Color matching and translucency of single-shade resin composites: effects of restoration thickness, background shade, and aging
Hamideh Sadat Mohammadipour, Saeed Rahimi Yazdi, Mohammad Javad Moghaddas Mashhad, Saber Babazadeh, Arsalan Shahri
Abstract
BACKGROUND: Achieving a seamless color match in resin composite restorations remains a significant clinical challenge due to variations in tooth structure and background shades. The aim of this in vitro study was to assess the effect of background shade, thermal aging, and composite thickness on color matching and translucency of three single-shade resin composites. METHODS: A total of 72 resin composite disks (12 mm diameter) were fabricated using three single-shade composites -Omnichroma (OMN), Charisma Diamond ONE (CDO), and Charisma Topaz ONE (CTO)- in two thicknesses (1.5 and 3 mm), resulting in six groups (n = 12 per group). Subsequently, three background disks were prepared from Estelite Sigma Quick in shades A1, A3, and B1, and the 72 composite disks were positioned on these background disks to form a two-layer assembly for evaluation. The L*, a*, and b* variables before and after thermocycling (10,000 cycles) were recorded and blending effect (BE) was calculated. The translucency was evaluated by using white and black backgrounds. The data were analyzed by Kolmogorov-Smirnov, ANOVA, Independent Samples T-test, and Tukey HSD tests with the significance level set at 5%. RESULTS: OMN exhibited a significantly superior BE compared to CTO and CDO, both before and after aging (p < 0.001). Color matching was significantly better at 1.5 mm than at 3 mm, except for CTO and CDO on the A3 background (p = 0.193 and p = 0.550, respectively). BE was highest on the A1 background, intermediate on B1, and lowest on A3 (p < 0.001). Translucency was significantly higher at 1.5 mm than at 3 mm (p < 0.001), except for CTO on A3 after aging (p = 0.198), while background shade did not affect translucency (p > 0.05). CONCLUSIONS: The BE of single-shade resin composite is material and thickness-dependent. Overall, OMN demonstrated superior shade matching across different backgrounds compared to CDO and CTO, at both thicknesses, before and after aging. CLINICAL SIGNIFICANCE: Understanding the influence of composite material, thickness, and underlying shade can optimize color matching in dental restorations, improving clinical outcomes and esthetics.