LOWER FIRST PREMOLARS

PART I. A DEFINITION AND CLASSIFICATION OF DISCRETE MORPHOLOGIC TRAITS

¹ Department of Anthropology, University of Arizona, Tucson, Ariz., and University of Kansas City Dental School, Kansas City, Mo.

1. The hereditary basis of the dentition long has been recognized.

2. With the exception of a single trait, Carabelli's anomaly, there has been no genetic analysis of common nonpathologic, morphologic dental characteristics.

3. The addition of genes governing dental features to the small poo1 of human genes for common phenotypic taits already established would be of great significance for furthering our understanding of the dynamics of human evolution, of race formation, and of population genetics.

4. Isolation, definition, and classification of morphologic dental traits that are of common occurrence are necessary preliminary steps to genetic analysis.

5. The lower first premolar was selected for study because of its wide range of morphologic variability. Previous studies of this tooth have not provided data amenable to genetic analysis.

6. Seventeen traits, and their common varieties, have been isolated and defined for the lower first premolar, based on observations of more than 800 teeth, both on casts and extracted premolars, representing a number of ethnic groups.