Dentoalveolar compensation in subjects with vertical skeletal dysplasia.

INTRODUCTION The purpose of this cephalometric study was to investigate vertical dentoalveolar compensation in untreated adults with excessive (long-face) and deficient (short-face) lower anterior face heights. METHODS Vertical and sagittal base relationships, vertical dentoalveolar dimension in the anterior region of the jaws, incisor inclination, overbite, and overjet were assessed in 112 short-face and 95 long-face subjects. The contribution of skeletal and dentoalveolar components to achieve a normal overbite was assessed by means of regression analysis. For the 2 most important independent variables of the regression equation, the values were calculated that would render an overbite of 2 mm. It was subsequently investigated whether the calculated value fell within the range of the sample. RESULTS In long-face subjects, overbite was mainly related to lower anterior face height; in short-face subjects, it was mainly related to mandibular anterior alveolar and basal heights. Dentoalveolar compensation occurred in both groups mainly by adaptations in mandibular incisor alveolar and basal heights. Molar height was unrelated to overbite. Cutoff values for achieving a positive overbite were calculated for lower face height and mandibular incisor alveolar and basal heights. CONCLUSIONS The lower face height mainly determines the overbite in long-face subjects, while in short-face subjects, lower dentoalveolar morphology influences overbite. Lower dentoalveolar compensation can maintain a normal overbite in long-face subjects to a limited extent.