Influence of fabrication method on the marginal fit of temporary restorations.

Computer-aided manufacturing (CAM) technology allows the use of different manufacturing techniques. This in vitro study aimed to evaluate the marginal fit of temporary restorations manufactured using conventional chairside methods, milling, and three-dimensional printing. Fifteen 3-element temporary restorations specimens were produced and categorized into three groups: non-digital, obtained using the conventional chairside method (GC); milled (GM); and three-dimensionally printed (GP). Marginal fit was assessed using scanning electron microscopy (SEM) performed under two conditions: one with only the central screw tightened, and the other with all three screws tightened. Horizontal misfit values were categorized as over-, equal-, and under-extended and qualitatively analyzed. Statistical analysis was performed using the Tukey-Kramer test (α=0.05). In the vertical assessment, three-dimensionally printed restorations demonstrated greater misfit than restorations obtained by milling and the conventional chairside method (P<0.05). In the horizontal assessment, the misfit in the GP group was significantly higher than that in the GM and GC groups. Restorations obtained using the conventional chairside method and milled provisional restorations showed more favorable results than three-dimensionally printed restorations.

Emerging trends and clinical recommendations for zirconia ceramic crowns: a concise review.

Introduction A little over ten years ago, zirconia crowns made their debut in the field of dentistry. Despite early problems with the chipping of veneering porcelain, clinical studies have demonstrated excellent performance. It is essential for a ceramic crown to have good aesthetic qualities, in addition to having good mechanical characteristics. The exceptional mechanical qualities of zirconia crowns and the simplicity with which they may be machined, employing computer-aided design and computer-aided manufacturing schemes, are primarily responsible for the widespread use of these materials in clinical settings. New ceramic-based materials, including monolithic zirconia, zirconia-containing lithium disilicate ceramics, and graded glass/zirconia/glass, have recently been launched in the field of dentistry. These newly discovered zirconia crown materials stem from varied technological approaches, each likely to lead to additional clinical advancements. At this point, it seems imperative to offer a concentrated report on the newer developments, along with essential clinical recommendations for best clinical outcomes with zirconia crowns.Types of studies This review article is a consolidation of several case studies, cohort studies and systematic reviews, as well as experimental and observational randomised control trials and other peer-reviewed articles.Results On reviewing, a concise list of clinical recommendations is generated, demonstrating that monolithic zirconia offers some clinical advantages over veneered zirconia crowns.Conclusion This review article discloses various clinical revelations and in-office recommendations for favourable usage of zirconia ceramic crowns that can lead to better patient outcomes and long-term clinical success rates.

A comparative evaluation of marginal fit and microleakage of computer-aided design/computer-aided manufacturing-milled zirconia and prefabricated posterior occlusal veneers: An in vitrostudy.

AIMS: The aim of this study was to compare the marginal fit of prefabricated occlusal veneers with computer-aided design/computer-aided manufacturing (CAD-CAM)-milled zirconia occlusal veneers in the posterior teeth. SETTINGS AND DESIGN: Forty extracted human maxillary premolars were divided into two groups of 20 each. Group 1 was prepared to receive prefabricated occlusal veneers, and Group 2 was prepared to receive CAD-CAM-milled zirconia occlusal veneers. MATERIALS AND METHODS: Prefabricated samples (Edelweiss) were selected for Group 1, whereas for Group 2, the tooth preparations were scanned, and occlusal veneers were fabricated using Exocad designing software and milling machine. After luting, both the groups were submerged in dye, sectioned, and evaluated for marginal fit and microleakage under a stereomicroscope using the microscope imaging software and its measurement tool. STATISTICAL ANALYSIS USED: Data collected were subjected to statistical analysis using SPSS 27.0. Intragroup and intergroup comparison was done using the Mann-Whitney U test. The Chi-square test was applied to check the depth of penetration of dye based on percentages. RESULTS: The marginal gap of zirconia occlusal veneers fabricated with CAD-CAM is higher compared to that of prefabricated occlusal veneers. Similarly, the depth of penetration of dye is higher in CAD-CAM-milled zirconia occlusal veneers than prefabricated occlusal veneers. CONCLUSION: The marginal fit of prefabricated occlusal veneer is better than the marginal fit of zirconia occlusal veneers fabricated with CAD-CAM. Similarly, it can also be concluded that the microleakage of prefabricated occlusal veneer is less compared to the CAD-CAM-milled zirconia occlusal veneers.

[Types and colors of 1 374 chair-side CAD/CAM all-ceramic restorations].

PURPOSE: To analyse the types of chairside CAD/CAM all-ceramic restorations and the color range of all-ceramic materials used so as to provide reference for the application of clinical chairside all-ceramic restoration and the color selection of all-ceramic materials. METHODS: IPS e.max CAD prostheses and related data were collected from January 2021 to December 2021 from the Department of Prosthodontics, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine. The number and type of restorations and the color of materials were investigated and analyzed by descriptive statistics. RESULTS: A total of 1 374 restorations were included, of which 624 were crown restorations, accounting for 45.41% of the total restorations. 516 cases were veneer, accounting for 37.55%; 219 were inlays, accounting for 15.94%; fixed bridges were all adhesive bridges, with the least number with only 15 cases, accounting for 1.09%. In terms of the selection of restoration materials, the use rate of low-transparent(LT) ceramic blocks was significantly higher than that of other transparent ceramic blocks. A was the most frequently used ceramic color. The most frequently used porcelain blocks for veneers were LTA2 and LTA1; for inlay were LTA3; for crowns were LTA2 and LTA3. The blocks used in the fixed bridges were all LT, and A3 color was the majority. CONCLUSIONS: Chairside CAD/CAM all-ceramic prostheses made of IPS e.max CAD materials have been widely used in clinical practice. The types of prostheses include veneer, inset, crown and fixed bridge. The most commonly used IPS e.max CAD blocks are LTA2, LTA3 and LTA1. These findings have certain guiding significance for the clinical restoration decision and the reserve of porcelain blocks in primary hospitals.

Comparing the accuracy of crown fitting between milling and 3D printing techniques using CAD/CAM technologies.

BACKGROUND: The accuracy of dental crowns is crucial for their longevity and effectiveness. OBJECTIVE: This study aims to investigate how the precision of crowns is affected by two different fabrication methods, either subtractive (milling) or additive (3D printing), within computer-aided design/computer-aided manufacture (CAD/CAM) technology. METHODS: A standardised digital scan of a maxillary first molar with a shoulder margin (.stl file) was used to design and fabricate crowns through both subtractive (milling) and additive (3D printing) processes. The crowns' marginal and internal fits were assessed comprehensively. Statistical analysis, including two-way ANOVA and independent t-tests, revealed significant differences in fitting accuracy between the two methods. RESULTS: Crowns produced via 3D printing demonstrated superior fitting with minimal marginal (14 ± 5 µm) and internal discrepancies (22 ± 5 µm) compared to milling (marginal: 22 ± 4 µm, internal: 23 ± 3 µm), indicating a statistically significant advantage in precision (p⁢s⩽ 0.022 for marginal fit). CONCLUSION: The findings suggest that 3D printing may offer a more accurate alternative to milling in the fabrication of digital dental prostheses, potentially revolutionising the field with its enhanced precision capabilities.

Advanced digital planning approach using a 3D-printed mock-up. A case report.

OBJECTIVE: A diagnostic mock-up is a key tool that allows a preview of the outcome of an esthetic restoration. With recent developments in CAD/CAM technology, it is important to understand the pros and cons of chairside digital dentistry and the restorative materials used. The aim of the present case report is to describe in detail the use of a 3D-printed mock-up fabricated from a polymer-based material for an esthetic treatment plan within a fully digital workflow. CASE REPORT: A 45-year-old female patient presented at the clinic concerned about her esthetic appearance and the color of her anterior incisors. After a conclusive diagnosis, a restoration was planned using ceramic veneers from maxillary premolar to premolar. For a preview visualization of the outcome, an intraoral scanner was used to obtain 3D images and to allow the design of a digital smile. The template STL file was exported to a 3D printer and a 0.6-mm mock-up in A3-shade 3D resin was produced after 25 min. The mock-up was tested through a try-in and approved by the patient. As a result, the printed mock-up was considered predictable and reliable for the final restoration. CONCLUSIONS: The ease, speed, and reduced costs derived from the digital workflow, in conjunction with the accuracy of the mock-up, made the procedure highly efficient and recommendable.

Working Models in the Digital Workflow: Are They Reliable?

PURPOSE: This position paper summarizes all relevant aspects of the use of working models derived from digital data in digital and hybrid workflows, aiming to (1) provide the reader with a comprehensive review of the types of models that currently can be produced from a digital file created by an intraoral scanner (IOS); (2) critically analyze issues that may undermine or compromise their reliability when requested for the fabrication of both tooth-borne and implant-supported fixed dental prostheses (FDPs); and (3) indicate the procedures to be implemented in order to overcome these issues and produce satisfactory restorations. MATERIALS AND METHODS: By way of a thorough literature review, the authors highlight the critical issues of milled and 3D-printed models, solid and alveolar, explaining the differences in terms of accuracy and reliability. RESULTS AND CONCLUSIONS: By describing the peculiarities of models with prepared natural teeth and those incorporating metal implant analogs, the clinical indications for their use are given while proposing the strategies that can be adopted to avoid errors during fabrication or to overcome inaccuracies.

Transferring emergence profile and position of interim restorative implant fixture. A novel digital technique.

The present technical article describes a protocol to digitally reproduce the emergence profile of an interim implant prosthesis (IP) and to transfer its macrogeometry into the definitive restoration. The purpose of this protocol was to minimize alterations in the gingival architecture developed during the interim restorative phase of a single implant that could potentially jeopardize its esthetic outcome. The process included obtaining an intraoral scan with the interim IP in situ, a duplicate of this intraoral scan that was used to capture the exact position of the implant, and an extraoral scan of the prosthesis. These data could then be imported into IOS software to create a model where the patients' soft tissue was incorporated with precision, allowing for the fabrication of a definitive crown with an optimal soft tissue adaptation. As there are few articles in the scientific literature that have reported a consistent method to replicate the emergence profile of an interim IP, the present technical article aims to highlight the potential of utilizing the emergence profile of an interim IP created by IOS software.

Replacement of unsatisfactory ceramic veneers with the aid of a digital workflow.

This case report focuses on the replacement of ceramic laminate veneers with suboptimal marginal fit and design, employing a digital workflow and CAD-CAM technology. The patient, a woman in her 30s, expressed concerns about the appearance and hygiene challenges of her existing veneers. A comprehensive assessment, including clinical examination, facial photographs and intraoral scanning, was conducted. Utilising CAD software, facial photographs and 3D models merged to create a digital wax-up, crucial in designing suitable veneers and addressing issues like overcontouring and a poor emergence profile. Following the removal of old veneers, a mock-up was performed and approved. Preparations ensured space for restorations with well-defined margins. The final restorations, milled with Leucite-reinforced vitreous ceramic, were cemented. At the 1 year follow-up, improved aesthetics, gingival health and functional restorations were observed. This report highlights the efficacy of digital workflows in achieving consistent and aesthetically pleasing outcomes in ceramic laminate veneer replacement.

Assessment of CAD/CAM Fabrication Technologies for Post and Core Restorations-A Narrative Review.

The primary objective of this study is to conduct a comprehensive review of the existing literature that discusses research on post and core restorations, covering aspects such as their composition, manufacturing methods, and clinical effectiveness. The methodology employed in this review encompasses the implementation of a well-defined search strategy, the establishment of criteria for inclusion and exclusion, and the selection of relevant studies to summarize their findings. To gather relevant literature published between 1993 and 2023, the research team conducted separate searches on PubMed, Web of Science, and Embase databases. In total, 168 titles were initially retrieved from these electronic databases. By applying the predefined exclusion criteria, the researchers identified 73 articles that specifically address the conventional and computer-aided design/computer-aided manufacturing (CAD/CAM) technologies employed in post and core restorations. These treatments are commonly employed to restore teeth that have received endodontic therapy and subsequently experienced loss of dental structure. The development of computerized technology for the creation of customized posts and cores has emerged as a straightforward and efficient alternative to traditional methods. The review synthesizes papers discussing the techniques and materials involved in CAD/CAM-based construction of post and cores. It explores strategies for restoring endodontically treated teeth, highlighting both direct and indirect approaches. Commonly mentioned materials include zirconia, composite resin, and hybrid ceramics. Despite the limited literature on CAD/CAM post and core procedures, the review emphasizes the necessity of further research to assess long-term outcomes and efficacy. Additionally, it suggests including implications for future research and clinical recommendations to enhance the depth and practical relevance of the review.

A systematic review of factors impacting intraoral scanning accuracy in implant dentistry with emphasis on scan bodies.

PURPOSE: The purpose of this systematic review was to explore and identify the factors that influence the accuracy of intraoral scanning in implant dentistry, with a specific focus on scan bodies (ISBs). METHODS: Following the PRISMA 2020 guidelines, this study conducted a thorough electronic search across MedLine, PubMed, and Scopus to identify relevant studies. Articles were screened based on titles, abstracts, and full texts for relevance. The Robins I tool assessed the risk of bias in various study types. Data extraction occurred based on predetermined parameters for studying specimens and assessing outcomes. RESULTS: 16 studies met the specified criteria and were consequently included in the systematic review. Due to variations in variables and methods across the selected studies, statistical comparison of results was not feasible. Therefore, a descriptive review approach was chosen, acknowledging the substantial heterogeneity in the reviewed literature. CONCLUSIONS: The precision of virtual scan results is contingent upon diverse characteristics of ISBs and implants. These factors encompass their placement within the dental arch, structural design, shape, material composition, color, and the manufacturing system, all of which contribute to scan accuracy. Additionally, considerations such as the intraoral scanner (IOS) type, scanning technique, use of scan aids, inter-implant distance, scan span, and the number of implants warrant evaluation. In the context of capturing implant positions, intraoral scanning with ISBs demonstrates comparable accuracy to traditional impression methods, particularly in single and short-span scenarios. However, the existing data lacks sufficient information on in vivo applications to formulate clinical recommendations.

Stress distribution on teeth restored with veneers using various incisal preparation designs: A 3D finite element analysis study.

STATEMENT OF PROBLEM: The type of veneer preparation is often chosen according to the patient's tooth structure and occlusion. Taking biomechanics into account in this decision-making process provides the clinician with more technical information on how to improve the clinical longevity of restorations. However, biomechanical analyses of veneer preparation designs are sparse. PURPOSE: The purpose of this 3-dimensional (3D) finite element analysis with microcomputed tomography (µCT) data obtained from realistic models was to assess the influence of different preparations for ceramic and composite resin veneers on restoration and resin layer stress distribution. MATERIAL AND METHODS: Four replicas of a central incisor were printed and prepared for laminate veneers with 4 different incisal edge designs: shoulder (SH), palatal chamfer (PC), palatal chamfer and oblique fracture involving the distal angle (OF-PC), and palatal chamfer involving horizontal incisal fracture (IF-PC). After fabrication and cementation of the veneers, the restored replicas were assessed with µCT, and 3D finite element models were built. A 100-N load was applied on the palatal surface at 60 and 125 degrees relative to the longitudinal axis. Maximum principal stress and stress distribution on the veneers, cement layer, and tooth structure were calculated and analyzed. RESULTS: The SH preparation exhibited better stress distribution than the PC preparation, and the cement layer and the veneer were subjected to lower stress. The IF-PC preparation had better stress distribution than the OF-PC. The shoulder and IF-PC showed higher stress on laminate veneers, but lower stress on the cement layer. Ceramic veneers exhibited lower stress than composite resin veneers. CONCLUSIONS: The different incisal preparations for laminate veneers influenced stress distribution on restorations and on the resin cement layer. The shoulder type preparation showed better stress distribution and the composite resin veneers showed unfavorable results compared with the ceramic veneers.

Digitalization: New era of dentistry.

The visual appeal of teeth and smiles significantly influences both how others perceive individuals and their self-image and confidence. The subjective nature of dental esthetics, varying greatly among patients and dental professionals, has made digital smile design tools essential for creating natural and personalized esthetics. Contemporary digital methods and workflows encompass all clinical phases, from diagnosis to the creation of a smile aligned with the patient's facial features, and the completion of the restoratives. Digital technologies not only streamline treatment planning, smile designing, and the creation of restorations but also enable effective and time-efficient collaboration among different dental specialists and dental laboratory technicians, enhancing overall patient care. The use of contemporary digital tools in interdisciplinary esthetic treatments is presented, underscoring the role of high magnification for precision, implant placement, minimal invasiveness, and clinical effectiveness.

Generative deep learning approaches for the design of dental restorations: A narrative review.

OBJECTIVES: This study aims to explore and discuss recent advancements in tooth reconstruction utilizing deep learning (DL) techniques. A review on new DL methodologies in partial and full tooth reconstruction is conducted. DATA/SOURCES: PubMed, Google Scholar, and IEEE Xplore databases were searched for articles from 2003 to 2023. STUDY SELECTION: The review includes 9 articles published from 2018 to 2023. The selected articles showcase novel DL approaches for tooth reconstruction, while those concentrating solely on the application or review of DL methods are excluded. The review shows that data is acquired via intraoral scans or laboratory scans of dental plaster models. Common data representations are depth maps, point clouds, and voxelized point clouds. Reconstructions focus on single teeth, using data from adjacent teeth or the entire jaw. Some articles include antagonist teeth data and features like occlusal grooves and gap distance. Primary network architectures include Generative Adversarial Networks (GANs) and Transformers. Compared to conventional digital methods, DL-based tooth reconstruction reports error rates approximately two times lower. CONCLUSIONS: Generative DL models analyze dental datasets to reconstruct missing teeth by extracting insights into patterns and structures. Through specialized application, these models reconstruct morphologically and functionally sound dental structures, leveraging information from the existing teeth. The reported advancements facilitate the feasibility of DL-based dental crown reconstruction. Beyond GANs and Transformers with point clouds or voxels, recent studies indicate promising outcomes with diffusion-based architectures and innovative data representations like wavelets for 3D shape completion and inference problems. CLINICAL SIGNIFICANCE: Generative network architectures employed in the analysis and reconstruction of dental structures demonstrate notable proficiency. The enhanced accuracy and efficiency of DL-based frameworks hold the potential to enhance clinical outcomes and increase patient satisfaction. The reduced reconstruction times and diminished requirement for manual intervention may lead to cost savings and improved accessibility of dental services.

Does the choice of the measuring technique affect the comparison of fit between zirconia and cobalt-chromium prostheses?

AIMS: The objectives of the study were to compare the adaptation of presintered zirconia and cobalt- chromium prostheses using microcomputed tomography (µCT), scanning electron microscopy (SEM), and stereomicroscope (SM). MATERIALS AND METHODS: Twenty-four fixed dental prostheses (FDPs) were fabricated on metal abutments, duplicated from maxillary first premolar and first molar prepared on a typodont model. Teeth were reduced to obtain chamfer of 1.2 mm and reduction occlusaly of 2 mm occlusal. Scanning of the abutments was done with random assignment to two groups receiving the FDPs made from soft-milled Co-Cr (n = 12) and zirconia (n = 12). Marginal and internal gaps were assessed using three evaluation techniques (X-ray microcomputer tomography, SEM, and stereomicroscopy). STATISTICAL ANALYSIS USED: Comparison of the results was made using Levene and analysis of variance tests (α =0.05). RESULTS: Irrespective of the material tested, statistical differences were found between the measuring techniques (P = 0.001 overall); the obtained mean gaps were for CT scan (92.60 ± 13.31), for SEM (101.92 ± 23.03), and for SM (113.44 ± 14.68): the multiple comparisons between techniques found a significant difference between CT and SM (P < 0.001), and SEM and SM (P = 0.025). When materials were compared within each measuring technique, Co-Cr showed lower values compared to zirconia in SEM (P < 0.001) and Stereo (P = 0.049); similar results were found in CT. CONCLUSIONS: Results values differed with the chosen measuring technique. Co-Cr prostheses had a better fit than zirconia prostheses in SEM and Stereo. µCT showed comparable results to SEM, smaller than SM results.

Trueness and precision of an intraoral scanner on abutments with subgingival vertical margins: An in vitro study.

OBJECTIVES: This study aimed to evaluate the accuracy of an intraoral scanner (IOS - Medit i700) on tooth abutments with vertical preparations at 2 depths below the free gingival margin, and to determine if the IOS can reproduce the area beyond the finish surface of the tested preparation geometry. METHODS: Two abutments for a maxillary first molar were designed by means of CAD software, with vertical preparations set at 1 and 2 mm below the gingiva. These abutments were subsequently printed in resin and placed on a reference model. The reference files consisted of scans made using a metrological machine on these abutments. Ten scans were made with the tested IOS on each sample, resulting in two study groups. The scans from the experimental groups were labeled "V-1″ for vertical preparation at 1 mm below the gingival margin and "V-2″ for 2 mm below. The analysis of these scans was performed using Geomagic Control X (3D SYSTEMS) to assess their trueness and precision in µm. Descriptive statistics with a 95 % confidence interval were employed, alongside independent sample tests, to ascertain any differences between the groups (α=0.05). RESULTS: Statistically significant differences were not found both for trueness (p=.104) and precision (p=.409), between the tested geometries. The mean values for trueness were V-1 = 37.5[31.4-43.6]; V-2 = 32.6[30.6-34.6]. About the precision, the mean values were V-1 = 20.5[8.4-32.5]; V-2 = 18.4[8.2-28.5]. In both the study groups, it was possible to detect the surface beyond the finish area. CONCLUSIONS: Within the limitations of this study, vertical preparation design allows for registration of the tooth anatomy beyond the finish area with IOS. Moreover, the mean accuracy values were clinically acceptable at both 1 and 2 mm below the gingival margin.

Accuracy of the intaglio surface of 3D-printed hybrid resin-ceramic crowns, veneers and table-tops: An in vitro study.

OBJECTIVES: The present study aims to examine the influence of the build angle on the accuracy (trueness and precision) of 3D printed crowns, table-tops and veneers with a hybrid resin-ceramic material. METHODS: One crown, on table-top and one veneer were printed in five different build angles (0°, 30°, 45°, 60°, 90°) (n = 50) with the digital light processing (DLP) system (Varseo XS, Bego) using hybrid resin (Varseo Smile Crownplus A3, Bego). All printed restorations were scanned using the laboratory scanner (D2000, 3Shape) and matched onto the initial reference design in metrology software (Geomagic Control X, 3D Systems). The root mean square error (RMSE) was calculated between the scanned and reference data. The data was statistically analyzed using the Tukey multiple comparison test and Wilcoxon multiple comparison test. RESULTS: The crown group showed higher trueness at 30° (0.021 ± 0.002) and 45° (0.020 ± 0.002), and table-tops at 0° (0.015 ± 0.001) and 30° (0.014 ± 0.001) (p < 0.0001). Veneers demonstrated higher trueness at 30° (0.016 ± 0.002) (p < 0.0001). All three restoration types demonstrated the lowest trueness at a 90° build angle and portrayed deviations along the z axis. The veneer and table-top groups showed the lowest precision at 90° (veneers: 0.021 ± 0.008; table-tops: 0.013 ± 0.003). The crown group portrayed the lowest precision at 45° (0.017 ± 0.005) (p < 0.0001). CONCLUSION: The build angle of DLP-printed hybrid resin-ceramic restorations influences their accuracy. CLINICAL SIGNIFICANCE: Considering the build angle is important to achieve a better accuracy of 3D-printed resin-ceramic hybrid restorations. This may help predict or avoid the interference points between a restoration and a die and minimize the clinical adjustments.

Precise tooth design using deep learning-based templates.

OBJECTIVES: In prosthodontic procedures, traditional computer-aided design (CAD) is often time-consuming and lacks accuracy in shape restoration. In this study, we combined implicit template and deep learning (DL) to construct a precise neural network for personalized tooth defect restoration. METHODS: Ninety models of right maxillary central incisor (80 for training, 10 for validation) were collected. A DL model named ToothDIT was trained to establish an implicit template and a neural network capable of predicting unique identifications. In the validation stage, teeth in validation set were processed into corner, incisive, and medium defects. The defective teeth were inputted into ToothDIT to predict the unique identification, which actuated the deformation of the implicit template to generate the highly customized template (DIT) for the target tooth. Morphological restorations were executed with templates from template shape library (TSL), average tooth template (ATT), and DIT in Exocad (GmbH, Germany). RMSestimate, width, length, aspect ratio, incisal edge curvature, incisive end retraction, and guiding inclination were introduced to assess the restorative accuracy. Statistical analysis was conducted using two-way ANOVA and paired t-test for overall and detailed differences. RESULTS: DIT displayed significantly smaller RMSestimate than TSL and ATT. In 2D detailed analysis, DIT exhibited significantly less deviations from the natural teeth compared to TSL and ATT. CONCLUSION: The proposed DL model successfully reconstructed the morphology of anterior teeth with various degrees of defects and achieved satisfactory accuracy. This approach provides a more reliable reference for prostheses design, resulting in enhanced accuracy in morphological restoration. CLINICAL SIGNIFICANCE: This DL model holds promise in assisting dentists and technicians in obtaining morphology templates that closely resemble the original shape of the defective teeth. These customized templates serve as a foundation for enhancing the efficiency and precision of digital restorative design for defective teeth.

Influence of CAD-CAM milling strategies on the outcome of indirect restorations: A scoping review.

STATEMENT OF PROBLEM: The influence of computer-aided manufacturing (CAM) parameters and settings on the outcomes of milled indirect restorations is poorly understood. PURPOSE: The purpose of this scoping review was to summarize the current CAM systems, parameters, and setting changes, and their effects on different outcomes of milled indirect restorations and aspects related to their manufacture. MATERIAL AND METHODS: The protocol of this review is available online (https://osf.io/x28ps/). Studies that used at least 2 different parameters (CAM units, number of axes, digital spacers, or protocols with different rotatory instruments, grit-sizes, milling speed, or others) for milling indirect restorations were included. A structured search up to July 2023 was performed by 2 independent reviewers for articles written in English in LILACS, MEDLINE via PubMed, EMBASE, Web of Science, and Scopus. RESULTS: Of 1546 studies identified, 22 were included in the review. Discrepancies were found between the planned and actual measured cement space, with a decreasing linear relationship impacting restoration adaptation at different points. The CEREC MC XL milling machine was the most used system in the included studies, with variations in bur types, milling modes, and number of burs uses affecting internal fit and surface trueness. The results demonstrated the better adaptation of restorations made with 5-axis over 3-axis milling machines. Lithium disilicate and zirconia were the most commonly used materials, and crowns and inlays were popular designs. Marginal and internal adaptation were the primary outcomes assessed using the various techniques. CONCLUSIONS: The study presented a comprehensive exploration of CAM systems and parameters, and their influence on indirect restorations. The planned cement space was not properly reproduced by the milling. Bur characteristics can affect restoration fit and trueness. The 5-axis units seem to result in better-adapted restorations compared with 3- and 4-axis units.

Accuracy of Dental Restorations Fabricated Using Milling vs 3D-Printed Molds: A Pilot Study.

PURPOSE: To compare the accuracy of 12 different dental restorations fabricated with milling or 3D-printed molds and robotically controlled casting. MATERIALS AND METHODS: Twelve dental restorations (11 inlays and onlays and 1 crown) were made per restoration type, one per each of the 12 different teeth models (total of 24 restorations). On each tooth preparation, two restorations were manufactured using different CAD/ CAM techniques: (1) milling and (2) robotically controlled casting and 3D-printed molds. In addition, twolayer restorations were manufactured with 3D-printed molds. The marginal and internal gaps were evaluated at 120 points per restoration based on micro-CT 3D imaging. Internal gaps were evaluated using a replica technique with silicone. RESULTS: Median values (interquartile ranges) for marginal gaps, middle internal gaps, and central internal gaps were significantly lower for 3D-printed mold restorations (44.3 [65.4] µm, 95.4 [96.2] µm, and 104.6 [78.1] µm) compared to milled restorations (58.4 [93] µm, 145.9 [85.8] µm, and 138.6 [65.7] µm). Internal gaps in the 3D-printed mold group were 6% to 51% smaller than in the milled group. CONCLUSIONS: The accuracy of restorations fabricated with 3D-printed molds may be preferable compared to milled restorations, except in the case of crown restoration. However, additional studies with a larger number of samples and different types of restorations are needed to confirm the results.