ObjectiveThe purpose of this study was to evaluate the effects of different polishing techniques on the surface roughness of dental porcelains.Material and MethodsFifty-five cylindirical specimens (15x2 mm) were prepared for each feldspathic (Vita VMK 95, Ceramco III) and low-fusing dental porcelain (Matchmaker). Fifty-five specimens of machinable feldspathic porcelain blocks (Vitablocs Mark II), (12x14x18 mm) were cut into 2-mm-thick slices (12x14 mm) with low speed saw. The prepared specimens were divided into 11 groups (n=5) representing different polishing techniques including control ((C) no surface treatment), glaze (G) and other 9 groups that were finished and polished with polishing discs (Sof-Lex) (Sl), two porcelain polishing kits (NTI (Pk), Dialite II (Di)), a diamond polishing paste (Sparkle) (Sp), a zirconium silicate based cleaning and polishing prophy paste (Zircate) (Zr), an aluminum oxide polishing paste (Prisma Gloss) (Pg), and combinations of them. The surface roughness of all groups was measured with a profilometer. The data were analyzed with a 2-way analysis of variance, and the mean values were compared by the Tukey Honestly Significant Difference test (α=0.05).ResultsFor all porcelain material groups, the lowest Ra values were observed in Group Gl, Group Sl, Group Pk, and Group Di, which were not significantly different from each other (p>0.05).When comparing the 4 different porcelain materials, the machinable feldspathic porcelain block group (Mark II) demonstrated statistically significantly less Ra values than the other porcelain materials tested (p<0.05). No significant difference was observed between the VMK 95 and Ceramco III porcelain groups (p=0.919), also these groups demonstrated the highest Ra values.ConclusionSubjected to surface roughness, the surfaces obtained with polishing and/or cleaning-prophy paste materials used alone were rougher compared to the surfaces finished using Sof-lex, Dialite, and NTI polishing kit. Polishing kits and discs were found more effective than the polishing pastes used alone or combined use with Sof-lex discs, thus improving surface smoothness.

BackgroundThe 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.MethodsA 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).ResultsThe 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).ConclusionIn 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.

BackgroundThe 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.MethodsTwenty 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.ResultsThere 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).ConclusionsIncreased ∆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.

Background/purpose: There is a lack of information in the few studies reporting on the stainability of dental porcelain materials. However no studies have been found that investigated effects of polishing methods and staining agents on the color stability of dental porcelains. The purpose of this study was to evaluate the effects of different polishing techniques on the color stability of various dental porcelains. Materials and methods: Fifty-five specimens were prepared for each of feldspathic (Vita VMK 95, Ceramco III), low-fusing porcelain (Matchmaker), and machinable feldspathic porcelain blocks (Vitablocs Mark II). The prepared specimens were divided into 11 groups (n Z 5) representing different polishing techniques including a control (no surface treatment), glaze, and nine other groups which were finished and polished with a polishing disc (Sof-Lex), two porcelain polishing kits (NTI, Dialite II), a diamond polishing paste (Sparkle), a zirconium silicatebased cleaning and polishing prophy paste (Zircate), an aluminum oxide polishing paste (Prisma Gloss), and combinations of these. Specimens were stored for 48 hours at 37 C in a coffee solution. The color of all specimens was measured with a colorimeter before and after exposure, and color changes (DE) were calculated. Data were analyzed with a two-way analysis of variance, and mean values were compared by the Tukey's honest significant difference test (a Z 0.05). Results: When comparing the four different porcelain materials, Ceramco III demonstrated the highest DE value. No significant difference was observed among the porcelain material groups of Mark II, Matchmaker MC, and VMK 95 (P Z 0.074). When comparing the polishing techniques, the lowest DE values were observed in Group Gl for all porcelain materials tested. No significant difference was observed among Groups Sl, Di, and Pk, (P Z 0.883), and these Groups demonstrated significantly higher DE values than Group Gl (P < 0.05).

ObjectiveAlthough the effectiveness of chemical cleansing against Candida albicans biofilm has been shown, the effective concentration of denture cleanser tablets has not been studied. The aim of this study was to assess the effect of three denture materials against Candida albicans biofilm and to determine effective concentrations of denture cleanser tablets.Material and methodsThe surface-roughness of Acron-hi™, QC-20™ and Deflex™ (n=45 per resin) resins was standardized by using a profilometer and their contact angle or surface free energy was calculated. C. albicans biofilm was formed on all three resins and were treated with Polident 3 min™, Corega™ and Fittydent™ cleanser solutions at various concentrations and both resin-biofilm and cleanser-biofilm interest were determined by using a MTT protocol according to the European Committee on Antimicrobial Susceptibility Testing's antifungal susceptibility testing (AFST-EUCAST). Scanning electron microscopy was used to compare the efficacy of different resin materials against C. albicans biofilm. Anticandidal activity and surface free energy statistical parameters were calculated by using 3-way and 1-way ANOVA, respectively (p<0.05).ResultsPolident 3 min™ and Corega™ tablets significantly inhibited (p<0.05) the proliferation of C. albicans against all denture resins at 27-37 mg/mL. Scanning electron microscopy results indicated that there was no significant difference among resin specimens regarding biofilm formation on dentures. We failed to find a significant relationship between surface free energy and the anticandidal effect of resin types. However, the polarity value of the resins was statistically associated with their anticandidal activity.ConclusionsThe polarity of the resins, the concentrations of tablets and the chemical content of the cleanser may directly affect C. albicans biofilm formations. Polident 3 min™ and Corega™ tablets should be suggested for patients who use any denture resin types, whereas the Fittydent™ tablet should only be proposed for those who use Deflex™, when two tablets are dropped into 150 mL water.