Genotoxicity and cytotoxicity of lingual bonded retainers coated with silver and titanium dioxide nanoparticles – A randomized controlled trial

Objectives The popularity of fixed retainers is also challenged by the heightened chance of plaque and calculus accumulation which can lead to carious lesions, gingival inflammation, and periodontal disease. Nanotechnology has been used to coat the surface of orthodontic appliances to control the biofilm with promising results although the information on toxicity is limited. This study aimed to evaluate the genotoxicity and cytotoxicity of lingual bonded retainers coated with silver (Ag) and titanium dioxide nanoparticles and compare them with conventional uncoated fixed retainers. Material and Methods 60 subjects of which 45 patients requiring retainers were randomly allocated to three experimental groups of 15 each (retainers coated with Ag, TiO 2 nanoparticles, and uncoated retainers, respectively). A fourth group of 15 patients not orthodontically treated was taken as baseline control. Oral mucosal scrapings from the tongue were taken at three time intervals: At debonding (T 0 ), at 3 months (T 1 ), and at 6 months (T 2 ). The smears were stained with Papanicolaou stain and studied under a light microscope for micronuclei (MN). Results All three experimental groups showed an increase in MN counts over a period of 6 months. Group I showed the highest count at T 1 and this was significantly greater than Group 3. Group 2 showed the highest count at T 2 but this was not significantly different from the other groups. Conclusion Lingual bonded retainers coated with Ag and TiO 2 nanoparticles are biocompatible and can be used clinically.