Frictional forces in stainless steel and plastic brackets using four types of wire ligation

Abstract

Objective: This in vitro study evaluated and compared the frictional resistance of stainless steel and polycarbonate (PC) composite brackets tied with metal wire and elastomeric ligation. Methods: Four stainless steel and four polycarbonate composite brackets for premolars were placed in a universal testing machine for the traction of a piece of 0.019 × 0.025-in wire at 0.5 mm/min and total displacement of 8 mm. Ligations were performed according to the following alternatives: metal ligation with Steiner tying pliers; metal ligation using Mathieu tying pliers; Morelli™ elastomeric ligation; and TP Orthodontics™ elastomeric ligation. Results and Conclusions: Elastomeric modules generated more friction than the metal ligations, and the ligation with the Mathieu tying pliers caused less friction than all the other conditions under study. PC brackets generated less friction than metal brackets, but the choice of material to be used in clinical conditions should take into consideration other variables, such as resistance to shearing and to fractures, as well as color stability and microorganism adherence.