Comparison of the Effects of Labial and Lingual Retraction of Canines Using Sliding Mechanics: an In-vivo Study

The purpose of this study was to compare labial and lingual forces of the rate of canine retraction and three dimensional control of the molar and canine using sliding mechanics.

Ten patients with Angle’s class I malocclusion with bimaxillary protrusion referred for first premolar extraction enrolled in this split mouth study. Forty canines were placed into four groups according to the arch and type of force: UB (upper canine–labial force), LB (lower canine–labial force), UL (upper canine–lingual force), and LL (lower canine–lingual force). The rate of retraction of the canine, molar and canine rotation, molar and canine angulation, and molar anchorage loss in the sagittal and vertical plane was assessed using study models and orthopantomographs (OPG). The paired and unpaired t tests were used for intra and inter group comparison. The significance level was 0.05.

The rate of canine retraction was significantly faster for labial forces than lingual forces using sliding mechanics (P<0.001). However, significantly greater amount of molar rotation was observed using lingual forces (P<0.001). There was no significant difference regarding canine rotation using labial forces (P<0.05). The molar anchorage loss in the sagittal plane was significantly lesser using lingual forces (P<0.001).

Canine retraction was faster when labial forces were applied using sliding mechanics whereas 3D-molar control was better when lingual forces were applied, which is advantageous for critical anchorage cases.