Role of lateral cephalograms in assessing severity and difficulty of orthodontic cases.

To assess the role of lateral cephalometric films in the evaluation of orthodontic patients, 16 certified orthodontists examined 80 sets of dental casts and lateral cephalograms. The patients included 5 subgroups: Class I with mild crowding, Class II Division 2, Class III, open bites, and bimaxillary protrusion. A 5-point Visual Analogue Scale was used to assess the degree of severity and difficulty of each case. Severity was defined as the degree of deviation from ideal occlusion, while difficulty was defined as the probability of attaining an ideal occlusion when all treatment options were available. The examiner then chose one or more of the following treatment options: growth modification, extraction, nonextraction, and surgery. All examiners scored the degree of severity and difficulty of each case with casts only at Time 1 (T1), then with casts and cephalograms at Time 2 (T2). The observed ratings from the Visual Analogue Scale were scored by using the Rasch model, which transforms the nonlinear ordinal ratings to a linear interval scale. Intersubgroup differences and differences between T1 and T2 difficulty and severity were assessed by using a 5 x 2 repeated measures analysis of variance. A paired t test examined the amount and direction of the differences between T1 and T2 of each subgroup. Multiple contingency tables were used to compare treatment option changes between all subgroups at each time. Severity and difficulty scores highly correlated. Analysis of variance showed significant differences among subgroups for both severity and difficulty; however, there were significant time differences for severity only. Paired t tests revealed a small increase in severity for the bimaxillary protrusive group and small but significant decreases for the subgroups Class II Division 2 and Class III when cephalograms were added. The multicontingency table analysis demonstrated that a significant number of examiners did change their treatment options at T2 for bimaxillary protrusive, nonextraction, and Class II Division 2 patients. It was concluded that lateral cephalometric films showed a significant influence on a clinician's determination on severity of some types of orthodontic malocclusions.