The effect of laser-activated bleaching with 445 nm and 970 nm diode lasers on pulp chamber temperature rise: an in vitro study

The aim of this study was to determine the pulp chamber temperature changes during bleaching procedures with irradiation from 445 nm and 970 nm diode lasers at different powers. A total of 120 human maxillary central incisors were used for this study. Diode lasers at two different wavelengths were irradiated in this evaluation: 970 nm at 1.5 W of power, 970 nm at 2 W, 445 nm at 1 W and 445 nm at 1.5 W. A thermometer was inserted into the pulp chamber and the temperature increase after bleaching was recorded. The results indicated that there was not a significant difference between the groups at the same wavelengths (P > 0.05). However, there was a significant difference between groups at different wavelengths (P < 0.05). The highest recorded pulp temperature increase was for the 970 nm diode laser with 2 W of power (2.0 +/- 0.5), and the lowest pulp temperature rise was 0.1 +/- 0.2 for the 445 nm diode laser with 1 W of power. According to the results of this study it can be concluded that the temperature elevation after bleaching with the diode laser at the wavelengths 970 nm and 445 nm is in the safe range, and both wavelengths with the parameters applied in this study can be used as prudent in-office bleaching techniques.