A comparative study of frictional resistance during simulated canine retraction on typodont model

Frictional resistance is an important counterforce to orthodontic tooth movement during sliding mechanics. This study was carried out to evaluate the effect of different bracket-archwire-ligation combinations on "resistance to sliding" during simulated canine retraction on typodont model.

the frictional resistance was tested between three modern orthodontic brackets-stainless steel, ceramic, and ceramic with metal slot (0.022-inch), and seven different archwires (0.019 × 0.025-inch)-stainless steel, nickel-titanium, Teflon coated stainless steel, stainless steel with the reverse curve of spee (RCS), Teflon coated stainless steel with RCS, Teflon coated nickel-titanium and nickel-titanium with RCS ligated with stainless steel ligature wire and regular clear elastomeric modules. All tests were carried out in a dry state on an Instron universal testing machine (crosshead speed: 0.5 mm/min). 10 measurements were made from each bracket-archwire-ligature combinations.

The highest mean frictional resistance was found in ceramic brackets with nickel-titanium RCS archwire ligated with elastomeric modules while minimum frictional resistance was found in stainless steel brackets with Teflon coated stainless steel archwire ligated with stainless steel ligature. Metal slot ceramic brackets generated significantly lower frictional forces than ceramic brackets, but higher values than stainless steel brackets. Teflon coated archwires shows highly significant reduction of the frictional resistance than their corresponding uncoated archwires. Archwires with RCS had the higher frictional resistance than normal counterpart archwires.

Ceramic brackets with metal slot and Teflon coated SS archwires seem to be a good alternative to conventional stainless steel brackets and archwires in space closure with sliding mechanics in patients with esthetic demands.