Myofunctional therapy

Myofunctional therapy involves appliances for orofacial muscle exercises to repattern the activity of the masticatory, tongue, lip, and cheek muscles and re-educate them in order to correct anomalies of tooth and occlusal position. Functional orthodontic appliances for this therapeutic approach include oral screens.

Oralscreens (vestibular screens) are simple appliances for increasing muscle activity by muscle exercises and tongue training for both the primary and the mixed dentition (Fig 10-82). Treatment with oral screens is a simple form of treatment. They can be used to:

• Carry out transverse development and shaping of the dental arches
• Eliminate harmful habits (habitual mouth breathing, finger sucking, lip biting, lip sucking)
• Eliminate disto-occlusion, open bites, and positional anomalies of the anterior teeth

The mechanism of action of oral screens consists of an active effect (myofunctional training) and a passive effect (pressure difference). The oral screen lying passively in the mouth shields against harmful influences of the cheek and lip muscles, allowing tongue pressure to have a dominant effect.The exercises with the oral screen have to be done several times a day to activate the right muscles.

During exercises, the patient tightly encloses the oral screen and pulls it out of the mouth against the resistance of the muscles. A distinct "plop" should be heard as this is done. Habitual mouth breathers are asked to switch to nasal breathing as the lips enclose the oral screen.

Stockfisch's kinetor is an appliance in the form of a double-cone activator block with lingual, elastic tube supports that press against the alveolar processes and the teeth during occluding and stimulate masticatory movements in all three planes of space, simultaneously stimulating the cheek muscles. It is used for jaw compression, protrusion with spaces and crowding, anterior crowding, deep vertical overlap, prognathism, and open bite. Expansion screws in the maxilla and mandible are used for this purpose. The kinetor is fabricated from ready-made parts, including four plastic parts to receive the exchangeable vestibular tubes, single tubes for raising the occlusion, and triple tubes for lowering the occlusion.

The tooth positioner made from silicone or other polymers helps to improve occlusion and intercuspation after multiband therapy or treatment with removable appliances. The tooth positioner is not a retainer but an active appliance for fixing a new masticatory pattern and a new intercuspation, for 1.0- to 1.5-mm corrections of tooth position, for controlled relapse before the use of a retainer, for patients who grind or clench, and for skeletal stabilization after maxillofacial surgery. The positioner is an appliance for eventual fine adjustment of the mandible into the centric posi-tion.This requires skull- and joint-related registration and fabrication in an articulator.

A diagnostic setup is first produced for fabrication of a tooth positioner. A setup is a saw-cut model in which all the teeth to be corrected are fitted with thin brass pins. The pins provide sufficient retention to the model teeth in the sagittal plane but allow changes of position in the vertical plane and rotation of the sawn-out model teeth.

The teeth in the setup are placed in the desired position without the sagittal relationship of the teeth being lost. In the correct position, all the teeth are fixed with adhesive wax and checked in the articulator via lateral movements. The positioner is then fabricated from silicone, self-curing acrylic, or thermoplastic resin. It is molded like a thick squash bite that encases all the teeth up to about 2 mm above the gingival margin; in the buccal and lingual area, it is 2 to 3 mm thick, and the interocclusal block is also about 2 mm thick.