Comparison of maxillary canine retraction patterns with the T-loop spring and the Ricketts maxillary canine retractor: A cone-beam computed tomography study

Introduction

This study aimed to detect the pattern of canine retraction movement using the T-loop spring (TLS) compared with the Ricketts maxillary canine retractor (RMCR).

Methods

A total of 31 patients treated with bilateral maxillary first premolar extraction, having their canines retracted by either the TLS or the RMCR, were included in this study. Each patient had two cone-beam computed tomography scans: before and after achieving a Class I canine relationship on each side. The outcome measures were the intragroup and intergroup differences in the crown and apex movement amount obtained using paired and independent t tests. In addition, the difference in the distribution of the controlled and uncontrolled retraction pattern resulting from each device was detected using the chi-square test.

Results

No significant differences were found between the two groups regarding the crown movement amount (P = 0.206). The apex showed insignificant distal movement in the TLS (P = 0.366) and a significant mesial movement in the RMCR (P = 0.019); the differences between them were significant (P = 0.022). The controlled and uncontrolled tipping distribution percentages were 67.9% and 32.1% for the TLS, respectively, whereas they were 50% and 50% for the RMCR, respectively, with a nonsignificant difference between the values.

Conclusions

The two different springs result in similar amounts of distal crown movement. The canine apex almost does not move when the TLS is used; however, it moves mesially when the RMCR is used. Both controlled and uncontrolled tipping patterns can occur during retraction with both springs, and their distribution is similar for both devices.