Maintenance of enamel properties after bleaching with high-concentrated hydrogen-peroxide gel containing calcium polyphosphate sub-microparticles

Objective To assessed the physical and chemical properties of human-enamel after treatment with an experimental bleaching gel containing 35%-hydrogen peroxide (HP) and calcium polyphosphate sub-microparticles (CaPP).Materials and methods Enamel/dentin specimens (4 x 4 x 3 mm) were obtained (n = 120) and allocated to different groups: control (saliva only); experimental (HP35%); commercial (whiteness-HP-Maxx); CaPP0.5% (HP35% + CaPP0.5wt%); CaPP1.5% (HP35% + CaPP1.5wt%). Three sessions were performed. The specimens' color was assessed using a spectrophotometer and the color (?E/?E-00) and bleaching index (?WID) determined. The surface roughness and microhardness were assessed with a roughness tester and Knoop indenter. Raman spectroscopy was performed to obtain the ratios between the areas under the 431, 580, and 1070 cm-1 and the 960 cm(-1) bands (430:960, 580:960, 1070:960). Kruskal-Wallis and Dunn compared the color, Ra, and SMH data. The Raman data was analyzed with Kruskal-Wallis and Dunn (a = 5%).Results The ?E,?E-00, and ?WID were similar among the bleached groups (p > 0.05). The roughness was not different between the groups (p > 0.05). After the 3rd session, CaPP0.5% had higher microhardness than the experimental (p < 0.05). The 1070:960 was higher in the experimental than in the CaPP1.5% and control (p < 0.05).Conclusions In human enamel, CaPP did not alter the bleaching effectiveness or roughness, and additionally, CaPP-containing gels increased the microhardness and preserved the mineral content when compared to the experimental without CaPP.Clinical relevance Experimental bleaching gels containing calcium polyphosphate sub-microparticles as a mineral source reduce the mineral content alteration and superficial microhardness reduction, known potential side effects of the in-office bleaching treatments.

Automated summary

This study assessed the effects of an experimental bleaching gel containing 35% hydrogen peroxide and calcium polyphosphate sub-microparticles on the physical and chemical properties of human enamel. The results showed that the addition of calcium polyphosphate did not alter the bleaching effectiveness or surface roughness, but it increased the microhardness and preserved the mineral content of the enamel.