Photopolymer resins are widely used in the production of dental prostheses, but their mechanical properties require improvement. We evaluated the effects of different zirconia filler contents and printing directions on the mechanical properties of photopolymer resin. Three-dimensional (3D) printing was used to fabricate specimens using composite photopolymers with 0 (control), 3, 5, and 10 wt.% zirconia filler. Two printing directions for fabricating rectangular specimens (25 mm × 2 mm × 2 mm) and disk-shaped specimens (φ10 mm × 2 mm) were used, 0° and 90°. Three-point bending tests were performed to determine the flexural strengths and moduli of the specimens. The Vickers hardness test was performed to determine the hardness of the specimens. Tukey’s multiple comparison tests were performed on the average values of the flexural strengths, elastic moduli, and Vickers hardness after one-way ANOVA (α = 0.05). The flexural strengths and elastic moduli at 0° from high to low were in the order of 0, 3, 10, and 5 wt.%, and those at 90° were in the order of 3, 0, 10, and 5 wt.% (p < 0.05). For 5 and 10 wt.%, no significant differences were observed in mechanical properties at 0° and 90° (p < 0.05). The Vickers hardness values at 0° and 90° from low to high were in the order of 0, 3, 5, and 10 wt.% (p < 0.05). Within the limits of this study, the optimal zirconia filler content in the photopolymer resin for 3D printing was 0 wt.% at 0° and 3 wt.% at 90°.

Demand for complete denture treatment is expected to rise over several decades. However, to date, no questionnaire on complete dentures, as evaluated by edentulous patients, has been shown to be reliable and valid. This study sought to assess the reliability and validity of Patient’s Denture Assessment (PDA), which provides a multidimensional evaluation of dentures among edentulous patients.

Individuals who are edentulous have a lower intake of fruit, vegetables, fiber, and protein compared with their dentate counterparts because tooth loss is accompanied by a decrease in ability to chew. Whether or not a combination of prosthetic rehabilitation and simple dietary advice produces improvement in dietary intake among edentulous persons is unclear. We aim to investigate the effect of a simultaneous combination of simple dietary advice delivered by dentists and provision of new complete dentures on dietary intake in edentulous individuals who request new dentures. Through a double-blinded, parallel, randomized controlled trial in which 70 edentate persons who request new complete dentures will be enrolled, eligible study participants will be randomly allocated to either a dietary intervention group receiving dietary advice or to a control group receiving only advice on the care and maintenance of dentures. Outcome measures include daily intake of nutrients and food items, assessed using a brief self-administered diet history questionnaire; antioxidant capacity, determined using blood and urine samples; nutritional status, assessed with the Mini-Nutritional Assessment-Short Form; oral health-related quality of life, assessed with the Japanese version of the Oral Health Impact Profile-EDENT and the Geriatric Oral Health Assessment Index; subjective chewing ability; masticatory performance, assessed using a color-changeable chewing gum and a gummy jelly; patient self-assessment of dentures; mild cognitive impairment, assessed with the Japanese version of the Montreal Cognitive Assessment; and functional capacity, assessed with the Japan Science and Technology Agency Index of Competence. Outcome measures, except for antioxidant capacity, are to be implemented at three time points: at baseline and at 3 and 6 months following intervention. Antioxidant capacity data are to be collected twice: at baseline and at 3 months following intervention. Differences between the groups at 3 and 6 months and within-group changes are to be compared using the paired t test. Simple dietary advice that can be implemented by a dentist would be more practical in clinical practice than tailored dietary counseling. The results of this study will provide beneficial information on dietary intake changes for both edentulous individuals requesting new complete dentures and dentists. University Hospital Medical Information Network Center Unique Trial Number: UMIN000017879 . Registered on 12 June 2015.

Mandibular overdentures retained by a single implant placed in the midline of edentulous mandible have been reported to be more comfortable and function better than complete dentures. Although single-implant overdentures are still more costly than conventional complete dentures, there are a few studies which investigated whether mandibular single-implant overdentures are superior to complete dentures when patient general satisfaction is compared. The aim of this study is to assess patient general satisfaction with mandibular single-implant overdentures and complete dentures. This study is a randomized crossover trial to compare mandibular single-implant overdentures and complete dentures in edentulous individuals. Participant recruitment is ongoing at the time of this submission. Twenty-two participants will be recruited. New mandibular complete dentures will be fabricated. A single implant will be placed in the midline of the edentulous mandible. The mucosal surface of the complete denture around the implant will be relieved for 3 months. The participants will then be randomly allocated into 2 groups according to the order of the interventions; group 1 will receive single-implant overdentures first and will wear them for 2 months, followed by complete dentures for 2 months. Group 2 will receive the same treatments in a reverse order. After experiencing the 2 interventions, the participants will choose one of the mandibular prostheses, and yearly follow-up visits are planned for 5 years. The primary outcome of this trial is patient ratings of general satisfaction on 100 mm visual analog scales. Assessments of the prostheses and oral health-related quality of life will also be recorded as patient-reported outcomes. The secondary outcomes are cost and time for treatment. Masticatory efficiency and cognitive capacity will also be recorded. Furthermore, qualitative research will be performed to investigate the factors associated with success of these mandibular denture types. Clinical outcomes, such as implant survival rate, marginal bone loss, and prosthodontic complications, will also be recorded. The results of this randomized crossover trial will clarify whether mandibular single implants and overdentures for edentulous individuals provide better patient general satisfaction when compared to conventional complete dentures. This clinical trial was registered at the University Hospital Medical Information Network (UMIN) Center (UMIN000017883).