The Effect of Photodynamic Therapy on Plaque in Orthodontic Patients

Patients allocated to the first group (n=10) will receive photodynamic therapy. Buccal/labial surface around the bracket of each tooth in the upper dental arch (from right to left second premolar) will be treated with toluidine blue based dye (155 mg/mL; LaserHF Paro-PDT, Hager \& Werken, GmbH \& Co. Kg, Duisburg, Germany). This photosensitive solution will be applied on teeth with the sterile syringe and left for 60 s. Then, the excess of the photosensitive solution will be rinsed with the sterile syringe containing a saline solution. Then, a 660 nm diode laser (Laser HF, Hager \& Werken, GmbH \& Co. Kg, Duisburg, Germany) will be used for photoactivation (power output 100 mW, power density 124.34 W/cm2 and continuous working mode). Buccal/labial surface of each tooth will be radiated for 60 s at approximately 5 mm away from the enamel surface. This intervention will be performed right after the placement of a fixed orthodontic appliance (T0), 6 weeks (T1) and 12 weeks (T2) later.

Tricalcium phosphate varnish with 5% NaF (Clinpro™ White Varnish, 3M ESPE 3M Deutschland GmbH, Germany) will be applied to the patients allocated to the second group (n=10). The varnish will be applied to the buccal/labial surfaces of 10 teeth in the upper dental arch (from right to left second premolar) according to the manufacturer's recommendations. This intervention will be performed right after the placement of a fixed orthodontic appliance (T0), 6 weeks (T1) and 12 weeks (T2) later.

Chlorhexidine varnish (1% CHX, 1% thymol; Cervitec® Plus, Ivoclar Vivadent AG, Schaan, Liechtenstein) will be applied to the patients allocated to the third group (n=10). The varnish will be applied to the buccal/labial surfaces of 10 teeth in the upper dental arch (from right to left second premolar) according to the manufacturer's recommendations. This intervention will be performed right after the placement of a fixed orthodontic appliance (T0), 6 weeks (T1) and 12 weeks (T2) later.