Researchers led by Dr. Dwayne D. Arola of the University of Maryland, have recently examined the role of aging and its affect on the reduction in fracture toughness of human dentin. The article appears on the Journal of the Mechanical Behavior of Biomedical Materials (October 2009 issue, pages 550-559). Dr. Arola and colleagues found that the average fracture toughness of old dentin was approximately 30% lower than young dentin. The researchers observed that the fracture toughness seemed to depend on the number of lumens, which is important in determining the mineral-to-collagen ratio and the variation in the degree of age-related sclerosis, or embrittlement, throughout dentin.
They were able to do this by examining the crack growth resistance of human coronal dentin using tissue obtained from patients 18 to 83 years of age and for crack extension oriented perpendicular to the dentin tubules. The authors stated that their “…primary objectives of this investigation were to quantify the fracture toughness of human dentin for cracks extending perpendicular to the dentin tubules and to characterize the influence of patient age on the crack growth resistance.
In the ending paragraph of the discussion of the journal article, the authors state, “Many of the current practices in the field of restorative dentistry are based on knowledge of the structure and properties of the tooth tissues. However, they have not necessarily been developed to accommodate changes in the mechanical properties that are associated with aging. Results of this investigation have provided further evidence that aging results in significant changes in the mechanical behavior of dentin and a reduction in the ‘damage tolerance’ of the tissue. With these findings in mind, the success of specific practices in the field of restorative dentistry may require special consideration in the treatment of seniors, or the development of age-sensitive methods of care.”