Description of Research

Restoration failures resulting from tooth fracture are one of the primary obstacles to lifelong oral health.  The overall hypothesis of our study is that the fracture of restored teeth is fostered by a reduction in the fatigue crack growth resistance of dentin with age. Fatigue cracks are often present in the dentin of restored teeth and their incidence increases with age of the patient.  Despite distinct changes in the microstructure of dentin with age, and an identification that tooth fractures occur more frequently in seniors, the influence of aging on the fatigue properties of dentin has remained virtually unknown.  We propose to quantify the fatigue crack growth properties of dentin as a function of patient age, microstructure and dentin tubule orientation, distinguish at what age the most significant changes take place, and identify the fundamental mechanisms responsible for the degradation in properties.  Fatigue crack initiation and growth is currently being evaluated in specimens prepared from the coronal dentin of extracted virgin molars and the mechanisms of these processes are being characterized using novel optical techniques.  Results of the study will begin to provide a fundamental understanding of the fatigue crack growth properties of dentin and their dependence on the microstructure.  That knowledge will help to identify the critical aspects of existing restorative treatments on the incidence of tooth fracture, and the potential need for new approaches in treatment of the aging dentate population to minimize the risk of these failures.   Our findings will help to facilitate development of new methods for strengthening the fatigue resistance of tooth tissues.

Publications:

• J. Ivancik, H. Majd, D. Bajaj, E. Romberg and D. Arola. “Contributions of Aging to the Fatigue Crack Growth Resistance of Human Dentin” Acta Biomaterialia (Under review)
• J. Ivancik, N.K. Neerchal, E. Romberg and D. Arola. “The reduction in fatigue crack growth resistance of dentin with depth” J Dent Res. 2011;90(8):1031-1036
• D. Arola, J. Ivancik, H. Majd, D. Bajaj, X. Zhang and A.F. Fouad.. “On the Microstructure and Mechanical Behavior of Radicular and Coronal Dentin” Int. Endod J 2011 (invited).
• D. Arola, D. Bajaj, J. Ivancik, H. Majd and D. Zhang. “Fatigue of biomaterials: Hard tissues" Int. J Fatigue 2010;32(9):1400-1412.