Evaluation of canine tipping during its retraction with sliding mechanics : an in vitro study

الملخص EN

Aims : the present study concerned with the evaluation of the effects of using different bracket, stypes (material and design), different arch wire types (shape and size) and different methods of retraction (elastic chain and closed coil spring) on the degree of tipping of canine during its retraction along an arch wire using typhoon simulation system (Armco).

Materials and methods : the standardization criteria were all typhoon teeth situated in well aligned position, covered and immobilized by the acrylic bite except canine, elastic chain and nickel titanium closed coil spring exerting 180 gm of force on canine measured carefully by tension gauge., the angle between bite plane extension, bar and canines extension bar was (90°) measured by protractor directly on photographs that were taken for typhoon using digital camera from both vertical and horizontal direction.

Results : the present study showed that sliding the canine on large rectangular arch wire (0.019 x 0.025 inch) gave rise to a significant de-crease in the degrees of tipping when compared with 0.018 inch and 0.018x0.022 inch arch wires were used.

Also, sliding the canine using ceramic brackets (0.022) inch gave rise to the significant decrease in the degree of tipping than when using stainless steel brackets.

Another finding of the present study showed that when using elastic chain as a method of retraction gave rise to a a significant decrease in the degree of tipping as compared with nickel–titanium closed coil spring and lastly the attachment of the method of retraction around the bracket tie wing rather than hook gave rise to the high degree of tipping.

Conclusion: It was concluded that the canine retraction with 0.019 x 0.025 inch wire on standard ceramic bracket (0.022) inch by elastic chain retraction method could be regarded as the best combination variables that produced less degrees of tipping While the opposite is true for canine retraction with 0.018 inch wire on Roth stain less steel bracket by closed coil spring.