Development of a Valid Severity Index of Malocclusion for Patients of Various Racial Profiles in the Mixed and Permanent Dentitions

Abstract

Indices of malocclusion have been developed to serve a variety of functions. These functions include diagnostic classification, epidemiological data collection, measurement of treatment need, measurement of treatment success, and determination of treatment complexity. Although numerous occlusal indices have been developed, there are still significant inadequacies that are present in the existing methods. Current occlusal indices do not quantitatively consider changes in facial profile or cephalometric variables that reflect the skeletal malocclusion. Furthermore, no index includes objective analysis of facial soft tissue characteristics. Finally, no published occlusal index analyzes all diagnostic records. These factors are often involved in the patient and doctor perception of treatment need. As a result, the current occlusal indices are inadequate and inaccurate in comprehensively assessing treatment need. A complete index of malocclusion with the objective analysis of all pretreatment records is necessary to accurately quantify treatment need. Recently, an index of malocclusion was developed at IUSD that evaluates a complete set of diagnostic records. This index was shown to be a valid measure of malocclusion for patients of non-Hispanic white descent in the permanent dentition. However, the index was not validated for patients of different races, or for patients in the mixed dentition. In the present study, pretreatment records (dental casts, intra-oral and extra-oral photographs, panoramic radiograph, and cephalogram) of 288 patients from the Indiana University Orthodontic Department were evaluated. The patients represented Asian, African-American, Hispanic, and non-Hispanic white patients in the permanent and mixed dentitions. For patients in the permanent dentition, thirty-six characteristics were scored and combined into a total score representing the new index. Thirty-three characteristics were totaled in a similar manner for patients in the mixed dentition. The scores of the new index were compared to subjective rankings of malocclusion severity from two orthodontic experts. Statistical analysis, for the most part, showed moderately strong correlations of the new index with the ratings of the orthodontic experts. It is the conclusion of this study that the new index is a reasonably valid measure of severity of malocclusion which can be considerably improved with additional developmental research.