Mini-screw implant or transpalatal arch-mediated anchorage reinforcement during canine retraction: a randomized clinical trial.

OBJECTIVE: To compare mesial movement of upper first molars during maxillary canine retraction using a pre-adjusted edgewise appliance provided by anchorage reinforcement and a transpalatal arch or mini-screw implant.

DESIGN: Randomized clinical trial.

SETTING: Department of Orthodontics and Dentofacial Orthopedics, Armed Forces Medical College, Pune, India.

SUBJECTS AND METHODS: From a cohort of subjects requiring the extraction of both upper first premolars and pre-adjusted edgewise appliances to correct their malocclusion, a total of 30 were randomly allocated to receive two different forms of anchorage reinforcement: group A--receiving mini-screw implant and group B--receiving a transpalatal arch Group A subjects received titanium mini-screw implants placed at the start of treatment between the maxillary second premolar and maxillary first molar. Maxillary second premolars were secured to the mini-screw implants using of 0.010-inch stainless steel ligature wire. Group B subjects received a custom-made transpalatal arch which was soldered to maxillary first molar bands. Active canine retraction was initiated in both groups on placement of a 0.019×0.025-inch stainless steel archwire using nickel titanium closed coil springs.

OUTCOME MEASURES: Mesial movement of the upper first molars as measured on pre- (T1) and post-treatment (T2) lateral skull radiographs.

RESULTS: The results showed that in group A the mean mesial movement of the first molars between T1 and T2 was 0.0 mm (SD 0.02; P = 0.90), whereas in Group B there was a mean forward movement of the first maolars of 2.48 mm (SD 0.71; P<0.001).

CONCLUSION: In this trial, mini-screw implants placed prior to levelling and aligning were able to provide absolute anchorage during maxillary canine retraction, in contrast to a transpalatal arch.