Traditionally, periodontal gum surgery has been used as a method to gain access to inflamed periodontal pockets around teeth. The outcome of these surgeries, however, is not always successful as there can be recurrence of inflammation and disease. The objective of this study is to assess the effectiveness of antimicrobial photodynamic therapy as an adjunct to mechanical debridement of residual periodontal pockets in patients having undergone periodontal surgery. Pocket probing depth (PPD), clinical attachment level (CAL), bleeding on probing (BOP), and plaque index (PI) will be evaluated at all sites as measures of inflammation and disease resolution.

A single-center, randomized, double-blind, longitudinal study will take place over 12 months. Twenty-eight systemically healthy patients (i.e. absence of uncontrolled diabetes mellitus, cancer, HIV, bone metabolic diseases, or disorders that compromise wound healing) enrolled in a supportive periodontal therapy program and patients at the University of Manitoba Graduate Periodontics Clinic, with at least one surgically treated site with a residual pocket probing depth of ≥ 5mm and bleeding upon probing and having signed the informed consent will be accepted into the study. PPD, CAL, BOP, and PI will be evaluated at these sites. A selected participant will have a full mouth periodontal charting completed prior to baseline measurements as part of their maintenance program.

Once selected the patient will see two clinicians: the examiner (hygienist) and operator (resident).

The examiner records the data (PPD, CAL, BOP, PI) of the entire dentition including the selected tooth or teeth, and provides preliminary hygiene treatment; the operator delivers the test treatments.

The treatment assignments are concealed to the patient and the examiner. The operator is unaware of previously recorded data except for pocket depth measurements and is not involved in the post-treatment evaluations (3,6,12 months). At 12 months, a full mouth re-evaluation will be completed by the examiner as part of the patient's maintenance program.

In the first visit, the examiner records the pocket probing depth, clinical attachment level, presence of bleeding on probing, and plaque index at six sites on involved teeth. Thorough scaling and root planing is performed under local anesthesia using periodontal curettes (Gracey, Hu-Friedy, USA) and an ultrasonic device (Piezo, Ultradent, USA). Once complete, the operator takes over. The patients are then randomly assigned to test or control groups by a computer-generated table. The protocol may be: A, the laser is activated during treatments with methylene blue; B, the laser is never activated during treatments with saline solution.

Antimicrobial photodynamic therapy is carried out in the residual pockets using the Periowave system (Ondine Biomedical Inc, Vancouver, Canada). The photosensitizing agent is methylene blue. Approximately 0.2 mL of the solution is applied over 60 seconds to each pocket with a blunt-ended side-port irrigator. The site is illuminated for 60 seconds to activate the agent using a disposable, light-diffusing tip that is introduced into the pocket via a diode laser (wavelength = 675 nm, 160 mW of output power). The control treatment consists of the same procedure, except that the photosensitizer is replaced with saline solution and the light-diffusing tip is kept in the pocket for 60 seconds without activating the laser. The patient is sent home with a home care package and oral hygiene instructions.

The second session is scheduled after 1 week. The operator applies the photosensitizer and activates the laser according to protocol A or B. The examiner maintains the patients on a 3-month hygiene schedule and reassesses the participants 3, 6, and 12 months after the treatment as well as reinforces oral hygiene instruction. Medical history, concomitant medication, and all adverse events are recorded. Clinical parameters are measured the same way as at baseline. All measurements will be calibrated.

Inclusion Criteria:

• Systemically healthy
• Enrolled in a supportive periodontal therapy program and a patient at the University of Manitoba Graduate Periodontics Clinic
• At least one surgically treated periodontal site with a residual pocket probing depth of ≥ 5mm and bleeding upon probing
• Completed informed consent

Exclusion Criteria:

• Patients with uncontrolled diabetes mellitus
• Patients with cancer
• Patients with HIV
• Patients with bone metabolic diseases
• Patients with disorders that compromise wound healing
• Patients undergoing radiation or immunosuppressive therapy
• Pregnancy or lactation
• Have had antibiotics therapy within the last three months
• Confirmed or suspected intolerance to methylene blue
• Any physical limitations or restrictions that might preclude normal oral hygiene procedures

All IPD will be made available in an anonymized (de-identified) form.

After conclusion of the study up until 5 years after completion of the study.

Once selected the patient will see two clinicians: the examiner (hygienist) and operator (resident).

The examiner records the data (PPD, CAL, BOP, PI) of the teeth, and provides preliminary hygiene treatment; the operator delivers the test treatments.

The treatment assignments are concealed to the patient and the examiner. The operator is unaware of previously recorded data except for pocket depth measurements and is not involved in the post-treatment evaluations (3,6,12 months)