Norwegian scientists have demonstrated that light sources often used as part of the tooth bleaching process do not contribute to the effectiveness of the process and may pose possible health risks.
Tooth bleaching is becoming a popular way to remove stains on the teeth caused by smoking, red wine, tea and coffee, in an attempt to achieve a Hollywood smile. The process used by dentists to bleach teeth involves applying an oxidising agent to the teeth and in some cases a light source is then shone onto the teeth.
Ellen Bruzell from the Nordic Institute of Dental Materials, Haslum, and colleagues, measured the effectiveness of teeth bleaching using seven different commercially available products, with and without using light sources. The claim that light-assisted tooth bleaching is more efficient than ordinary bleaching has not been substantiated in the literature, explains Bruzell. She says that they found a ‘lack of additional whitening effect when light is used compared to bleaching without light’.
The team also demonstrated that for the majority of the light sources tested, the amount of radiation a person is exposed to during the bleaching process poses a risk of damage to the skin and eyes if proper protection is not used. Thomas Attin, an expert in preventative and restorative dentistry from the University of Zurich, Switzerland, comments that this study is very interesting and says that ‘the aspect that the light sources used for bleaching may cause some risks (not only to the teeth) is new.’
Bruzell also found an increase in exposed perichymata (grooves on the surface of the tooth enamel) on the bleached teeth compared to unbleached control teeth, showing that the tooth bleaching process removes part of the pellicle that covers the enamel’s surface, making the teeth more vulnerable to mechanical stress.
Bruzell says she is now carrying out a study on the effectiveness of first time tooth bleaching. Future work may also include investigating the effects of optical radiation on oral tissue and looking into the adverse effects of repetitive tooth bleaching, she adds.