- Low-risk inclusion: < 3 mm of attachment loss, no pockets > 4 mm, possess no radiographic bone loss, and < 20 sites with bleeding on probing (BOP). Low-risk cohort will be comprised of at least > 50% of the subjects above age 35 in order to exam low risk patients in other age strata (so as to decrease potential bias towards a younger population in the low risk cohort).