Optical Properties of Resin-composites and Dental Substrates With Different Thickness

Objectives: This study evaluated the optical properties (color, translucency and fluorescence) of resins composite of different degrees of translucency, and tooth substrates (enamel and dentin).
Methods: Ninety bovine incisors were used, resulting in 45 dentin and 45 enamel disks (6mm diameter and 0.5, 1 or 1.5 mm in thickness). Ninety discs of Charisma, Filtek Z350 and Direct Empress (for enamel and dentin) resins at same dimensions were built. Methods: Color measurements were measured against white and black backgrounds with a spectrophotometer (CM-2600d, Konica Minolta) and recorded under a D65 light source, which reflects daylight. CIELAB parameters of each specimen were recorded. Translucency was calculated using the translucency parameter (TP) formula. Fluorescence readings were performed using a fluorescence spectrophotometer (RF-5301PC, Shimadzu Corp) with excitation at 365nm. Data were analyzed using 3-way ANOVA and Tukey’s post hoc tests (α=0.05).
Results: The 3 way - ANOVA (type of substrate, characteristics of substrate (enamel or dentin), and thickness) revealed statistically significant differences for all factors, as well as the interaction between them (p <0.05), for the measurement of fluorescence, translucency and color. Dentin specimens (1.5mm) showed highest fluorescence (128.33 A.U.), while Filtek Z350 (dentin-1.0mm) showed the lowest fluorescence (29.84 A.U.). For translucency analysis, dentin and enamel substrates showed no differences for same thickness, while resin specimens for dentin presented lower translucency than for enamel. Color evaluation showed more variation of L and a coordinate for thickness variation.
Conclusions: The thickness influenced fluorescence, color and translucency of the materials and substrates studied.