Early treatment of vertical skeletal dysplasia: The hyperdivergent phenotype

This cephalometric study evaluated an early nonextraction treatment approac h for patients with severe vertical skeletal dysplasia and maxillary transv erse constriction. Thirty-eight patients, 8.2 years (+/- 1.2 years) of age, were treated for 1.3 years (+/- 0.3 years) with lip seal exercises, a bond ed palatal expander appliance, and a banded lower Crozat/lip bumper. The bo nded palatal expander functioned as a posterior bite-block and was fixed in place throughout treatment. Patients with poor masticatory muscle force (7 9%) wore a high-pull chincup 12 to 14 hours per day. A control group was ma tched for age, sex, and mandibular plane angle. Treatment changes for chinc up and other patients were not significantly different. Overall, treatment significantly enhanced condylar growth, altered it to a more anterosuperior direction, and produced 'qrue" forward mandibular rotation 2.7 times great er than control values. Posterior facial height increased significantly mor e in patients than in controls, and the maxillary molars showed relative in trusion. In treated patients, articular angle increased, genial angle decre ased, and the chin moved anteriorly twice as much as in controls. Treatment also led to increased overbite and decreased overjet. Maxillary and mandib ular expansion did not cause the mandibular plane angle to increase. The 16 patients with openbite malocclusions exhibited a 2.7 mm increase in overbi te and inhibition of growth in anterior lower facial height. The aggregate of individual changes demonstrates a net improvement, indicating this treat ment approach may be suited for hyperdivergent patients with skeletal discr epancies in all 3 planes of space.