Quantitative analysis of KTP laser photodynamic bleaching of tetracycline-discolored teeth

Photodynamic bleaching is a recently developed method that may be suitable for photo-oxidation of difficult internal stains. This study examined the outcomes of photodynamic bleaching for treatment of confirmed cases of tetracycline discoloration, when used as a single-appointment procedure.

Digital analysis of standardized pre- and post-treatment digital photographs of a total of 90 maxillary incisors from 23 adult patients undergoing photodynamic bleaching was undertaken. The patients were treated by a visible green KTP laser (wavelength 532 nm) combined with a rhodamine-B photosensitizer gel (Smartbleach) applied to the teeth and activated for 30 sec. Each tooth underwent four cycles of 30 sec of laser exposure. Digital image analysis was undertaken in a blinded manner, and we examined changes in the four maxillary incisors in terms of blue pixel intensity (yellowness).

Least squares linear regression analysis and a one-tailed paired t-test using the matched pairs of pre- and post-treatment data for mean blue pixel intensity showed that a significant lightening effect was achieved by the bleaching treatment. Significant increases in blue pixel intensity (reductions in yellowness) occurred in 78% of the teeth treated.

In-office KTP laser photodynamic bleaching provides a clinically useful improvement in tooth shade in teeth with tetracycline discoloration.