Bilateral distalization of maxillary first molars in a group of adult patients after extraction of maxillary second molars using infra-zygomatic mini-implants: A prospective clinical trial

Abstract

Background: It is now possible to predictably distalize maxillary first molars in nongrowing patients with the infra-zygomatic gear distalizer and to improve malocclusions without having to extract the premolars and regardless of the patient's compliance. The purpose of this study was to investigate the amount and rate of distal movement of the maxillary first molars using our proposed appliance after extraction of maxillary second molars.

Methods: Ten nongrowing female patients successfully treated with our proposed appliance were the subjects of this study. The amount, rate, and type of distalization, were analyzed through upper jaw cone beam computed tomography (pre- and post-treatment) and scanned casts taken on a monthly interval.

Results: The average amount of distalization of the maxillary first molars was 4.03 mm at the crown level and 2.88 mm at the root level. The rate of distalization had an average of 0.61 mm per month with a maximum of 0.79 mm in the first month because of the regional acceleratory phenomena after extracting the maxillary second molar.

Conclusions: The maxillary first molars were distalized in a significant manner and all patients reached a Class I relation within an average duration of 6.4 months. The proposed appliance proved to be a viable noncompliance modality to distalize maxillary first molars correcting maxillary Class II malocclusions characterized by maxillary protrusion or maxillary incisor crowding.

Keywords: Distalization; Distalization Rate; Extraction; Infra-zygomatic mini-implant; Maxillary second molar Extraction; Skeletal anchorage.