Combined Use of Retraction and Torque Arch with Mini-Screws: A Cephalometric Study

Abstract

Objective: Our objective was to investigate and quantify the treatment of micro-implant-aided retraction and torque (R&T) arch on dentofacial structures. Methods:Twelve patients (mean age 21.2 years) who required orthodontic camouflage treatment were included in the study. Following the canine distalization, mini-screws were placed between maxillary first molars and second premolars, and R&T arch was applied for the retraction of incisors. The vertical retraction arms of the arch were adjusted between the apex of the lateral incisor and the alveolar bone so that the retraction force passed through the center of resistance of four incisors and forced the incisors to bodily retraction. Closed coil-springs applying 150 gr of force were used to retract the incisors. The retraction period lasted for 217±34 days.Results: SNA and NV-A decreased (p<0.05), indicating alveolar bone remodeling around Point A. The reduction in the SNA caused a statistically significant decrease in the ANB (p<0.01). SN/1, NA/1, NA-1, and overjet decreased significantly (p<0.01), depending on the retrusion of the incisors. The distances from the apex and incisal point of the central incisor to the SV reference plane also decreased significantly (p<0.01), revealing a nearly parallel movement of the incisors. Anchorage loss of the molars and decrease in nasolabial angle were not significant (p>0.05). Conclusion:A combined use of R&T arch with mini-screws is an effective method to retract the incisors without anchorage loss. The type of movement is nearly parallel.