Over-bite and vertical changes following first premolar extraction in high angle cases.

AIMS AND OBJECTIVES Orthodontists generally agree that nonextraction treatment is associated with downward and backward rotation of the mandible and an increase in the lower anterior face height (LAFH). They also agree that extraction line of treatment is associated with upward and forward rotation of the mandible and decrease in the LAFH. The intent of this cephalometric investigation was to examine the wedge hypothesis, that the vertical dimension collapses after first bicuspid extraction. The present study was undertaken to evaluate the cephalometric overbite and vertical changes following first premolar extraction in high angle cases. MATERIALS AND METHODS Forty-five adult patients having high mandibular plane angle, i.e. Gogn--SN more than or equal to 32° having class I molar and canine relation were included. Pre and post-treatment lateral cephalograms were measured and compared to analyze the cephalometric changes. RESULTS There was no decrease in the overbite and vertical changes following first premolar extraction in high angle cases. CLINICAL SIGNIFICANCE The facial complex does increase in size with growth, but mandibular plane while moving inferiorly, remain essentially parallel to its pretreatment position due to residual growth and treatment mechanics. CONCLUSION The study concluded that, There was no decrease in the vertical facial dimension, overbite and mandibular plane angle. However, it should be interpreted with caution, given the small sample size.