Regional material heterogeneity in craniofacial cortical bone of the genus Pan

Abstract

Examination of craniofacial biomechanics necessitates regional material properties data as a foundation. We studied the pattern of material properties in the craniofacial complex of the genus Pan. Our aim was to characterize the elastic properties of the chimpanzee craniofacial cortical bone regionally. Former studies substantiate similarities in patterns of these properties within closely related primate species. Specimens were harvested from the craniofacial cortical bone of five adult chimpanzees. A continuous wave ultrasonic technique was used to measure velocities. Elastic coefficients and technical constants derived from mathematical equations quantified elastic properties. Regional comparisons of data using one‐way ANOVA revealed variations in elastic properties. Significant differences were observed in regional density (P< 0.001). The alveolar region displayed the least thick (mean=1.35 mm) and dense (mean=1630mg/cm3) cortical bone. Results for elastic moduli are significant E1 (P<0.007), E2 (P<0.009) and E3 (P<0.001). Shear moduli were prominent in all of the planes; larger values of G23 indicate stiffer bone. Poisson's ratio was also observed to be significant in v23 (P< 0.019). Greatest anisotropy was seen in the zygomatic arch (E2/E3=0.61). Findings suggest that mechanical properties of cortical bone in the chimpanzee craniofacial skeleton are influenced by its density, architecture and loading patterns in response to functional demands of the cranium.Grant Funding Source: NSF Hominid grant 0725141