Journal of prosthodontic research最新文献

Purpose: Titanium dental implants are widely regarded as the gold standard for tooth replacement because of their mechanical strength and biocompatibility. However, cases of titanium hypersensitivity have been reported, raising concerns about immune-mediated complications in susceptible patients. This systematic review aimed to provide an updated synthesis of the available clinical evidence on titanium hypersensitivity, including diagnostic methods, and management strategies.

Study selection: A systematic search was conducted in PubMed, Scopus, Web of Science, and EBSCO databases following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines. The Population, Exposure, and Outcome (PEO) framework was used to identify primary studies published until July 14, 2025, reporting titanium hypersensitivity related to dental implants, diagnostic modalities, and case outcomes.

Results: Of 1,761 retrieved studies, 9 met the inclusion criteria. These comprised one prospective study and eight case reports involving 21 patients and 33 titanium implants, 20 of which were diagnosed as titanium hypersensitivity cases based on skin testing, immunological assays, histological or immunohistochemical analysis, or clinical symptoms. In 17 cases, implant removal was required, whereas three were managed by abutment replacement.

Conclusions: Despite the limited evidence, current data indicate that titanium hypersensitivity is rare but clinically relevant. Titanium micro-particles often originating from early mechanical wear may act as immunological co-factors in susceptible patients, underscoring the need for standardized and sensitive diagnostic protocols to support early and accurate identification.

Patients: This report describes the digital workflow for the design and fabrication of a telescopic prosthesis that incorporates a polyetherketoneketone (PEKK) primary crown and PEKK framework to restore multiple teeth in the mandible of a 56-year-old female patient. The process includes intraoral scanning, computer-aided design, digital milling of the telescopic crown and PEKK framework, and 3D printing of the casts. Good retention, mastication, aesthetics, and biological outcomes are observed in the four-year follow-up.

Discussion: Two clinical outcomes are observed. (1) A PEKK telescopic prosthesis can be fabricated using digital workflows, which demonstrates an initial retention value sufficient for intraoral function. (2) No significant wear or decline in the retention force is observed over a four-year follow-up period.

Conclusions: The PEKK telescopic prosthesis facilitated favorable outcomes when restoring extensive mandibular tooth loss. We suggest that PEKK can be effectively used in the fabrication of telescopic prostheses supported by natural teeth.

Purpose: This study aimed to develop an artificial intelligence (AI) system using a convolutional neural network (CNN) to design major connectors for removable partial denture (RPD) frameworks. Unlike rule-based or case-matching expert systems, the proposed model automatically generated RPD designs from comprehensive oral data using gradient-weighted class activation mapping (Grad-CAM) enhancing explainability.

Methods: Data were obtained from 1000 RPDs (457 maxillary, 543 mandibular) designed by prosthodontic specialists, including 255 dental variables from oral examinations. Ten CNN models were constructed sequentially to predict denture type (resin/metal), unilateral/bilateral design, absence/presence of a major connector, and four and two connector types for the maxilla and mandible, respectively. This sequential prediction followed clinical logic. Model performance was assessed by accuracy, sensitivity, specificity, positive and negative predictive values, and F1 score. Grad-CAM was employed to visualize input factors influencing predictions.

Results: The CNN models predicted major connector types with high accuracy (maxilla: palatal bar/strap, 93.0%; palatal plate, 87.1%; horseshoe bar, 89.5%; and mandible: lingual bar or plate, 87.3%). Heatmaps highlighted clinically relevant features including periodontal condition, dentition defects, and occlusal relationships as key determinants.

Conclusions: This study demonstrated the feasibility of an AI-based system for predicting RPD major connector types with acceptable performance. The system is expected to provide valuable support to dentists by minimizing the variability owing to differences in clinical skills and experience. Grad-CAM visualization enhances interpretability, enabling both clinicians and patients to better understand the reasoning behind the RPD design process. Ultimately, this approach could improve consistency, efficiency, and training in prosthodontics.

Purpose: This review critically examined the impact of various whitening toothpaste formulations on color stability, surface roughness, gloss, and microhardness of dental restorative materials.

Study selection: A comprehensive literature search yielded 101 articles from PubMed, 159 from Embase, and 617 from SCOPUS, spanning 1983-2024, of which 33 met the inclusion criteria.

Results: Studies have shown that whitening toothpastes influence color change and surface characteristics. Hydrogen peroxide (HP) formulations are generally effective in achieving color alteration, although their impact on microhardness and roughness varies. Charcoal-based toothpastes tend to increase surface roughness because of their abrasive nature, whereas blue covarine toothpaste provide some brightening effects but are also associated with higher roughness. Results regarding nanohybrid and microhybrid composites were mixed; some studies found nanohybrids to be superior in color stability, whereas others favored microhybrids. However, nanohybrids are more susceptible to roughness changes due to whitening agents, whereas nanofilled composites consistently demonstrate better surface integrity under abrasive conditions.

Conclusions: These findings highlight the importance of selecting toothpaste formulations that align with restorative material properties to optimize esthetic results without compromising durability. Although HP formulations show promise in balancing whitening efficacy with surface preservation, their long-term effects require further study. Additionally, continued research is needed to refine the formulations, particularly for charcoal and blue covarine, to reduce abrasiveness and extend restoration longevity.

Purpose: We aimed to evaluate the trueness and adaptation of the intaglio surfaces of complete denture metal frameworks fabricated using selective laser melting (SLM) with different building orientations (0°, 45°, and 90°).

Methods: Cobalt-chromium maxillary complete denture metal frameworks were fabricated at 0°, 45°, and 90° using SLM. Trueness measurements were conducted using the best-fit alignment method of three-dimensional inspection software, and adaptation was evaluated using the silicone replica technique. Nonparametric Kruskal-Wallis and Bonferroni tests were performed to determine differences among the groups (P = 0.05).

Results: No significant differences were observed in the root mean square (RMS), positive, and negative deviation values between 0° and 45° group (P > 0.05), and the median, first quartile, and third quartile of each were considered clinically acceptable. For the 90° group, the RMS, positive deviation, and negative deviation values were significantly higher than those of the other groups (P < 0.05). The overall adaptation of the 45° group was better than that of the 0° and 90° groups (P < 0.05), whereas the 0° and 90° groups showed no significant difference (P > 0.05).

Conclusions: The trueness and adaptation of the intaglio surface of cobalt-chromium maxillary complete denture metal frameworks were affected by the building orientation through SLM. Considering both trueness and adaptation, 45° is recommended as the most efficient build orientation for clinical applications.

Purpose: Supports are essential for ensuring dimensional accuracy in 3D printing; however, an excessive number of supports compromises printing efficiency. This study aimed to investigate how a varying number of support arrangements affects the precision and trueness of 3D-printed dentures.

Methods: Three denture base printing files were designed, each with different numbers of supports: 40 (group 40), 55 (group 55), and 70 (group 70). Thirty samples were printed and measured across the groups. Accuracy was evaluated by assessing trueness and precision using the root mean square error (RMSE). The error areas in each group were analyzed through micro-computed tomography (micro-CT) 3D imaging.

Results: Group 70 showed a significantly lower RMSE for trueness than Group 40 (P < 0.05), but showed no significant difference from Group 55 (P ≥ 0.05). For precision, Group 70 outperformed both Groups 40 and 55 (P < 0.05), which did not differ significantly (P ≥ 0.05). Micro-CT revealed no mismatches in the palatal region. Discrepancies-areas where the supports in Groups 40 and 55 did not accurately align with those in Group 70-were predominantly observed at initiation points of overhangs in thinner sections.

Conclusions: Based on these results, this study recommends placing support structures strategically around overhangs and thin-walled areas to enhance the accuracy of 3D-printed denture fabrication. These findings indicate that optimizing support placement, rather than merely increasing the number of supports, is crucial in improving the quality and reliability of 3D-printed dental prostheses.

Purpose: This study aimed to investigate the association between xerostomia severity and oral health-related quality of life (OHRQoL) across various functional occlusal statuses among older adults.

Methods: This cross-sectional study recruited 202 outpatients (130 females and 72 males) from a dental university hospital in Japan. Assessments included the Summated Xerostomia Inventory (SXI) for xerostomia, Oral Health Impact Profile-14 (OHIP-14) questionnaire for OHRQoL, saliva collection, and functional occluding units (FOUs). Analyses included Mann-Whitney U tests and regression models. A directed acyclic graph was constructed to identify potential confounders and mediators and ensure appropriate adjustment in the regression models.

Results: The mean age of the participants was 73.7 (SD: 7.6) years, ranging from 60-89 years, and 64.4% were females. The median SXI score was 7 (IQR: 6-8), and 14.4% had a score of 10 or more. The participants with xerostomia had higher OHIP scores than those without xerostomia (median, 15 vs. 9; P = 0.003). Salivary flow measures were not associated with the OHIP scores. However, SXI and FOUs were associated with the OHIP scores in the regression analysis (R²=29.7%). The subgroup analysis revealed that participants with a more FOUs had a stronger association between xerostomia and OHRQoL.

Conclusions: Among the older adults in this study, those with xerostomia and fewer functional occlusions had poorer OHRQoL. The relationship between dry mouth symptoms and OHRQoL was particularly robust among patients with better functional occlusion, suggesting that xerostomia management deserves attention even in patients with well-maintained dentition.

Purpose: This study aimed to investigate the effect of light-curing on the fracture load of glass-ceramic discs bonded to dentin.

Methods: IPS e.max CAD (lithium disilicate) and Celtra Duo (zirconia-reinforced lithium silicate) glass-ceramic discs, each 7 mm in diameter, were bonded to flattened dentin using three different cementation strategies. The discs varied in thickness, measuring 0.8 mm and 1.5 mm. The three strategies implemented were as follows: (1) SBU/ULT(AL): auto-cured adhesive and light-cured resin cement, (2) SBU/ULT(LL): light-cured adhesive and light-cured resin cement, and (3) resin composite, which served as the positive control. The fracture loads of eight specimens from each group were evaluated after storing the samples for one week and one year. Data were analyzed using linear mixed-effects models with a significance level of 0.05.

Results: The thickness of the ceramic material and the cementation strategy significantly influenced the fracture load (P < 0.05). Ceramics bonded using SBU/ULT(LL) and composite cement, regardless of thickness, demonstrated significantly higher fracture loads than those bonded using SBU/ULT(AL) (P < 0.05). Ceramics with a thickness of 0.8 mm bonded with either SBU/ULT(LL) or composite cement exhibited fracture loads comparable to those of 1.5 mm thick ceramics bonded with SBU/ULT(AL) (P > 0.05).

Conclusions: Light-curing the adhesive separately from the resin cement (SBU/ULT(LL)) and employing composite cement are recommended strategies for cementing glass ceramics with dentin to enhance fracture load resistance.

Purpose: To investigate the remnant cement in the subgingival regions (RCS) of abutments fabricated with different CAD/CAM parameters, including margin curvature radius, convergence angle, top fillet radius, and subgingival abutment shape.

Methods: Twelve experimental groups were fabricated to test the following parameters: abutment margin curvature radii of 0.8 mm, 1.2 mm, and 1.6 mm; convergence angles of 4°, 8°, and 12°; top fillet radii of 0.6 mm, 1.0 mm, and 1.4 mm; and subgingival abutment shapes of straight, S-curve, and concave. A constant amount of cement was injected into each crown. Vertical and continuous loads were applied to each specimen using a universal machine. RCS values were measured using a 3D intraoral scanner and an analytical balance. Statistical analysis was performed using one-way analysis of variance followed by post hoc Tukey test (α = .05).

Results: Regarding margin curvature radius, RCS values were significantly higher in the order of 1.6 mm, 1.2 mm, and 0.8 mm (P < 0.001). For convergence angle, higher RCS values were observed at 12° > 8° > 4°(P < 0.001). Among subgingival abutment shapes, concave yielded the highest RCS values, followed by S-curve and straight (P < 0.001). No significant differences in RCS values were found among the groups with different top fillet radii (P > 0.05).

Conclusions: Within the limitations of this study, a smaller margin curvature radius, smaller convergence angle, and straight subgingival shape were associated with reduced RCS length, surface area, and weight.

Purpose: This study evaluated the cytotoxicity of clinically available dental cements containing resin: conventional adhesive resin cement (ARC), self-adhesive resin cement (SARC), and resin-modified glass-ionomer cement (RMGIC), focusing on their degree of conversion (DC) and effects on cellular responses.

Methods: The DC of all the groups was measured over two weeks under light-free conditions. Cell viability, morphology, and apoptosis were assessed in gingival fibroblasts, dental pulp stem cells, and macrophage cells after exposure to extracts from specimens with different DC values. Eluate analysis was performed using attenuated total reflectance-Fourier transform spectroscopy and gas chromatography/mass spectrometry.

Results: The DC increased rapidly within 20 min for ARC and SARC, reaching a plateau at 24 h, while RMGIC showed a slower increase. ARC and SARC exhibited significant cytotoxicity at lower DC levels, with improved cell viability as DC increased. RMGIC displayed minimal cytotoxicity across all DC levels. Analysis revealed unreacted monomers and other substances contributing to cytotoxicity, with apoptotic effects correlating to their concentration in the eluates.

Conclusions: DC significantly influences the cytotoxicity of resin-containing dental cements, with ARC and SARC showing higher cytotoxic effects at lower DC levels compared with RMGIC. Considering DC levels may guide clinicians in minimizing adverse effects when selecting these cements. Dental cements containing resin can release substances that may affect cell viability.