IADR Abstract Archives
Effects of Mastication on Static Friction in an Orthodontic Appliance
The study objectives were to: 1. quantify forces applied by orthodontic ligation of different types, and 2. test the hypothesis that mastication vibration reduces friction in vivo in an orthodontic appliance. Five experienced and five novice clinicians ligated sections of (0.019 x 0.025²) stainless steel (ss) arch wire to (0.022 x 0.028²) ss brackets, using (0.010²) ss ligature wire. Participants ligated 15 samples tightly and 15 samples loosely. A single operator ligated 15 samples with elastic ligatures. A universal tester was used to obtain ligation force values (Fligation) for all samples. Mean Fligation values for tight, loose and elastic ligation were reproduced in in vivo friction measuring devices to evaluate the effects of chewing on the apparent static coefficient of friction (µs). Ten subjects chewed gum unilaterally for 1 minute at 60 Hz on one side and then the other. This was repeated one week later. The measuring devices were tested ex vivo and in vivo to compare µs values. Mean Fligation values for tight ss ligation were 1470 ± 915 g, for loose ss ligation were 618 ± 578 g and for elastic ligation were 1600 ± 177 g. A significant difference (p £ 0.01) was found between tight and loose ss ligation samples for all clinicians pooled. Average Fligation values of 1445 g and 441 g were reproduced for tight and loose ligation, respectively, in the in vivo devices. The results showed no significant difference (p > 0.01) between ex vivo and in vivo µs values for tight and loose ss ligation. However, for elastic ligation in vivo µs values were significantly greater (p £ 0.01) than ex vivo µs values. The clinical data did not support the hypothesis that mastication vibration reduces friction. This study was supported by the AAOF.