Part A of the study will evaluate up to 6 study arms, depending on the microbiology response evaluated. Before dosing of C16G2, eligible subjects will undergo professional dental prophylaxis on Day 0. Clinic visits for all Study Arms include Visit 1 (Screening/Days -21 to 0), Treatment Visits 2 through 6 (Baseline/Day 0 through Day 4), and follow-up Visits 7 through 11 (Day 5, 8, 12, 19 ± 1 and 33 ± 2).