A prospective clinical trial was started to study growth modification by a 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 another 2 months after removal of the Herbst appliance. Surface models were registered on the anterior cranial base and on the symphysis. 70 cases with different vertical growth patterns have been included between 12 and 20 years old.
Preliminary results show forward projection of Pogonion between 3 and 7mm. Some retroclination of the upper incisors occurred and in all cases the lower incisors were retroclined during treatment. Bone modeling of the whole ramus rather than condylar growth stimulation is responsible for the mandibular changes. Forward projection of the chin is the result of true mandibular lengthening, true mandibular rotation, and glenoid fossa modeling in a lesser degree. Thanks to 3D imaging the impact of true mandibular rotation on the growth of the chin can be accurately quantified.
Elimination of dento-alveolar compensations in the mandible thanks to miniplate anchorage is a breakthrough in Class II dento-facial orthopedics, reducing the need for orthognathic surgery.
Learning Objectives:
After this session, attendees will be able to:
Improve the outcome of Class II orthopedics.
Understand mandibular growth changes by bone anchored Herbst appliance.
Use CBCT images to explain mandibular growth changes by Class II orthopedics.
