The effect of bracket width on frictional force between bracket and arch wire during sliding tooth movement

Choi, Won Cheul; Kim, Tae Woo; Park, Joo Young; Kwak, Jae Hyuk; Na, Hyo Jeong; Park, Du Nam

Abstract

Frictional force between the orthodontic bracket and arch wire during sliding tooth movement is related to many factors, such as the size, shape and material of both the bracket and wire, ligation method and the angle formed between the bracket and wire. There have been clear conclusions drawn in regard to most of these factors, but as to the effect of bracket width on frictional force there are only conflicting studies. This study was designed to investigate the effect of bracket width on the amount of frictional forces generated during clinically simulated tooth movement. Three different widths of brackets (0.018x0.025"standard), narrow (2.40mm), medium (3.00mm) and wide (4.25mm) were used in tandem with 0.016x0.022" stainless steel wire. Three bracket-arch wire combinations were drawn on for 4 minutes on a testing apparatus with a head speed of 0.5mm/min and tested 7 times each. To reproduce biological conditions, dentoalveolar models were designed with indirect technique using a material with similar elastic properties as periodontal ligament (PDL). In addition, to minimize the effect of ligation force, elastomer was used with added resin, which was attached to the bracket to make up for the discrepancies of bracket width. The results were as follows: 1. Maximum frictional force for each bracket-arch wire combination was: Narrow (2.40mm) : 68.09+/-4.69 gmf Medium (3.00mm) : 72.75+/-4.98 gmf Wide (4.25mm) : 72.59+/-4.54 gmf 2. Frictional force was increased with more displacement of wire through the bracket slot. 3. The ANOVA post-hoc test showed that the bracket width had no significant effect on frictional force when tested under clinically simulated conditions (P>0.05)