Histological study of an upper incisor and molar of a bonobo (Pan paniscus) individual

Abstract

Work based on ground sections of teeth has provided accurate information on dental development in extant and extinct hominoid species. In contrast to radiographic studies, histological work is usually carried out using relatively small sample sizes. However, incremental lines in enamel and dentine enable us to interpret stages of crown formation and to establish patterns of dental development. Although these types of studies have been carried out in modern humans, common chimpanzees, gorillas, orangutans, and gibbons as well as in some extinct hominoids, almost nothing is known about the bonobo (Pan paniscus). In this paper we present some aspects of dental development for a young female with the I1 crown just completed. Ground sections were obtained for the right I1 and M1. The spacing between successive cross striations was measured in the outer, middle and inner portions of occlusal, lateral and cervical thirds of the enamel. The periodicities of the striae of Retzius were obtained, and the number of striae/perikymata were used to calculate the lateral formation time. Prism length and the average distance between cross striations were used to determine the cuspal formation time. Spacing between cross striations shows a gradual increase from the inner to the outer portions, and a decrease from the occlusal to the cervical region, as observed in modern humans and great apes. It is noteworthy that average values in this P. paniscus individual appear to be high. Crown formation time of this P. paniscus I1 was short. In addition, the perikymata packing pattern in P. paniscus was also different from that of G. gorilla and P. troglodytes, in that the number of perikymata increased towards the cervix.