Occlusal and functional conditions after surgical correction of anterior open bite deformities.

The dental occlusion and alterations in orofacial muscles were studied in 267 patients whose severe anterior open bite had been treated with a Le Fort 1 intrusion osteotomy with or without an advancement sagittal split osteotomy about 6 years ago. Only 17% of those patients showed anterior contact, and 20% had no vertical overlap of mandibular and maxillary central incisors at all. Tongue position, activity of masticatory muscles, lip competence, lip-incisor relationship, and breathing mode were assessed. Statistically significant correlations were found between tongue positions and occlusion in both the anterior and the posterior regions. In addition, the activity of the masticatory muscles, habitual mouth posture, and interlabial distance were each significantly correlated to overbite, open bite, and overjet. The interlabial distance was also significantly correlated with both breathing mode and mentalis muscle activity. The activity of the masticatory muscles was negatively correlated with tongue position.