered without further chairside shade adjustments.

CONCLUSIONS

Successful color evaluation and adjustment were achieved using the combination of multicolored 3D-printed model and try-in pastes. The use of this approach saved time for stump shade taking and fabrication of tooth-colored dies.

CLINICAL SIGNIFICANCE

A multicolored 3D-printed model can be a useful tool for color evaluation and adjustment of ceramic restorations.

Accuracy of three digital waxing-guided trial restoration protocols for controlling the depths of tooth preparation for ceramic veneers

STATEMENT OF PROBLEM

The accuracy of digital waxing-guided trial restoration protocols that have been implemented with ceramic veneers has not been reported.

PURPOSE

The purpose of this in vitro study was to evaluate the accuracy of 3 digital trial restorations fabricated from digital waxing for ceramic veneers.

MATERIAL AND METHODS

A uniform 0.3-mm digital waxing added to the facial surface of 30 maxillary central typodont incisors was created in a software program. The trial restorations were fabricated on typodont teeth with autopolymerizing acrylic resin by using a silicone index based on 3-dimensionally printed casts designed from the digital waxing. The 30 maxillary central incisors were divided into 3 groups: the depth cutter (0.5 mm, Komet) (DC) group, the round bur (1.5 mm, Diatech) (RB) group, and the specially designed calibrated depth bur (laser mark of 0.5 mm, Gaofeng) (CD) group. The 3 groups were randomly prepared with a random number table by 2 experienced prosthodontists aiming to produce an even facial clearance of 0.5 mm. The dimensional differences in the standard tessellation language (STL) files between the surfaces of the original teeth, digital waxing, trial restorations, and prepared teeth in the software program were measured and analyzed at the same 9 points on the labial surface. One-way ANOVA with a post hoc test was used to identify significant discrepancies between trial restorations and waxing and differences in the reduction depth of typodont teeth (RDT) and the reduction depth (RD) among the 3 techniques (α=.05). The mean relative differences (MRDs) were calculated to determine the accuracy (%).

RESULTS

The thickness of the trial restorations was significantly greater than that of the digital waxings, with a discrepancy of 0.20 ±0.14 mm, especially at the cervical site. With the use of a trial restoration, the RDTs of the middle (-0.01 ±0.11 mm) and cervical locations (0.09 ±0.20 mm) showed significantly smaller preparation depths than did the other locations. Significant differences in RD were found among the 3 guided techniques (P<.05). Group DC presented the most accurate result of 0.51 ±0.08 mm with an MRD of 2%, whereas the results of 0.57 ±0.10 mm with an MRD of 14% and 0.60 ±0.11 mm with an MRD of 20% were obtained from group RB and group DC, respectively.

CONCLUSIONS

The trial restoration was significantly thicker than its corresponding waxing. The DC technique presented the most accurate reduction result among the 3 protocols examined.

Accuracy of the preparation depth in mixed targeted restorative space type veneers assisted by different guides: An in vitro study

PURPOSE

Most veneers are mixed targeted restorative space (MTRS)-type restorations that are partially within the original tooth and require inconsistent preparation depths. This study aimed to evaluate the accuracy of the preparation depth for MTRS veneer preparation.

METHODS

MTRS veneer preparation models were developed using the twisted maxillary central incisor (MCI) as the original tooth and the standard MCI as the waxing. Veneer preparations were performed using freehand (MF), silicone (MS), thermoplastic (MT), 3D-printed uniform (MD), and auto-stop (MA) guides. The prepared and original MCI were scanned and superimposed using a custom-made base. The mean absolute differences (MADs) were measured to evaluate the accuracy of the preparation depth. Statistical analysis was performed using the multivariate analysis of variance (MANOVA) test (α=0.05).

RESULTS

The accuracy of the preparation depth was 0.237±0.090, 0.191±0.099, 0.149±0.078, 0.093±0.050, and 0.059±0.040 mm in MF, MS, MT, MD, and MA, respectively. The MADs between the groups were significant (P<0.05). The accuracy of the trial restoration was 0.140±0.081 mm in the MS, and the accuracy of the guiding tube was 0.055±0.033, 0.036±0.011, and 0.033±0.010 mm in the MT, MD, and MA, respectively.

CONCLUSIONS

In MTRS veneer preparation for MCI, tooth preparation guides improved the accuracy of the preparation depth by visualizing the TRS profile and providing clear measurement points. The accuracy of the guide is influenced by its flexibility, and the accuracy of the preparation depth is affected by the accuracy of the measurement points.

Creating a hybrid smile design workflow: The analog brain drives the digital technology

OBJECTIVE

This article will explain and demonstrate the application of analog smile design techniques and concepts as a precursor for digital smile design implementation. The application of these techniques will be described with two case presentations that will demonstrate the incorporation of these analog methods into digital smile design programs.

CLINICAL CONSIDERATIONS

Digital smile design workflows can be more efficient and require less chair time but must be based on an understanding and application of basic smile design principles to apply the digital techniques successfully.

CONCLUSIONS

The application of basic smile design techniques to digital workflows resulted in excellent clinical outcomes for both a localized treatment plan and a full mouth restorative rehabilitation.

CLINICAL SIGNIFICANCE

Digital smile design is quickly being adopted into dental practices. However, the digital design must be created by the clinician and be based on a thorough understanding of basic esthetic and restorative principles to achieve predictable successful clinical outcomes.

Smile Design and Treatment Planning-Conventional versus Digital-A Pilot Study

INTRODUCTION

Several methods are currently available for providing a preview of the prosthodontic treatment, including computer simulations, 3D models, wax-ups, and mock-ups. The aim of this study is to compare the aesthetic aspects and assessment of conventional versus digital prefigurative methods.

METHODS

The study included 5 patients and 3 observers, for each of whom a wax-up was made in both the conventional and digital techniques. The analog method, which implied a mock-up molding with a silicone matrix of the wax-up, was compared to a digital workflow, which consisted of a mock-up milling from a digital design. The patient's clinical mock-ups were recorded with digital photographs and assessed for nine different criteria by three observers.

RESULTS

The analysis has shown a balanced assessment of the aesthetic criteria without any significant difference between the analog and digital prefigurative methods.

CONCLUSIONS

Between the two wax-ups (conventional and digital), there were some variations in smile and dental criteria; however, the obtained data were very similar. When it comes to the smile criteria, the general average grades of the mock-ups conducted using the conventional method are slightly higher than the ones using the digital technique.

An Innovative 3D Printed Tooth Reduction Guide for Precise Dental Ceramic Veneers

Tooth reduction guides allow clinicians to obtain the ideal space required for ceramic restorations. This case report describes a novel design (CAD) for an additive computer-aided manufactured (a-CAM) tooth reduction guide with channels that permitted access for the preparation and evaluation of the reduction with the same guide. The guide features innovative vertical and horizontal channels that permit comprehensive access for preparation and evaluation of the reduction with a periodontal probe, ensuring uniform tooth reduction and avoiding overpreparation. This approach was successfully applied to a female patient with non-carious lesions and white spot lesions, resulting in minimally invasive tooth preparations and hand-crafted laminate veneer restorations that met the patient's aesthetic demands while preserving tooth structure. Compared to traditional silicone reduction guides, this novel design offers greater flexibility, enabling clinicians to evaluate tooth reduction in all directions and providing a more comprehensive assessment. Overall, this 3D printed tooth reduction guide represents a significant advancement in dental restoration technology, offering clinicians a useful tool for achieving optimal outcomes with minimal tooth reduction. Future work is warranted to compare tooth reductions and preparation time for this guide to other 3D printed guides.

A diagnostically and digitally driven tooth preparation protocol by using a patient monitoring tool with an intraoral scanner

Finding the right balance between the preservation of tooth structure and providing adequate space for the restorative material is a major challenge in prosthetic dentistry. A technique is presented using the patient monitoring tool available in standard software programs of an intraoral scanner to constantly monitor preparation dimensions in relation to the optimal definitive restoration.

Digitally designed reduction guide to correct proclined anterior teeth: An aid before fabricating trial restorations

Restoring teeth with ceramic laminate veneers is most often an additive procedure. However, when proclined anterior teeth are being treated, a misfitting silicone matrix will lead to inaccurate trial restorations, affecting evaluation of the definitive esthetic result and leading to inaccurate definitive preparations. Using the digital technology, a 3-dimensionally printed reduction guide can be used to remove the proclined areas as the first step before trial restorations. Then, the trial restorations and made and then the definitive preparations made through them.

Retrospective Long-Term Clinical Outcome of Feldspathic Ceramic Veneers

The purpose of this study was to evaluate the clinical outcome of feldspathic ceramic laminate veneers over a 7-year period using minimally invasive techniques, such as vertical preparation (without prosthetic finish line), or no preparation (no-prep). A total of 170 feldspathic ceramic veneers were cemented in the anterior region, including 70 maxillary and 100 mandibular veneers, after special conditioning of the teeth and restorations. The veneers were evaluated using the FDI World Dental Federation criteria evaluation kit after recalling all the patients between February and June 2021. In total, 14 feldspathic veneers failed and were replaced with lithium disilicate because of core fracture, and 10 cases of chipping occurred on the ceramic surface and were polished. The overall survival rate was 91.77% for up to 7 years of function, with a failure rate of 8.23%. In this retrospective survival analysis, the failures, including the fracture of veneers and dental hard tissue, occurred both in prep and no-prep teeth. No failures were observed in veneers with a maximum thickness of 0.5 mm compared to those with a maximum thickness of 1 mm, 1.5 mm, 2 mm, and 2.5 mm.

Detailed three-dimensional orthodontic tooth repositioning to improve restorative outcome

The case describes the interdisciplinary treatment of a 23-year-old woman with a Class III malocclusion, missing an upper right lateral incisor, abrasion of the maxillary incisal edges, anterior gingival margin discrepancies, and gingival recession. Initially, the patient was treated with fixed appliances combined with orthognathic surgery. The extraction of the upper left lateral incisor and bilateral canine substitution plan was chosen. At the end of the surgical and orthodontic treatment, the restorative treatment with six veneers was accomplished to improve smile esthetics. Despite the missing lateral incisors, the patient showed a natural, good-looking final result. A symmetric incisal plane was established, a functional occlusion with average vertical and horizontal overlap was set, and the bone scallop and consequently the gingival margins were leveled. The interdisciplinary approach hid all of the initial esthetic defects of the case. The result highlights how to obtain a remarkable improvement of the smile outcome with a well-functioning masticatory system.

Accuracy of Reduction Depths of Tooth Preparation for Porcelain Laminate Veneers Assisted by Different Tooth Preparation Guides: An In Vitro Study

PURPOSE

To evaluate the accuracy (trueness and precision) of reduction depths of guided veneer preparation assisted by four tooth preparation guides.

MATERIALS AND METHODS

Fifty resin artificial teeth were randomly divided into five groups (n = 10): a freehand group (F), silicone guide group (S), thermoplastic guide group (T), 3D printed uniform guide group (D), and 3D printed auto-stop guide group (A). A preparation for a window veneer on the maxillary right central incisor was performed by two surgeons who used tooth preparation guides for assistance. The maxillary right central incisors were scanned before and after the preparation. The reduction depths were measured in the cervical, middle, and incisal thirds of the prepared surface, and depth maps were created using Geomagic Control X software. The accuracy of the reduction depths at each third was evaluated using both trueness and precision values. The trueness of the reduction depths was determined by calculating the mean absolute differences (MADs) compared to the planning depth, and precision was determined by the standard deviation (SD). The collected data were statistically analyzed using one-way ANOVA and the least significant difference test (α = 0.05).

RESULTS

The MAD ± SD values of the reduction depths in the cervical-third region in groups F, S, T, D, and A were 0.19 ± 0.04, 0.12 ± 0.03, 0.09 ± 0.02, 0.07 ± 0.02, and 0.05 ± 0.01 mm, respectively. In the middle-third region, the MAD ± SD values of groups F-A were 0.19 ± 0.05, 0.13 ± 0.02, 0.09 ± 0.01, 0.06 ± 0.01, and 0.05 ± 0.01 mm. In the incisal-third region, the MAD ± SD values were 0.27 ± 0.05, 0.16 ± 0.04, 0.11 ± 0.03, 0.07 ± 0.01, and 0.05 ± 0.01 mm, respectively. Significant differences in trueness and precision values were found across different groups (F = 45.378, p = 0.000), where group F showed higher MADs than the other 4 groups (p = 0.000), and the highest MADs were detected in group S among the 4 groups in all regions (p = 0.000). Group T showed significantly higher MADs than groups D (P = 0.008) and A (p = 0.001), except in the cervical-third region, where no significant difference was observed between groups T and D (p = 0.077). There was no significant difference between groups D and A (p = 0.148). The deviation map showed significant differences among groups (F = 15.963, p = 0.000), group T presented less deviation than group F (p = 0.000) and group S (p = 0.027) and showed more deviation than group A (p = 0.007).

CONCLUSION

Tooth preparation guides provided more accuracy for veneer preparation than freehand preparation. Among the 4 guides, the 3D printed auto-stop guide presented the lowest absolute difference (0.05 mm) and the silicone guide showed the highest absolute difference of preparation (0.12-0.16 mm).

Three-dimensional digital evaluation of thickness accuracy of mock-ups fabricated by silicone matrices: An in vitro study

PURPOSE

Although mock-ups have been widely used in dental esthetic rehabilitation, their accuracy has not been quantitatively evaluated, and the methods of fabricating mock-ups are various. This in vitro study investigated the thickness accuracy of mock-ups fabricated with different silicone matrices.

METHODS

Mock-ups of maxillary anterior teeth were respectively fabricated by 72 silicone matrices that were equally divided into four groups (n=18 for each group) according to two variables of the silicone matrices: labial margin position (equigingival or cover labial gingiva for 1-2 mm) and palatal notches (with or without notches on the palatal side of silicone matrices). The thickness accuracy of the mock-ups was analyzed using 3D scanning and 3D deviation analysis techniques compared with diagnostic waxing. The thickness change ratios of the mock-ups were compared using a two-way analysis of variance (ANOVA). One-way ANOVA and Kruskal-Wallis tests were used to compare differences in thickness change ratios between different teeth in each group.

RESULTS

The thickness accuracy of the mock-ups was significantly affected by the labial margin position and the palatal notches of the silicone matrices, respectively, in the labial area and the incisal area. The most accurate mock-ups were made using silicone matrices with equigingival labial margins and palatal notches. The thickness accuracy of the mock-ups was also inconsistent on different teeth.

CONCLUSIONS

The mock-ups fabricated by silicone matrices were thicker than the diagnostic waxing. The application of silicone matrices to equigingival labial margins and palatal notches was beneficial to the thickness accuracy of mock-ups.

Multipurpose application of custom, rigid, clear matrix for fabricating trial restorations, tooth preparation guides, and interim veneers

Interim veneers present an esthetic and functional challenge for restorative dentists. Moreover, inadequate fit or trauma to the soft tissue during their fabrication or subsequently may affect soft-tissue health and stability and lead to bleeding that will compromise the adhesive cementation of the definitive ceramic veneers. This article describes a technique for the atraumatic fabrication of interim veneers with a custom, rigid, clear matrix designed for multipurpose use during the patient's restorative care. Based on a diagnostic waxing, the clear matrix is made and first used for the fabrication of the trial restorations and as a tooth-preparation guide. Subsequently, it is used for the atraumatic fabrication of interim veneers with a photopolymerizing direct restorative material.

Restoration of localised erosive wear using a combination of dental materials: a conservative approach

Objectives To present the treatment approach for the restoration of localised anterior erosive wear using a combination of dental materials.Clinical considerations A patient presented in a private dental practice concerned about the aesthetics of his anterior teeth. The patient's history and clinical examination revealed erosive wear on the labial and palatal aspects of his maxillary central incisors and right lateral incisor. The formulated treatment plan was to restore the teeth in a conservative way. A diagnostic wax-up was performed and confirmed with the patient with chairside mock-up. The treatment provided included direct composite restorations, replacement of a porcelain-fused-to-metal crown on his left lateral incisor with a porcelain-fused-to-zirconia crown, and lithium disilicate ceramic veneers on the worn labial surfaces of the central incisors and the right lateral incisor. The preparations for the ceramic veneers were carried out with the aid of the diagnostic mock-up, thus minimising the need for tooth removal of the worn teeth.Conclusions Pre-operative planning for tooth surface loss cases can help to ensure that little or no remaining tooth structure is removed during the restorative procedures. A strict bonding protocol is crucial to ensure longevity of the restorations.

Fabrication of a facially generated tooth reduction guide for minimally invasive preparations: A dental technique

This article describes a 3D virtual diagnostic analysis for treatment planning an esthetically driven functional rehabilitation by using computer-aided design and computer-aided manufacturing (CAD-CAM) technology. In this protocol, a digitally planned diagnostic waxing (exocad DentalCAD) was used to visualize the proposed tooth position and the presence of areas without sufficient material thickness for the prospective additive restorations. This approach uses an additively manufactured clear resin guide to selectively reduce surfaces of a tooth erupted beyond the proposed occlusal plane. By using a 3D-printed occlusal reduction guide, the digital diagnostic waxing is accurately represented, tooth reduction controlled, and adequate occlusal clearance for the required restorative material thickness provided with a minimally invasive approach.

Guided tooth preparation device fabricated with a complete digital workflow: A dental technique

Guided tooth preparations allow clinicians to provide fixed dental prostheses for dentate patients in an efficient manner. One approach uses a digital preparation device technique where the preparation of a tooth needing a crown is guided by a device. Compared with conventional techniques, this method allows for accurate abutment preparation more efficiently and with improved quality. By controlling tooth preparation, this method preserves natural tooth structure and provides adequate clearance for the restorative material. To illustrate this technique, an adhesive minimally invasive fixed complete-mouth rehabilitation was provided by using a 3D-printed digital preparation device.

A stereolithographic template for computer-assisted teeth preparation in dental esthetic ceramic veneer treatment

OBJECTIVE

This article describes a digital dental esthetic ceramic veneer treatment workflow using a stereolithographic template for teeth preparation.

CLINICAL CONSIDERATIONS

We have presented the case of a 33-year-old woman with dental fluorosis who wanted an esthetic ceramic veneer treatment. A digital smile design was created on a virtual patient, and a virtual diagnostic wax-up was made. Based on the suggested ceramic material thickness, virtual teeth preparation was performed on the diagnostic wax-up. A special-teeth preparation template was then created digitally and fabricated using a stereolithographic technique. This template guided the teeth preparation using a special bur with a stopper. The veneers were fabricated by CAD/CAM and delivered good esthetics and function.

CONCLUSIONS

The stereolithographic tooth reduction template helps realize digital restorative planning. It provides better control of the reduction depth of the labial and incisal preparation, making the operation simpler.

CLINICAL SIGNIFICANCE

The digital dental esthetic ceramic veneer treatment workflow described here using a stereolithographic template for teeth preparation helped with the accurate control of reduction depth for minimally invasive teeth preparation, making the operation simpler, which is a significant improvement over the previous methods.

Layperson and Dental Professional Perception When Evaluating Their Own Virtually 2D or 3D Simulated Esthetic Discrepancies

PURPOSE

To analyze the perceptions of laypersons, dental students, and dentists regarding disparities of the maxillary dental midline and the occlusal plane (OP) when analyzing their own 2D or 3D clinical simulation.

MATERIAL AND METHODS

20 participants per group volunteered (N = 60). Intraoral and facial scans, and a photograph were obtained from each participant. Two simulation groups were created: 2D and 3D groups, which were subdivided into two subgroups. In the first subgroup, the OP was modified by 1-degree increments without changing the maxillary midline. In the second subgroup, the OP was modified by the same increments, but the maxillary midline was altered to match the OP inclination. Participants were asked to rate the simulations on a 1-to-6 scale and a question survey. Ordinal logistic regression (OR) was used to analyze the ratings.

RESULTS

Tilt of the OP had the strongest negative effect on the ratings which was further amplified by the dental midline inclination (OR = 0.122). Midline modification alone did not affect the ratings (OR = 0.744). 3D simulations had a stronger positive effect on the ratings compared to 2D simulations. For dental students, the positive rating effect of 3D simulations was similar to dentists. For laypersons, the positive rating effect of 3D simulations compared to the 2D simulations decreased relative to dentists. The survey revealed that 45% of the dentists, 80% of the students, and 50% of the laypersons preferred the 3D simulation.

CONCLUSIONS

The type of dimensional representation affected the esthetic perception of all participants. 3D simulations obtained higher esthetic ratings for the same esthetic discrepancy than 2D simulations. However, all participants' ratings decreased with increased tilt of the OP and were further decreased with the inclination of the dental midline.

Influence of Preparation Depth and Design on Stress Distribution in Maxillary Central Incisors Restored with Ceramic Veneers: A 3D Finite Element Analysis

PURPOSE

To evaluate the influence of different preparation designs and depths on the stress field developed in maxillary central incisors restored with veneers made with different ceramic materials using finite element analysis (FEA).

MATERIALS AND METHODS

A linear static three-dimensional finite element analysis model was used with the aid of reverse engineering to develop digital models of maxillary central incisors restored with ceramic veneers, according to two different preparation depths (thin vs deep) and two different preparation designs (feather edge vs butt joint). Three ceramic systems were tested: (i) feldspathic porcelain, (ii) heat pressed glass ceramic IPS Empress 2 (Ivoclar Vivadent AG), and (iii) heat pressed glass ceramic IPS e.max-Press (Ivoclar Vivadent AG). Each model was subjected to a compressive force of 200N applied to the palatal surface 2 mm below the incisal edge. The longitudinal axis of the restored tooth formed an angle of 130^o with the direction of the force. The biomechanical behavior of the different models was examined according to the von Mises stress criterion. Statistical analysis was performed using nonparametric confidence interval estimation using bootstrapping.

RESULTS

The maximum observed stress values were calculated and found to be similar between prepared and intact teeth. The cervical margin of the veneers displayed the highest von Mises stress values. Irrespectively of the depth and preparation design, the biggest von Mises stress values were observed at the veneer structures with the following order: (i) IPS Empress 2, (ii) IPS e.max-Press, (iii) feldspathic (p = 0.001). Preparation depth resulted in statistically significant differences (p = 0.001) in the stress distribution in the majority of tested structures. As the preparation depth was increased, the stresses within the veneer structure and the tooth structures were decreased. No statistically significant differences were detected in the stresses among the different restored models, when the preparation design was considered.

CONCLUSIONS

This FEA study suggests that ceramic veneers could restore the biomechanical behavior of prepared central incisors and made it similar of that of an intact tooth. Regardless of the preparation depth and design and the ceramic system used, the cervical margin of ceramic veneers presents the highest von Mises stress values. When feldspathic porcelain was compared with lithium disilicate (IPS e.max Press), the latter displayed the lowest transfer of stresses to dental tissues. An increase in preparation depth resulted in a statistically significant stress decrease in both the veneer and the tooth.

Milled versus moulded mock-ups based on the superimposition of 3D meshes from digital oral impressions: a comparative in vitro study in the aesthetic area

Background

Aesthetic porcelain veneers proved to be a long-term reliable prosthetic solution, ensuring minimal invasiveness. The use of veneers requires an adhesive cementation technique, so maintaining as much enamel as possible is to ensure lasting success. A diagnostic mock-up is a key tool that allows a preview of the outcome of the aesthetic restoration: it is obtainable both in an analog and digital way. With the recent developments in impression technology and the ever so fast growing use of CAD-CAM technologies it is useful to understand the pros and cons of either one of these techniques (analog and digital) in order to identify the easier and more convenient workflow in aesthetic dentistry.

Methods

After taking pictures and impressions of the dental arcs of a patient in need of aesthetic rehabilitation, 52 resin models were produced and a digital drawing of the smile was outlined. Both an analog and a digital wax-up were obtained from two of the 52 models: the latter was obtained using digital impressions and a dedicated software. The analog wax-up was then used to produce 25 matrices that have later been used to mould 25 resin mock-ups using a traditional moulding protocol (Control Group - CG). The digital wax-up was used to mill 25 PMMA mock-ups. Each mock-up, both milled and moulded (total 50), was then laid on the other 50 resin models as a digital impression of it was taken. The STL. files of the milled mock-ups were compared with the 3D CAD wax-up made using a specific software. The STL. files of the analog printed mock-ups were compared with the traditional wax-up design. A statistical analysis was carried out to evaluate the difference between the groups.

Results

The statistical analysis showed a significant difference (P > 0.01) between the mean value of the distance between the points of the overlapping STL. meshes in GC (0.0468 mm) and in TG (Test Group - TG) (0,0109 mm).

Conclusions

The study showed a difference in accuracy between traditional moulded and milled mock-ups compared to their original wax-up. The data analysis reports that the digital method allows for greater accuracy. Within the limitations of this study, a fully digital workflow is to considered more reliable when it come to creating an esthetic mockup: the digital procedure has been shown to be more accurate than the one made manually which is much more operator dependent and it brings an increase to the chance of error, and that could ultimately affect the final result.

Minimal invasive microscopic tooth preparation in esthetic restoration: a specialist consensus

By removing a part of the structure, the tooth preparation provides restorative space, bonding surface, and finish line for various restorations on abutment. Preparation technique plays critical role in achieving the optimal result of tooth preparation. With successful application of microscope in endodontics for >30 years, there is a full expectation of microscopic dentistry. However, as relatively little progress has been made in the application of microscopic dentistry in prosthodontics, the following assumptions have been proposed: Is it suitable to choose the tooth preparation technique under the naked eye in the microscopic vision? Is there a more accurate preparation technology intended for the microscope? To obtain long-term stable therapeutic effects, is it much easier to achieve maximum tooth preservation and retinal protection and maintain periodontal tissue and oral function health under microscopic vision? Whether the microscopic prosthodontics is a gimmick or a breakthrough in obtaining an ideal tooth preparation should be resolved in microscopic tooth preparation. This article attempts to illustrate the concept, core elements, and indications of microscopic minimally invasive tooth preparation, physiological basis of dental pulp, periodontium and functions involved in tool preparation, position ergonomics and visual basis for dentists, comparison of tooth preparation by naked eyes and a microscope, and comparison of different designs of microscopic minimally invasive tooth preparation techniques. Furthermore, a clinical protocol for microscopic minimally invasive tooth preparation based on target restorative space guide plate has been put forward and new insights on the quantity and shape of microscopic minimally invasive tooth preparation has been provided.

Four-dimensional digital prediction of the esthetic outcome and digital implementation for rehabilitation in the esthetic zone

A technique for 4-dimensional (4D) digital prediction of the outcome of esthetic dentistry for a virtual patient is presented. Static 3D images (which incorporate predicted precise dentition and facial soft tissue in different smiling positions) can be converted into dynamic 3D images by using 3D intraoral imaging, 3D face imaging, and various computer software programs. This strategy can improve the visual perception and quality of esthetic prediction. In addition, the predicted esthetic outcome can be implemented by replicating the contour and shape of digital wax patterns in the definitive ceramic restorations.

[Minimal invasive microscopic tooth preparation based on endodontic, periodontal and functional health]

Tooth preparation is the primary and core operation technique for dental esthetic restoration treatment, due to its effect of providing restoration space, bonding interfaces and marginal lines for dental rehabilitation after tooth tissue reduction. The concept of microscopic minimal invasive dentistry put forward the issue of conducting high-quality tooth preparation, conserve tooth-structure, protect vital pulp and periodontal tissue simultaneously. This study reviewed the concepts, physiology background, design and minimal invasive microscopic tooth preparation, and in the meantime, individualized strategies and the two core elements of tooth preparation (quantity and shape) are listed.

Virtual diagnostics and guided tooth preparation for the minimally invasive rehabilitation of a patient with extensive tooth wear: A validation of a digital workflow

The recent evolution of digital technologies in dentistry has enabled virtual 3D diagnostic analysis of a dentition before treatment, allowing for virtual, minimally invasive treatment planning. In this report, an extensively worn dentition was 3D virtual analyzed at an increased vertical dimension of occlusion. Virtual waxing (exocad DentalCAD; Exocad) and subsequent analysis of the need for minimally invasive preparations were performed. Areas of each tooth without adequate clearance for the minimal thickness of a definitive restoration (set at 1.5 mm in the software), including the amount of tooth substance to be removed (GOM Inspect; GOM), were visualized in color. A preparation guide was virtually designed according to this diagnostic plan (3-matic; Materialise) and 3D printed (Connex3 Objet260; Stratasys) from resin (VeroMagenta RGD851; Stratasys). The teeth were minimally prepared using the guide, and the amount of preparation was validated by superimposing the scan of the prepared model on the initial scan and comparing it with the diagnostic plan.

Interdisciplinary interface between fixed prosthodontics and periodontics

Although periodontal factors do not usually have a direct effect on the survival of a fixed prosthesis, harmony between the prosthesis and the periodontium is critical otherwise esthetics, the longevity of the prosthesis and the periodontium will be compromised. A close interdisciplinary relationship between periodontics and prosthodontics is therefore necessary to avoid an unsatisfactory treatment outcome, requiring extensive and expensive retreatment. The design of the prosthesis, the number and quality of the abutment teeth, the preparation and the pontic, the occlusion and the material need to be considered when planning prosthodontic treatment. The location of the preparation margin and the contour and emergence profile of the prosthesis will influence the response of the gingival tissues to the prosthesis. Pontic design and cleansibility also contribute to the response of the gingival tissues as well as to the clinical and esthetic outcome. Even an optimal pontic design will not prevent inflammation of the mucosa adjacent to the pontic if pontic hygiene is not maintained by removal of plaque. Case selection and the patients' ability to carry out adequate oral hygiene are therefore essential for longevity of the prosthesis, and regular reviews provide an opportunity for early detection and treatment of failures.

A Step-by-Step Conservative Approach for CAD-CAM Laminate Veneers

The use of CAD/CAM technology has allowed the fabrication of ceramic restorations efficiently and with predictable results. Lithium disilicate is a type of glass ceramic material that can be used for the elaboration of laminate veneers, being monolithic restorations which require characterization through a covering ceramic in order to achieve acceptable esthetic results. The next case report shows a predictable clinical protocol for the rehabilitation of the anterior teeth through the preparation of CAD/CAM veneers (e.max CAD, Ivoclar Vivadent, Liechtenstein) which have been characterized by a nanofluorapatite ceramic (e.max Ceram, Ivoclar Vivadent, Liechtenstein) through the layering technique.

Use of Feldspathic Porcelain Veneers to Improve Smile Harmony: A 3-Year Follow-up Report

Abstract This case report describes an esthetic treatment to improve the shape and alignment of the anterior teeth, reestablishing smile harmony, using feldspathic porcelain veneers. Results of clinical follow up after 36 months are also presented. The advantages, disadvantages and limitations of the technique are detailed with reference to the relevant literature. This suggests that the success of treatment depends on adequate conditions of bonding between the veneers and the tooth complex, which involves parameters such as the strength and durability of the bond interface. Therefore, the clinical success of feldspathic porcelain veneers depends on the accurate selection of cases and correct execution of clinical and laboratory procedures. The rehabilitation involved from first right premolar to the left with feldspathic porcelain veneers made on refractory dies. After the 3-year follow up, excellent clinical results and patient satisfaction were achieved.

Consequences of experience and specialist training on the fabrication of implant-supported prostheses: A survey

STATEMENT OF PROBLEM

Fabricating fixed restorations on implants requires that dentists stay up-to-date with the scientific publications.

MATERIAL AND METHODS

A questionnaire containing 29 questions was sent to dentists, members of the Israeli Society of Prosthodontics, and university faculty members. Differences were evaluated using the chi-square and Fisher exact tests and Mann-Whitney U and Wilcoxon tests for questions enquiring into the frequency of use of certain methods (α=.05).

RESULTS

A total of 155 questionnaires were completed by 84 general dental practitioners and 71 specialists and residents. Statistical differences (P<.05) were found in the course of the fabrication of the implant-supported prostheses in the diagnostic waxing, trial restoration, and impression-making processes. Trial restorations were often used by residents and specialists before starting an esthetic restoration. Diagnostic waxing was used when treating patients with complex esthetic needs, mainly by prosthodontists (P=.019). A custom tray for impression making was used more by residents and specialists than by general dental practitioners (P<.001). The open tray technique for impression making of single or up to 3 implants was performed mainly by residents, specialists, and general dental practitioners with professional experience of fewer than 15 years. General dental practitioners used primarily plastic or metal trays for impression making.

CONCLUSIONS

Significantly, impression techniques and the use of custom open trays, diagnostic waxing, and trial restorations were performed by residents, specialists, and dentists with fewer than 15 years of experience.

Esthetic Rehabilitation through Crown Lengthening Surgery and Conservative CAD/CAM Veneers: A Multidisciplinary Case Report

This case report describes a successful multidisciplinary approach used to improve the smile esthetics of a patient presenting with excessive gingival display, asymmetric gingival margins, and small upper anterior teeth and lower anterior teeth. The treatment combined esthetic crown lengthening, dental bleaching, and restorative dentistry using CAD/CAM veneer. The 6-month follow-up examination confirmed the stability of the modification and absence of adverse effects.

Exploring the versatility of gingiva-colored composite

Gingival recession has a diverse etiology. The consequences may include gingivitis, periodontitis, and hypersensitivity. Whereas the management can include surgical treatment options, sometimes a more conservative, yet still esthetic approach may be required. The use of gingiva-colored composites provides one such alternative and can be applied to varying presentations of the problem. While surgical treatment can be successful in re-creating favorable esthetic anatomy as well as achieving accurate tissue contour in cases when minor amounts of tissue are reconstructed, long-term results vary because of the vascularity and complexity of the interdental space. Factors such as cost, healing time, discomfort, and variable long-term results make surgery an unpopular choice. If tooth-colored restorative materials are utilized to restore cervical tooth exposure as a result of severe recession, the disproportionate appearance of the visible crown may give a dissatisfying result. Gingiva-colored composite provides dental practitioners with a versatile material that can be used to directly restore cervical defects caused by gingival recession, thus correcting the appearance of the gingival anatomy. It offers a treatment option that may increase patient satisfaction through the provision of a cost-effective, minimally invasive solution with highly esthetic results.