ABSTRACT:
Background: Periodontitis is an inflammation that occurs in the periodontium and is caused by the host immune responses and subgingival plaque bacteria. Subgingival plaque bacteria can initiate periodontal disease because they have the potential to induce the release of proinflammatory cytokines. Mechanical debridement alone not always possible to completely remove pathogenic bacteria that cause periodontal infections due to accessibility and location. New treatments, such as photodynamic therapy, which uses lasers, can offer an alternative option. Photodynamic therapy is a non-invasive therapy that uses photons of light energy for medical purposes. The mechanism of photodynamic therapy is based on a triad consisting of a photosensitizer, a light source, and molecular oxygen. Microorganisms first absorb the photosensitizer, then are activated by light of a specific wavelength. Photosensitizer can transfer the received energy to molecular oxygen and convert oxygen into ROS, then cause the death of microorganisms by affecting their membranes, proteins, and nucleic acids. Doxycycline is widely used in periodontal therapy and is known to act as an exogenous photosensitizer. Objective: The aim of the research was to evaluate the potential of doxycycline as a photosensitizer in photodynamic therapy against subgingival plaque bacteria. Method: The research used the diffusion method to test the bacterial inhibition with 4 replications. This research was divided into 6 groups: (1) control, (2) photodynamic therapy, (3) 0,0125% doxycycline with photodynamic therapy, (4) 0,025% doxycycline with photodynamic therapy, (5) 0,05% doxycycline with photodynamic therapy, and (6) 0,1% doxycycline with photodynamic therapy. Subgingival plaque bacteria were collected from stock and put into a reaction tube that contained liquid BHIB. After that, the subgingival plaque bacteria culture was incubated for 48hours at 37ºC, and then the subgingival plaque bacteria culture was planted on Mueller Hinton agar with the spreading technique. Filter paper was inserted into each of the doxycycline concentrations and placed on the petridish that has been planted with subgingival plaque bacteria. Photodynamic therapy with a wavelength of 405nm for 30 seconds was exposed to the paper. Then, the agar plates were incubated for 48 hours at 37ºC. Result: The avarage inhibition zone of subgingival plaque bacteria was obtained in the following groups: (1) 0mm, (2) 13.375mm, (3) 14.6125mm, (4) 15.450mm, (5) 17.325mm, and (6) 19.2875mm. Conclusion: The doxycycline 0.1% concentration group that is combined with photodynamic therapy for 30 seconds has the biggest inhibition zone in the subgingival plaque bacteria.