Objectives To compare canine retraction using NiTi closed coil springs vs elastomeric chains comprehensively in a split-mouth randomized controlled trial. Materials and Methods The canines in 64 quadrants were randomly retracted into the first premolar extraction spaces using NiTi closed coil springs or elastomeric chains, in the maxilla and mandible. The retraction force was 150 g. Cone beam computed tomography scans and study models were obtained before the start of canine retraction and 6 months later. The rate and total amount of canine retraction, canine rotation, tipping, and root resorption were evaluated. A visual analogue scale was used to evaluate patients' pain experience. Results The two methods were statistically similar for dental changes, rate of canine retraction, and root resorption. However, patients reported significantly more days of pain with the elastomeric chain compared to the NiTi closed coil springs. Conclusions Within the constraints of the current study, using either NiTi closed coil springs or elastomeric chains as force delivery systems for canine retraction results in no significant difference in the rate of canine retraction, tipping, rotation, or root resorption. Pain experience during retraction using elastomeric chains is more significant yet needs further investigation.

Background: In extraction cases, canine torque is of primary importance. Failure to maintain the root within the cancellous bone predisposes to root resorption and periodontal breakdown. Positive torque in the bracket or wire may prevent the proximity of the root and cortical bone as well as the subsequent side effects. Objective:The aim of this study was to evaluate the torque control provided by 0.022" Roth prescription brackets during canine retraction with sliding mechanics. Materials and methods:Twenty-one patients (19.2 ± 2.7 years) with various malocclusions involving canine retraction were included in the trial. Cone beam computer tomography was acquired before and six months after the start of canine retraction. The change in canine torque was calculated from the pre-and post-retraction 3-dimensional images. Torque was measured for maxillary and mandibular canines as the angle between the canine's long axis and the mid-sagittal plane. The paired t-test was used to evaluate the change in torque.Results: Statistically significant increase in the angle occurred for the maxillary (3.088±5.627°) and mandibular (2.971±5.427°) canines. Conclusion:Canines could express labial crown inclination during retraction despite the absence of a positive built-in bracket torque.

No abstract