Dr. Hugo De Clerck - Bone Anchored Orthopedics for Correction of Class II and Class III growth

Many malocclusions are the reflection of a skeletal disharmony that may be vertical and/or sagittal, due to an excessive or insufficient activity of cranial growth centers. By application of heavy forces orthodontists try to stimulate or restrain growth activity to improve facial balance and get a stable occlusion. Therefore, it is important to know which growth centers can be affected by orthopedics, which force system is recommended, what is the biological outcome we may expect, and what are the clinical results reported in the literature? 

The main goal of class III orthopedics by face mask therapy is to stimulate growth of sutures and to move the maxilla forward. Since more than 50 years it’s the state of the art to treat class III growth in early mixed dentition. Many clinical studies have shown that the growth stimulation is rather small and since tooth born anchorage is used in the maxilla, important dento-alveolar compensations are found. Skeletal anchorage may help to reduce the movement of teeth. Miniscrews can reinforce the anchorage of the upper frame or lower canines, and with miniplates in upper and lower jaw a pure skeletal anchorage can be used. Thanks to 3D imaging the orthopedic outcome can be better quantified and not only maxillary changes but also modeling changes in the glenoid fossa and even in the mandible can be visualized. 

Activators, Bionators, Twin blocks, Herbst appliances, Carriere Motion, Fränkl appliances, Forsus springs, Precision Wings … are used to correct a class II malocclusion but also for their beneficial effects on cranio-facial growth. More precisely a growth stimulation of the mandible is often claimed. However, there is poor evidence that functional appliances are resulting in a clinically significant amount of forward growth of the mandible. Forward projection of the chin during growth is the result of 1) an increase in true mandibular length 2) bone modeling in the glenoid fossa, and 3) true mandibular rotation. With 3D imaging we can accurately quantify each of these growth mechanisms.

All class II orthopedics result in a proclination of the lower incisors, especially by Herbst treatment. Indirect anchorage with miniscrews may reinforce the lower canines and limit the movement of the incisors. However, if direct anchorage is used by miniplates in the lower canine region, dento-alveolar compensation can be completely eliminated in the lower jaw and may increase the skeletal changes. Therefore, 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. More than 70 cases have been included between 12 and 20 years old with different vertical growth patterns. Preliminary results show forward projection of Pogonion between 3 and 7 mm. Some retroclination of the upper incisors was found, but in all cases the lower incisors were retroclined after treatment. Bone modelling of the whole ramus and glenoid fossa rather than condylar growth stimulation are responsible for the mandibular changes, forward projection of the chin, and improvement of the soft tissue profile.

Master Orthopedic Expertise: Dr. Hugo De Clerck's global leadership in skeletal anchorage and orthopedics offers invaluable insights for your practice.

Enhanced Orthopedic Understanding: Gain comprehensive insights into dento-facial balance and effective force systems for improved clinical outcomes.

Revolutionizing Class III Treatment: Explore cutting-edge face mask therapy and 3D imaging techniques for precise orthopedic quantification.

Unraveling Class II Complexities: Discover the intricacies of growth mechanisms and 3D imaging applications for effective Class II orthopedic treatment.

Advanced Orthopedic Applications: Explore the impact of bone-anchored Herbst appliances on mandibular changes and soft tissue profiles, unlocking transformative clinical perspectives.