Mandibular condylar structure and growth in Macaca fascicularis are related to skeletal rather than dentitional development.

Mandibular condyles of eight male monkeys (Macaca fascicularis), ranging in weight from 1.5 to 3.0 kg, were examined using histometric, radioautographic and stereologic techniques. The animals were classified on the basis of their dentitional and, as judged from radiographs of the hand and wrist, of their skeletal development. This allowed morphometric parameter means to be plotted as a function of four dentitional and five skeletal levels of maturation. The influence of dentitional and skeletal age on total parameter variations was examined by calculating factorial analyses of variance. Although consistent and well defined within each method, condylar parameter changes plotted over skeletal age were essentially different from those over dentitional age. Whereas the latter were difficult, if not impossible, to interpret, the former closely resembled the age-related curves displaying the elongation of short bones of the fingers in M. fascicularis. Furthermore these parameter changes were also consistent with longitudinal alterations in mandibular growth as assessed radiographically in man. The analyses of variance suggested that animals exhibiting the same degree of skeletal as compared to dentitional development, particularly at late stages of maturation, were markedly more homogeneous with respect to the majority of the morphometric parameters examined. Therefore, somatic maturation rather than the stage of tooth eruption should be the basis for estimating biological age in growth studies of the mandibular condyle.