Journal of Prosthodontics-Implant Esthetic and Reconstructive Dentistry最新文献

Purpose: Integration of three-dimensional (3D) facial scanning into digital workflows has become increasingly important for enhancing treatment planning and esthetic evaluation. However, limited data exists on the accuracy of various methods of merging facial scans with cone beam computed tomography (CBCT) scans. The purpose of this study is to compare the accuracy of integrating 3D facial scans with CBCT scans using the iterative closest point (ICP) algorithm versus a radiopaque (RO) marker technique.

Materials and methods: This prospective clinical study included 15 patients who received CBCT scans and 3D facial scans in repose and smile positions. The Digital Imaging and Communications in Medicine (DICOM) datasets from the CBCT scans containing RO markers were integrated with the standard tessellation language (STL) files from the facial scans in Exocad software using two methods: RO alignment and the ICP algorithm. The datasets from both groups were statistically compared using a paired t-test (α = 0.05).

Results: The means for the six subsets merged by the ICP algorithm ranged from 1.47 to 2.0 mm, and the means for the RO markers were 0.13 to 0.15 mm. The novel RO markers method was statistically significant and more accurate than the ICP algorithm (p < 0.001).

Conclusions: Merging 3D facial scans to CBCT using radiopaque markers demonstrated higher trueness compared to the ICP algorithm under the conditions tested. This technique may serve as a reliable alternative for improving integration accuracy in digital dental workflows, particularly where precise facial landmark preservation is essential.

Purpose: To synthesize evidence from systematic reviews on artificial intelligence (AI) applications in prosthodontics and implant dentistry, focusing on clinical applications, AI model performance, and quality of evidence.

Methods: A comprehensive search was conducted in PubMed (MEDLINE), Scopus, Web of Science, Embase, and The Cochrane Library databases, identifying systematic reviews published from 2018 to 2025. Inclusion criteria comprised systematic reviews evaluating AI in prosthodontics or implant dentistry, published in English. Narrative reviews and reviews from other dental specialties were excluded. Two reviewers independently performed study selection and data extraction, and the methodological quality of the included systematic reviews was assessed using A Measurement Tool to Assess Systematic Reviews (AMSTAR-2) tool. This umbrella review was registered in the International Prospective Register of Systematic Reviews (PROSPERO) database (CRD420251067048).

Results: Eleven systematic reviews were included. AI demonstrated substantial capability in prosthodontics for caries and fracture detection (with an accuracy of ∼82%-89%), automated tooth shade matching, and prosthesis design. In implant dentistry, AI algorithms accurately identified implant types on radiographs (∼95.6% pooled accuracy), optimized implant placement planning, and predicted treatment outcomes with moderate accuracy (62.4%-80.5%). Performance was strongest for radiographic identification and anatomic segmentation tasks in implant dentistry. It was more modest for preparation margin detection and objective shade matching in prosthodontics, as well as for multivariable prognosis and for detecting maxillary edentulous sites in implant dentistry. Convolutional neural networks (CNNs) consistently outperformed traditional algorithms in image-based tasks. However, AI prediction of long-term outcomes showed moderate performance due to data limitations and biological variability. Overall, although four reviews were rated as high quality, the majority exhibited low or critically low methodological quality, primarily due to a lack of a priori protocol registration and incomplete bias assessment.

Conclusion: AI applications in prosthodontics and implant dentistry may enhance diagnostic and planning workflows, especially for recognition and segmentation tasks. Nevertheless, most evidence comes from early-stage, retrospective, or highly controlled studies, highlighting the need for prospective clinical validation and higher-quality systematic reviews before routine clinical adoption can be recommended.

Purpose: Bilayered restorations have both the strength of the substructure material and the esthetics of the veneer material; however, they should have appropriate bonding between the two materials. This study aimed to evaluate the shear bond strength (SBS) according to the substructure material and veneering technique used in bilayered restorations.

Materials and methods: The experimental group was divided into four groups (n = 15 per group) based on the substructure materials (cobalt-chromium [Co-Cr] alloy and 3 mol% yttrium-stabilized tetragonal zirconia polycrystal [3Y-TZP]) and veneering techniques (pressing and layering). Veneering was performed with disk shape (diameter: 5 mm, height: 2 mm) on a substructure using each veneering technique. Shear stress was applied to the interface of the substructure and the veneering ceramic using a universal testing machine. The shear bond strength, according to the substructure and veneering technique, was analyzed using a two-way analysis of variance with a post-hoc Tukey's honestly significant difference test. The failure mode was observed, and the surface was analyzed using a scanning electron microscope and energy-dispersive spectroscopy.

Results: The shSBS of the Co-Cr alloy and 3Y-TZP substructure was not different (p > 0.05); however, the pressing technique showed a higher SBS than the layering technique (p < 0.05). The SBS did not differ depending on the veneering technique in the Co-Cr alloys (p > 0.05), whereas the SBS in the pressing technique was higher than that in the layering technique for 3Y-TZP (p < 0.05). In the layering technique, the Co-Cr alloy showed a higher SBS than 3Y-TZP (p < 0.05). In the failure mode, mixed failure occurred most frequently in all groups. Extensive elemental interdiffusion was observed through the opaque layer in the Co-Cr alloy, regardless of the veneering technique. In 3Y-TZP, a wider range of elemental interdiffusion was observed in the pressing technique than in the layering technique.

Conclusions: In bilayered restorations with a 3Y-TZP substructure, the pressing technique yielded higher bonding strength than layering. Using the layering technique, 3Y-TZP showed a lower SBS than the Co-Cr alloy. In bilayered restorations using 3Y-TZP as a substructure, the veneering technique and thermal compatibility of the materials must be considered.

Purpose: The purpose of this in vitro study was to evaluate the effect of the angulation degree of multi-unit abutment (MUA) on the prosthetic screw-joint stability using a reverse torque test of the prosthetic screw and a pull-out test of the bonded coping.

Materials and methods: Thirty specimens with a two-implant segmental portion of an implant-supported fixed dental prosthesis design were prepared. Titanium copings (Variobase; Straumann USA) were cemented to the zirconia specimens (ZirCAD; Ivoclar Vivadent) using RelyX Universal Cement and Scotchbond Universal Plus Adhesive (3 M ESPE). The groups were defined as follows: Group S-S: straight implant + 0° MUA and straight implant + 0° MUA, used as the controls; Group S-17: straight implant + 0° MUA and 17° angulated implant + 17° MUA; and Group S-30: straight implant + 0° MUA and 30° angulated implant + 30° MUA. The initial torque value and initial reverse torque values of prosthetic screws were recorded using a digital torque gauge (Model HTGS-15; Imada Inc.). Zirconia specimens and cemented titanium copings were treated with thermal cycling (5000 cycles of 5°C-55°C, dwelling time 20 s). After this limited thermal cycling, all prosthetic screws were replaced with new screws to connect the zirconia plate to MUAs with tightening to 15 Ncm. All specimens were then subjected to masticatory simulation using cyclic loading treatment (300 N, 1.5 Hz in a 37°C water bath for 5000 cycles). At the end of the cyclic loading, final reverse torque values were recorded. A pull-out test of the cemented coping was conducted using a universal testing machine with a crosshead speed of 5 mm/min for all specimens. Failure patterns of the titanium copings and damage to the prosthetic screws were examined under an optical microscope. Mixed-effects linear modeling and estimated marginal means were used to analyze torque value changes. One-way ANOVA was used to analyze retentive force values from the pull-out test at α = 0.05.

Results: The torque value loss percentage of individual abutments ranged from 16.43% to 28.78%. There was a significantly higher torque value loss of Group S-30 when compared to Group S-S before cyclic loading (p = 0.01). After cyclic loading treatment, there is an increased torque value loss in Group S-S compared with before cyclic loading (p = 0.02). No statistically significant differences in pull-out force were observed among groups (p = 0.689). Debonding of titanium coping occurred in Group S-S only, while prosthetic screw deformations occurred 100% in Group S-30.

Conclusions: Prosthetic screw loosening was expected to occur at the same rate in all tested groups after cyclic loading treatment. However, when complications such as debonding of titanium coping or prosthetic screw fracture occurred, the modes of failure differed in each group.

Purpose: To evaluate the impact of posterior occlusal morphology, build angulation, and support configuration on the occurrence of isolated islands in a three-dimensional (3D) printing slicing software when printing a full arch implant-supported prosthesis.

Materials and methods: Three maxillary implant-supported full-arch prostheses were designed with similar intaglio and anterior teeth and different posterior morphology based on cusp angulations, including shallow (10°), medium (20°), and steep (33°). Each digital file was transferred to slicing software and nested in different angulations (0°, 15°, 30°, 45°, and 90°), and supports were created using different configurations (thin, standard, and thick). The sliced file from each configuration was evaluated for the presence of isolated islands of print where the printed material was left unsupported. The effect of independent variables and number of isolated islands, time to print, number of layers, and volume of the resin to print were analyzed with a three-way ANOVA test with a significance level set at 5%.

Results: The mean number of isolated islands (minimum 0 and maximum 11.9) in the slicing software was significantly affected by all three investigated variables (p < 0.05). Steep occlusal morphology reduced the chance of developing islands after slicing. The standard and thick support configuration reduced the number of islands when compared with the thin support configuration. In terms of build angulation, 0° resulted in the highest number of islands, and 90° build angulation resulted in no islands. Increasing the thickness of support and steeper cusp angulation significantly increased the amount of resin required to print (p < 0.05). Increasing the build angulation significantly increased the time to print, number of layers, and amount of resin to print (p < 0.05).

Conclusions: Slicing software can produce isolated unsupported areas that have the potential to cause print failure of a full arch implant-supported prosthesis. Based on the present findings, shallower posterior occlusal anatomy, thinner supports, and 0° build angulation increased the chance of developing isolated islands in a slicing software.

Purpose: This study aimed to evaluate and compare the marginal and internal fit of permanent crowns fabricated using three different DLP 3D printers and their corresponding permanent resin materials. The fit was quantitatively assessed using micro-computed tomography (micro-CT) and digital 3D analysis.

Materials and methods: A premolar tooth was prepared according to conventional ceramic tooth preparation protocols and scanned with an intraoral scanner (TRIOS 5). The resulting standard tessellation language (STL) file was imported into the software for design. A total of 24 crowns were fabricated using three different printer and resin combinations (n = 8): an Asiga printer with Saremco Crowntec permanent resin (Group S), a Denta Fab printer with Power Resin C&B permanent resin (Group C), and a SprintRay printer with Crown permanent resin (Group SP). These crowns were then re-scanned with an intraoral scanner to obtain STL files. Marginal, axial, and occlusal alignment were calculated and compared using 3D analysis software and micro-CT software. As the data were normally distributed, comparisons were made using one-way ANOVA. The significance level was set at p < 0.05.

Results: In the marginal area, Group SP demonstrated significantly superior fit compared to Group S (p = 0.002) and Group C (p = 0.0005). No statistically significant difference was observed between Group S and Group C (p = 0.245). The findings obtained from both micro-CT and 3D superimposition analyses were consistent, confirming the reliability and agreement of the two evaluation methods.

Conclusion: This study demonstrates that crown restorations fabricated using 3D printers exhibit significant variations in fit depending on the type of resin employed. In particular, the resin used in Group SP tended to show improved marginal adaptation compared to Groups S and C, which exhibited comparable results. These findings may offer guidance for clinical decision-making regarding the selection of 3D printing systems and resins for crown fabrication in prosthodontic applications.

Purpose: This study aimed to develop a novel and efficient digital workflow for designing and manufacturing 3D-printed definitive maxillofacial obturator prostheses based on multi-source data fusion and various digital techniques, as well as to evaluate its feasibility through a randomized self-controlled study.

Materials and methods: Participants with maxillary defects were recruited for the study. A digital impression was obtained by fusing intraoral scanning data and computed tomography (CT) images. The framework and artificial-teeth-obturator were designed separately using multiple dental design software programs, fabricated through additive manufacturing (AM), and finally assembled precisely into one unit with the help of specially designed auxiliary positioning and connecting structures. For comparison, a conventional prosthesis was also made for each participant. The adaptation of both conventional and digital prostheses was evaluated and compared using the silicone rubber lining method through deviation analysis. Additionally, the chairside impression time for both conventional and digital treatments were recorded and compared.

Results: The digital workflow for designing and manufacturing maxillofacial prosthesis was successfully realized. The chairside impression time was shortened (p < 0.001). The adaptation of the digital prosthesis, including framework (349.89 ± 121.56 µm), obturator (420.08 ± 166.01 µm), and the whole prosthesis (408.36 ± 118.05 µm), proved suitable for clinical application. No statistically significant difference was observed between the digital and conventional prostheses.

Conclusion: The newly established digital workflow for the fabrication of definitive maxillofacial obturator prostheses reduced chairside impression time and the number of appointments, featuring clinically acceptable adaptation. This approach has potential for future applications in the treatment of patients with maxillofacial defects.