Introduction

Direct composite resins are used for aesthetic restorations, but achieving ideal shade match is challenging. Multi-shade composites require various increments and shade options, which increase clinical time and inventory. Single-shade composites rely on a chameleon effect for shade adaptation, but their long-term color stability remains uncertain.

Objectives

The present in vitro study aimed to evaluate and compare the color matching ability of two single-shade composite resins (Omnichroma and Vittra APS Unique) to one conventional multi-shade composite resin (Filtek Z350) in different tooth shades (A1, A2, and A3.5) using visual scoring and spectrophotometric analysis (ΔE). The study also sought to assess and contrast the color stability of these materials after undergoing thermocycling.

Material and methods

Thirty extracted maxillary premolars were divided into A1, A2, and A3.5 shade groups (n = 10 each group). Class V cavities were prepared on the buccal and palatal surfaces, and Class II slot were prepared on the proximal surfaces. Buccal cavities were restored with Omnichroma, palatal cavities with Vittra APS Unique, and proximal cavities were restored with Filtek Z350 in corresponding A1, A2, and A3.5 shades. Color evaluation was performed visually by calibrated observers and instrumentally using a spectrophotometer before and after thermocycling. Color differences (ΔE) were calculated to assess initial color matching and post aging color stability.

Results

Visual scores of Omnichroma and Vittra APS Unique were comparable to Filtek Z350 across all shade groups, with no statistically significant differences observed. However, spectrophotometric ΔE values revealed significant differences between single-shade and conventional composites in the A2 and A3.5 groups. Vittra APS Unique in shade A3.5 showed the highest ΔE value. After thermocycling, Vittra APS Unique demonstrated greater ΔE changes compared to Omnichroma, indicating reduced color stability.

Conclusions

Single-shade composites achieved acceptable color matching in lighter shades, but performed less effectively in darker shades. Thermocycling negatively affected stability, particularly for Vittra APS Unique.