Objectives: To evaluate clinically and radio graphically, the healing following nonsurgical treatment of periapical lesions when Photo Activated Disinfection(PAD), triple antibiotic paste and calcium hydroxide was used as root canal disinfectant. Material and methods: Sixty patients (20 for PAD, 20 for triple antibiotic paste, 20 for calcium hydroxide) with periapical lesions in the maxillary and mandibular anterior region were selected from the outpatient section of the Department of Conservative Dentistry & Endodontics, Govt. Dental College, Kozhikode to participate in this study. The patients were selected with a preoperative score of 4 or 5. There were no significant differences for the PAI Scores between the three groups at the start of the experiment .Intracanal disinfection was done in the three groups followed by obturation. The patients recalled at 3,6, 12,18 months interval. Results: At 18 months follow up 15 % of cases failed in calcium hydroxide group,5% in triple antibiotic paste and no failure cases were seen in PAD group. Success criteria were divided into strict and loose, while the former had statistically significant p value the latter did not. Kruskal-Wallis Test showed an increased mean value for PDT and a significant change in p value.Bonferroni post hoc test was done to compare if there is any significant change bet - ween groups. Only significant change was found between calcium hydroxide and photoactivated disinfection . Conclusion: PAD was more effective intracanal disinfectant at 6,12 and 18 months.