Comparison Study Of Friction Force Among Lock-loose Bracket, Six Wings Bracket And Conventional Bracket

Objective:With the main wings or all the six wings ligated, the frictions ofLock-loose brackets and conventional six wings brackets were measuredwhen they were sliding along archwires in dry and artificial salivaenvironment, compared with traditional brackets and self-ligatingbrackets.Methods:Lock-loose brackets, conventional six wings brackets,traditionalbrackets and self-ligating brackets were used to compose with0.016" and0.018" stainless steel round archwires and0.018×0.025" and0.019×0.025" stainless steel rectangular archwires. Two different ligatingmethods were applied on Lock-loose brackets and conventional six wingsbrackets, i.e. main wings ligated and all the six wings ligated. Frictionswere tested by electronic universal testing machine and the surface statesof the stainless steel rectangular archwires were observed with Atomicforce microscopy (AFM) before and after mechanical traction. Results:When the main wings of Lock-loose brackets and six wings bracketswere ligated, the frictions of the four different stainless steel archwireswere close to zero, and the difference with traditional brackets wassignificant (P<0.05);When the all six wings of Lock-loose brackets wereligated, the frictions of four different stainless steel archwires were higherthan those of the conventional six wings brackets(P<0.05); When0.018×0.025" rectangular archwires were used, frictions of Lock-loosebrackets with all the six wings ligated were maximum (P<0.05). Frictionsin dry state were higher than that in wet state (P<0.05). Conclusion TheLock-loose bracket can adjust the friction efficiently with differentligating methods, which solve the contradiction between low friction andstrengthening anchorage.Conclusions:1. Lock-loose bracket can adjust the friction efficiently withdifferent ligating methods, which solve the contradiction between lowfriction and strengthening anchorage.2.Lock-loose bracket have improved the friction performancesuccessfully by forming a ridge based on the bottom of bracket slot.3. Frictions in dry state were higher than that in wet state (P<0.05),so theartificial saliva played a role in lubrication.