Qualitative and Quantitative Assessment of Treatment Difficulty of Class II Patients

The purpose of this study was to determine the physical characteristics and facial types that orthodontists perceive as difficult to treat, and to investigate how their perceptions’ relate to the duration of treatment among Class II patients. A survey completed by 122 practicing orthodontists evaluated perceptions of treatment difficulty associated with 16 individual characteristics and 14 facial types, all pertaining to Class II malocclusions. Records of 211 consecutively treated Class II patients ages 10-14 were collected from three private practices. Treatment duration, demographics, pre-treatment cephalograms, and intraoral photographs were evaluated. Orthodontists perceived open bite, impactions, excessive gingival display, and hyperdivergence as the most difficult characteristics to treat, with open bite as the most difficult individual characteristic (8.7 ± 1.6) and facial type component. In the patient sample, open bite, excessive overjet, Class II molar severity, ANB>7°, IMPA>105°, U1-SN, deep bite, the male sex, and Herbst treatment were associated with increased treatment duration, with open bite adding 9.2 months to treatment. Overbite, overjet, U1-SN, sex, treatment start age, and molar Class II explained 23.3% of the variability in treatment duration. This study concluded that open bite is perceived as the most difficult factor to treat and is the most important predictor of increased treatment duration, though excessive overjet and Class II molar severity are also indicative of increased treatment duration. Although orthodontists perceived hyperdivergence and protrusive lower incisors as difficult to treat, neither was strongly associated with treatment duration. U1-SN, however, was closely associated with treatment duration. Of the factors investigated, overbite, overjet, U1-SN, and molar Class II severity may be the most important components to include in a difficulty index