Fatigue and fracture of bovine dentin

Abstract

ABSTRACT-In this paper, the fatigue and fracture properties of bovine dentin are evaluated using in vitro experimental analyses. Double cantilever beam (DCB) specimens were prepared from bovine maxillary molars and subjected to zeroto-tension cyclic loads. The fatigue crack growth rate was evaluated as a function of the dentin tubule orientation using the Paris law. Wedge-loaded DCB specimens were also prepared and subjected to monotonic opening loads. Moiré interferometry was used to acquire the in-plane displacement field during stable crack growth, and the instantaneous wedge load and crack length were acquired to evaluate the crack growth resistance and crack tip opening displacement (CTOD) with crack extension. The rate of fatigue crack growth was generally larger for crack propagation occurring perpendicular to the dentin tubules. The Moiré fringe fields documented during monotonic crack growth exhibited non-linear deformation occurring within a confined region adjacent to the crack tip. Both the wedge load and CTOD response provided evidence that a fracture process zone contributes to energy dissipation during crack extension and that dentin exhibits a rising R-curve behavior. Results from this preliminary investigation are being used as a guide for an evaluation of the fatigue and fracture properties of human dentin.

Striations Resulting from Fatigue Crack Growth in Dentin

“…Examples are shown in Figure 6. Similar cracks in the dentin of restored teeth were reported by Arola et al [9]. The sectioned teeth were then broken along the crack and the fracture surface was examined using profilometry and power spectrum analysis.…”

“…A number of in vitro studies on cyclic crack growth in bovine [8][9][10], elephant [11,12] and human dentin [13][14][15] have been conducted in the recent past. These studies have been successful in quantifying the fatigue properties of dentin.…”

“…While it is plausible that fracture in the restored tooth results from a single catastrophic load, it is generally believed that such failures are the result of subcritical cracking induced by repetitive stresses, i.e., fatigue [3]. Damage induced by restorative processes can grow with time due to cyclic stresses resulting from mastication and can enable complete fracture of the tooth [4][5][6][7].A number of in vitro studies on cyclic crack growth in bovine [8][9][10], elephant [11,12] and human dentin [13][14][15] have been conducted in the recent past. These studies have been successful in quantifying the fatigue properties of dentin.…”

Stress ratio contributes to fatigue crack growth in dentin

“…250 m wide) on both sides the crack boundary. 10 The nonlinear zone remained after crack extension and established the presence and contribution of permanent deformation to crack extension. Thus, the decrease in m with increasing R for fatigue loading of the bovine DCB specimens appears to have resulted from the increasing component of viscoplastic contributions to crack growth.…”

“…9 In fact, the fatigue properties of tooth tissues and dental restorative materials are just beginning to receive meaningful attention. The mechanics of fatigue crack growth and fracture in dentin was recently evaluated by Arola et al, 10 and it was found that there was a host of complex mechanisms contributing to crack extension under monotonic and cyclic loads. A complementary study by Arola and Rouland 11 identified that the average fatigue crack growth rate in bovine dentin was approximately 5E-6 mm/ cycle and dependent on the dentin tubule orientation.…”