Friction and binding occur when sliding mechanics are used in the treatment of orthodontic patients. The original ceramic brackets had greater friction than metal brackets resulting in extended treatment times. Objective: To compare friction of two new ceramic brackets (GAC's Mystique-G & Unitek's Clarity-U) using a metal bracket (GAC's MicroArch-M) and a high friction ceramic bracket (Unitek's Transbond-T) as controls. Methods: 019 x .025 steel archwires were tested without ligatures. Each upper bicuspid .022 bracket was tested five times with a new wire. A testing apparatus similar to that of Mah et al (J Dent Res, 2003) and (Omana JCO, 1992) was used which applied a variable tipping torque to the bracket and wire while recording the friction, torque and angle. After measuring friction at fixed angles (0, 2.7, 4.9 and 5.9 degrees), a cyclical torque (angle 0 to 5.9 degrees) was applied and "dynamic friction" was measured. Data was analyzed with multifactorial ANOVA and Tukey-Kramer tests at p<0.05. Results: Friction increased as the tipping angle increased for all brackets (p<0.0001). Friction was not significantly different between any brackets at 0 and 2.7 degrees (averages = 12 and 66 gm). At 4.9 and 5.9 degrees, average friction of T (300 and 430 gm) was statistically higher than M (130 and 170 gm); G (250 and 300 gm) and U (210 and 290 gm) exhibited less friction than T but more than M, but these differences were not statistically significant. There were no differences between any bracket's dynamic friction. Conclusions: Methods were able to distinguish between the friction of the high and low friction controls. Differences between the G and U were small and are not likely to be clinically relevant. This research was supported by a grant from GAC International.

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