EFFECT OF FIXED ANTERIOR BITEPLANE THERAPY - A RADIOGRAPHIC STUDY

Orthodontic treatment of eight overbite cases with a maxillary fixed l ingual arch appliance with anterior biteplane involved a reduction in overbite of 4 to 7 mm between the upper and the lower front teeth and a first molar separation of 2 to 4 mm. After a treatment period of 3.5 to 5 months, occlusal contact between the upper and the lower molars was established. The appliance was then removed, and permanent overbit e reduction was secured with an edgewise appliance. With the subtracti on technique, 15 temporomandibular joints were radiographically invest igated in the retruded position for change of condylar position on the glenoid fossa before and directly after insertion of the appliance, a s well as after achieved molar contact. All condyles changed position directly after the bite opening, indicating that pure rotation did not occur. The direction of movement varied not only between subjects but also between the two condyles of each subject. With one exception, no ne or very small further positional changes occurred during treatment. No imaged signs of hard structure remodeling were observed. It may be concluded that other factors than change of condylar position must be responsible for the therapeutic effect of the bite-opening appliance that has been demonstrated in an earlier study.