Effects of Bleaching Gels on Dental Enamel Crystallography.

Purpose The aim of the present research was to analyse the effects of two bleaching agents, on the enamel crystallography by means of X-ray diffraction. Material and methods Twelve human sound posterior teeth, were collected for the present study (n = 12) and from each tooth two enamel slabs were obtained and randomly assigned to one of two different bleaching protocols. The first protocol involved an in-office bleaching agent (hydrogen peroxide 37.5%/ SDI Polaoffice+), and the second an at-home whitening product (carbamide peroxide 16%/ PHILIPS Zoom! NiteWhite). X-ray diffraction readings were made before and after applying the treatments in order to analyse the peak intensity and crystal domain size. Additionally, scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) were carried out to identify the composition correctly. Statistical analysis included repeated measures analysis of variance (p ≤ 0.05). Results: Peak intensity in spectra obtained by X-ray diffraction had a tendency to diminish, mostly in the at-home bleaching group. The analysed data approximate a decrease in the crystal domain size among the samples treated for longer periods of time. Statistical analysis depicted no statistically significant differences among the experimental groups (p ≥ 0.05). Conclusions: Crystal domain size had a tendency to decrease, mostly when the enamel was treated by bleaching gels that had to be applied by prolonged periods of time.