RESUMEN
STATEMENT OF PROBLEM: Clinical information regarding the color stability of lithium disilicate veneers by using different methods of evaluation is scarce. PURPOSE: This clinical trial aimed to evaluate whether digital photographs are a reliable method of clinically assessing the color stability of lithium disilicate veneers. Standardized digital photographs (ELAB) were compared with the VITA Easyshade spectrophotometer (ES) at baseline and at a 6-month follow-up. MATERIAL AND METHODS: A split-mouth model was used in this randomized clinical trial to assess the performance of ceramic veneers (N=162), which were produced by either the CAD (IPS e.max CAD; n=81) or PRESS technique by heat pressing (IPS e.max PRESS; n=81), including the color dimension assessment. The ELAB evaluation was performed by making digital photographs with polarized light and a white balance (WhiBal) card. These data were transferred to the Adobe Lightroom CC2015 software program in RAW extension. The Digital Color Meter App (Apple) was used to measure L∗, a∗, and b∗ coordinates in this method. The ES color evaluation was performed with a spectrophotometer (Easy Shade) (control group) in the CIELab system. Measurements were performed 1 week after cementation (baseline) and at a 6-month follow-up. Data collected by the ELAB and ES methods were analyzed by a blinded calibrated operator to calculate ΔE by using the Mann-Whitney-Wilcoxon test (α=.05). RESULTS: For all periods, the comparison among ELAB and ES methods (P=.331), CAD×PRESS by ELAB (P=.658), and CAD×PRESS by ES (P=.833) showed no statistically significant differences. CONCLUSIONS: Standardized digital photographs (ELAB) were shown to be a straightforward and available resource for evaluating the color stability of lithium disilicate veneers, manufactured by CAD or PRESS.
RESUMEN
PURPOSE: The purpose of this study was to evaluate the shear bond strength of different sealant and filling materials, used in minimally invasive dentistry, to human enamel. MATERIALS AND METHODS: Thirty-five sound extracted third molars were selected. The crowns were longitudinally sectioned, embedded in polystyrene resin, and grounded until a flat enamel surface was reached. The samples were assigned into seven groups (n = 10), according to the materials: G1-Fluoroshield; G2-Clinpro; G3-Dyract AP; G4-F2000; G5-Vitremer; G6-Fuji IX; G7-Vidrion F. All materials were applied according to the manufacturer's instructions. The samples were stored in distilled water at 37 degrees C for 24 h and submitted to a shear bonding strength test in a universal testing machine with a crosshead speed of 0.5 mm/min. The failure sites were observed in Scanning Electron Microscopy (SEM). The data were submitted to ANOVA and Tukey's tests (p < 0.05). RESULTS: The mean values (MPa) of shear bond strength were for Fluroshield (25.92 +/- 8.83), Vitremer (20.41 +/- 13.34), Dyract AP (17.08 +/- 6.38), Clinpro (12.82 +/- 8.38), F2000 (8.71 +/- 3.74), Fuji IX (7.64 +/- 2.57), and Vidrion F (4.54 +/- 2.11). Fluroshield resin sealant and Vitremer resin modified glass-ionomer showed statistically higher shear bond strength values than the conventional glass ionomer (GIC) cements. Clinpro and F2000 showed bond strength values with statistical difference only from Fluroshield. The failure mode varied among the groups. The majority of samples presented mixed failure. CONCLUSION: FluroShield and Vitremer showed better performance of shear bond strength to enamel than conventional GIC.
