Clinical alteration of mandibular growth: what we know after 40 years

Objective: To identify pre-treatment cephalometric variables for the prediction of individual mandibular outcomes of functional jaw orthopedics (FJO) followed by fixed appliances in Class II patients treated at the peak in mandibular growth. Materials and Methods: The study was performed on 51 subjects (24 females, 27 males) with Class II malocclusion. First phase of therapy was accomplished with a twin block in 16 subjects, a stainless steel crown Herbst in 15 subjects, and with an acrylic splint Herbst in 20 subjects. Lateral cephalograms were available at the start of treatment with FJO and at the completion of fixed appliance therapy. All subjects received FJO at the peak in mandibular growth (CS 3 at T1). Individual responsiveness to Class II treatment including FJO was defined on the basis of the T2-T1 increment in total mandibular length (Co-Gn) when compared with untreated Class II subjects. Results: Discriminant analysis identified a single predictive parameter (Co-Go-Me°) with a classification power of 80%. Pre-treatment vertical and sagittal parameters were not able to improve the prediction based upon the mandibular angle. Conclusion: A Class II patient at the peak in skeletal maturation (CS 3) with a pre-treatment Co-Go-Me° smaller than 125.5° is expected to respond favorably to treatment including FJO. A Class II patient at CS 3 with a pre-treatment value for Co-Go-Me° greater than 125.5° is expected to respond poorly to treatment including FJO.