Color change of laminate veneer restorations applied to bleached teeth

Aim: The aim of the present study was to examine the color stability of laminate veneer restorations fabricated with various CAD/CAM materials applied to bleached teeth.
Materials and methods: Eighty maxillary central incisors extracted due to periodontal, orthodontic, or trauma problems were used. The teeth were embedded in acrylic blocks and divided into eight groups (n = 10). Groups A, B, C, and D were bleached with a vital bleaching agent before preparation, and the teeth were prepared for laminate veneer restorations. Groups E, F, G, and H were prepared without bleaching. Groups A and E were restored with GC Initial LiSi HT Blocks A1, Groups B and F with GC Initial LiSi LT Blocks A1, Groups C and G with IPS e.max CAD HT Blocks A1, and Groups D and H with IPS e.max CAD LT Blocks A1. All restorations were adhesively cemented and aged for 2 and 5 years with thermal cycling. Color measurements of the restorations were taken with a spectrophotometer at baseline and after 2 and 5 years of aging.
Results: Teeth in all the bleached groups showed more color changes than those in the unbleached groups. After 2 years of aging, the least color change was observed with GC Initial LiSi LT (ΔE00 = 0.808) and IPS e.max CAD LT (ΔE00 = 0.813) materials, which were used on unbleached teeth, and the most color change was observed with GC Initial LiSi HT (ΔE00 = 0.934) and IPS e.max CAD HT (ΔE00 = 0.923) materials, which were used on bleached teeth. After 5 years of aging, the least color change was observed with IPS e.max CAD LT (ΔE00 = 0.831) and GC Initial LiSi LT (ΔE00 = 0.839) materials, which were used on unbleached teeth, and the most color change was observed with GC Initial LiSi HT (ΔE00 = 0.957) and IPS e.max CAD HT (ΔE00 = 0.938) materials, which were used on bleached teeth.
Conclusions: Bleaching and translucency affect color stability. No difference was detected between the color changes of GC Initial LiSi and IPS e.max CAD materials. The increase in aging time increased the color changes of all materials.
Clinical significance: Bleaching and laminate veneer restorations may be preferred in many patients. For this reason, the long-term color changes of laminate veneer restorations applied to bleached teeth is clinically very relevant. The present study aimed to evaluate the effect of tooth bleaching on the long-term color stability of laminate veneer restorations fabricated with various CAD/CAM materials of different translucencies.