Reduction in Fracture Resistance of the Root with Aging
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2017-09-01
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Elsevier Inc.
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Introduction: The incidence of vertical root fracture in endodontically treated teeth increases with patient age. This study evaluated the microstructure, chemical composition, and mechanical properties of radicular dentin as a function of aging. Methods: Single-rooted teeth were obtained from adult donors ranging from age 15 to older than 80 years. Beams were extracted from the middle third of the root and subjected to 4-point flexure to failure to evaluate strength of dentin in terms of donor age. Based on the strength distribution, the fatigue strength of root tissue from young (<= 30 years) and old (>= 55 years) donor teeth was evaluated via cyclic flexure loading. The microstructure and chemical composition of radicular dentin from the 2 groups were evaluated as a function of distance from the root apex using microscopy and Raman spectroscopy, respectively. Results: The strength decreased with age by approximately 25 MPa per decade, which resulted in a significant difference (P <= .0001) between the young (199 +/- 36 MPa) and old (122 +/- 11 MPa) groups. There was also a significant difference (P <= .0001) in fatigue strength between the young and old age groups. Both the mineral-to-collagen ratio and degree of cross-linking increased with age, with the largest changes identified in the apical and middle thirds, respectively. Conclusions: There is a reduction in the damage tolerance of radicular dentin with increasing age. This degradation appears to result from changes in the microstructure, corresponding chemical composition, and increase in collagen cross-linking with age, and is most severe near the root apex.