PREDICTIVE VARIABLES FOR THE OUTCOME OF EARLY FUNCTIONAL TREATMENT OFCLASS-III MALOCCLUSION

The aim of this study was to select a model of cephalometric and occlu sal predictive variables for the results of early treatment of Class I II malocclusion, due to mandibular protrusion in the deciduous dentiti on. Lateral cephalograms and dental casts of 45 subjects (22 boys and 23 girls) with Class III malocclusion in the deciduous dentition were analyzed at the start of treatment (mean age 5.57 +/- 0.85 years). The patients were treated with a functional appliance (removable mandibul ar retractor). All subjects were reevaluated after a mean period of 9. 54 +/- 2.28 years comprising active treatment plus retention. At this time, the sample was divided into two groups according to occlusal cri teria: successful group (23 subjects) and unsuccessful group (22 subje cts). Stepwise variable selection on the measurements at the time of f irst observation identified three predictive variables: the inclinatio n of the condylar axis in relation to the stable basicranial line (Con dAx-SBL), the inclination of the nasal line to the mandibular line (NL -ML), and the transverse width of the mandibular arch measured at the first deciduous molars. Discriminant analysis assigned a classificativ e power of 95.55% to the predictive model. On the basis of the equatio n generated by the multivariate statistical method, outcome of early t reatment for each new case with Class III malocclusion in the deciduou s dentition can be accordingly predicted. The important role of both v ertical and transverse relationships in Class III prognosis was emphas ized.