Evaluation of the risk associated with the use of blue light polymerizing sources

Abstract

Recently, concern has been expressed that the blue light sources used to initiate polymerization of dental material may cause retinal damage. Maximum permissible daily exposure times for four blue light-curing units were calculated using the criteria of the American Conference of Governmental and Industrial Hygienists. For direct viewing of the light sources, maximum permissible exposure varies between 12 and 30 min for the light sources tested. In practice, it is more likely that the operator will be exposed to light reflected from the patient's mouth. This allows a relaxation in maximum permissible exposure to between 40 and 100 min daily. Several manufacturers have now produced safety shields and glasses to protect dental personnel from eye hazards. Three such products were evaluated and results showed that they do eliminate potentially harmful blue light. It is concluded that, given current usage, the risk to most users of blue light polymerizing sources is minimal. However, surgery personnel with cumulative daily exposure times of the order of 1 h should consider the use of appropriate protective eyewear.