The Goshgarian transpalatal bar is a fixed appliance that can be used in the treatment of Class II malocclusions. This study examines the effects of the appliance on the maxillary molars and determines the force-activation characteristics of the appliance with a laboratory model. The pretreatment and posttreatment cephalometric films and dental cast records of 11 patients with Class II malocclusions are evaluated. Results show that Class II correction is achieved as a result of distobuccal rotation and distal tipping of the activated molar. A potential negative side effect on the nonactivated molar is a slight mesial movement. Both intermolar and interbicuspid widths were substantially increased with buccal root torquing. Intrusion and extrusion of the molars did not occur. The distal and transverse forces generated by the Goshgarian palatal bar were linear, however, when distal activation exceeded 35°, the appliance became plastic. Transverse forces were twice as great as with a quad helix and distal forces were one fourth to one eighth of those generated with a headgear.
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