Effects of intraoral maxillary protraction with repetitive rapid palatal expansions and constrictions

Abstract

Objective The purpose of this study was to evaluate the effects of intraoral maxillary protraction with repetitive rapid palatal expansions and constrictions using double hinged expander in maxillary retrognathism cases.Methods 29 subjects aged 7 to 13 years were randomly assigned to the following two groups.Observation group:intraoral maxillary protraction with repetitive rapid palatal expansions and constrictions using double hinged expander.Control group:facemask maxillary protraction with rapid palatal expansion using Hyrax expander.Cephalometric analysis with traditional cephalometric measurements and a rectangular coordinate system was used to compare the pre and post-treatment cephalographs.Results The treatment course in observation group (7.04 months) was significantly shorter than that in control group (11.04 months) (P＜0.01).Significant difference in forward movement of maxilla was observed between observation group (A-Np increased 1.28mm) and control group (A-Np increased 2.03 mm) (P＜0.05).The quantity of mandibular downward and backward rotation was found significantly smaller in observation group (P＜0.05).Significant counterclockwise rotation of functional occlusal plane was found in observation group(P＜0.01),while the rotation in control group was clockwise.Conclusions Intraoral maxillary protraction with repetitive rapid palatal expansions and constrictions using double hinged expander is an effective and efficient method in the early treatment of maxillary retrognathism patients.It results in a slightly less maxillary forward movement than the conventional facemask maxillary protraction with rapid palatal expansion using Hyrax expander. Key words: Rapid palatal expansion; Maxillary protraction; Maxillary retrognathism