Tekin YH, et al. J Adv Prosthodont. 2020 Oct;12(5):283-290. https://doi.org/10.4047/jap.2020.12.5.283

The purpose of this study was to investigate the effects of staining solutions and surface finishing on the colour stability and translucency of hybrid ceramic (HC) and resin nanoceramic (RNC) materials. Twenty four groups consisting of 10 specimens (240 specimens in total) were created out of HC and RNC, including six groups to be stored in distilled water served as the controls groups. The Vita Enamic technical set, Shofu polishers, medium and fine rubber wheels and Sof-Lex polishing discs were used as polishing instruments. Cola, tea, and coffee were used as staining solutions. The colour differences (∆E*) and translucency parameter (TP) were evaluated by a spectrophotometer. Data were analysed by a One-way Analysis of Variance (ANOVA) and Mann-Whitney U test. There was a statistically significant difference between the ∆E* values of the HC specimens in the coffee groups and the ∆E* values of the other HC groups (p < 0.05). The ∆E* values of the RNC specimens in the coffee and tea groups were not different from the specimens in the cola groups (p > 0.05). The TP values of the polished groups were higher than the Sof-Lex groups and the Shofu groups on both HC and RNC materials (p < 0.05). Increased ∆E* values were observed in HC specimens stored in a coffee solution compared to the specimens stored in a tea or cola solution. Both of the RNC specimens stored in coffee and tea had higher ∆E* values than the RNC specimens stored in the cola. The TP values of both HC and RNC specimens stored in the coffee solution decreased.

Keywords Candida albicans; Surface properties; Denture cleansers; Denture bases

The purpose of this study is to evaluate the wear and fracture strength of crowns and three-unit partial fixed dental prosthesis (FDP) fabricated using by Bruxzir and Incoris TZI as recently introduced monolithic zirconia materials. A total of sixteen crowns and sixteen three-unit FDPs were fabricated using Bruxzir and Incoris TZI (n = 8). All specimens were subjected to a 2-body wear test in a dual axis chewing simulator for 1,200,000 loading cycles against steatite antagonist balls. The fracture strength and volumetric loss were recorded. The obtained data were statistically analyzed by 2-way ANOVA testing (α = 0.05). The mean volumetric loss of the crowns was higher than that of the three-unit FDPs (p < 0.05). Of the two monolithic systems, Incoris TZI exhibited more wear than Bruxzir. The fracture strengths of Bruxzir crowns and FDPs were found to be higher than those of the crowns and FDPs fabricated with Incoris TZI (p < 0.05). In in vitro test conditions, Bruxzir and Incoris TZI monolithic zirconia systems are fracture-resistant for the crown and FDP application against physiologic chewing forces owing to dynamic aging. Among newly developed monolithic zirconia materials, Bruxzir is found to be more resistant to fracture compared to the Incoris TZI.

To improve the flexural strength and flexural modulus of polymethyl methacrylate (PMMA), copolymerization of PMMA with 10, 20, 30, and 40% (v/v) of either ethyl-methacrylate, butyl-methacrylate (BMA), or isobutyl-methacrylate (IBMA) was carried out. Test specimens were fabricated from heat-cured resin. The flexural strength was measured using a 3-point bending test. The chemical characterization and the copolymerization mechanisms of the copolymer resins were confirmed by 1H-NMR and FTIR. The flexural strength data were analyzed by applying two-way variance analysis. PMMA was reinforced by ethyl-methacrylate, BMA and IBMA copolymerization. Flexural strengths of the BMA and IBMA copolymers were significantly higher than those of the control group. Maximum flexural strength and modulus resulted from a 40% concentration of IBMA. The flexural strength and modulus values of all copolymer groups were found to be higher than those of the control group. The flexural moduli of the BMA and ethyl-methacrylate groups were similar to those of the control.