The characteristics of patients who seek evaluation for dentofacial problems that might require orthognathic surgery for effective treatment, and the characteristics of those who accept surgery, are needed in planning the management of this patient group. Using data from the National Center for Health Statistics that were published in the 1970s, we evaluated the number of patients who would be expected to need surgical-orthodontic treatment based on the severity of their malocclusion and compared this with the percentage who sought treatment by making appointments for evaluation in the Dentofacial Clinic at the University of North Carolina ( Fig 1 ). We estimated that the most severe 5% of all Class II patients and the most severe 33% of Class III patients were potential candidates for orthognathic surgery. It was particularly difficult to determine treatment needs for long-face patients from the data for open-bite prevalence, because although two thirds of this group had an anterior open bite, a third did not. The prevalence of long-face problems was calculated by assuming that an open bite greater than 3 mm indicates a skeletal long-face problem; we hoped that false negatives (long face but no open bite) would be balanced by false positives (open bite but normal face height) and estimated that 25% of this group would need surgery. By using these estimates, the data showed that patients with Class II malocclusion were underrepresented in the group seeking treatment, whereas Class III patients were modestly overrepresented, and open-bite patients were greatly overrepresented ( Fig 1 ).

The expected and actual percentages of patients who sought evaluation in the University of North Carolina Dentofacial Clinic, 1979-1989. Patients with Class II problems (mandibular deficiency) were underrepresented in the clinic population compared with their prevalence in the general population, Class III patients (maxillary deficiency or mandibular prognathism) were overrepresented, and long-face patients were greatly overrepresented.

The most recent study of the prevalence of various types of malocclusion in the United States (National Health and Nutrition Examination Survey [NHANES] III, published in the 1990s) provides data for types of malocclusion by severity of the deviations from normal. Figures 2 and 3 , calculated from the NHANES III data, show the prevalence for overjet and incisor overlap, respectively. For both, it is reasonable to expect that essentially all extreme deviations and some severe deviations from ideal relationships would lead to a need for orthognathic surgery. The NHANES data also show that the prevalence of extreme reverse overjet (Class III) is 3 times higher in Asians than in blacks or whites, and twice as great in Hispanics (Mexican Americans). Extreme overjet (Class II) is twice as prevalent in black and Hispanic people as in white people. Extreme open bite (long face) is 7 times more prevalent in African Americans than in whites and is almost never observed in Hispanics. Dental and facial asymmetry were not evaluated in the NHANES III.

Overjet (Class II) and reverse overjet (Class III) in the US population, 1989-1991. Most of those with extreme deviation from the ideal and some but not all with severe deviation would be candidates for orthognathic surgery.

Open-bite and deepbite relationships in the US population, 1989-1991. As with overjet, those with the most severe deviation from ideal would be candidates for orthognathic surgery.

The NHANES III data made it possible to calculate what percentages of the US population would fall into the grades in the index of treatment need (IOTN) that was developed in the United Kingdom in the 1980s to help in the selection of patients for orthodontic treatment in the National Health Service. We did this for the 3 major racial-ethnic groups (white, black, Hispanic [Mexican-American]) that were included in the NHANES III. The prevalence of IOTN grades 4 and 5 (severe) is much greater in blacks than in whites or Hispanics, whereas mild problems (IOTN grade 2) are more frequent in whites than in blacks and much more frequent than in Hispanics ( Fig 4 ). As Figure 4 also shows, from 1989 to 1991, orthodontic treatment was much more likely to be received by white people than either of the other groups. The extent to which that has changed since then has not been documented.

Orthodontic treatment need by severity of the problem for white, black, and Hispanic (Mexican American) youths aged 12 to 17 years, 1989-1991, and the percentage of each group who reported receiving orthodontic treatment. The prevalence of severe and very severe problems (IOTN grades 4 and 5) was nearly twice as great in blacks than either whites or Hispanics.

The change in the prevalence of skeletal Class I, Class II, and Class III in the population who sought evaluation in the dentofacial program at the University of North Carolina over a 20-year span up to the mid-1990s is shown in Figure 5 . In this data set, most of the Class I patients were seeking surgical correction of facial asymmetry, but a few long-face patients who had no anteroposterior problem were included. There was a modest but steady decline in Class II patients, with fluctuations but no long-term trend toward change in the prevalence of Class III.

Data for the prevalence of Class I, Class II, and Class III patients evaluated in the University of North Carolina Dentofacial Clinic in 2-year increments in 1979 and 1980 to 1997 and 1998. Class I patients with no anteroposterior discrepancy were largely seeking correction of asymmetry, but this group also included some long-face patients. The percentage of Class II patients declined slowly but steadily; the percentages of Class III and Class I patients fluctuated but showed no sustained change.

Has the distribution of patients seeking and receiving surgical treatment changed since the turn of the 21st century? Our clinical impression was that both the number and proportion of Class III patients have greatly increased; to evaluate this, we compared the characteristics of surgery patients at the University of North Carolina in 1996 through 2000 with those in 2006 through 2010.