Combined treatment of open bite - long-term evaluation and relapse factors

Some patients with open bite who have been treated with combined fixed orthodontic appliances and bimaxillary osteotomy relapse in the vertical dimension after the end of treatment following initially successful correction of the vertical dimension. The aim of this study was to identify those parameters that raise the tendency to relapse.

Nineteen patients who underwent combined treatment using fixed orthodontic appliances and bimaxillary osteotomy due to open bite (overbite < 0 mm), were examined and documented at least 2 years after surgery. Pre- and post-orthodontic and pre- and post-operative study models and lateral head films were analyzed. Overbite reduction after the end of treatment was considered as relapse.

In our study cohort, the appearance of relapse in the vertical correlated with the enlargement of Björk's sum angle (odds ratio 10.7) and Jarabak's ratio (odds ratio 7) by means of surgery, as well as with dysfunctional habits persisting after treatment such as mouth breathing (odds ratio 12.5) and a visceral swallowing pattern (odds ratio 8.3). The existence at baseline of isolated anteinclination of the anterior maxilla or isolated steep inclination of the mandible also made vertical relapse more probable (odds ratio 7.5).

Particularly deserving of attention during the combined interdisciplinary treatment of patients with open bite are the achieved reduction in posterior facial height by surgical posterior impaction of the maxilla, as well as correction of dysfunctional parameters during swallowing and breathing.