Translation and rotation of the mandible during habitual mouth opening movement in children with anterior reverse bite in the primary dentition

Translation and rotation of the mandible during habitual mouth opening move ments were studied in 13 children with skeletal-based anterior reverse bite (reverse bite group) and in 13 children with normal occlusion (normal occl usion group) whose dental stage was the primary dentition. Movements were r ecorded by an opto-electronic movement-analyzing system that could measure mandibular movements with six degrees of freedom. Inferior translation of t he mandible was analyzed at the left primary central incisor, both of the p rimary canines, and both of the primary second molars. Anterior translation of the mandible was analyzed at both of the condyles. Rotation of the mand ible was measured in the sagittal plane. The results showed that the associ ations between the translation and rotation of the mandible during habitual mouth opening in the reverse bite group differed from those in the normal occlusion group. The reverse bite group had greater anterior translation of both of the condylar points than did the normal occlusion group. No signif icant differences were found in the inferior translation or rotation of the mandible between the two groups.