A comparison of radiographic and anatomical evidence of tooth development in infant apes.

This study assesses dental development in a sample of 8 known-age infant orangutans and chimpanzees in order to examine discrepancies between radiographic analyses of tooth development and the actual developing teeth. All crania were radiographed and any developing teeth then extracted for comparison. The height of deciduous teeth was measured both on the radiographs and on the extracted teeth to assess the accuracy of radiographic tooth measurements. A comparison between the radiographic and actual measurements of the deciduous teeth reveals substantial discrepancies. For permanent teeth, the degree of radiographic underestimation of tooth development was found to vary depending on the tooth being studied, its stage of development (early stages are particularly problematic) and the radiographic techniques used. Examination of the dissected teeth also revealed earlier times of onset of calcification for I2(2), C1(1), P3-4(3-4) and M2 than reported in previous studies. For the canine and M2(2), upper and lower homologues appear to begin development at different times, but there is no apparent difference in onset times between other upper and lower homologues.