Comparative evaluation of maxilar effects of rapid maxilar expansion with Haas and Hyrax appliances

Marco Antônio SCANAVINI, Sílvia Augusta Braga REIS, Marcelo Matiello SIMÕES, Regina Ap. Rossi GONÇALVES

Aim: the purpose of this cephalometric study was to evaluate, by lateral cephalograms, the changes in maxilar positioning after rapid disjunction of the midpalatal suture, following the use of two types of maxillary disjunction appliances, checked in different phases, and the likely differences between the two appliances Haas and Hyrax. Methods: the sample comprised of 93 lateral cephalograms, taken before treatment (pre-disjunction), immediately after disjunction and at the end of levelling, obtained from 31 brazilian youths with both genres and average age of 13 years and 2 months. Results and Conclusions: both types of appliances showed similar results, with anterior and lower displacement of maxila right after disjunction. Lower displacement was without rotation, and mainttened stable until the end of levelling. Anterior displacement, however, was not stable and cephalometric measurements like SNA and Nperp-A tended to returned to initial values at the end of levelling.

Keywords: Rapid maxillary expansion. Cephalometry. Maxilla.

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