Effect of Intermediate Agents and Preheated Composites on Repair Bond Strength of Silorane-Based Composites

Objectives: Repairing composite restorations is a challenging procedure especially when two different types of composites are used. This study aimed to compare the repair strength of silorane-based composite (SC) (Filtek P90) with that of preheated SC, methacrylate composite (MC)(Z250), flowable MC (Filtek Supreme Plus) and different adhesive/composite combinations. Materials and Methods: Eighty-four SC specimens were fabricated and randomly divided into seven groups (G). In the control group (G7), SC was bonded immediately to SC. The other specimens were water-aged for two months and were then roughened, etched and repaired with the following materials: G1) Silorane Adhesive Bond (SAB)/SC; G2) Preheated SC; G3) SAB/MC; G4) Adper Single Bond (SB)/MC; G5) Flowable MC/MC; G6) Preheated MC. After water storage and thermocycling, the repaired specimens were subjected to shear bond strength testing. The data were analyzed using ANOVA and Tukey’s test. Results: Preheated SC and MC, flowable MC and SAB/SC resulted in bond strength comparable to that of the control group. Preheated SC showed significantly higher bond strength when compared to SAB/MC (P=0.04) and SB/MC (P<0.001). Bond strength of SB/MC was significantly lower than that of the other groups (P<0.05), except for SAB/SC and SAB/MC. Conclusion: All repairing materials except for SB/MC resulted in bond strength values comparable to that of the control group. Repair with preheated SC yielded the highest bond strength.

The effect of ceramic thickness on opalescence

OBJECTIVES Creating a tooth-like appearance by use of dental ceramics is still a challenge. Opalescence is a unique property of dental enamel, attempted to be mimicked by dental restorative materials. This study aimed to assess the effect of ceramic thickness on opalescence. MATERIALS AND METHODS Twenty-four discs were fabricated of feldspathic ceramic, IPS e.max, zirconia and Enamic ceramics with 10 mm diameter and 0.5 and 1 mm thicknesses (n = 12). The opalescence of ceramic specimens was calculated by measuring the difference in yellow-blue axis (CIE ∆b*) and red-green axis (CIE ∆a*) between the transmitted and reflected spectra. One-way ANOVA was applied to compare the opalescence of different ceramic specimens with variable thicknesses at .05 level of significance. RESULTS The opalescence of feldspathic, IPS e.max, zirconia and Enamic ceramic specimens with 0.5 mm thickness was 1.06 ± 0.15, 3.39 ± 0.15, 1.98 ± 0.15 and 1.44 ± 0.15, respectively. By increasing the thickness to 1 mm, the opalescence of feldspathic, IPS e.max, zirconia and Enamic ceramics changed to 1.12 ± 0.15, 1.47 ± 0.15, 3.85 ± 0.15 and 2.00 ± 0.15, respectively. In all groups except for IPS e.max, the mean opalescence of 1-mm-thick specimens was higher than that of 0.5-mm-thick specimens. CONCLUSION Type and thickness of ceramic affect its opalescence. The opalescence of all ceramic specimens tested in this study with 0.5 and 1 mm thicknesses was lower than that of the enamel

Effect of glazing and polishing on opalescence and fluorescence of dental ceramics

Abstract Objective Tooth enamel has opalescence and fluorescence, which should be mimicked by esthetic dental restorations. The purpose of this study was to compare the effects of glazing and polishing on the opalescence and fluorescence of dental ceramics. Materials and Methods Twenty‐four discs were fabricated of feldspathic, IPS e.max, zirconia, and Enamic ceramics with 10 mm diameter and 0.5 and 1 mm thicknesses (n = 12). Of the discs fabricated with 0.5 and 1 mm thicknesses, half of them were glazed and the remaining half were polished (n = 6). Opalescence was calculated as the difference in yellow‐blue (CIE ∆b*) and red‐green (CIE ∆a*) color axes between the transmitted and reflected colors. The fluorescence of specimens was measured by a novel technique. Data were analyzed using two‐way analysis of variance at a 0.05 level of significance. Results In all groups (except for the Enamic ceramic), the mean opalescence of polished specimens (e.max = 2.704, feldspathic = 1.67, zirconia = 3.143) was higher than that of glazed specimens (e.max = 2.163, feldspathic = 1.016, zirconia = 2.690). The mean opalescence of glazed Enamic specimens (2.140) was higher than that of polished specimens (1.308). The fluorescence of glazed and polished specimens was not significantly different. Conclusion Surface treatment (glazing/polishing) affects the opalescence, but not the fluorescence of dental ceramics evaluated in this study

Effect of glazing and polishing on opalescence and fluorescence of dental ceramics

OBJECTIVE: Tooth enamel has opalescence and fluorescence, which should be mimicked by esthetic dental restorations. The purpose of this study was to compare the effects of glazing and polishing on the opalescence and fluorescence of dental ceramics. MATERIALS AND METHODS: Twenty-four discs were fabricated of feldspathic, IPS e.max, zirconia, and Enamic ceramics with 10 mm diameter and 0.5 and 1 mm thicknesses (n = 12). Of the discs fabricated with 0.5 and 1 mm thicknesses, half of them were glazed and the remaining half were polished (n = 6). Opalescence was calculated as the difference in yellow-blue (CIE ∆b*) and red-green (CIE ∆a*) color axes between the transmitted and reflected colors. The fluorescence of specimens was measured by a novel technique. Data were analyzed using two-way analysis of variance at a 0.05 level of significance. RESULTS: In all groups (except for the Enamic ceramic), the mean opalescence of polished specimens (e.max = 2.704, feldspathic = 1.67, zirconia = 3.143) was higher than that of glazed specimens (e.max = 2.163, feldspathic = 1.016, zirconia = 2.690). The mean opalescence of glazed Enamic specimens (2.140) was higher than that of polished specimens (1.308). The fluorescence of glazed and polished specimens was not significantly different. CONCLUSION: Surface treatment (glazing/polishing) affects the opalescence, but not the fluorescence of dental ceramics evaluated in this study