Effects of Immediate and Delayed Canine Retraction after Premolar Extraction

Aim of Study: To evaluate the rate and change in angulation of canine distal movement and compare between immediate and delayed canine retraction groups. Materials and Method: A total of 40 canines which had been retracted with 50 g of force in the premolar extraction site were included in this study. The date of maxillary first premolar extraction and canine retraction of each patient were recorded and used to categorised the data into 5 groups; immediate retraction and delayed retraction of 1 week, 2 weeks, 3 weeks, and 4 weeks after premolar extraction. The 3-D digital models and lateral cephalograms were recorded before canine retraction (T0) and after completed canine retraction (T1). The amount of canine distal movement was measured from the 3-D digital models (T1-T0), and the rate of tooth movement each month was calculated. The change in canine angulation was measured from lateral cephalograms. The movement rates and change in angulation of each group were compare using one-way ANOVA and multiple comparisons. Results: The mean rate of canine movement was 0.98 + 0.28 mm/month. The mean change in angulation was 6.01 + 4.01 degree. The movement rate and amount of change in angulation of the canines that were immediately retracted and those with delayed retraction of 1 to 4 weeks were not significantly different (P > 0.05). Conclusion: Immediate canine retraction and delayed retraction of 1 to 4 weeks after premolar extraction was not significantly different in the rate and type of tooth movement. Keywords: Canine retraction