Cephalometric markers to consider in the treatment of Class II Division 1 malocclusion with the bionator

The principal aims of this study were to find the cephalometric predictors for good treatment results of bionator therapy and to justify bionator therapy as an early phase I treatment for patients with Class II Division 1 malocclusion. Forty subjects who had Class II Division 1 malocclusion and who were treated with the bionator were selected for this study. They were classified into a good treatment result group and a poor treatment result group in reference to the posttreatment molar relationship, posttreatment overbite and overjet, posttreatment profile, and existence of relapse. Thirty-one cephalometric variables were analyzed on the pretreatment lateral cephalograms by t-test to evaluate differences between the 2 groups. The variables that differed significantly were analyzed by discriminant analysis to assess their predictability. The study showed that horizontal growth pattern, close to normal anteroposterior relationship between the maxilla and mandible, upright mandibular incisor, and retrusive lower lip were important predictors for good results. In particular, protrusion of the lower lip was the most important factor for the determination of the treatment results. In addition, the treatment times were much shorter for patients with these good predictors. The present study supports the premise that bionator therapy can produce clinically stable and favorable results if the patients are appropriately selected with the use of these diagnostic criteria.