Journal of Prosthetic Dentistry最新文献

Statement of problem: Three-dimensional finite element analysis (3D FEA) allows for the accurate simulation of stress distribution and identification of potential failures in posterior indirect restorations. By combining microcomputed tomography (μCT) with FEA, more realistic and reliable models can be created, improving the accuracy of predictions.

Purpose: The purpose of this 3D FEA study using μCT data was to assess the effect of different restorative materials on stress distribution in partial posterior restorations and the resin cement layer.

Material and methods: Four replicas of a mandibular first molar were prepared for different partial posterior preparations: inlay, onlay, 1-piece endodontic crown, and occlusal veneer. For each model, monolithic posterior restorations were simulated with 4 different restorative materials: composite resin, lithium disilicate glass-ceramic, polymer-infiltrated ceramic, and zirconia. After the fabrication and luting of the restorations, μCT images of the specimens were obtained and 3D finite element models built. An evenly distributed load of 500 N was applied, simulating 3 occlusal contacts. The maximum value of maximum principal stress and stress distribution on the restorations, cement layers, and tooth structure was calculated and analyzed.

Results: One-piece endodontic crowns had lower stress, whereas inlays showed higher stress. Of the restorative materials, zirconia and glass-ceramic had the highest stress on the restorations, followed by polymer-infiltrated ceramic and composite resin. This difference between the restorative materials was larger for inlays and 1-piece endodontic crowns than for onlays and occlusal veneers. Cuspal coverage in the onlay preparation had lower and more evenly distributed stress than the intracoronal inlay preparation.

Conclusions: The different tooth preparations for single-unit posterior partial restorations influenced the stress distribution on the restoration, resin cement layer, and remaining tooth structure.

Statement of problem: The relationship between masticatory function based on paired teeth-functional tooth units (FTUs) and cognition has yet to be evaluated and reported in a nationally representative sample.

Purpose: The purpose of this population-based study was to investigate the association between masticatory function measured by FTUs and cognition in individuals aged 60 and older using data from the National Health and Nutrition Examination Survey (NHANES) 2011-2014.

Material and methods: Data from NHANES 2011-2014 were used. The number of FTUs was defined as pairs of opposing natural and artificial teeth in the posterior region. Cognitive function was assessed using the Consortium to Establish a Registry for Alzheimer's Disease (CERAD) test, the Animal Fluency Test (AFT), and the Digit Symbol Substitution Test (DSST). Weighted multivariable linear regression and subgroup analyses were conducted to assess the association between FTUs and cognitive performance. Sensitivity tests were conducted on functional dentition and the presence of FTUs.

Results: The regression models revealed a significant positive association between FTUs and cognitive performance among AFT, DSST, and global cognition. Individuals with higher FTU scores demonstrated better performance in verbal fluency, processing speed, sustained attention, working memory, and global cognition.

Conclusions: A significant and independent association was demonstrated between masticatory function as measured by FTUs and cognitive function in adults aged 60 and older.

Keratinized mucosa surrounding dental implants fulfills both esthetic and functional purposes, while regular free gingival graft (FGG) surgeries often lead to color and texture mismatch. The present clinical report describes a novel surgical technique designed for situations with inadequate keratinized mucosa width and color inconsistency around implants in the esthetic zone. The rationale for this technique is reviewed.

Statement of problem: Different instruments have been used to measure the marginal gaps of crowns in vitro. However, a comprehensive systematic review is lacking.

Purpose: The purpose of this systematic review was to evaluate the existing literature on the instruments used for the in vitro marginal gap measurement of ceramic single crowns before cementation and to determine whether the crown material and method of fabrication influenced the marginal gap.

Material and methods: The search was conducted in 2024 across the EBSCO Host, Scopus, PubMed, and Web of Science databases by following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and predefined eligibility criteria. Eligible articles were screened to evaluate 6 instruments for measuring crown marginal gaps: direct view microscopy, scanning electron microscopy, impression replica, cross-sectioning, microcomputed tomography, and 3-dimensional (3D) superimposition. The normality of the data was assessed by using the Kolmogorov-Smirnov test, and the differences in mean marginal gap were statistically evaluated using the Welch ANOVA (α=.05).

Results: Ninety-two articles were included, with 77 documenting single measurement instruments and 15 using a combination of 2 or more measurement instruments. Direct view microscopy was the most used instrument and appeared in 31 (40%) of the studies. No significant differences in mean marginal gap (F=2.09, P=.077) were found across the 6 measurement instruments. Across all studies, excluding those using 3D superimposition, the mean ±standard deviation number of marginal gap measurements per crown was 34.3 ±50.6. Among the 77 studies using a single measurement instrument, 64 used computer-aided design and computer-aided manufacturing (CAD-CAM) technology to fabricate the crowns. CAD-CAM crowns had a mean ±standard deviation marginal gap of 78.9 ±28.6 µm (n=64) compared with 71.6 ±29.5 µm (n=13) for crowns manufactured using conventional methods. Zirconia and lithium disilicate were the most researched materials. Zirconia crowns recorded a mean ±standard deviation marginal gap of 69.4 ±34.2 µm for 972 crowns, which was significantly different (P=.045) from lithium disilicate with a mean ±standard deviation marginal gap of 92.2 ±42.5 µm for 602 crowns.

Conclusions: Direct view microscopy was the most used marginal gap measurement instrument for ceramic single crowns before cementation, and CAD-CAM was the most used crown fabrication method. No significant differences in mean marginal gap were found among the 6 marginal gap measurement instruments.

The accuracy of diagnostic trial restorations depends on the rigidity of the restoration index. However, as the index becomes stiffer, its removal from the mouth without the detachment of the underlying trial restoration can be challenging, especially in patients where a diagnostic trial restoration is required for a complete arch rehabilitation. The present manuscript describes a step-by-step hybrid technique to transfer the virtual diagnostic waxing into the patient's mouth by using a 2-piece index. An additively manufactured custom tray relined on a diagnostically waxed cast using polyvinyl siloxane material is used to fabricate a silicone index. The presented technique provides an index with higher rigidity and uniformity compared with conventional methods, enabling sequential removal after the polymerization of the resin interim material.

Statement of problem: Different treatments for maxillary defects have been described, but a meta-analysis of these treatments to provide clinical guidance is lacking.

Purpose: The purpose of this systematic review and network meta-analysis was to evaluate the effect of tissue-supported obturator prostheses and other rehabilitation treatments for patients with maxillary defects on patient-reported outcome measures (PROMs) assessed through quality of life (QoL) questionnaires.

Material and methods: Inclusion criteria were parallel-arm randomized controlled trials (RCTs) and nonrandomized studies of intervention (NRSIs) with a tissue-supported obturator as one of the treatments. Nine databases and nonpeer-reviewed literature were searched. Independent reviewers selected studies, extracted data, and assessed the risk of bias. Seven outcomes were analyzed separately for RCTs and NRSIs: appearance, mastication, pain, social contact, speech, swallowing, and QoL. A Bayesian random-effect network meta-analysis (NMA) calculated mean differences (MD) and 95% credible interval (Crl) for each treatment comparison. Data interpretation followed the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) approach and the magnitude of the effect was calculated as the minimal important difference (MID) - the minimal clinical benefit for the patient - for each outcome.

Results: The review included 4 RCTs and 9 NRSIs. Most studies had a high and critical risk of bias. There were 7 treatments: no reconstructive or rehabilitative treatment, surgical obturator, interim obturator, tissue-supported obturator, implant-supported obturator, magnet obturator, and flap, totaling 120 treatment comparisons (56 among RCTs and 64 among NRSIs). Some treatments reached the minimum clinical benefit (MID). However, the 95%Crl crossed the null effect line for all treatment comparisons, indicating that any treatment can be efficient. The certainty of the evidence was very low for all comparisons, mainly because of the risk of bias, indirectness, intransitivity, and imprecision.

Conclusions: No treatment was better than another for any outcome. More RCTs comparing treatments for the rehabilitation of maxillary defects are encouraged to improve the evidence.

Statement of problem: Implant-supported removable partial dentures (RPDs) are an effective treatment, but an overview of publication trends on this topic is lacking.

Purpose: The purpose of this publication overview of implant-supported RPDs, focusing on study design, citations trends, journals impact factor, and literature gaps.

Material and methods: Data were retrieved from the Web of Science (WoSCC) until November 2024. Articles reporting clinical trials, case reports, in vitro studies, and reviews were included. Quantitative differences in impact factor and citations for retentive component and study designs were analyzed with 2-way ANOVA followed by Tukey HSD. Factors influencing citation counts were also considered with a Poisson regression model (α=.05).

Results: A total of 155 articles published from 1974 to 2024 were analyzed, showing a significant publication rise in the last decade (n=112; 72.3%). The impact factor ranged from 1.7 to 4.8, with prospective (n=49) and in vitro (n=40) studies the majority. Japan led in contributions (n=24), and the Journal of Prosthetic Dentistry (n=19) had the most articles. The citations number was influenced by study type and retentive component, with prospective and RCT studies and frictional components receiving the highest citations. No significant differences were found in impact factor (P>.05).

Conclusions: Gaps exist regarding the long-term performance, function, and cost-benefit of implant-supported RPDs and more randomized clinical studies involving periodontal health, prosthesis complications, digital manufacturing, and treatment patients with Kennedy Classes III and IV are needed.