Comparison of Frictional Resistance to Sliding on Pre-Adjusted Edgewise Brackets using Three Different Methods of Ligation and the Effect of Fluoride Mouth Rinse on Friction - An Invitro Study.

Background: Friction has an important role in clinical orthodontics. The friction occurring between archwire and bracket during sliding can considerably reduce the rate of intended tooth movement and produce undesirable movement of the anchor teeth. Two factors determine the amount of friction during sliding mechanics are the coefficient of friction between contacting surfaces and the forces applied between those surfaces. The coefficient of friction is mainly determined by wire roughness, texture, or hardness of the surface which will get altered in complex oral environment. The force applied between bracket and arch wire is determined by the force exerted by the ligation. The present study focused to evaluate the effect of three methods of ligation and to find out the role of fluoride mouth rinse on friction . Aim: To compare the frictional resistance to sliding on pre adjusted edge wise brackets using three different methods of ligation and the effect of fluoride application on friction. Methods: 90 custom made bracket mounting templates were divided into three ligation groups - elastomeric modules, stainless steel ligatures and super slick. Each group consisted of 30 samples. Tests were conducted in three environmental conditions namely dry, wet by immersed in artificial saliva and after fluoride mouth rinse application. Testings were conducted on Precision Universal Tester using 5N of tensile force to pull the archwire through the bracket slot at a crosshead speed of 20 mm/min through a distance of 5 mm. The force required to initiate the sliding (static friction), which is represented by a peak in the beginning of digital readout was recorded. Results: Super slick ligation demonstrated significantly lower friction than other two groups (p<0.05) in all the three environmental conditions. When each ligation was tested under three conditions, friction significantly increased after fluoride application (p