A Study Of The Frictional Force Of Bracket-wire-ligature Structure

Objective To study the effect of brackets, wires and ligatures on the frictional force of bracket-wire-ligature, and to investigate the most significant factor that affected it by the friction experiment.Materials and Methods Five different kinds of stainless steel brackets (four indigenous and one imported ) were used in combination with stainless steel archwires of four different sizes (0.45mm and 0.50mm round, 0.017x0.025" and 0.019x0.025" rectangle). Wire movement along the bracket was implemented by means of the HT-9102 universal testing instruments. Frictional force was measured at four ligature force(50g. 150g. 300g. 500g) of 0.25mm stainless ligature and elastomeric ligature.Results The greater the maximal static friction was, the greater the dynamic friction was. At the ligature force of 150g, there was significant difference among the indigenous brackets; The frictional forceof indigenous brackets combined with indigenous round wires was greater than that of the indigenous ones combined with the rectangle wires imported; on the contrary, the frictional force of imported brackets combined with indigenous round wires was less than that of the imported ones combined with the 0.019x0.025" wires of imported. The frictional force of bracket-wire-ligature increased linearly with the augment of ligature force, and the frictional force of elastomeric ligature was more than that of the stainless one of 500g ligature force.Conclusion The greater the maximal static friction was, the greater the dynamic friction was. At special ligature force(such as 150g) and with the same material, the velvet difference had important effect on the frictional force. Frictional force increased linearly with the argument of ligature force, and the frictional force of elastomeric ligature was more than that of the stainless one at 500g ligature force. Ligature was the most significant factor that affected the frictional force.