Effects of home bleaching on surface hardness and surface roughness of an experimental nanocomposite

OBJECTIVE: Home bleaching agents may not be safe for composite resins. The purpose of this study was to evaluate the effects of 10 and 20% Opalescence(®) PF home bleaching agents on the surface roughness and hardness of universal nanocomposite (Filtek Z350), anterior nanocomposite (KeLFiL), and nanohybrid composite (TPH 3). MATERIALS AND METHODS: Fifty-four composite resin samples with 18 samples for each type of composite resin were prepared using acrylic molds (4 × 2 mm). Each type of composite resin was further divided into three groups [n = 6 controls were placed in distilled water for 14 days and the other two groups of n = 6 were bleached with 10 and 20% carbamide peroxide (CP), respectively for 14 days]. Surface hardness of the composite resin was tested with a Vickers hardness tester, whereas surface roughness was tested with atomic force microscopy (AFM). RESULTS: There were significant changes in the surface hardness of KeLFiL and TPH 3. However, all the tested materials showed no significant changes in the surface roughness. CONCLUSION: After 14 days of home bleaching treatment, there was no adverse effect on the surface roughness of all three composite resins, although the surface hardness for KeLFiL and TPH 3 were significantly reduced.