COMPARISON OF THE EFFECTS OF PASSIVE POSTERIOR BITE-BLOCKS WITH DIFFERENT CONSTRUCTION BITES ON THE CRANIOFACIAL AND DENTOALVEOLAR STRUCTURES

Posterior bite-blocks that are used in the early treatment of skeletal open bite, produce a forward and upward mandibular rotation by transm itting the masticatory muscle forces to the buccal dentoalveolar regio ns and preventing their vertical growth. Increasing the vertical dimen sion of the face artificially causes skeletal adaptations to occur not only in the dentoalveolar region but also in the other regions of the craniofacial complex. The effects of passive posterior bite-blocks, c onstructed in two different heights, were investigated for two treatme nt groups, in comparison to an untreated control group. Two treatment groups comprised of 25 growing patients, who had skeletal open bite an d skeletal/dental Class I or Class II malocclusions, and one control g roup consisting of 14 growing patients were used. These groups were ma tched concerning their age, sex, and vertical and sagittal skeletal ce phalometric and dental characteristics. Passive posterior bite-blocks of 5 and 10 mm heights were applied to the subjects of the treatment g roups respectively for 18 hours per day. Untreated control subjects we re observed for 7 to 9 months. The findings of this study revealed tha t the downward and backward mandibular relation continued in the contr ol group, increasing the lower facial height significantly, whereas in the treatment groups, the skeletal open bite was treated and the mand ible rotated upward and forward. The increase of the height of the pos terior bite-blocks had a significant effect on the anterior mandibular rotation and in the increase of the genial angle.