Growth Stimulation of the Mandible by a Bone Anchored Herbst Appliance

Proclination of lower incisors, and in a lesser degree distalization of upper molars, are responsible for a posterior shift of the mandible during the first months of treatment with conventional Herbst appliance. Proclination of lower incisors can be avoided by using miniplate anchorage in the lower jaw. Therefore, a series of 90 class II growing individuals were treated with a hybrid Herbst appliance: bone anchored in the mandible and tooth supported in the upper jaw. Active treatment time was 10 months. A CBCT was taken at the start of treatment and 2 months after removal of the Herbst appliance. Surface models were registered on the anterior cranial base and on the symphysis. In all cases lower incisors were retroclined. Distalization of the upper dentition was compensated by a progressive lengthening of the connectors. In one year, a forward growth of the chin by 3 to 7mm was found as a result of true mandibular lengthening, true mandibular rotation, and glenoid fossa modeling.