A clinical investigation of the correction of unilateral first molar crossbite with a transpalatal arch.

The correction of a unilateral first molar crossbite with a Goshgarian type of transpalatal arch was evaluated in 35 children from 6 years, 8 months to 15 years, 11 months old. Fifteen of the children were treated with an arch activated for expansion only and 20 children with an arch activated in a similar way but with the inclusion of buccal root torque of the anchorage tooth. With both types of activation, the arches worked in a statically determinate system, i.e., the tooth in crossbite was allowed to tip buccally. The movements of the first molars as a result of the treatment were monitored by measurements on dental casts and frontal cephalometric roentgenograms. In addition, the width of the midpalatal suture was measured on occlusal roentgenograms of the maxilla. In the children treated with an arch activated only for expansion, the molars on both sides of the dental arch moved buccally during the treatment. In the children treated by torque activation, on the other hand, there was a considerable buccal movement of the molar on the side of the crossbite without any significant buccal movement of the anchorage tooth. In individual cases, the molar on the noncrossbite side moved and tipped palatally and in some cases buccally but to a minor degree. With both types of activation, there was only a slight change in inclination of the transverse occlusal plane through the first molars; the plane opened up slightly toward the side of the crossbite. For both types of activation, there was a slight widening of the palatal suture during the treatment.(ABSTRACT TRUNCATED AT 250 WORDS)