Effect of hydrogen-peroxide-based home bleaching agents on enamel hardness

The aim of this in vitro study was to examine the effect of four commercial hydrogen-peroxide-based home bleaching agents on enamel microhardness. Fifteen human molars conserved in water for no more than 3 months were sectioned mesio-distally. The buccal and lingual surfaces were included in self curing acrylic resin, and the 30 specimens were ground until 600 grid (n=6). At baseline, 6 indentations (Vickers) were made on each of the 6 surfaces of each group, under load of 100g for 30s. Bleaching procedure was performed for 2 weeks with: 4.5% hydrogen-peroxide (Perfecta, Premier), 5.5% hydrogen-peroxide (DayWhite, Discus Dental), 7.5% hydrogenperoxide (DayWhite, Discus Dental), a polyethylene-strip whitening system containing 5.3% hydrogen-peroxide (Whitestrips, Procter&Gamble) and 10% carbamide peroxide (Opalescence, Ultradent) was used as control. After bleaching time, the specimens were rinsed and maintained in fresh artificial saliva, changed daily. A t-test compared each bleaching agent before and after treatment. The results showed that none of the five commercial home bleaching agents reduced the enamel microhardness. I t was concluded that all the five commercial home bleaching agents evaluated in our study showed no adverse effects on enamel microhardness