Journal of prosthodontic research最新文献

Purpose: This retrospective clinical study aimed to evaluate the clinical outcomes of surveyed monolithic computer-aided design and computer-aided manufacturing (CAD/CAM) zirconia crowns for abutment teeth in removable partial dentures (RPDs).

Methods: Patients who received monolithic surveyed zirconia crowns were clinically examined. The crowns were examined according to the modified United States Public Health Service criteria, and Kaplan-Meier survival was determined. The effect of different variables on the survival and success rates was assessed using Cox regression analysis (α = 0.05).

Results: A total of 297 crowns of 275 patients were evaluated over a mean period of 7 years. The cumulative survival and success rates were 95.6% and 91.2%, respectively. Complications were in the form of secondary caries (n=12), minor chipping (n=9), and debonding (n=5). A higher number of failures was observed in the mandibular molars (P < 0.05).

Conclusions: Surveyed monolithic zirconia crowns demonstrated high survival after 7 years of service. Monolithic zirconia is an excellent alternative to metal ceramic crowns for RPD abutments.

Patient: A 26-year-old man with localized tooth wear and demand for aesthetic rehabilitation of the anterior teeth presented to our department. The patient reported excessive consumption of energy drinks. Furthermore, multiple trauma and tooth fractures have occurred in the past.

Discussion: In the present case, three-dimensional (3D)-printed restorations were used to restore the vertical dimensions according to the Dahl concept. An indirect build-up using noninvasive restorations has been demonstrated to be beneficial due to its pleasing aesthetic outcome and the advantage of the 3D printing process. Adhesive bonding was adapted from previous studies using direct composite materials. Thus far, whether, and to what extent, the color of these restorations changes remains unclear. Furthermore, the material wear should be evaluated in future studies.

Conclusions: Moreover, 3D-printed, noninvasive restorations made of a computer-aided design/computer-aided manufacturing hybrid material are suitable for the application of the Dahl concept. Aesthetic improvement in combination with minimally invasive pretreatment of the teeth and subsequent noninvasive restorations led to the rehabilitation of the vertical dimension of occlusion. After a follow-up period of two years, harmonious occlusal conditions were observed in the posterior region.

Purpose: This study evaluated biomechanical behavior of endocrown and post-core restorations produced from computer aided design/computer aided manufacturing (CAD/CAM) and traditional materials in severely damaged teeth that lack a ferrule and assessed the associated failure risk of resin cement.

Methods: A phantom maxillary central incisor and mandibular second premolar were trimmed 1 mm coronally to the cemento-enamel junction, the root canals were enlarged, and the teeth were scanned. Data were transferred to a solid modeling software. Twenty-two models were constructed, including endocrowns (hybrid ceramic, lithium disilicate, and polyetheretherketone [PEEK]) and post-cores (glass-fiber post/composite core; glass-fiber single-piece post-core; PEEK single-piece post-core; gold single-piece post-core). Hybrid ceramic and lithium disilicate crowns were modeled on the post-cores. Loads of 100 N for the central incisor and 300 N for the premolar were applied in a 45° oblique direction. von Mises stresses were analyzed on both root dentin and restorations, and the failure risks for the resin cement were calculated.

Results: The highest stresses were found at the roots of the PEEK endocrown (37.6 MPa) for the central incisor and of the lithium disilicate endocrown for the premolar (40.0 MPa) among endocrown groups. PEEK endocrowns had the lowest stress within the restoration and presented a higher risk of cement failure. The glass-fiber post/composite core groups demonstrated the highest adhesive and cohesive failure risks for post cement.

Conclusions: For the central incisor and mandibular premolar, lithium disilicate and PEEK endocrowns, respectively, generated less stress at the root. However, PEEK endocrowns had a higher risk of cement failure.

Purpose: This study aimed to explore the association between oral function and mental health status in older adults and to determine the potential mediating roles of fruit and vegetable intake and social interaction.

Methods: This cross-sectional study included 478 community-dwelling older adults aged ≥75 years in Japan. Oral functions (occlusal force, masticatory performance, tongue pressure, tongue-lip motor function, and swallowing function), mental health status, dietary assessment, frequency of outings and interactions with others, and the following confounders were evaluated: educational level, financial satisfaction, residential status, comorbidities, and cognitive function. Structural equation modeling was used to assess the following: (a) a basic model, which hypothesized that oral function has a direct effect on mental health status, and (b) a mediation model, which hypothesized that fruit and vegetable intake and social interaction have potential mediating effects on the association between oral function and mental health status.

Results: The basic model revealed a positive direct association between oral function and mental health status (standardized coefficient = 0.10, P = 0.04). Fruit and vegetable intake and social interactions were identified as mediators; however, no direct association with oral function was observed in the mediation model (P = 0.28), indicating that oral function was indirectly associated with mental health status through the mediating effects of fruit and vegetable intake and social interactions.

Conclusions: Oral function showed a significant association with mental health status in community-dwelling older adults. Fruit and vegetable intake along with social interactions mediate this relationship.

Purpose: Restoring ferrule-lacking, noncircular canal endodontically treated teeth (ETT) poses challenges owing to the increased susceptibility to root fracture and post dislodgement. We aimed to evaluate the influence of different post and core materials on the stress distribution and maximum Von Mises stress in ETT.

Methods: Four three-dimensional models were generated using different customized post and core materials: gold alloy, resin nanoceramic, polyetheretherketone (PEEK), and polyetherketoneketone (PEKK). A static load of 200 N was applied at an angle of 45 ° to the occlusal surface. The stress distribution and maximum Von Mises stress were analyzed using finite element analysis.

Results: The stress distribution patterns in all the models were concentrated in the tooth structure, post and core, and cortical bone. The gold model exhibited stress accumulation predominantly on the buccal side along the post length, with the highest maximum Von Mises stress value (330.69 MPa). The resin nanoceramic model exhibited an even stress distribution. The PEEK and PEKK models showed stress transfer to adjacent structures with the lowest maximum Von Mises stress values in the post and core sections (21.50 MPa and 29.46 MPa, respectively).

Conclusions: Different post and core materials influenced the stress distribution and maximum Von Mises stress values in ferrule-lacking, noncircular canal ETT. Resin nanoceramics have emerged as promising alternative materials, exhibiting an even stress distribution owing to their similar elasticity to dentin, thus potentially mitigating the risk of root fracture and post debonding.

Purpose: Psoriasis is a complex, chronic inflammatory keratosis of unclear origin that is challenging to treat. In patients with psoriasis suspected of having metal allergies, the removal of oral metallic prostheses contributes to the alleviation of psoriasis symptoms. However, the relationship and mechanism of the metal removal effect and improvement in psoriasis symptoms in patients with metal allergies are unknown. This study aimed to investigate the relationship between metal allergies and psoriasis using an animal model.

Methods: In the metal allergy model, 4-week-old rats were sensitized and treated with nickel (II) chloride (NiCl₂) solution (provocation model). In the psoriasis model, imiquimod (IMQ) cream was applied to the shaved dorsal skin of rats (IMQ model). To create a psoriasis/metal-allergy composite rat model, we combined the provocation and IMQ models (provocation + IMQ model). Macroscopic observation, histological analysis, and quantitative gene expression analyses were performed to evaluate outcomes.

Results: In the IMQ model, psoriasis-like symptoms were visually observed from day 2 to day 9. In the provocation + IMQ model, psoriasis-like symptoms persisted for at least 11 days. Histological analysis revealed epidermal thickening and an increase in the number of interleukin (IL)-17-positive cells in the provocation + IMQ model on days 7 and 9. The gene expression of IL-17 in the submandibular lymph nodes and spleen increased in the provocation + IMQ model.

Conclusions: The induced state of Ni allergy may contribute to the maintenance of psoriasis pathology through IL-17 activity.

Purpose: This retrospective cohort study evaluated the accuracy of analog versus virtual wax-ups in prosthetic-driven planning and guided surgery.

Methods: There were 73 patients with a single missing posterior tooth who underwent either an analog or virtual wax-up design following a prosthetic-driven concept. Intraoral scans of the final restoration were performed 1 year after completion of the restoration. The accuracy was assessed by comparing the deviation between the final restoration and the wax-up (analog or virtual) of each patient at the prosthetic level. The maximum deviation in six areas (buccal top, buccal mid, buccal bottom, lingual top, lingual mid, and lingual bottom) was recorded. The accuracy was also assessed at the implant level by comparing the deviation between the virtual new implant position, which was redesigned based on the final restoration as the new wax-up, and the planned position. The mean deviations in the coronal, apical, angular, and depth measurements were recorded. A two-tailed independent t-test and a one-way analysis of variance were used.

Results: Statistically significant differences were observed between the buccal (P = 0.03) and lingual tops (P = 0.03) at the prosthetic level. Significant differences were observed in the angular (P < 0.01) and coronal (P = 0.01) deviations at the implant level. There were smaller deviations between the analog wax-ups and final restorations regardless of the prosthetic or implant level.

Conclusions: Analog wax-ups were preferable to virtual wax-ups for preoperative design in computer-guided implant surgery.

Purpose: To determine the effect of wall thickness on the fracture load of hollow-structured zirconia teeth fabricated using 3D printing.

Methods: The geometry of an artificial ceramic tooth (mandibular right first molar) was copied and modified. The final test group design yielded wall thicknesses of 0.30, 0.50, 0.75, and 1.00 mm. Twenty zirconia specimens from each group were fabricated using a 3D printer. Artificial teeth were divided into subgroups of teeth that remained hollow (hollow teeth) or were filled with resin (filled teeth). Fracture load tests were performed, and each artificial tooth was examined using a digital microscope. Analysis of variance was used to compare the fracture resistance of the artificial zirconia teeth among the conditions, followed by pairwise Tukey's tests. T-tests were used to compare the fracture resistance between the hollow and filled teeth within the test groups.

Results: The fracture resistance of artificial zirconia teeth decreased significantly (P < 0.001) with decreasing wall thickness. The mean fracture load reached ≥500 N for wall thicknesses of 0.75 mm and 1.00 mm. Resin filling of crowns significantly improved the fracture load of very thin walls. Microscopy revealed that most occlusal surfaces of the hollow teeth were completely fractured, whereas all the fracture surfaces of the filled teeth were incompletely fractured.

Conclusions: Artificial zirconia teeth offer sufficient fracture resistance for clinical use when the wall thickness is ≥0.75 mm, regardless of the presence of resin filling.

Purpose: The primary aim of this study was to determine the continuation and success rates of oral appliance (OA) therapy for patients in whom continuous positive airway pressure (CPAP) therapy failed. The secondary aim was to identify predictive factors for the long-term use of OA in patients with CPAP failure.

Methods: A total of 81 patients who failed with CPAP use were included in this study. Patients who had been using OA for more than 1 year at follow-up visits were assigned to Group S, whereas those who discontinued OA or were lost to follow-up within 1 year were assigned to Group D. We investigated the continuation and success rates of OA therapy, as well as predictive factors for its long-term use for those with CPAP failure.

Results: Of the 81 patients, 60 were in Group S and 21 were in Group D; 74.0% of patients with CPAP failure continued OA therapy for more than 1 year. The apnea-hypopnea index was reduced from 41.3±21.7/h to 12.4±6.5/h with OA therapy. The only significant predictor of long-term OA use in patients with CPAP failure was awareness of the effectiveness of OA therapy after 1 month (P = 0.003, odds ratio: 9.731, 95% confidence interval: 2.146-44.119).

Conclusions: Patients who recognized the effectiveness of OA treatment in the early stages were more likely to continue using OA therapy long-term.

Purpose: The aim of this systematic review was to analyze the reported flexural strength values of commercially available translucent zirconia materials. Additionally, data were evaluated to assess the impact of different specimen preparations and test methods.

Study selection: This systematic review was conducted according to the PRISMA guidelines. Electronic searches were performed to identify in vitro studies published between January 1, 2013, and March 15, 2025, that reported flexural strength values of translucent zirconia and included the names of the tested materials and manufacturers. Flexural strength values were analyzed to assess the effects of yttria content, specimen processing, surface treatments, and test methods using Kruskal-Wallis analysis of variance (α = 0.05) and forest plots.

Results: A total of 78 laboratory studies met the inclusion criteria. The overall flexural strength values were significantly higher for 4Y-PSZ (803± 233 MPa) than for 5Y-PSZ materials (570 ± 116 MPa) (P = 0.005). Specimen processing, surface treatments, and test methods significantly affected the flexural strength values for 5Y-PSZ (P < 0.001) but not for 4Y-PSZ (P > 0.05).

Conclusions: This systematic review highlights the challenges in comparing the flexural strength values of translucent zirconia owing to differences in processing parameters. Further standardization of test methods and adherence to ISO 6872 would improve comparability. Our findings support the clinical use of 4Y-PSZ for three-unit fixed dental prostheses (FDPs) and 5Y-PSZ for three-unit FDPs in the anterior region based on ISO 6872.