(1) Hadassah School of Dental Medicine, The Hebrew University of Jerusalem, Israel.
(2) Hadassah Hospital, Jerusalem, Israel
(3) Institute of Computer Science, The Hebrew University of Jerusalem, Israel

The main objective of this study was to develop a three dimensional computerized model for analysis of dental ontogeny and phylogeny. This from direct comparison of the dentine-enamel junction and outer enamel surface of recent and fossil teeth delineated on serial C-t scans. The model was designed and tested using teeth from archaeological samples. Serial C-t scans were taken at 0.5 mm intervals along intact M1's and DM2's, using an elscint scanner. The XYZ co-ordinates of specified locations on each scan were entered into a data base and used to create a three dimensional model delineating the relationship between cusp tips at the outer enamel surface (OES) and dentine enamel junction (DEJ). Various size and shape analyses were then carried out to determine the relation of intercusp distances and angles at the DEJ and OES of these teeth to their developmental sequence as reported in the literature. The results indicate an inverse association between duration of development, and mesio-distal asymmetry . We propose that this reflects differences in the spatial and temporal ordering of the onset of mineralization, that can be applied to the study of growth rates in fossil teeth.

Keywords: Serial C-t scans; dental ontogeny; hominid evolution molars; computerized modelling of growth trajectories