The International journal of prosthodontics最新文献

Purpose: To examine the effect of gastric acid on the surface roughness of additive and subtractive manufacturing resin.

Materials and methods: In this study, two subtractive-manufacturing CAD/CAM resin nanoceramics (Cerasmart 270 [CS], Lava Ultimate [LU]) and two additive-manufacturing 3D-printing permanent resins (VarseoSmile Crownplus [VSP], Crowntec [CT]) were used. CS and LU samples were turned into 10-mm-diameter cylinders with a scraper and cut into 2-mm slices on the cutting device. CT and VSP samples were produced on a 3D printer (2-mm thickness, 10-mm diameter; n = 15). All samples were exposed to a cycle of 60 seconds of gastric acid, 5 seconds of distilled water, and 30 minutes of artificial saliva, six times a day for 10 days. Surface roughness mean (Ra) and depth (Rz) were measured with a contact profilometer at baseline and after gastric acid cycling. Data were analyzed using SPSS (version 22.0), one-way ANOVA, post-hoc Tukey, and independent t tests (P < .05).

Results: Ra and Rz values of CT and VSP were significantly higher than CS and LU at baseline and after the gastric acid cycle (P < .05). After the gastric acid cycle, the Ra and Rz values of all materials increased significantly compared to baseline (P < .05), but the Ra values of all materials were at a clinically acceptable level (< 0.2 µm).

Conclusions: Although additive-manufacturing 3D-printing permanent resins offered higher roughness values, they were still at a clinically acceptable level. Therefore, they can be used as an alternative to subtractive-manufacturing CAD/CAM resin nanoceramics.

Purpose: To provide a comprehensive overview of the two-color chewing gum mixing ability test's use across dental and medical fields, highlighting its potential for standardizing masticatory performance (MP) assessment and improving clinical decision-making.

Materials and methods: A scoping review was conducted on PubMed/MEDLINE, following the PRISMA-ScR guidelines. Abstracts of research papers were screened for suitability, and full-text articles were obtained for those that satisfied the inclusion criteria.

Results: After the screening, 73 articles were selected and considered eligible for this review in addition to another 11 studies identified from manual searching. A total of 84 studies were therefore included in this scoping review. Overall, 20 articles related to the development and the improvement of the two-color chewing gum mixing ability test over the years were identified and discussed. Additionally, 64 studies investigated the test's application to assess MP in different fields of dentistry and medicine.

Conclusions: The two-color chewing gum mixing ability test has been successfully adopted in the assessment of masticatory function not only in dentistry but also in general medicine.

Purpose: To investigate the effect of layer thickness, printing orientation, and post-curing time on the optical properties including the Commission Internationale de L'ecraige (CIE) color coordinates (L*, a*, and b*), color difference (ΔE00) with target shade, relative translucency parameter (RTP00), and opalescence parameter (OP) of additively manufactured resin material for interim fixed dental restorations.

Materials and methods: A total of 270 disc specimens were additively manufactured using biocompatible interim resin material (TEMP, Power Resins) with varying layer thicknesses (25, 50, and 100 µm), printing orientations (0, 45, and 90 degrees), and post-curing times (10, 20, and 30 minutes; n = 10). Optical properties were measured using a spectrophotometer. Data were analyzed using three-way ANOVA, Tukey HSD, and Bonferroni post-hoc tests (α = .05).

Results: Layer thickness, printing orientation, and post-curing time significantly influenced the optical properties (P < .05). All three-way interactions were significant (P < .05), except for L* and b* parameters (P > .05). Increasing layer thickness, printing orientation, and post-curing time resulted in increased yellowness and ΔE00, while lightness and OP decreased. A greater layer thickness increased redness and decreased RTP00, while increased printing orientation and post-curing times decreased redness and increased RTP00.

Conclusions: The optical properties of additively manufactured resin are significantly affected by the printing parameters. The most favorable optical properties were observed with 25-µm thickness, 0-degree orientation, and 10 minutes of post-curing. Adjusting these parameters facilitates the optimization of esthetic outcomes while necessitating consideration of the associated changes in optical properties.

Purpose: To evaluate color changes in 3D-printed acrylic restorations of varying thicknesses and exposed to different post-curing durations.

Materials and methods: Three virtual full-contour maxillary central incisor crowns with different buccal thicknesses (1.0, 1.5, and 2.0 mm) were designed and manufactured using a 3D printer and a photopolymer (n = 9 per thickness group). The lightness, hue, and chroma of the restorations were measured at baseline (prior to post-curing) and again at 5-minute intervals up to 30 minutes during the post-curing process using a spectrophotometer. Color changes (ΔE) were calculated by comparing the CIE L*, a*, b* coordinates at different time points to the baseline values. Repeated-measures ANOVA and Tukey post-hoc tests were used for statistical analysis (α = .05).

Results: The ΔE increased significantly within the first 5 minutes of post-curing and was more gradual thereafter in all thickness groups. The ΔE values were significantly higher in the 1.5- and 2.0-mm-thickness groups compared to the 1.0-mm-thickness group. The C* coordinate was seen to increase significantly within the first 5 minutes of post-curing and did not change significantly afterward.

Conclusions: During post-curing, the hue of 3D-printed polymeric restorations changed to yellowish and reddish shades, the brightness decreased, and the saturation increased. Most color changes occurred within the first 5 minutes of post-curing and were also more noticeable in thicker restorations.

Purpose: The investigation into the capacity of PEEK material clasps to deliver sufficient retention force, maintain morphological stability, and exhibit fatigue resistance over prolonged periods is of significant importance.

Material and methods: This study employed a fatigue testing machine to simulate clinical scenarios with varying concave depths (0.25mm, 0.50mm, 0.75mm) and conducted 7200 cycles of fatigue tests on clasps made of different materials. The initial retention force, dynamic changes in retention force, and deformation values of the clasps were measured and analyzed, and their surface morphology was observed using Scanning Electron Microscopy (SEM).

Results: The initial retention force of A-type PEEK clasps exhibited an increase with the concave depth, whereas no significant difference was observed in the initial retention force of B-type PEEK clasps at different concave depths. Following fatigue cycling, the retention force of PEEK clasps decreased more gradually compared to metal clasps, with PEEK-A clasps demonstrating more stable retention force in deeper concave conditions. Furthermore, after prolonged fatigue cycles, PEEK clasps exhibited smaller permanent deformation than metal clasps, and their surface remained smoother without evident wear or cracks.

Conclusions: In comparison to metal clasps, PEEK clasps offer more stable retention force and reduced permanent deformation in long-term clinical applications, making them more suitable for periodontal disease abutments with deeper concavity.

Objectives: This study aimed to investigate the effects of two differently colored (pink, yellow) effervescent Vitamin C tablets on discoloration and surface roughness of three denture base materials.

Materials and methods: Ninety disc-shaped samples (n=30) were prepared from heat-polymerized PMMA (Probase/HP), CAD/CAM-milled PMMA (M-PM Disc/CDCM), and 3D-printed resin (Dentabase/3DP). Samples were immersed in 200 mL water containing one effervescent Vitamin C tablet (Apexis Sambus Nigra or Sunlife Vitamin C) daily for 2 minutes at 24 °C for 30 days. Surface roughness (Ra) was measured using a contact profilometer, and color measurements were recorded with a spectrophotometer. Scanning Electron Microscope images were obtained at magnifications of 500×, 1000×, and 5000×. Data were analyzed using Wilcoxon Signed-Rank, Kruskal-Wallis, and Fisher-Freeman-Halton tests (p<0.05).

Results: Both vitamin solutions caused a significant increase in surface roughness and discoloration in all materials (p<0.001). 3DP samples showed higher roughness values compared to other groups at baseline and after immersion (p<0.001). All materials exhibited visible color changes after the immersion period.

Conclusion: Effervescent Vitamin C tablets may adversely affect the surface properties of denture base resins. Patients using such supplements, especially with 3D-printed prostheses, should be informed about potential changes in color and surface quality.

Purpose This study aimed to quantitatively compare the occlusal characteristics after delivery of mandibular first molar implant prostheses fabricated via a full-digital workflow with the occlusal characteristics of contralateral teeth. Methods Forty patients who had undergone single mandibular first molar implant surgery were enrolled. A full-digital workflow was employed to fabricate prostheses with titanium abutments and zirconia crowns, with crown morphological data sourced from the software's built-in database. Standardized occlusal adjustments were performed after prosthesis insertion. The posterior regions on the implant side (pre- and post-adjustment, P1 and P2) and on the contralateral side (T) were intraorally canned. By analyzing the average occlusal clearance (AOC), the minimum occlusal clearance (MOC), and the inclination of cusps (IC), the occlusal and morphological features of implant prostheses were compared with those of contralateral teeth. Additionally, the vertical occlusal adjustment amount (VOAA) of implant prostheses was measured. Results The AOC-P2 was 152.11 ± 61.34 μm and MOC-P2 was 123.43 ± 58.89 μm, with the ΔAOC(P2-T) was 95.03 ± 70.35 μm and the ΔMOC(P2-T) was 115.14 ± 61.60 μm. The mean inclination of all 5 cusps at P1 and P2 was 25.96 ± 3.77° and 17.39 ± 3.19°, respectively (p < 0.001), with a mean ICA-P2/ICA-T ratio of 0.89 ± 0.24. The mean inclination of the functional cusps at P2 was 18.81 ± 5.04° (ICF-P2/ICF-T: 1.08 ± 0.53), and that of the non-functional cusps was 15.26 ± 3.56° (ICNF-P2/ICNF-T: 0.79 ± 0.39). The average VOAA was 110.89 ± 56.72 μm. Conclusions: the occlusal clearance of the implant prosthesis post-adjustment was approximately 100 μm greater than that of the contralateral tooth, and the cusp inclination was about 89% compared to the contralateral tooth. These findings provided a theoretical foundation for the accurate digital occlusal design of single posterior implant prostheses in fully digital workflow. The tooth morphology database for this specific software may require additional modification to be utilized in the fabrication of implant restorations, especially through reduction of non-functional cusp inclination. Additionally, establishing a dedicated database for implant restoration fabrication is essential.

Radicular dens invaginatus (RDI) is a developmental malformation often associated with severe periodontal destruction and a poor prognosis. Currently, no standardized treatment guidelines exist for RDI. Due to the complex and variable anatomy of affected teeth, one of the primary challenges in managing RDI is accurately locating and debriding the invaginated region while preserving pulp vitality and maintaining dental structural integrity. Therefore, this case report presents a clinical decision-making approach for the digitally assisted management of RDI. A female patient's maxillary left canine was diagnosed with RDI, complicated by infection and periodontal tissue loss, while pulp vitality remained intact. To ensure precise localization and thorough debridement of the invaginated lesion while preserving pulp vitality and tooth integrity, a dual surgical approach was designed using digital technology. Following infection removal, bioactive materials were applied for cavity filling, and guided tissue regeneration was performed. After a one-year follow-up, pulp vitality was successfully maintained, and periodontal tissue healing was achieved.

Purpose: The present study aimed to compare the performance of seven AI chatbots (ChatGPT 3.5, 4, 4o, Gemini, Claude 3, Copilot, and Llama) with that of U.S. prosthodontic residents on the National Prosthodontic Resident Examination (NPRE) from 2011 to 2023.

Materials and methods: NPRE exam files and answer keys were obtained from the American College of Prosthodontists (ACP). AI-generated responses were collected using standardized prompts that requested only letter answer choices. Each chatbot's first response was recorded and compared to the official exam key. Performance was evaluated as the percentage of correct responses, and results were compared with the average scores of human participants. Statistical analysis included repeated measures ANOVA and Bonferroni post-hoc comparisons.

Results: Statistically significant differences were found between the different groups (p<0.001). ChatGPT 3.5 achieved the highest scores, followed by Claude 3 and Llama, while Copilot performed significantly worse than residents. Other chatbots demonstrated performance levels comparable to human participants, but with notable variability across AI models.

Discussion: The findings suggest that AI chatbots, particularly ChatGPT 3.5, can perform at or above the level of prosthodontic residents on standardized examinations. However, differences in chatbot capabilities, training data, and inconsistencies in performance raise concerns about reliability. While AI has potential as a supplementary learning tool, its use should be guided by critical evaluation.

Conclusions: AI chatbots demonstrate adequate performance on specialized academic exams, but variability across models highlights the need for further assessment before integration into dental education and professional practice.