Stability and relapse after surgical-orthodontic correction of skeletal open-bite deformities

Aim: The aim of this study was to evaluate the adaptive changes and the functional behavior of soft tissue and orofacial muscles after surgical correction of skeletal open bite and to show their influence on occlusion and their contribution to relapse. Method: The study utilized 91 patients, 42 males and 49 females, aged 18 to 36 years, 37 with skeletal class III malocclusions and 22 with skeletal class I malocclusions and 32 skeletal class II. All patients originally had an anterior open bite without vertical overlap of the central incisors. 64 patients had undergone bimaxillary orthognatic surgery; 27 patients only Le Fort I osteotomy. Were assessed anterior and posterior tongue position, lip competence, lip incisor relationship, masticatory muscle activity and breathing mode. Results: Demonstrated that statistically strong correlation were found between anterior and posterior tongue positions and occlusion. Lack of anterior contact and of a strong interdigitation allowed tongue interpositioning. The activity of the masticatory muscles and habitual mouth posture were correlated to open bite, over jet and over bite. The lower lip and the tongue had more effect on the position of incisors than does the upper lip. The improvement of breathing mode was probably due to the increase in lip competency. The interlabial distance was significantly correlated with mentalis muscle activity. Conclusion: After surgical correction of anterior skeletal open bite, surely the adaptive changes in the orofacial complex of adults, contribute to cause the relapse. The occlusion should be as stable and optimal as possible to eliminate reasons for relapse.