A clinical study on openbite & relapse tendency after IVRO of the mandibular prognathism

ABSTRACT

IVRO is one of the most common procedures to setback prognathic mandible. Since 1993 we have set-up our own protocol for functional physiotherapy(Park's protocol) after IVRO. This is a study on openbite and relapse tendency after IVRO followed by our protocol. We obtained lateral cephalograms of twenty-seven patients which were taken immediately after surgery, 3 months, 6 months and 1 year postoperatively. Changes in positions of each point were analyzed. The results were as follows 1. No remarkable openbite occured during the first year after IVRO. Upper teeth, lower teeth and anterior mandible moved upward, it seems to show that post-op orthodontic treatment did not contribute to reduce openbite tendency during post-op period. Rater, the lower teeth and mandible moved with the upper teeth as the compensation mechanism. 2. Lower Incisal Edge moved anteriorly up to 6 months, so overjet decreased from 3.3mm to 2.9mm during the first six months. Skeletal changes in anterior mandible showed slight anterior movement, therefore showing slight relapse tendency, but it represented no statistical significance. 3. The physiotherapy according to our protocol was used for only a month after operation, but there was no openbite tendency, and the occlusion was stable over one year.