Friction between archwires of different sizes, cross-section and alloy and brackets ligated with low-friction or conventional ligatures.

OBJECTIVE

To test the null hypothesis that no statistically significant difference in frictional resistance is noted when round or rectangular archwires are used in conjunction with low-friction ligatures (small, medium, or large) or conventional ligatures.

MATERIALS AND METHODS

A total of 10 stainless steel brackets, a 0.022-in slot, and various orthodontic archwires, ligated with low-friction ligatures or conventional ligatures, were tested to compare frictional resistance. The archwires employed were 0.014-in and 0.016-in nickel titanium (NiTi), 0.018-in stainless steel (SS), 0.016 x 0.022-in NiTi, 0.016 x 0.022-in SS, 0.017 x 0.025-in titanium molybdenum alloy (TMA), 0.017 x 0.025-in NiTi, 0.017 x 0.025-in SS, 0.019 x 0.025-in SS, and 0.019 x 0.025-in NiTi. Each bracket/archwire combination was tested 10 times in the dry state at an ambient temperature of 34 degrees C.

RESULTS

Low-friction ligatures with round archwires showed statistically significantly lower frictional resistance than did conventional ligatures. When coupled with 0.016 x 0.022-in NiTi and SS, no statistically significant difference was observed among the four groups. When coupled with 0.017 x 0.025-in archwires, low-friction ligatures showed statistically significantly greater frictional resistance than was seen with conventional ligatures. When coupled with 0.019 x 0.025-in NiTi, low-friction ligatures showed statistically significantly greater frictional resistance than did conventional ligatures, but no difference among the four groups was observed with the 0.019 x 0.025-in SS. No significant difference was assessed among low-friction ligatures of different sizes.

CONCLUSION

Low-friction ligatures show lower friction when compared with conventional ligatures when coupled with round archwires, but not when coupled with rectangular ones.