Analysis of association between posterior crossbite, median line deviation and facial asymmetry / Análisis de la asociación entre mordida cruzada posterior, desviación de la línea mediana y asimetría facial

Facial asymmetry is a common human characteristic and can occur on many levels, originate of genetic factors, and can be caused by traumas or due to cross bite and/or muscular disability. The aim of this study was to evaluate the relation between posterior crossbite, median line deviation and facial asymmetry. For this study 70 children aged between 3 and 10 years-old were examined and photographed. Using Microsoft Office Power Point 2007, horizontal lines and one vertical line on median line were drawn, to subjectively analyze facial discrepancies. In relation to overjet, the majority of children (78.6%) showed normal relation, followed by high overjet (17.1%), anterior crossbite (4.3%). In relation to overbite, the majority of children (60%) showed normal relation, 27.1% anterior opened bite (negative overbite), and 12.9% showed high overbite. Posterior crossbite was present in 27.1% of children. Among them, 68.4% showed unilateral crossbite on right side, 21.1% bilateral crossbite and 10.5% unilateral crossbite on left side. The relation between posterior crossbite and facial asymmetry, according to Fisher´s Exact Test (p=0.0970), there was no statistically significant association. In relation to median line, the association was statistically significant with posterior crossbite (p=0.0109) and with facial asymmetry (p=0.0310). There was association between posterior crossbite and median line deviation. There was no association between posterior crossbite and facial asymmetry

La asimetría facial es una característica humana común que puede ocurrir en diferentes niveles, originarse por factores genéticos, ser causada por traumas o mordida cruzada como resultado o discapacidad muscular. El objetivo de este estudio fue evaluar la relación entre la mordida cruzada posterior, desviación de la línea mediana y asimetría facial. Fueron evaluados 70 niños entre 3 y 10 años de edad mediante examen clínico y fotográfico. Utilizando Microsoft Power Point Office 2007, se dibujaron líneas horizontales y una línea vertical en la línea mediana, para analizar subjetivamente las diferencias faciales. En relación con el resalte, la mayoría de los niños (78,6%) mostró relación normal, seguido por un resalte aumentado (17,1%) y mordida cruzada anterior (4,3%). En relación con la sobremordida, la mayoría de los niños (60%) mostró relación normal, 27,1% una mordida abierta anterior (sobremordida negativa) y 12,9% mostró una sobremordida aumentada. La mordida cruzada posterior estuvo presente en 27,1% de los niños. Entre ellos, el 68,4% presentaba mordida cruzada unilateral del lado derecho, 21,1% mordida cruzada bilateral y el 10,5% mordida cruzada unilateral en el lado izquierdo. No hubo asociación estadísticamente significativa entre la mordida cruzada posterior y asimetría facial según la prueba exacta de Fisher (p=0,0970). En relación a la línea mediana, se observo una asociación estadísticamente significativa entre mordida cruzada posterior (p = 0,0109) y asimetría facial (p=0,0310). Existe asociación entre la mordida cruzada posterior y la desviación de línea mediana. No hubo asociación entre la mordida cruzada posterior y asimetría facial

Association between overbite and craniofacial growth pattern

The purpose of the present study was to assess the association between overbite and craniofacial growth pattern. The sample comprised eighty-six cephalograms obtained during the orthodontic pretreatment phase and analyzed using the Radiocef program to identify the craniofacial landmarks and perform orthodontic measurements. The variables utilized were overbite, the Jarabak percentage and the Vert index, as well as classifications resulting from the interpretation of these measurements. In all the statistical tests, a significance level of 5 percent was considered. Measurement reliability was checked by calculating method error. Weighted Kappa analysis showed that agreement between the facial types defined by the Vert index and the direction of growth trend established by the Jarabak percentage was not satisfactory. Owing to this lack of equivalency, a potential association between overbite and craniofacial growth pattern was evaluated using the chi-square test, considering the two methods separately. No relationship of dependence between overbite and craniofacial growth pattern was revealed by the results obtained. Therefore, it can be concluded that the classification of facial growth pattern will not be the same when considering the Jarabak and the Ricketts anayses, and that increased overbite cannot be associated with a braquifacial growth pattern, nor can openbite be associated with a dolichofacial growth pattern.