 The purpose of this study is to evaluate the effectiveness of the Er:YAG laser, as an adjunct to scaling and root planing, in removing microbial bacteria. Participants with chronic periodontitis will be randomized to have one quadrant undergo scaling and root planing using hand instruments and ultrasonic scaler alone, while a second quadrant will receive the same treatment, with the addition of the Er:YAG laser. Outcomes studies will be traditional periodontal clinical parameters at 6 weeks and 3 months after treatment. Microbial cultures will be performed at baseline and 3 months to compare survival and re-population by periodontal microorganisms. 