The investigators wish to assess whether intensive periodontal therapy will reduce the burden of chronic periodontal disease and will cause regression or prevent progression of atherosclerosis assessed by a surrogate end-point (carotid intima-media thickness) at 24 months compared to control periodontal therapy.

Inclusion Criteria:

1. Participants must be ≥ 18 years-old.
2. Participants must have moderate to severe periodontitis (at least 30 periodontal pockets > 4mm with Bleeding on Probing) and radiographic signs of bone loss.
3. Participants must have voluntarily signed the informed consent.

Exclusion Criteria:

1. Female participant is pregnant or lactating or of childbearing and not using acceptable methods of birth control.
2. Participant is on chronic treatment (i.e., two weeks or more) with specific medications known to affect periodontal status (phenytoin or cyclosporine) within one month of baseline visit.
3. Participant knowingly has HIV or Hepatitis.
4. Participant has limited mental capacity or language skills such that simple instructions cannot be followed or information regarding adverse events cannot be provided.
5. Participant on chronic antibiotic therapy or who require antibiotic coverage for periodontal procedures.
6. Participant had a course of periodontal therapy in the preceding 6 month