Comparison of Maxillary Canine Retraction with Sliding Mechanics and a Retraction Spring: a Three-dimensional Analysis Based on a Midpalatal Orthodontic Implant

The purpose of this study was to compare maxillary canine retraction with sliding mechanics and a Ricketts canine retraction spring, using a midpalatal orthodontic implant as a measuring reference. Eight patients (three males and five females) were examined. Because maximum posterior anchorage was required in all subjects, osseointegrated midpalatal implants were used. To examine tooth movement, impressions of the maxillary arch were made at each appointment and cast in die stone. A three dimensional (3D) surface-scanning system using a slit laser beam was used to measure the series of dental casts. The results demonstrated that 3D analysis of tooth movement based on a midpalatal orthodontic implant provided detailed information on canine retraction. The results also suggested that a canine retracting force of 1 N or less was more effective not only for sliding mechanics but also for the retraction spring. However, the sliding mechanics approach was superior to the retraction spring with regard to rotational control.