Dentoalveolar and arch dimension changes in patients treated with miniplate-anchored maxillary protraction.

Abstract

The aim of this study was to evaluate dentoalveolar and arch dimension changes in 2 miniplate-anchored maxillary protraction protocols in relation to an untreated control group using 3-dimensional digital models. Thirty growing Class III subjects with maxillary deficiency in the late mixed or early permanent dentition phase were randomly divided into 3 groups. In group 1 (n=10), patients were treated with skeletally anchored facemasks anchored with miniplates placed at the zygomatic buttress. In group 2 (n=10), patients were treated with Class III elastics extending from infrazygomatic miniplates in the maxilla to symphyseal miniplates in the mandible. Group 3 (n=10) was an untreated control group. The decision to discontinue orthopedic treatment was made when the patients had 3 to 4mm of positive anterior overjet. Pretreatment, posttreatment, and observation 3-dimensional digital models were analyzed, superimposed, 3 dimensionally mapped, and sectioned. In this study, there were no significant changes in maxillary arch depth and maxillary or mandibular intermolar width before and after maxillary protraction or after the observation period in the control group. The mandibular arch depth decreased by a small but statistically significant amount only in groups 1and 3. Superimposition of the pretreatment and posttreatment or observation maxillary 3-dimensional digital models showed minimal clinically significant dentoalveolar changes. Miniplate-anchored maxillary protraction protocols can accomplish maxillary advancement by eliminating movements of teeth and dentoalveolarchanges. No spontaneous improvement in transverse deficiency was detected after correction of the anteroposterior deficiency at this age. Consequently, patients with transverse maxillary deficiency should have rapid maxillary expansion before or during the miniplate-anchored protraction period to improve the transverse deficiency.