effects of ktp laser bleaching on traumatized tooth enamel

background bleaching of traumatized discolored teeth is considered an important issue in esthetic dentistry. various methods have been introduced for bleaching, some of which may have adverse effects on soft or hard tissues of the tooth. objectives the objective of the study was to evaluate the effects of ktp laser bleaching on enamel of traumatized teeth. materials and methods a square of 36 mm2 was chosen on the labial surface of 32 extracted teeth. the corners were drilled in order to indicate the location precisely. the shade of each sample was recorded and the teeth were divided into four groups, each with eight teeth: group a (smartbleach with ktp laser for 30 seconds), group b (smartbleach with g-light for 5 minutes), group c (only smartbleach for 10 minutes) and group d (control group with no bleaching). after one session of bleaching, shade assessment was performed again. in another experiment on nine teeth, smartbleach with ktp laser was used for 150 seconds to 1500 seconds. the samples were critically processed and observed by using scanning electron microscope (sem) to assess enamel damage. data was statistically analyzed using kruskal-wallis test (confidence interval level were set at 95%). results smartbleach was highly effective when used with ktp laser (p = 0.0419). enamel damage was observed after frequent ktp bleaching and 750 seconds of ktp bleaching was recognized as the limit by morphological evaluation via sem, indicating a major difference between under and over 750 seconds of bleaching. conclusions application of ktp laser may increase the bleaching effect of smartbleach, nevertheless it may cause some enamel damage.