Orthopedic appliances (Most of which are also called functional appliances) are those appliances that modify occlusion between the maxillary and mandibular teeth towards a more normal relationship. They are also involved in modifying soft and hard tissue as well as masticatory muscle function, attempting to redirect the patient’s growth and development to a more desirable path.
There are removable and fixed functional appliances.
Removable appliances are fitted onto the patient’s teeth according to the doctor’s directions. Removable appliances can be removed, so that patients may maintain a high level of oral hygiene, and also enjoy their meals. This, however, is their greatest disadvantage: Their success depends entirely on the patient’s compliance, which is not usually a given.
Fixed operating appliances, although they somewhat impede the maintenance of a high level of oral hygiene, are more effective in achieving the desired treatment outcome, because they remained fixed to the patients teeth 24/7.
The Herbst is an orthopedic (functional) appliance that is often used to treat specific types of orthodontic problems.
This appliance is bonded to patients’ teeth and remains attached in place throughout the duration of treatment. It is usually fitted onto the upper and lower molars and premolars. It pushes the lower jaw (mandible) forward, in order to correct severe cases of mandibular retrognathia.
A palatal expansion appliance, the Hyrax-type expansion screw, is used when the upper teeth are not aligned with the lower. This expansion screw is incorporated into the Herbst appliance. The purpose of the Hyrax is to expand the maxilla (upper jaw).
The Herbst appliance and its variations, although they impede somewhat the maintenance of a high level of oral hygiene, are more effective in achieving the desired treatment outcome. For this reason, patients being treated with a Herbst appliance must visit their family dentist frequently (every 4-6 months).
Twin Block Appliance