Professional Dental Bleaching Effect on Single-Shade Restorations Color Match

Objectives: To evaluate the color shift of single-shade composite restorations after dental bleaching.
Methods: Class V cavities were prepared on the buccal surfaces of 80 extracted human molars. Teeth were randomly divided into 4 groups (20 teeth for each group) and restored with 4 single-shade composite resins: Omnichroma (OM), Clearfil Majesty ES-2 Universal (CL), Essentia Universal (ES), and Venus Diamond One (VE).
Dental bleaching was performed on the teeth surfaces using Opalescence Boost PF 40%, twice for 20”.
Instrumental evaluations were carried out 24h after restorations (T₀), and 24h (T₁) and 1 week (T₂) after bleaching procedures using a spectrophotometer. L*, a*, b*, C*, and h° were registered and used to calculate ΔE_ab and ΔWI_D.
Results: Instrumental evaluation (ΔE_ab) revealed statistically significant differences between materials (p<0.05). At T₀ OM vs ES (p<0.001), OM vs VE (p=0.001), CL vs ES (p<0.001), CL vs VE (p<0.001), at T₁ OM vs VE (p<0.005), VE vs CL (p<0.001), VE vs ES (p=0.023). Statistically significant differences for OM between T₀ and T₁ (p<0.001) and OM between T₀ and T₂ (p<0.001), VE between T₀ and T₁ (p=0.003), VE between T₀ and T₂ (p=0.033), ES between T₀ and T₂ (p<0.002), ES between T₁ and T₂ (p=0.016), CL between T₀ and T₁ (p<0.001), CL between T₀ and T₂ (p<0.001).
ΔWI_D revealed statistically significant differences between materials (p<0.05). At T₁ OM vs CL (p<0.001), OM vs ES (p<0.001), OM vs VE (p<0.001), CL vs VE (p<0.001), at T₂ OM vs CL (p<0.031), OM vs ES (p<0.001), OM vs VE (p<0.001), CL vs ES (p=0.018), CL vs VE (p<0.001). Statistically significant differences between OM T₁ and OM T₂ (p<0.001).
Conclusions: Within the limitations of this study the four tested single-shade composites showed a good color correspondence with the surrounding tooth and this correspondence remains effective also after bleaching procedures.