Edentulation Alters Material Properties of Cortical Bone in the Human Craniofacial Skeleton: Functional Implications for Craniofacial Structure in Primate Evolution
Article first published online: 16 MAR 2010
Copyright © 2010 Wiley-Liss, Inc.
The Anatomical Record
Special Issue: From Head to Tail: New Models and Approaches in Primate Functional Anatomy and Biomechanics
Volume 293, Issue 4, pages 618–629, April 2010
How to Cite
Dechow, P. C., Wang, Q. and Peterson, J. (2010), Edentulation Alters Material Properties of Cortical Bone in the Human Craniofacial Skeleton: Functional Implications for Craniofacial Structure in Primate Evolution. Anat Rec, 293: 618–629. doi: 10.1002/ar.21124
- Issue published online: 16 MAR 2010
- Article first published online: 16 MAR 2010
- Manuscript Accepted: 11 JAN 2010
- Manuscript Received: 7 JAN 2010
- NIH Grant. Grant Number: NIDCR-K08 DE00403
- National Science Foundation Physical Anthropology HOMINID Program. Grant Number: NSF BCS 0725126, 0725183
- cortical bone;
Skeletal adaptations to reduced function are an important source of skeletal variation and may be indicative of environmental pressures that lead to evolutionary changes. Humans serve as a model animal to investigate the effects of loss of craniofacial function through edentulation. In the human maxilla, it is known that edentulation leads to significant changes in skeletal structure such as residual ridge resorption and loss of cortical thickness. However, little is known about changes in bone tissue structure and material properties, which are also important for understanding skeletal mechanics but are often ignored. The aims of this study were to determine cortical material properties in edentulous crania and to evaluate differences with dentate crania and thus examine the effects of loss of function on craniofacial structure. Cortical bone samples from 15 edentulous human skulls were measured for thickness and density. Elastic properties and directions of maximum stiffness were determined by using ultrasonic techniques. These data were compared to those from dentate crania reported in a previous investigation. Cortical bone from all regions of the facial skeleton of edentulous individuals is thinner than in dentate skulls. Elastic and shear moduli, and density are similar or greater in the zygoma and cranial vault of edentulous individuals, whereas these properties are less in the maxilla. Most cortical bone, especially in edentulous maxillae, has reduced directional orientation. The loss of significant occlusal loads following edentulation may contribute to the change in material properties and the loss of orientation over time during the normal process of bone remodeling. These results suggest that area-specific cortical microstructural changes accompany bone resorption following edentulation. They also suggest that functional forces are important for maintaining bone mass throughout the craniofacial skeleton, even in areas such as the browridges, which have been thought to be little affected by function, because of low in vivo strains found there in several primate studies. Anat Rec, 293:618–629, 2010. © 2010 Wiley-Liss, Inc.