Tooth whitening: what we now know

Abstract

Current research about tooth whitening shows that it is safe and effective when manufacturer's protocol is followed, yet there are risks of which the profession and users should be aware. This update provides a summary of current research and assessment of the safety and efficacy of tooth whitening regimens.

Background: Tooth whitening has become one of the most frequently requested dental procedures by the public. The public has come to demand whiter, more perfect smiles and in response many choices for tooth whitening have been made available. These include home-based products such as toothpastes, gels, and films, as well as in-office based systems where products containing highly concentrated bleaching agents are applied under professional supervision. The profession and public have been aware of certain risks related to tooth whitening such as increased tooth sensitivity and gingival irritation. New research has shown that there are other risks such as tooth surface roughening and softening, increased potential for demineralization, degradation of dental restorations, and unacceptable color change of dental restorations. The new research is also focused on optimizing whitening procedures to reduce tooth sensitivity and to increase the persistence of the whitening.

Methods: Current reports in the literature are reviewed that are related to the use of peroxide based whitening methods. These reports include in vitro studies for method optimization and mechanism as well as clinical studies on effects of various whitening regimens.

Conclusions: When manufacturer's instructions are followed, hydrogen peroxide and carbamide peroxide based tooth whitening is safe and effective. Patients should be informed of the risks associated with tooth whitening and instructed on identification of adverse occurrences so that they may seek professional help as needed.

Keywords: Tooth whitening; bleaching; bleaching risks; carbamide peroxide; hydrogen peroxide; hypersensitivity; light activation; restoration bleaching.

Figure 1

Examples of tooth staining. Extrinsic staining examples: A. Smoking; B. Wine stain; and C. Food stain. Intrinsic staining examples: D. Age yellowing; E. Decay; F. Orthodontic white spot lesion; G. Mild fluorosis; H. Amalgam restoration; I. Tetracycline stain; J. Genetic (amelogenesis imperfecta); K. and Non-vital coloring.

Figure 2

Chemistry of chromogen bleaching. A. β-carotene is an example of an organic chromogen with many conjugated double bonds; B. Chemical reaction of hydrogen peroxide with a chromogen double bond; and C. Chemical reaction of sodium hypochlorite with a chromogen double bond.