Evaluation of Micro-organism in Ligated Metal and Self-ligating Brackets using Scanning Electron Microscopy: An In Vivo Study

BACKGROUND: The objective of the study was to determine the sites of plaque accumulation and to compare the plaque accumulated with metal and self-ligating orthodontic brackets in order to know which bracket type had a higher plaque retaining capacity. MATERIALS AND METHODS: The study was done on 20 subjects who were scheduled for orthodontic treatment including extraction of four premolars and fixed orthodontic appliances. Mesh-backed edgewise metal brackets ligated with steel ligatures and self-ligating brackets were bonded to the premolars to be extracted using composite (Transbond XT, 3M). The subjects were told to continue their normal oral hygiene regimen. Teeth were extracted at 1, 2, and 3 weeks after bracket bonding. Plaque attached to the buccal surfaces was stained using plaque disclosing agent. The teeth were then immersed in fixative containing 4% formaldehyde and 1% glutaraldehyde in phosphate buffer for 24 h, followed by 0.1 M phosphate buffer for 12 h. The specimens were then mounted on aluminum stubs, and sputter coated with gold prior to Scanning electron microscopy examination. RESULTS: The results showed that increased retention of plaque in metal brackets ligated with steel ligatures and comparatively less in self-ligating brackets at the base of the brackets. CONCLUSIONS: This study highlights that higher retention of plaque in metal brackets ligated with steel ligatures and comparatively less plaque retention in self-ligating brackets. Excess composite around the bracket base is the critical site of plaque accumulation associated with fixed appliances due to its rough surface texture.