Morphological parameters as predictors of successful correction of Class III malocclusion

The aim of the study was to assess pre-treatment cephalometric parameters a nd measurements of the size of the apical bases as predictors of successful orthodontic correction of Class III malocclusions. Pre- and post-treatment lateral cephalograms and study models of 80 complet ed Class III subjects were examined to obtain 23 cephalometric parameters t aken mainly from the analyses of McNamara and Schwarz, and to measure the s ize of the apical bases. Success of occlusal correction was evaluated as th e percentage change of peer assessment rating score during treatment, which was used as the dependent variable in multivariate statistical analyses te sting the predictive value of the parameters assessed. No improvement in the Class III skeletal pattern occurred during treatment and the treatment effects were confined to dentoalveolar changes. With the exception of the percentage midfacial length/mandibular length ratio, the n et sum of maxillary and mandibular length differences, the mandibular ramus height/mandibular body length ratio and the gonion angle, most cephalometr ic parameters of pre-treatment craniofacial morphology assessed were poor p redictors of successful correction of Class III malocclusions. Assessment o f the size relationship of the maxillary and mandibular apical bases was th e strongest predictor of occlusal correction achieved and may serve as a va luable diagnostic addition in the prediction of successful treatment outcom e.