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

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)

An experimental study of dynamic frictional resistance between orthodontic bracket and arch wire / 대한치과교정학회지

This investigation was designed to determine the effects of wire size, bracket width and the number of bracket on bracket-wire dynamic frictional resistance during simulating arch wire-guided tooth movement in vitro. For simulation of an arch wire-guided tooth movement, we simulated tooth, periodontal ligament and cancellous bone. Maxillary premolar and 1st molar were simulated as real sized resin teeth, the simulated resin teeth which its root was coated by polyether impression material which its elastic modulus is similar to periodontal ligament were embedded in steel housing with inlay wax which its elastic modulus is similar to cancellous bone. Stainless steel wires in four wire size (0.016, 0.018, 0.016 x 0.022, 0.019 x 0.025 inch) were examined with respect to three (stainless steel) bracket widths (2.4, 3.0, 4.3mm) and the number of medium bracket(one, two, three) included in the experimental assembly under dry condition. The wires were ligated into the brackets with elastomeric module. The results were as follows : 1. In all the brackets, frictional resistance increased with increase in wire size. But, statistically similar levels of frictional resistance were observed between 0.018 inch and 0.016 x 0.022 inch wires in narrow bracket and also between 0.016 inch and 0.018 inch wire in wide backet. 2. The frictional forces produced by 0.016 inch wire were statistically similar levels in all the brackets. In 0.018 inch round wire, wide bracket was associated with lower amounts of friction than both narrow and medium brackets. In 0.016 x 0.022, 0.019 x 0.025 inch rectangular wire, wide bracket produced larger friction than both narrow and medium brackets. In all the wires, narrow and medium bracket demonstrated no statistical difference in levels of frictional resistance. 3. Frictional resistance increased with increase in number of medium bracket. 0.016 inch round wire demonstrated the greatest increment in frictional resistance, followed by 0.019 x 0.025, 0.016 x 0.022 inch rectangular wire which were similar level in increment of frictional resistance, 0.018 inch wire demonstrated the least increment. The increments of frictional resistance were not constantly direct proportion to number of bracket.