Fracture-toughening mechanisms responsible for differences in work to fracture of hydrated and dehydrated dentine

Kahler, Bill; Swain, Michael V.; Moule, Alex

Affiliations

¹Biomaterials Science Research Unit, Faculty of Dentistry, and Aerospace, Mechanical and Mechatronic Engineering, University of Sydney, NSW 2006, Australia

²Endodontist, 141 Queen Street, Brisbane, Qld. 4000, Australia

Abstract and keywords

This study investigates the nature of deformation and differences in the mechanisms of fracture and properties of dentine where there has been a loss of moisture, as may occur with removal of the pulp in the endodontic treatment of teeth. Controlled fracture toughness testing was conducted on bovine teeth to determine the influence of hydration on the work of fracture of dentine. Significant differences (p<0.01) were observed between the fracture toughness of hydrated (554±27.7 J/m²) and dehydrated (113±17.8 J/m²) dentine. Observations of the crack tip region during crack extension revealed extensive ligament formation occurred behind the crack tip. These ligaments provide considerable stability to the crack by significantly increasing the work of fracture, thereby acting as a fracture-toughening mechanism. Micro-cracking, reported as a fracture-toughening mechanism in bone, is also clearly seen. A zone of in-elastic deformation may occur as hydrated specimens revealed upon crack extension, a region about the tip that appeared to suck water into the structure and to exude water behind the crack tip. In dehydrated dentine, no in-elastic zone was observed. Micro-cracking is present though the cracks are smaller, straighter and with less opening than hydrated dentine. Only limited ligament formation just behind the crack tip was observed. These differences resulted in a significantly lower work of fracture with unstable brittle fracture characteristics. Based on these results, several fracture-toughening mechanisms were identified in dentine, with micro-cracking not considered the most important. These findings may be relevant for bone, a similar mineralised hydrated tissue.

Keywords: Dentine; Bone; Work of fracture; Fracture-toughening mechanisms; Micro-cracking

Links

DOI: 10.1016/S0021-9290(02)00327-5

PubMed: 12547360

WoS: 000181003500009

History

Accepted: 2002-09-23

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Cited By (18)

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2004	Angker L, Nijhof N, Swain MV, Kilpatrick NM. Influence of hydration and mechanical characterization of carious primary dentine using an ultra-micro indentation system (umis). Euro J Oral Sci. 2004;112(3):231-236.
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