Effect of a new bleaching agent formulation containing hexametaphosphate and fluoride on enamel esthetic efficacy and microhardness
Objectives: The aim of the study was to evaluate in vitro the addition of sodium hexametaphosphate (HMP) in the presence or not of sodium fluoride (F) to 35% hydrogen peroxide (PH) on the esthetic efficacy and hardness enamel. Methods: Bovine enamel blocks were selected by initial surface hardness (SHi) and divided into 5 experimental groups (n = 10): 1) Gel based on 35% PH (PH); 2) Gel PH + 0.1% F (PH/F); 3) Gel PH + 1% HMP (PH/HMP); 4) Gel PH + 0.1% F + 1% HMP (PH/F/HMP) and 5) Gel HP Blue 35% [FGM - Dental Products (HP Blue)]. The gels were applied once, during 3 sessions of 40 minutes/session, every 7 days. Then, the color change was measured and the final surface hardness (SHF), percentage of surface hardness loss (%SH) were determined. Data were submitted to ANOVA and followed by Student's t test (p < 0.001). Results: The gels had similar whitening efficacy. The PH/F/HMP bleaching agent reduced %SH by 60%, 56.7% and 54% when compared to treatment with the HP Blue, PH and PH/HMP gels, respectively (p < 0.001). Conclusions: It was concluded that the addition of HMP and F in a conventional bleaching gel reduced enamel demineralization when compared to its counterpart, promoting a similar bleaching effect.