A Preliminary Description of the Dental Morphology of the Peruvian Indian

¹ Dental Section, Oklahoma Medical Research Institute, Oklahoma City, Oklahoma

This report is a preliminary effort to characterize the dental morphology of the Indians inhabiting the interior of Peru. It is based on observations and measurements made on stone models representing 53 individuals. Although the data are fragmentary and are a composite of Indians from five different tribes, it provides an initial odontologic description of a hitherto unreported population.

On the basis of the data presented, Peruvian Indians can be described as having generally large teeth. All the incisors were shovel-shaped with frequent marginal ridging on the labial surface, which resulted in double and three-quarter double shovelshaped forms. There was a relatively frequent occurrence of barrel-shaped lateral incisors. A high percentage of the maxillary first molars had four cusps, but the hypocone was reduced in size in about half of the molars. The maxillary second and third molars showed an increasing tendency toward loss of the hypocone; more than half of the third molars had only three cusps.

The occurrence of a definite cusp of Carabelli on the maxillary first molar was relatively infrequent, but there was a high frequency of intermediate expressions of this trait. A high percentage of the second and third maxillary molars showed a complete absence of Carabelli's cusp. All of the mandibular first molars had five cusps; about 70 per cent of these had the typical Dryopithecus pattern.

Few of the second and third mandibular molars had the Y formation of grooves, but the presence of five cusps on these molars was frequent. None of the mandibular molars had the Y4 pattern.

The protostylid was found on an unusually large number of teeth being expressed to some degree on 70 per cent of the first mandibular molars and on 45 and 13 per cent of the second and third molars, respectively.

Although it is not possible to characterize the racial stock of the Peruvian Indians on the basis of this small sample, it is quite apparent that the dentition of this population has many of the traits that have been previously recognized as typically Mongoloid.