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Objectives The aim of this study is to compare the fit of all-ceramic crowns fabricated from conventional silicone impressions with the fit of all-ceramic crowns fabricated from intraoral digital impressions. Methods Twenty patients with 26 posterior teeth with a prosthetic demand were selected for the study. Two crowns (Straumann-Zerion) were made for each preparation. One crown was fabricated from an intraoral digital impression system (IDI group; Cadent-iTero), and the other crown was fabricated from a conventional one-step silicone impression (CI group; Express Penta Putty and Body Light). To replicate the interface between the crown and the preparation, each crown was cemented on its corresponding clinical preparation with ultra-flow silicone (Express Ultra Light Body). Each crown was embedded in resin to stabilize the registered interface, cut in 2-mm-thick slices in a buco-lingual orientation. Internal misfit was measured in microns using stereomicroscopy with a magnification of ×40. Measurements were taken at different landmarks: margin, chamfer angle, axial, crest, and occlusal fosse. After checking for normality, data was analyzed using paired Student’s t test ( α  = 0.05). Results Fit values were significantly affected by the impression technique ( p  = 0.000). Mean internal misfit and mean marginal misfit were 111.40 μm (SD = 54.04)/80.29 μm (SD = 26.24) for the crowns of the IDI group and 173.00 μm (SD = 92.65)/133.51 μm (SD = 48.78) for the CI group. Conclusion All-ceramic crowns fabricated from intraoral digital impressions with parallel confocal technology demonstrated a clinically acceptable internal and marginal fit as conventional impression. Clinical significance Intraoral digital impressions as initial step to the digital workflow could further improve the marginal adaptation of all ceramic single crowns. Trial registration http://www.isrctn.com/ISRCTN16111844

Objectives To compare the fit of all-ceramic crowns fabricated from conventional silicone impressions with the fit of all-ceramic crowns fabricated from intraoral digital impressions. Methods Thirty patients with 30 posterior teeth with a prosthetic demand were selected. Zirconia-based ceramic crowns were made using an intraoral digital impression system (Ultrafast Optical Sectioning technology) (digital group, D) and 2-step silicone impression technique (conventional group, C). To replicate the interface between the crown and the preparation, each crown was cemented on its corresponding clinical preparation using ultra-flow silicone. Each crown was embedded in resin to stabilize the registered interface. Specimens were sectioned in buccolingual orientation, and internal misfit was measured at different areas using stereomicroscopy (×40). Data was analysed using Student’s t test and Mann-Whitney test (α = 0.05). Results No statistically significant differences were found ( P  > 0.05) between two groups. The mean internal misfit and mean marginal misfit were 170.9 μm (SD = 119.4)/106.6 μm (SD = 69.6) for group D and 185.4 μm (SD = 112.1)/119.9 μm (SD = 59.9) for group C. Conclusion Ceramic crowns fabricated using an intraoral scanner are comparable to elastomer conventional impressions in terms of their marginal and internal fits. The mean marginal fit in both groups was within the limits of clinical acceptability. Clinical significance Impressions based on Ultrafast Optical Sectioning technology can be used for manufacturing ceramic crowns in a normal workflow, with the same results as silicone conventional impressions .

ObjectivesThe purpose of this in vitro study was to assess and compare the marginal and internal fit of machine-milled crowns designed using three different CAD software programs.Materials and methodsDigital impressions of the master zirconia casts containing the prepared molar were obtained using an intraoral scanner. The obtained standard tessellation language (STL) files were imported into three CAD software programs (Multi-CAD, Blue-Sky CAD, and InLab), and crown designs were generated. Crown design digital STL files were used to mill crowns with a five-axis dental milling machine. The internal and marginal fits of the fabricated crowns over the master-prepared tooth were assessed using the triple-scan protocol and digital analysis techniques. The 3D marginal and internal fit values of the fabricated crowns from the designs generated by the three CAD programs were evaluated and statistically compared using one-way analysis of variance (ANOVA) and post hoc Tukey’s tests (α = 0.05).ResultsThere were no significant differences in the internal fit of the crowns designed by the three CAD programs (p > 0.05). However, there were significant differences in the mean marginal fit (p = 0.009) of the crowns. The marginal fit values for the InLab-designed crowns were significantly better than those for Multi-CAD (p = 0.03) and Blue-Sky CAD (p = 0.012) groups.ConclusionsAll three CAD programs can design clinically acceptable crowns in terms of internal and marginal fit. InLab crowns outperformed the Multi-CAD and Blue-Sky CAD programs in terms of marginal fit.Clinical relevanceIt is critical to test the ability of newly released CAD programs to design acceptable virtual crowns that can be transformed into actual crowns with optimal marginal and internal fit to existing clinical tooth preparations/conditions to ensure the high technical quality and long-term success of fabricated crowns.

(1) Objective: To compare the marginal and internal fit of 3D-printed and milled three-unit fixed dental prostheses (FDPs) made from tetragonal zirconia polycrystal (3Y-TZP). (2) Methods: Three-unit FDPs were designed for a typodont maxillary model with crown preparation for the second premolar and second molar. Nominal cement gap widths were set to 30 µm at the margins and 80 µm internally. A total of 40 FDPs (n = 10/group) differing in wall thickness (w = 0.6/1.0 mm) and support structures (with/without a stiffening frame) were fabricated from 3Y-TZP by 3D printing. A total of 10 milled FDPs with w = 0.6 mm served as a control group. After adhesive cementation on the respective replicated maxillary models, FDPs were sectioned and the cement gap dimension was assessed with a digital microscope. The marginal and internal fit found for the different test groups were compared using non-parametric tests. (3) Results: The best marginal fit—qualified by median/maximum marginal gap width—was given for milled FDPs (79/127 µm vertical; 85/171 µm tangential), whereas the marginal fit of 3D-printed FDPs with w = 0.6 mm and regular support structures was the worst (144/284 µm vertical; 107/198 µm tangential). Use of an additional support frame improved the marginal fit of 3D-printed FDPs, in particular FDPs with w = 0.6 mm (108/197 µm vertical; 87/161 µm tangential). (4) Conclusions: 3D-printed zirconia FDPs showed conditionally comparable marginal and internal fit as their milled counterparts, but with slightly higher scattering. When fabricating thinner 3D-printed FDPs, additional support structures are mandatory to achieve clinically well-fitting restorations.

Background: Minimal evidence exists on the efficacy of different digital manufacturing techniques in the fabrication of precise dental working models and provisional prosthesis. Aim of study: The objective was to evaluate the effect of two digital fabrication techniques (CAD/CAM milling and 3D printing) on the accuracy of PMMA working models and marginal fit of PMMA provisional prosthesis. Materials and methods: Two abutment teeth of modified typodont were prepared. A reference stone model was fabricated, and an optical impression was performed to obtain a CAD reference model. Four CAM milled working models and four printed working models were fabricated. CAD software was used to design the provisional prostheses. Group A tested four milled provisional prosthesis, and group B tested four 3D printed prosthesis. The 3D accuracy of working models was assessed by superimposition of the control reference working model on the CAD test working model. A stereo-optical microscope was used to assess vertical marginal fit of the provisional dental prosthesis. Student’s t and Mann–Whitney U tests were utilized to compare the two groups. Results: Results showed no statistically significant difference between the two tested groups. Conclusion: The two digital working model fabrication techniques recorded comparable accuracy. Similarly, 3D printed provisional prosthesis showed comparable marginal fit to the CAD/CAM milled ones.

Background In this study, we aimed to compare the marginal and internal fit of single-crown restorations fabricated using digital and conventional impression techniques, and to evaluate the potential advantages of digital impressions over conventional polyvinyl siloxane-based methods. Materials and methods A total of 120 extracted maxillary first molars were randomly assigned to two groups ( n  = 60 each): the conventional impression group (polyvinyl siloxane) and the digital impression group (TRIOS 3 intraoral scanner, 3Shape A/S, Copenhagen, Denmark). Standardized tooth preparations and CAD/CAM fabrication (IPS e.max CAD, Ivoclar Vivadent AG, Schaan, Liechtenstein) were performed for all samples. Marginal and internal fit were assessed using both the silicone replica technique and micro-computed tomography (micro-CT). Measurements were analyzed using independent samples t-tests. Intraobserver and interobserver reliability were evaluated using intraclass correlation coefficients (ICC). Results The digital impression group demonstrated significantly smaller marginal and internal gaps compared to the conventional group in both evaluation methods. In silicone replica analysis, marginal gaps were 45.8 ± 6.7 μm (digital) and 61.3 ± 7.5 μm (conventional) ( p  < 0.001); internal gaps were 84.5 ± 10.8 μm (digital) and 102.7 ± 12.1 μm (conventional) ( p  < 0.001). Micro-CT analysis confirmed these findings with marginal gaps of 43.2 ± 5.9 μm (digital) and 59.8 ± 6.4 μm (conventional) ( p  < 0.001), and internal gaps of 81.3 ± 9.6 μm (digital) and 98.4 ± 11.3 μm (conventional) ( p  < 0.001). Intraobserver and interobserver ICC values exceeded 0.95, indicating excellent measurement reliability. Conclusions Digital impression techniques provided significantly superior marginal and internal adaptation compared to conventional polyvinyl siloxane-based impressions for single-crown restorations. The improved accuracy, combined with workflow efficiency and patient comfort, supports the clinical adoption of digital impression systems.

Statement of the problem The clinical performance of ceramic crowns is influenced by overall marginal adaptation. A recently introduced advanced lithium disilicate ceramic requires further evidence compared to conventional lithium disilicate in terms of vertical marginal fit. Purpose of the study To assess the vertical marginal fit of crowns constructed from advanced and conventional lithium disilicate materials. Materials and methods Ten ( n  = 10) ceramic crowns were constructed and randomly assigned to two groups: Group (T) with CEREC Tessera crowns ( n  = 5) and Group (E) with IPS e.max CAD crowns ( n  = 5). Vertical marginal fit was evaluated using a stereomicroscope at 10X magnification both before and after cementation, with twenty equidistant measurement points recorded for each crown. Each crown was cemented to its corresponding natural molar tooth using Totalcem resin cement. Mann-Whitney U test was used to compare the two material groups. Wilcoxon signed-rank test was used to compare between vertical marginal fit before and after cementation ( P  ≤ 0.05). Results The overall vertical marginal fit between the two groups showed no significant difference, whether before or after cementation. However, both groups exhibited a statistically significant decrease in vertical marginal fit after cementation. Conclusion Advanced lithium disilicate shows advantageous properties concerning mean marginal gap values exhibiting comparable performance to IPS e.max CAD. Clinical implications CEREC Tessera demonstrated marginal fit values within clinically acceptable limits, supporting its reliability as a novel chairside material suitable for use in restorative dentistry.

The aim of this study was to compare the quality of different computer-assisted-design and computer assisted manufacturing systems (CAD-CAM) generated by only one scanner, focusing on vertical fit discrepancies and the mechanical properties. A master model was obtained from a real clinical situation: the replacement of an absent (pontic) tooth, with the construction of a fixed partial denture on natural abutments with three elements. Nine scans were performed by each tested and 36 copies were designed using a dental CAD-CAM software (Exocad). The frameworks were manufactured using three-axis and five-axis, with the same batch of the chrome-cobalt (CrCo) alloy. The frameworks were not cemented. A focus ion beam-high resolution scanning electron microscope (FIB-HRSEM) allowed us to obtain the vertical gap measurements in five points for each specimen. Roughness parameters were measured using white light interferometry (WLI). The samples were mechanically characterized by means of flexural tests. A servo-hydraulic testing machine was used with a cross-head rate of 1 mm/min. One-way ANOVA statistical analysis was performed to determine whether the vertical discrepancies and mechanical properties were significantly different between each group (significance level p < 0.05). The overall mean marginal gap values ranged: from 92.38 ± 19.24 µm to 19.46 ± 10.20 µm, for the samples produced by three-axis and five-axis machines, respectively. Roughness was lower in the five-axis machine than the three-axis one, and as a consequence, the surface quality was better when the five-axis machine was used. These results revealed a statistically significant difference (p < 0.005) in the mean marginal gap between the CAD-CAM systems studied. The flexural strength for these restorations range from 6500 to 7000 N, and does not present any statistical differences’ significance between two CAD-CAM systems studied. This contribution suggests that the number of axes improves vertical fit and surface quality due to the lower roughness. These claims show some discrepancies with other studies.

Background The success of a restoration largely depends on the quality of its fit. This study aimed to investigate the fit quality of monolithic zirconia veneers (MZVs) produced through traditional and digital workflows. Methods A typodont maxillary right central incisor was prepared. The maxillary arch with the prepared tooth was scanned with Trios 3 Pod intra-oral scanner (IOS), which served as a pattern to create thirty 3D resin models through printing. Additionally, thirty conventional impressions of the maxillary with the prepared tooth were taken using polyvinyl siloxane (PVS) impression material. These impressions were cast using dental gypsum products to create thirty stone dies, which were then scanned externally. Sixty MZVs were milled from multi-layered zirconia disks. The marginal and internal gaps of restorations were assessed using the silicone replica technique. Results The highest marginal accuracy for both the conventional and digital impression groups was observed in the cervical area, with values of 74.6 μm and 61.9 μm, respectively. The smallest internal gaps for both groups were also recorded in the cervical area, at 109.9 μm for the conventional group and 109.7 μm for the digital group. The digital group exhibited better marginal fit, particularly in the incisal and mesial areas (79.3 μm and 75.7 μm, respectively), compared to the conventional group (88.1 μm and 90.8 μm). No statistically significant differences in internal fit were observed. Conclusion MZVs fabricated using the digital workflow exhibited superior marginal fit compared to those fabricated using the conventional workflow, though both techniques yielded clinically acceptable results.

Background High-speed sintering has emerged as a promising innovation for enhancing the efficiency of dental prosthesis fabrication. However, its impact on marginal adaptation remains a critical factor in ensuring the long-term clinical success of restorations. The aim of the study to evaluate the marginal fit of high-speed and regular-speed-sintered zirconia crowns. Methods A maxillary right second molar on a typodont was prepared for an all-ceramic crown. A PVS impression was taken and a Type V stone master cast was fabricated. This cast was scanned via a laboratory scanner to produce 20 milled zirconia crowns. The crowns were divided into two groups ( n  = 10). Group A was subjected to a fast-sintering program, whereas group B was sintered via a conventional-speed-sintering program. Marginal fit was assessed via a stereoscopic microscope at four well-defined points (mid-distal, mid-lingual, mid-mesial, and mid-buccal) on each crown. Three readings were taken at each point. The marginal gaps of both groups were compared via the Wilcoxon signed-rank test. Results Statistically significant difference between groups A and B ( p  < 0.001) was revealed. Although the mean marginal gap in both groups was below the clinically acceptable limit (< 90 μm), the fast-sintering program produced restorations with a larger marginal gap than the restorations sintered via the conventional program. Conclusion Crowns produced via both sintering programs were clinically acceptable, although the regular-speed-sintering program yielded a significantly superior marginal fit.