Er,Cr:YSGG Laser Bleaching on Tooth Color and Sensitivity

Immediately after applying the bleaching agent, the gel on the left upper and lower hemiarches (teeth 21-25 and 31-35) was irradiated using an Er,Cr:YSGG laser (2780 nm). Specifically, an Er,Cr:YSGG solid-state laser device (Waterlase MD Turbo, BIOLASE, Irvine, CA, USA) equipped with a Z-type glass tip (MZ8) measuring 800 μm in diameter and 6 mm in length was used. This tip was attached to the laser system's gold handpiece. The laser parameters for the treatment included an average output power of 1.25 W, a pulse duration of 700 μs (S-mode), and a pulse repetition rate of 10 Hz, without water or air flow, according to a previous study. Each tooth received two 15-s irradiation intervals, one for each 20-min session (totaling 30 s), while maintaining the laser handpiece approximately 2.5 cm from the tooth surface, perpendicular to the enamel. The gel was irradiated using a scanning mode, with the handpiece moved slowly in both horizontal and vertical directions at a speed of 2 mm/s.