Mini-implant anchorage for maxillary canine retraction: A pilot study

Abstract

This clinical pilot study evaluated the stability, surrounding soft-tissue health, and patient comfort and acceptance of a mini-implant used as anchorage for maxillary permanent canine retraction. The study was conducted in the Graduate Orthodontic Clinic of the University of Oklahoma College of Dentistry. The sample comprised 16 subjects who had maxillary first premolars extracted. In each patient, Ortho Implants (IMTEC, Ardmore, Okla) were placed laterally in the maxillary alveolar ridge between the roots of the permanent first molars and the second premolars by an oral surgeon. All retraction was accomplished on 0.017 x 0.025-in stainless steel archwires in 0.022-in slots by using nickel-titanium springs stretched from the implant head to the brackets on the canines. Placement protocol strongly affected the stability of the implants; 1 protocol resulted in the loss of 51% of the implants (19 of 39), and the second protocol resulted in 100% stability (10 of 10). The surrounding soft tissue remained healthy around stable implants and less healthy around implants that were unstable or lost. Patient comfort was excellent in all but 1 patient. Rates of canine retraction were calculated monthly and varied widely from +6.1 to -1.5 mm per month. Excessive crown tipping into the extraction spaces was observed in 4 of the 28 retracted canines and was related to the method of ligation of the canine to the archwire. Ortho Implants are adequate anchorage for maxillary canine retraction when properly placed.