Does bond integrity of bleached enamel increases with phototherapy? A systematic review

The aim of the current systematic review was to evaluate the efficacy of phototherapy (PT) on bond strength of bleached enamel.

Electronic databases including MEDLINE (PubMed), ISI Web of Science, Scopus, ScIELO, LILACS and EMBASE until January 2019. The addressed focused question was: "Does PT increase the bond integrity of bleached enamel?" Only in-vitro studies evaluating the effect of PT compared with bleaching agent or no phototherapy were included. The outcome measures of interest was shear bond strength.

A total of 5 in-vitro studies were included. Different concentrations of hydrogen peroxide were used in the included studies. The frequency of laser used in the included studies ranged from 20 Hz to 60 Hz. Pulse duration was reported in only 3 studies that ranged from 100 μs to 320 μs. The overall main outcomes of the included studies showed that in 4 studies, application of phototherapy resulted in significantly higher bond integrity of bleached enamel as compared to enamel which underwent acid etching with bleaching alone, while 1 study showed comparable shear bond strength of bleached enamel achieved by PT as compared to bleaching alone.

The evidence from the current systematic review suggests that phototherapy increases the bond strength of bleached enamel. Further in-vitro studies should be performed in order to obtain stronger conclusions.