Mathematical models of longitudinal mandibular growth for children with normal and untreated Class II, division 1 malocclusion

Two-level polynomial models are used to estimate and compare the mandibular growth of French-Canadian children between 6 and 15 years of age with normal occlusion and untreated Class II, division 1, malocclusion. With the exception of annual growth velocity, the curves describing the amount and direction of growth for the cephalometric landmark gnathion are comparable for children with normal and malocclusion. Growth deficiencies for children with malocclusion, approximating 0.4 cm/yr for boys and 0.2 cm/yr for girls, accumulate throughout the age range producing significant differences at the older ages. Peak childhood and pubertal velocities are estimated to occur at 8.7 and 14.1 for boys and 7.7 and 12.9 for girls, respectively. Growth direction changes in a curvilinear manner throughout the age range.