213ASSESSMENT OF THE ANTIBACTERIAL ACTIVITY OF NANO SILVER COATED , UNCOATED AND TEFLON/TOOTH-COLOURED ORTHODONTIC NITI ARCHWIRES AGAINST S.MUTANS, E.COLI, STAPH. AUREUS, BACILLUS SUBTILIS & CANDIDA SPECIES AND CYTOTOXICITY ASSAY OF UNCOATED AND COATED WIRESOrthodontic archwires are used as a medium to apply the optimum forces through the brackets onto the teeth. These archwires release the energy stored in them upon placement on the teeth by applying forces, moments and torque via orthodontic brackets. Patients have difficulty in maintaining adequate oral hygiene and the appliance provides additional sites for microorganisms to bind and colonize. The resultant increase in oral microbial count places the patient at higher risk for enamel demineralization and periodontal disease. Various studies have demonstrated the effect of silver, zinc oxide, titanium oxide nanoparticles on multiple organisms. Among the various metals, silver is known for its antimicrobial activity against gram positive and negative bacteria, fungi, protozoa and certain viruses including antibiotic resistant strains. This study will evaluate the efficiency of silver nanoparticle coated orthodontic Niti archwires for their antibacterial property against Steptococcus mutans, E.coli, Staph aureus, Bacillus subtilis& Candida species.mds.narayanan@gmail.comResearch922019Orthodontic archwires,Periodontal disease,Antimicrobial activityS.Narayanan,C.Sabarigirinathan,Saurab Goel,K.Saidath,A.Siddharthan,Balashanmugam,D.DeepihaPhD student, PAHER, Rajasthan, India.,Professor and HOD, Dept of Prosthodontics, Tamilnadu Govt Dental College & Hospital, Chennai, India.,Professor, Pacific Dental College, Pacific University, Rajasthan, India.,Professor, Dept of Orthodontics and Dentofacial Orthopedics, A B Shetty Memorial Institute of Dental Science, India.,Professor, MIT, Chennai, India.,CLRI, Chennai , India,Dept of Prosthodontics, Tamilnadu Govt Dental College & Hospital, Chennai, India.