Archwire vibration and stick-slip behavior at the bracket-archwire interface

Introduction: It is unknown whether or not intraoral vibrations affect stick-slip behavior at orthodontic bracket-archwire interfaces. In this study, we evaluated bracket-archwire stick-slip behavior as a function of ligation method and archwire vibration. Methods: In-vivo archwire vibrations were measured to obtain frequencies and amplitudes for ex-vivo testing. A piezoresistive accelerometer ligated to the maxillary right canines of 6 subjects transduced the intraoral vibrations. All subjects gave informed consent to participate. Amplitude and frequency of the vibrations were quantified and used in a bench-top friction testing apparatus. Active and passive ligation methods were compared for 9 vibration scenarios. The amount of time to move the bracket along a stainless steel wire was recorded in 90 trials. Analysis of variance and post-hoc tests were used for statistical analyses of the data. Results: During carrot biting, orthodontic wire vibrations had a mean frequency of 98 Hz and a peak-to-peak mean amplitude of 151 mV. The bench-top stick-slip measurement trials containing medium (150 mV) and high (190 mV) amplitude vibrations had significantly less friction (ln, s), 4.81 ± 2.08 and 4.67 ± 2.00, respectively, than those subjected to low (110 mV) amplitudes, 5.80 ± 1.39 (P = 0.04). There were no significant differences between passive and active ligation methods. Conclusions: Amplitudes of archwire vibrations affect stick-slip behavior at the bracket-archwire interfaces.