There are many types of orthopedic (as opposed to orthodontic) appliance s used when the lower jaw has not grown enough, resulting in skeletal and bite discrepancies. Fixed appliances include the herbst, Jasper Vektor, and mara (mandibular anterior repositioning appliance). Removable appliances include the twin block, mono block, and bionator. Orthopedic appliances try to get the lower jaw to grow in a forward direction, providing a better relationship with the upper jaw and improving the facial profile. The bite relationship is also improved because the lower teeth move forward with the lower jaw.
Fixed appliances have the advantage of being attached to the teeth and are not removable , so compliance with appliance wear is not an issue. The down side is that they are fairly bulky and can rub on the cheeks and gums , making them uncomfortable. There is also a tendency for them to break , or, in the case of the herb st appliance, come apart. This can require extra trips to the orthodontist to have them repaired. The other major issue is hygiene. They are difficult to clean around, increasing the potential for damage to the teeth and gums.
Removable appliances tend to be more comfortable to wear than fixed appliances. Learning to talk while wearing them does take a little work, but can be mastered in most cases. They can also be removed for eating, activities like sports, and oral hygiene, which is a major benefit. Compliance can be an issue, however. Removable appliances require at least 20 hours of wear each day, so patient cooperation is essential for them to be effective.
A key factor that is required for any orthopedic appliance to make the desired changes is that the patient must be growing. The ideal age in my opinion is from 8 to 10. I find that this age group tends to be the most compliant if removable appliances are to be used and growth potential is not an issue. Orthopedic appliances have been shown to be effective during adolescent years, as late as 14 or 15 if enough growth potential remains. Orthopedic appliances are not an option once growth is complete. Jaw surgery, know as orthognathic surgery , is required if these patients want to improve their skeletal relationships.
By Gary W. Greer, DDS, MSD