Introduction: Plaque induced periodontitis is the second most common oral disease worldwide after dental caries. Documents from animal experiments proved that NSAIDs can reduce the inflammation and the rate of resorption of alveolar bone thus, stabilize the periodontal condition. In the last 10 years, diode laser also has been highly recommended as a treatment modality for periodontal inflammatory diseases due to its anti-inflammatory effect, ability to accelerate the healing process and its pain reduction ability.
 Materials and Methods: 84 albino rats were divided into 4 groups. Group I is the negative control group which did not subjected to any procedure, group II is the positive control group which is subjected to ligature induced periodontitis but did not take any treatment, group III is the diode laser group which is subjected to ligature induced periodontitis and treated by diode laser irradiation after removal of the ligature and group IV is the ibuprofen group which is subjected to ligature induced periodontitis and treated by ibuprofen syrup for 4 days after removal of the ligature.
Results: inflammatory cell count was measured in all specimens stained by H&E and area fraction was measured in all specimens stained by MMP-1 immuno histochemical marker. Total amount of inflammatory cells and MMP-1 decreased by time with a significant difference between treatment groups and positive control group.
Conclusion: Diode laser irradiation showed greater and faster reduction in inflammation than ibuprofen.