After a full-mouth scaling and root planning (SRP), the periodontal pockets of teeth selected to receive antimicrobial photodynamic therapy (aPDT) will be irrigated with distilled water. Shortly thereafter, the dye will be applied (phenothiazine hydrochloride- 10mg/mL) from the bottom of the pocket. After 1 minute, irrigation will be performed with distilled water to remove the excess of dye. The stained area will be irradiated with a diode laser (660 nm and a 60 mW/cm²). Six sites per tooth under treatment will be irradiated (10 seconds/ site). The applications of aPDT will be repeated in the same way until the second week (days: 2, 7,14). Before the application, the supragingival plaque will be removed.