Skip to main content

14-04-2013 | Oral medicine | Article

Enamel craze lines show weak link with peroxide-induced sensitivity


Free abstract

medwireNews: Tooth sensitivity is a common but short-lived side effect of bleaching with hydrogen peroxide, a study by Turkish researchers indicates.

The study also found a trend toward greater sensitivity in teeth with craze lines, which may warrant evaluation in a larger population.

Mutlu Özcan (University of Zürich, Switzerland) and co-authors investigated whether microcracks in the surface of the tooth enamel, known as craze lines, would influence sensitivity after bleaching.

The team studied 23 patients who successfully completed in-office tooth-whitening using a 15% hydrogen peroxide gel bleaching kit and light activation.

Of 460 treated teeth, 226 (49%) had enamel craze lines detected using blue light transillumination. The number of craze lines ranged from two to 16 per patient.

Based on questionnaires completed by the patients on day 1 following bleaching, 61 (13%) teeth experienced sensitivity. The number of sensitive teeth ranged from zero to seven per patient, corresponding to 0-35% of the total treated teeth.

The incidence of sensitivity was 15% in teeth with craze lines and 11% in teeth without craze lines; there was a positive but weak correlation between these two variables, note Özcan and team.

Importantly, however, tooth sensitivity became less frequent and less severe in the 5 days following bleaching and by day 6 no patient reported any tooth sensitivity whatsoever.

Writing in Odontology, the researchers note that craze lines do not extend to the dentin; nevertheless, previous in vitro studies have suggested that peroxide could penetrate enamel and dentin and enter the pulp chamber.

"Therefore enamel craze lines could increase the diffusion rate of the peroxide gel into the dentin and consequently into the pulp, causing a higher incidence of tooth sensitivity," they explain.

The results of this study found a trend toward greater sensitivity following bleaching in teeth with craze lines. The association was weak, however.

"Thus, it cannot be assured that the existence of enamel craze lines is in direct relation with tooth sensitivity, or that craze lines can increase the potential of a higher diffusion of the peroxide gel into the dentine and pulp chamber," Özcan et al conclude.

"This hypothesis has to be verified in larger populations or with in vitro studies."

medwireNews ( is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2013

By Joanna Lyford, Senior medwireNews Reporter