Are there morphological and structural changes in the enamel as a consequence of dental bleaching?

This summary is based on the article published in Materials Letters: New approach to determine the morphological and structural changes in the enamel as consequence of dental bleaching (February 2015)

I. Izquierdo-Barba, C. Torres-Rodríguez, E. Matesanz, M. Vallet-Regí

Context

• Dental bleaching is commonly carried out to correct discolouration of anterior teeth. Most bleaching agents are strong oxidizing agents and the most popular bleaching agent includes hydrogen peroxide ⁽¹⁾.
• Although this bleaching agent is highly effective in lightening tooth colour, concerns have been expressed regarding to associated post-bleaching complications including alteration in the surface morphology of enamel and dentin, change in its chemical composition, increase in its permeability, and notable changes in its mechanical properties ^{(2, 3)}.
• There is a strong necessity to develop a different approach to determine the real consequences of bleaching treatment by using an unchangeable and entire tooth.
• The environmental scanning electron microscopy, the electron probe micro analyzer and X-ray diffraction techniques have been used to evaluate the effects of 38% (p/v) hydrogen peroxide treatment onto morphological, chemical and structural features in the human enamel and dentin.
• Although such effects have been widely investigated with several techniques, including XRD and SEM, the novelty of this study lies in the techniques and methodology used to characterize the human teeth after bleaching treatment.
• This approach allows to carry out the analyses without any previous pretreatment, such as powdering, dried or metal sputtering, and its study in the same tooth piece before and after bleaching, which avoids the possible intrinsic differences derived from the use of different pieces.

Purpose of the Study

• To determine the effects of dental bleaching with H2O2 38% (w/v) during 20 min on the morphological, chemical and structural features of human molar teeth.

Key Findings

• Neither the structural nor the chemical features of enamel and dentin are altered after bleaching treatment.
• Nonetheless, the morphology of the enamel is notably altered, with the appearance of channels with very pronounced pores. These channels could make enamel more susceptible to bacterial attack.
• The major scientific relevance of this study relies on the techniques and methodology used to deeply characterize the teeth after bleaching treatment, putting an end to the controversies on the different effects found in the literature, and setting novel standard protocols for future studies.

References

List of references included in the study (PDF)