Effect of whitening on microleakage and color stability of composites

Objective: to study the effect of whitening treatments on color stability and microleakage of flowable composites in vitro. Methods: Three flowable composites, two nanofilled (GF-Grandio Flow and FSP-Filtek Supreme Plus) and one microhybrid (GDL-Gradia Direct LoFlo), were used to restore 120 Class V cavities in extracted third molars using bonding agents from the same manufacturer (Futurabond NR, Adper Single Bond Plus and G-Bond). Restorations were polished and thermal cycled (5oC, 55oC, 30”, 1000). Color of the restorations was evaluated with a colorimeter to derive the L*a*b* values. The restorations were then immersed in tea solution for 24 hours and rinsed. Color of restorations was measured again. Half (60) of the restorations were then subjected to treatments by 38% H2O2 (Opalescence Xtra Boost) and the color was evaluated for the third time. The restorations were then stained in tea solution again and the final color evaluation was done. Color changes were calculated as ΔL*, Δa*and Δb* and ΔE. All restorations were immersed in 2% basic fuchsin for 24 hours and microleakage was assessed with a stereomicroscope. Results: Following immersion in tea solutions, all restorations showed significant changes in L* a* b* values (p<0.05). Following whitening treatments, the lightness (L*) of all restorations recovered (p<0.05) but not colors represented by a* and b* (P>0.05). Whitening treatments increased the stain resistance of FSP and GF as indicated by less change in ΔE values. FSP/Single Bond Plus had significantly less microleakages on the occlusal margins than GDL/G-Bond and GF/Futurabond NR (p<0.05). Whitening treatments with did not affect the microleakage of all restorations. None of the flowable composite/adhesive achieved acceptable bonding when the margin was below CEJ. Conclusions: Color stability and microleakage of flowable composites were not negatively affected by whitening treatments. Flowable composites should not be used in Class V cavities involving CEJ.