Journal of Prosthetic Dentistry最新文献

Statement of problem: Intraoral scanners (IOSs) can be used to digitize complete arches with multiple dental implants; however, the influence of intraoral scanning technology and scan body system selection on accuracy in maxillary complete arches remains unclear.

Purpose: The purpose of this clinical study was to evaluate the accuracy in the maxillary arch, encompassing both trueness and precision, of 2 distinct intraoral scanning systems and 2 diverse scan body systems in comparison with the conventional reference method.

Material and methods: Two participants were recruited with 6 maxillary bone-level implants (JDEvolution Plus; JDentalCare) placed in positions corresponding to the right first molar, right canine, right central incisor, left central incisor, left canine, and left first molar. All implants had multiunit abutments (Conical Abutment Straight; JDentalCare) screwed to the implants. Definitive casts from 2 edentulous maxillary impressions were made using a conventional method. The casts were digitized to create reference models using a laboratory scanner (E3; 3Shape A/S). Two experimental groups were created based on the IOS used: the TRIOS 3 group (TR3) and the Primescan group (PS). Two subgroups were generated depending on the scan body system used to digitize the spatial position of the implants: IPD scan body (IPD) and DAS scan body (DAS). The digital implant scan discrepancies between the control group and experimental scans were calculated. The normality of the data was assessed using the Shapiro-Wilk test (α=.05). Two-way ANOVA and post hoc pairwise comparison tests were used to compare the trueness, precision, and interaction between the intraoral scanner and the scan body (α=.05) RESULTS: Statistically significant differences (P<.001) were found between the intraoral scanners tested. No significant differences were found between the IPD and DAS scan body systems (P=.649), and none were found for the interaction between the IOS and the scan body (P=.524). Significant differences were observed between the following groups: PS-IPD and TR3-IPD, PS-IPD and TR3-DAS, PS-DAS and TR3-IPD, and PS-DAS and TR3-DAS (all P<.001).

Conclusions: The combination of intraoral scanner and scan body system is crucial to improve the accuracy of digital complete arch intraoral implant scans. In the maxillary arch, the Primescan IOS obtained the highest accuracy when compared with the TRIOS 3 IOS, independently of the scan body system used.

Statement of problem: In recent years, there has been an increasing interest in measuring maximal occlusal force in light of the advances in digitally supported dentistry. However, studies on the assessment of changes in maximum occlusal force are sparse.

Purpose: The purpose of this clinical study was to assess the repeatability of maximal occlusal force measured at regular time intervals.

Material and methods: One hundred participants (50 male, 50 female, aged 20 to 36 years) with a complete dentition were recruited for this study. Group 15S, 30S, 1M, and 3M repeated occlusal force measurements after 15, 30 seconds, 1 minute, or 3 minutes, 5 or 6 times, respectively. Group 8H repeated occlusal force measurements 3 times a day in the morning, afternoon, and evening with intervals of 6 to 8 hours for 5 consecutive days, 15 times in total. Two-way repeated measures ANOVA and post hoc pairwise comparison with a Bonferroni adjustment was applied to assess the measurements.

Results: In general, the measurements of repetition 1 were significantly lower than of repetition 2, 3, 4, or 5 (P<.05). Within groups, participants in Group 3M showed significantly higher occlusal force measurements in repetitions 3, 4, and 5 compared with repetition 1 (P<.05). The differences in these measurements were more pronounced in male participants.

Conclusions: The maximal occlusal force measured at regular time intervals showed a lack of repeatability. The first measurement showed a statistically significantly lower value compared with the second, third, fourth, and fifth measurements in the 5 consecutive measurements. The interval between measurements significantly affected the repeatability of maximum occlusal force measurements.

Statement of problem: A critical gap remains in understanding how the architectural philosophies of different large language models (LLMs) perform in specialized clinical domains conducted in non-Indo-European languages, particularly regarding the effectiveness of Chain-of-Thought (CoT) reasoning models compared with those optimized for local languages.

Purpose: The purpose of this study was to compare the performance of 6 LLMs with distinct architectural philosophies (CoT-reasoning, general-purpose, and Korean-optimized) on the prosthodontics section of the Korean Dental Licensing Examination (KDLE) and to contextualize their performance with published human averages.

Material and methods: A total of 161 Korean-language, text-only multiple-choice questions from the prosthodontics section of the KDLE (2020-2024) were presented to 6 LLMs (ChatGPT-o1, ChatGPT-4o, DeepSeek-R1, DeepSeek-V3, Gemini 1.5 Flash, and CLOVA X). Each test set was posed 6 times. The questions were further classified into 5 domains: diagnosis and treatment planning, mandibular movements and occlusal relationships, removable complete denture, removable partial denture, and fixed prosthodontics. Performance was measured by percentage accuracy and analyzed using the Cochran Q and post hoc McNemar tests (α=.05). LLM scores were contextually benchmarked against the average performance of human examinees.

Results: Significant performance differences were observed among the models (P<.001). The CoT-based model, ChatGPT-o1, achieved the highest overall accuracy (80.54%); the total human average (79.51%) fell within this LLM's 95% confidence interval. ChatGPT-4o (71.84%) and DeepSeek-R1 (70.19%) also demonstrated consistent passing-level performance. The Korean-language-optimized model, CLOVA X, obtained the lowest score (34.37%). The performance ranking of the models within individual domains generally mirrored the overall ranking.

Conclusions: LLMs with CoT-reasoning architectures can achieve passing-level accuracy on non-English dental licensing examinations at a level contextually comparable to the human average, but performance varied significantly by architecture, and localized language optimization did not ensure domain expertise.

Despite advancements in digitally assisted dentistry, the digital workflow still presents limitations in challenging clinical situations. New artificial intelligence (AI)-assisted tools and the reverse scan technique can be used to improve the digital workflow for complete arch implant-supported prostheses, ensuring an accurate and predictable treatment workflow. The present report describes the integration of AI-assisted esthetic virtual simulation to a reverse scan body recording for complete mouth implant-supported prostheses.

Statement of problem: Clinicians aim to restore dental implants with contours that replicate the natural crown. However, evidence directly comparing the emergence angles of posterior implant-supported fixed dental prostheses (FDPs) with those of natural crowns is lacking, and the influence of FDP emergence angles on peri-implant bone loss remains inconclusive.

Purpose: The purpose of this retrospective clinical study was to compare the emergence angles of posterior implant-supported FDPs with those of natural crowns and to evaluate the effect of prosthesis contours on peri-implant bone stability.

Material and methods: Clinical records and periapical radiographs of patients with posterior single implants and with at least a 6-month follow-up after definitive restorations were evaluated. Edentulous space width (ESW), implant placement depth (IPD), mesial and distal emergence angles (EAs) of the natural teeth (EA_Tooth), implant abutments (EA_Ab), and implant-supported crowns (EA_Res, EA_ResAb) were measured. Pearson correlation analysis was performed to evaluate the correlations between the implant emergence angles and the ratio of the edentulous space to implant diameter (ESW/∅). The suggested implant placement depth was proposed for different implant diameters based on ideal emergence angles. Univariate binary logistic regression analyses were performed to evaluate the effects of prosthesis contour and other variables on marginal bone stability (α=.050).

Results: Eighty-nine implants of 75 participants were included. Overall, the EAs of implant-supported crowns (EA_Res, EA_ResAb) were significantly greater than those of EA_Tooth (P<.05). The EA_Res and EA_ResAb were positively correlated with ESW/∅ (P<.05), and EA_Res was negatively correlated with IPD (P<.05). The suggested implant placement depths at molars were generally greater than at premolars. The emergence angles were not significantly associated with peri-implant marginal bone stability (P>.05).

Conclusions: The emergence angles of posterior implant-supported FDPs were greater than those of the natural tooth. The difference was more pronounced in molar sites than in premolar sites. However, the contour of an implant-supported FDP was not associated with peri-implant bone level change.

Statement of problem: Marginal fit is a key determinant of crown success. Variable marginal gap values have been reported in the literature, referencing multiple contributing factors. A consolidated analysis of systematic reviews is required to clarify the reports.

Purpose: The purpose of this umbrella review was to quantitatively synthesize findings from systematic reviews of in vitro studies that evaluated marginal gaps and assessed the influence of the crown type, crown fabrication material, measurement instrument, abutment tooth material, tooth type, and crown fabrication method on the marginal gap.

Material and methods: The search was conducted in June 2025 using the EBSCO Host, Scopus, PubMed, and Web of Science databases following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and predefined eligibility criteria. Eligible systematic reviews were critically appraised using the Joanna Briggs Institute (JBI) Critical Appraisal Checklist. Umbrella analyses were performed using the Welch test for unequal variances, the Games Howell post hoc test, and multiple regression adjusted with robust clustered standard error and the Wald test for robust model-level evaluation (α=.05).

Results: Seventeen systematic reviews, reporting a mean marginal gap of 79.4 ±22.8 µm were included. No significant differences were observed in mean marginal gap across different crown types (F=0.37, P=.775) or crown fabrication materials (F=0.48, P=.784). Crowns assessed using the impression replica instrument showed significantly larger marginal gaps (β=37.86, P<.001) compared with microscopy. No significant differences were found between the marginal gaps of crowns fabricated using conventional (88.0 ±35.0 µm) and computer-aided design and computer-aided manufacturing (CAD-CAM) (80.3 ±35.0 µm) methods across crown types (F=1.00, P=.319).

Conclusions: Crown type, crown fabrication material, and crown fabrication method demonstrated no significant effect on marginal gaps. The impression replica instrument overvalued marginal gaps in comparison with microscopy. Based on the results of this study, the contemporary acceptable limit for in vitro crown marginal gap is 120 µm.

A straightforward intraoral gothic arch tracer for recording the centric relation (CR) of digitally fabricated dentures is described. The gothic arch tracer and evaluated dentures were 3-dimensionally (3D) printed in a single step using polylactic acid. The tracing plate was located on the palatal side of the maxillary denture, with 3 needles arranged in an equilateral triangle connected to the fixation plates on the anterior side of the mandible. The height of the needles ensured the occlusal vertical distance (OVD) and stability of the maxillary and mandibular evaluation dentures. Computer-aided design and computer-aided manufacturing (CAD-CAM) facilitated the parallel alignment of the maxillary tracing plate, occlusion plane, and mandibular fixed plate, ensuring smooth mandibular motion tracing and making it easier to determine the CR of digitally fabricated dentures, saving clinical time.

This clinical report describes the use of digital tools to create an accurate virtual patient using low-cost 3-dimensionally printed reference devices and a custom digital tooth library derived from a donor who was a relative of the patient. A virtual diagnostic waxing was performed to facilitate a prosthetically guided treatment plan for the rehabilitation of a partially edentulous maxilla.

Statement of problem: Displacement of zirconia restorations is among the most frequent failures. Airborne-particle abrasion (APA) with aluminum oxide (Al₂O₃) has been studied to increase surface roughness, energy, and wettability, thereby improving bond strength. Therefore, a systematic review is needed.

Purpose: The purpose of this systematic review and meta-analysis was to evaluate how APA with Al₂O₃ affects the bond strength of zirconia ceramics.

Material and methods: Following the population, intervention, control, outcome, and study design (PICOS) framework, searches were conducted in the MEDLINE (via PubMed), Web of Science, Scopus, and Embase databases through December 2024, without language restrictions. Included studies involved flat zirconia specimens bonded to composite resin, dentin, or enamel, with APA as the intervention and untreated surfaces as controls. Outcomes were shear, microshear, tensile, or microtensile bond strength. Two authors independently screened titles, abstracts, and full texts. Risk of bias was assessed, and data were analyzed using Cochrane Review Manager. Core Grading of Recommendations Assessment, Development and Evaluation (CORE GRADE); certainty assessment was performed with adaptations for in vitro studies.

Results: Thirty-four studies met the inclusion criteria. Common biases involved lack of sample size calculation and operator blinding. Most APA protocols significantly improved bond strength to dentin, enamel, or composite resin. However, microshear tests on dentin showed no significant difference. High heterogeneity was found. Funnel plots for shear and microtensile tests showed no asymmetry, but microshear results suggested publication bias. Publication bias analysis was not possible for tensile bond strength because of limited data. Certainty of evidence ranged from moderate to very low.

Conclusions: APA significantly increased bond strength compared with no treatment, especially when bonding zirconia to enamel or composite resin. APA after sintering proved more effective than before sintering.

Statement of problem: Within-enamel preparation provides higher bond strength in minimally invasive esthetic treatment. However, determining the distribution of enamel thickness on the labial surface of human incisors remains difficult.

Purpose: The purpose of this in vitro study was to reconstruct and map the labial enamel thickness of the maxillary and mandibular incisors.

Material and methods: Sixty human incisors, including 20 maxillary central incisors (MxCIs), 20 maxillary lateral incisors (MxLIs) and 20 mandibular incisors (MdIs), were scanned using microcomputed tomography. The labial enamel was reconstructed into 3-dimensional models and divided into 9 segments (mesial-cervical, central-cervical, distal-cervical, mesial-middle, central-middle, distal-middle, mesial-incisal, central-incisal, and distal-incisal segments). The enamel thicknesses of different segments of the labial enamel were measured and analyzed. Statistical analysis was performed using the paired t test and analysis of variance (α=.05).

Results: The enamel thickness of MxCIs was 0.461 to 0.966 mm, the enamel thickness of MxLIs was 0.346 to 0.984 mm, and the enamel thickness of MdIs was 0.343 to 0.792 mm. The labial enamel thickness was significantly different between the maxillary and mandibular incisors (P<.05). In all incisors, the enamel was thickest in the incisal region and significantly thinner in the cervical region (P<.05). The distal enamel was significantly thicker than the mesial enamel in MxCIs (P<.01), whereas the central enamel was thicker than the mesial enamel in MdIs (P<.01).

Conclusions: The labial enamel thickness was significantly different between the maxillary and mandibular incisors (P<.05). Horizontally, the mesial enamel was thinner than the distal enamel in the MxCIs, whereas the central enamel was thicker than the mesial enamels in the MdIs. Vertically, the labial enamel thickness increased from the cervical region to the incisal region in all incisors.