Effects of Bleaching Gels on Dental Enamel Crystallography

Oral Health Prev Dent. 2021;19(1):7-14. doi: 10.3290/j.ohpd.b875523.


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.

Keywords: X-ray diffraction; bleaching agent; enamel crystallography.

MeSH terms

  • Carbamide Peroxide
  • Crystallography
  • Dental Enamel
  • Gels
  • Humans
  • Hydrogen Peroxide
  • Microscopy, Electron, Scanning
  • Tooth Bleaching Agents* / pharmacology
  • Tooth Bleaching*


  • Gels
  • Tooth Bleaching Agents
  • Carbamide Peroxide
  • Hydrogen Peroxide