A comparison of different ligation methods on friction.

INTRODUCTION: An elastomeric module with a polymeric coating has been developed to reduce the friction of sliding mechanics. This in-vitro study examined the stability of the coating and compared the frictional properties of coated modules with those of other common ligation methods. METHODS: Six ligation methods (regular uncoated, slick [coated], conventional silver, easy-to-tie, silicone-impregnated, and standard silver modules) were used with standard stainless steel brackets and 0.019 x 0.025-in archwires, and resistance to movement was measured. Two self-ligating (Speed [Strite Industries, Cambridge, Ontario, Canada] and Damon 2 [Sybron Dental Specialities Ormco, Orange, Calif]) brackets were also tested. RESULTS: The Damon 2 self-ligating brackets produced less friction than the other ligation methods, followed by the coated modules. There was no significant difference between the frictional resistance of brackets ligated with regular uncoated, silicone-impregnated, and easy-to-tie modules. Speed self-ligating brackets produced less friction than regular uncoated, conventional silver, and standard silver modules. The frictional properties of coated modules were not significantly affected by repeating the test 5 times or by storage in saliva for a week. CONCLUSIONS: Damon 2 brackets produced no recordable friction of ligation. Coated modules produced 50% less friction than all other ligation methods except Damon 2. The coating was resistant to the simulated effects of the oral environment. Different methods of human saliva application were found to affect the frictional properties of the coating.

The effect of ligation method on friction in sliding mechanics.

During orthodontic tooth movement with the preadjusted edgewise system, friction generated at the bracket/archwire interface tends to impede the desired movement. The method of ligation is an important contributor to this frictional force. This in vitro study investigated the effect of ligation method on friction and evaluated the efficacy of the new slick elastomeric modules from TP Orthodontics (La Porte, Ind), which are claimed to reduce friction at the module/wire interface. Slick modules were compared with regular nonslick modules, stainless steel ligatures, and the SPEED self-ligating bracket system (Strite Industries, Cambridge, Ontario, Canada). The effect of using slick modules with metal-reinforced ceramic (Clarity, 3M Unitek, Monrovia, Calif) and miniature brackets (Minitwin, 3M Unitek) was also examined. Results showed that, when considering tooth movement along a 0.019 x 0.025-in stainless steel archwire, saliva-lubricated slick modules can reduce static friction at the module/archwire interface by up to 60%, regardless of the bracket system. The SPEED brackets produced the lowest friction compared with the 3 other tested bracket systems when regular modules were used. The use of slick modules, however, with all of the ligated bracket types tested significantly reduced friction to below the values recorded in the SPEED groups. Loosely tied stainless steel ligatures were found to generate the least friction.