Influence of Whitening Protocols on Color of Resin Composites

Objectives: The aim of the present study was to assess in vitro the influence of whitening therapies on color alterations of microparticled and nanofilled resin composites.
Methods: Sixty specimens of each resin composite, Z350 XT (Z) – 3M/ESPE (nanofilled) and Durafill (D) – Heraeus Kulzer (microparticled), were fabricated. The baseline color was measured with a spectrophotometer using the CIE L* a* b*. Specimens were divided into three groups according to whitening protocol: no whitening - NW, 38% hydrogen peroxide whitening - HP (1h weekly, for 2 weeks), and 15% carbamide peroxide - CP (8h daily, for 2 weeks). The final color was measured after whitening protocol. Group not receiving whitening remained in water for 2 weeks prior to final color reading. Two-way ANOVA and Tukey’s test analyzed data, both with 5% significance level.
Results: ΔE (range 1.090 to 1.882) and ΔL (range –0.461 to 0.777) were not influenced by resin type nor whitening therapy (p>0.05). Δb was influenced by type of resin and whitening therapy (p<0.0001). D tended to blue chroma with CP. Z tended to be less bluish with both whitening protocols.
Conclusions: The type of resin and whitening therapy did not influence color or luminosity of tested groups. Changes detected in the b* coordinate may not influence the overall clinical color perception.