Cephalometric and clinical diagnoses of open bite tendency

Pretreatment lateral cephalometric radiographs of patients between 10 and 16 years of age were searched for persons who met criteria commonly used for identifying patients with "open bite tendencies." Results indicate that different measures of open bite tendency identify different patients. Of 50 patients with sella-nasion-mandibular plane angles greater than 40 degrees, only 11 had upper facial height/lower facial height ratios less than 0.70; of 50 patients who had occlusal plane-mandibular plane angles greater than 22 degrees, only 15 had posterior facial height/anterior facial height ratios of less than 0.58. Of the 250 patients who exhibited some well-accepted cephalometric indication for excessive vertical dimension, only 13% had actual anterior open bites. When clinicians ranked their own patients according to the difficulty in controlling excessive vertical growth during treatment, measurements such as the mandibular plane angle, upper to lower facial height ratio, and anterior to posterior facial height ratio did not predict treatment responses.