Compensation for vertical dysplasia and its clinical application

Abstract

The purpose of this study was to quantitatively evaluate skeletal and dental compensation in patients with vertical skeletal dysplasias and to determine which dentoalveolar parameters compensate for vertical jaw discrepancies. Cephalometric analyses were performed on pre-treatment lateral cephalographs of 186 orthodontic patients (120 females and 66 males; mean age 15 years 11 months) who met the selection criteria. SN-MP angle was used to classify the facial patterns as: hyperdivergent > 36 degrees, normo = 28-36 degrees, and hypo < 28 degrees. Analysis of variance (ANOVA) was used to determine statistical differences between the means in the three vertical facial types. To evaluate dental compensation quantitatively, correlation analyses were performed to find associations between skeletal and dental parameters. To further elucidate the compensatory nature of the lower incisors, regression analyses and scattergrams were obtained, with SN-MP as a measure of the vertical skeletal discrepancy. ANOVA showed statistically significant differences for most of the skeletal variables, but only for lower incisor height and inclination among the dentoalveolar parameters. Correlation analyses demonstrated significant relationships between various skeletal variables. LI-MP showed a negative relationship with SN-MP, whereas LAMdH demonstrated a positive linear relationship with SN-MP. Among all dentoalveolar heights, UAMxH showed the weakest, and LAMdH the strongest, associations with skeletal parameters. The variability in dentoalveolar compensation therefore demands individualized diagnosis and treatment planning. LAMdH and LI-MP parameters were the most likely, whereas UAMxH was the least likely parameter to compensate for vertical dysplasia.