Orthodontic treatment of openbite and deepbite high-angle malocclusions

The aim of the investigation was to assess the effect of orthodontic treatm ent on dentoskeletal morphology in children with openbite and deepbite high -angle malocclusion. Subjects (n = 54) in the mixed dentition with a hyperd ivergent mandibular plane angle (high-angle, NSL/ML greater than or equal t o 40 degrees) were surveyed. Pre- and posttreatment lateral roengenographic cephalograms were analyzed. Subjects were divided into three subgroups acc ording to the amount of pretreatment overbite: < 0 mm = insufficient/no com pensation (openbite); 0 - 4 mm = acceptable compensation (normal overbite); > 4 mm = overcompensation (deepbite). Pretreatment, 20% of the high-angle cases exhibited insufficient dentoskeletal compensation (overbite < 0 mm), and 35% displayed overcompensation (overbite > 4 mm). Influences of habits such as lip sucking and tongue-thrust swallowing were more common in the op enbite group. No major difference in treatment approach could be found betw een subgroups. In 82% of the openbite group and 90% of the deepbite group, overbite was corrected by orthodontic treatment. The mandibular plane angle was unaffected in both groups. The mechanisms of overbite correction diffe red between groups. The openbite group exhibited a significant decrease in interjaw-base angle. Increases in anterior and posterior dentoalveolar heig hts were comparable. The deepbite group showed no significant changes in sk eletal morphology. The increase in dentoalveolar height was approximately t wice as large posteriorly as anteriorly. The majority of children (80%) wit h high-angle morphology had a positive pretreatment overbite, thus exhibiti ng compensation of jaw-base hyperdivergency. Orthodontic treatment of high- angle malocclusions did not influence the mandibular plane angle in openbit e or deepbite cases. Overbite correction was accomplished by tipping the ma xilla downward anteriorly in openbite subjects, and by controlling incisor eruption in deepbite subjects.