One phase treatment for Class II malocclusion with high-pull headgear followed by fixed orthodontic appliances resulted in correction to Class I molar through restriction of horizontal maxillary growth with continued horizontal mandibular growth and vertical skeletal changes unaffected. The anteroposterior molar correction and skeletal effects of this treatment were stable long term.

Angle (1907A) defined Class II malocclusion as the occlusal relationship of the first permanent molars such that, "[The] lower molar [is] distally positioned relative to upper molar, line of occlusion not specified." The definition of Class II has broadened since then to include an anteroposterior discrepancy between the maxillary and mandibular dentitions, which may be solely dental, skeletal, or a combination of both. According to Fisk (1953), there is usually both a skeletal and dental contribution to a Class II malocclusion. Forward displacement of the maxilla or the maxillary dentition could, by definition, result in a Class II malocclusion. However, a deficiency in the mandible is more commonly the cause. Such deficiency can include mandibular hypoplasia, mandibular retrusion, or the mandibular teeth being positioned posteriorly within a normal mandible. The most common characteristic present in Class II patients is mandibular skeletal retrusion (McNamara, 1981). Treatment modalities that affect mandibular retrusion are therefore very important in orthodontic practice. Incidence of Class II Malocclusions Class II malocclusions are relatively common in the general population and therefore constitute a significant percentage of the cases treated by practicing orthodontists. When Angle studied the incidence of Class II malocclusion in 1000 Caucasians, he found 69% were class I, 23% were class II, and 3.4% were class III (Angle, 1907A). Massler and Frankel (1951) found similar results for children aged 14 to 18 years, as did Goldstein and Stanton (1936) for white American children between the ages of 2 and 12. However, these percentages vary between races. Horowitz (1970) determined that Caucasians develop the highest percentage of Class II malocclusions when compared to other races (22.5%), while Garner and Butt (1985) showed that Black