The present study aims to evaluate photodynamic therapy (PDT) using Zinc oxide as a photosensitizer as an adjunct to scaling and root planing (SRP) in the management of chronic periodontitis.

Following full mouth SRP, each quadrant will be randomly assigned by simple randomization using a computer generated randomization technique into one of the following four treatment modalities.

Group 1 (control) - Application of placebo gel followed by sham PDT (Directing the Light cure device without turning on the light beam).

Group 2 -Application of Zinc oxide gel followed by sham PDT. Group 3 - Application of placebo gel followed by PDT. Group 4 - Application of Zinc oxide gel followed by PDT. The procedure mentioned for each group will be performed on all periodontal pockets in the assigned quadrant at baseline, end of 1 week and 1 month from the first session.

Clinical parameters and microbial profile will be recorded at baseline (before commencement of Periodontal treatment), end of 1 month and end of 3 months following periodontal treatment.

Zinc oxide gel/placebo gel will be placed into the periodontal pockets using a blunt cannula ensuring that starting from the bottom, it completely fills the periodontal pockets. The gel will be retained in the pocket for 5 minutes. The perio tip will be attached to the hand piece of the light cure unit (Wavelength: 420-480nm. Light power: 1200mw/cm2 in continuous mode) and light will be activated for 60 seconds. Following this, the pockets will be irrigated with normal saline solution (0.9%Sodium chloride).

Inclusion Criteria:

• Patients of both genders diagnosed with chronic periodontitis in the age group of 30 to 50 years with good systemic health.
• Presence of a minimum of 20 teeth and at least one site with probing pocket depth (PPD) of 4-7 mm and clinical attachment level (CAL) of 2 mm or greater, in each of the four quadrants.

Exclusion Criteria:

• Patients who have undergone periodontal therapy during the previous 6 months of commencement of the study.
• Subjects on antibiotics or immunosuppressant medication 6 months prior to the study.
• Chronic Smokers, Alcoholics, Smokeless tobacco users.
• Subjects with acute illnesses/acute intraoral lesions.
• Pregnant women and lactating mothers.
• Medically compromised subjects.

This is a Split Mouth Double Blind Randomized Controlled Clinical Trial in which both participants and care provider are blinded.