A Comparative Study Of Frictional Resistances Between Different Design Self-ligating Brackets

Objective:1.To compare the level of friction resistance(FR)of different design self-ligating brackets using various bracket-wire combination in dry state during orthodontic phase of leveling and aligning.2.To compare the level of friction resistance(FR)of different design self-ligating brackets coupled with stainless steel archwire in dry state during the orthodontic phase of space closure.Materials and methods:1.The testing maxillary model was classⅠmalocclusion with mild crowding,different design self-ligating brackets and conventional brackets was bonded. Passive self-ligating bracket (Damon), active self-ligating bracket (Tomy) and conventional brackets ligating by elastometric modules and stainless steel ligature wires were coupled with three types of archwires (0.012-inch\0.014-inch \0.016-inch round nickel-titanium archwire) respectively.The static and kinetic friction resistance of each bracket- archwire couple was examined in the dry state during leveling and alignment phase.2.The testing model was severe crowding malocclusion treated by extraction, self-ligating brackets (Damon,Tomy) and conventional brackets ligating by elastometric modules and stainless steel ligature wires were coupled with 0.019×0.025 inch stainless steel archwire.The static and kinetic friction resistanc of each bracket-archwire couple was examined in the dry state during space closure phase.Result:1.During leveling and aligning phase,if the material and the size of the archwire is same ,the maximum static and kinetic friction resistanc of Damon group is the lowest , the maximum static and kinetic friction resistanc of Tomy group is significant higher than Damon group, the maximum static and kinetic friction resistanc of stainless steel ligature is higher than Tomy group , the maximum static and kinetic friction resistanc of elastometric modules group is the highest.2.During leveling and aligning phases, the maximum static and kinetic friction resistanc of same bracket system increase with the size of arch wire increase .3.During the space closure phase,the maximum static and kinetic friction resistanc of Damon group is the lowest,Tomy group is significant higher than Damon group,stainless steel ligature group is higher than Tomy group and the maximum static and kinetic friction resistanc of elastometric ligature group is highest.Conclusion:During any orthodontic phase,the friction resistanc of self-ligating brackets significant lower than conventional bracket, the friction resistanc of passive self-ligating bracket is significant lower than active self-ligating bracket.