Correlation of condylar kinematics in children with gender, facial type and weight

The aim of the study has been to describe the normal range of mandibular movements and condylar kinematics in children as well as to test the null hypothesis that these variables are not associated with gender, facial type and weight. The sample was comprised of 92 healthy children (7.2–10.6 years old) and 40 adult controls (18–34.7 years old). Examinations included the maximal mouth opening capacity and laterotrusion to the right and to the left. The condylar path inclination angle was calculated at 3mm and 5mm protrusion of the mandible. Kinematic variables were registered using the ultrasonic JMA system. Maximal mouth opening capacity averaged 46.73mm for the children and 53.53mm for the adults. The mean values of the lateral movements were 9.36mm to the right and 9.62mm to the left for the boys, and 9.91mm and 9.68mm for the girls, respectively. Mean condylar path inclination in the children was 36.5° (right) and 36.2° (left) at 3mm of protrusive movement, and 34.3° (right) and 34.0° (left) at 5mm of protrusive movement. Associations of the kinematic variables with gender, weight, or facial type were insignificant. Younger school children have not yet reached the maximum mouth-opening capacity. Correlation analysis suggests some weak, but insignificant associations of gender, facial type and weight with mouth opening, laterotrusion and the condylar path inclination angle. The null hypothesis was not rejected.