Immediate skeletal effects of rapid maxillary expansion at midpalatal suture opening with Differential, Hyrax and Haas expanders

Abstract

Objective: The aim of this study was to test the null hypothesis that there is no difference at the midpalatal suture opening after rapid maxillary expansion (RME) using Expander with Differential Opening (EDO), Hyrax-type and Haas-type expanders. Methods: Occlusal radiographs of 52 patients (19 males and 33 females; average age= 9.46?1.20 years) treated with RME were divided into three groups, according to the expander used: EDO (n=17), Hyrax-type (n=21) and Haas-type (n=14). The evaluated variables were: A) Distance between the maxillary central incisors at the incisal edge; B) Distance between the alveolar ridges at the midpalatal suture; C) Suture opening at 10-mm distance from the crest to posterior, at the midpalatal suture; D) Suture opening at 20-mm distance from the crest to posterior, at the midpalatal suture; and E) Suture opening at 30-mm distance from the crest to posterior, at the midpalatal suture. To assess the normality of variables, the Shapiro-Wilk test was performed. For intergroup comparison, ANOVA with a significance level of 5% was used. Results: At the region A, Hyrax-type (4.66 mm) and EDO (4.87 mm) groups presented larger openings than the Haas-type group (3.43 mm). In regions B and C, EDO showed a statistically significant greater opening than the Haas-type group. In region D, a smaller opening of the midpalatal suture was observed in the Haas-type group, compared to the Hyrax-type and EDO groups. Conclusions: EDO and Hyrax-type produced greater immediate skeletal effects, compared with Haas-type, but these differences were about 1 mm and might not be clinically significant.

Dental arch changes comparison between Expander with Differential Opening, Hyrax‐type and Haas‐type expanders: A prospective clinical study

“…However, similar results were presented comparing EDO and Hyrax‐type expanders, where no statistically difference was found in the maxillary arch length after RME between the tooth‐borne expanders 7 . A previous study assessed the immediate effects of RME achieved by EDO and Haas‐type group, in the distance between maxillary central incisors at incisal edge, a greater diastema was promoted by EDO (4.87 mm) when compared to Haas‐type group (3.43 mm) 22 . This finding could explain the reason for the reduction of maxillary arch length in EDO when compared to Haas‐type group in this current study.…”

“…7 A previous study assessed the immediate effects of RME achieved by EDO and Haas-type group, in the distance between maxillary central incisors at incisal edge, a greater diastema was promoted by EDO (4.87 mm) when compared to Haas-type group (3.43 mm). 22 b Chi-squared test was used to compare sex and posterior maxillary discrepancy. In this study, 61 patients in the mixed dentition with posterior crossbite were treated with RME protocol.…”