Posterior crossbite and rapid maxillary expansion in mixed dentition stage : electromyographic, ultrassonographic and cephalometric / Mordida cruzada posterior e expansão rapida da maxila na fase da dentição mista : avaliação eletromiografica, ultrassonografica e cefalometrica

AUTOR(ES)
DATA DE PUBLICAÇÃO

2010

RESUMO

The aim of this thesis, comprised by three manuscripts, was to analyze the masticatory muscles of children with posterior crossbite (PCB) before and after rapid maxillary expansion (RME); as well to analyze if there are vertical and sagittal skeletal differences resulted by the uses of the banded or bonded RME appliance. In articles 1 and 2, 55 children (aged between 6 and 10 years, both gender) were divided into three groups: control group (normocclusion, n=24), unilateral (n=18) and bilateral (n=13) PCB groups. The children having PCB were submitted to RME using the Hyrax modified appliance. Ultrassonographic (US) and surface eletromyographic (EMG) exams were initially made in both groups (T1). In children having PCB, the evaluation was repeated nearly four months after RME (T2). The data were compared intra- group (between sides and between T1 and T2) and inter- group (at T1 and T2). In article 1, US thickness and EMG activity of the massteres and anterior temporalis muscles were analyzed during rest and dental clenching. A possible correlation between muscle thickness and EMG activity was also evaluated. The results showed that: the muscular thickness of patients with PCB at T1 and T2 were similar to those of control group; the EMG activity of the bilateral PCB group presented some differences compared to the other two groups; the EMG activity and muscular thickness of bilateral PCB did not modify at T2, but the masseter thickness of unilateral PCB patients decreased during rest; muscular asymmetry occurred in patients with and without PCB; positive correlation between EMG and US was found only in the control group during clenching. In article 2, the EMG activity of massteres and anterior temporalis muscles were analyzed during habitual and unilateral chewing. The results showed that: the control, unilateral and bilateral PCB groups presented symmetric EMG activity during habitual chewing; the control and bilateral PCB groups, at T1 and T2, presented the working side muscles more active during unilateral chewing, which occurred in unilateral PCB group only at T2; the EMG activity of unilateral PCB group decreased at T2 and did not modified in bilateral PCB group; some inter groups differences in EMG activity were found among the groups at T1 and T2. The article three was performed in two groups of 26 children (aged between 6 and 10 years, both gender), submitted to RME using the banded (Hyrax group) or bonded (bonded group) appliance. Lateral cephalometric radiographs were analysed before the treatment and at least ten months after retention. The results showed that skeletal differences after RME were similar with banded and bonded RME appliances-According to the three articles, it can be concluded that masticatory muscles thickness and EMG activity asymmetries occured in children with and without PCB. The muscular thickness of PCB children, before and after treatment, was similar to that of no crossbite children. Different muscular electrical activity between children occured independent of PCB or mandible deviation. The thickness and EMG activity of children with unilateral PCB decreased after treatment, but these characteristics did not modify in children with bilateral PCB. The vertical and sagittal skeletal changes after RME were similar with bonded and bonded appliances.

ASSUNTO(S)

eletromiografia cefalometria electrmyography malocclusion maloclusão ultrasonografia ultrasonography cephalometry

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