The Reduction in Fatigue Crack Growth Resistance of Dentin with Depth

Abstract

The fatigue crack growth resistance of dentin was characterized as a function of depth from the dentino-enamel junction. Compact tension (CT) specimens were prepared from the crowns of third molars in the deep, middle, and peripheral dentin. The microstructure was quantified in terms of the average tubule dimensions and density. Fatigue cracks were grown in-plane with the tubules and characterized in terms of the initiation and growth responses. Deep dentin exhibited the lowest resistance to the initiation of fatigue crack growth, as indicated by the stress intensity threshold (ΔK th ≈ 0.8 MPa•m 0.5 ) and the highest incremental fatigue crack growth rate (over 1000 times that in peripheral dentin). Cracks in deep dentin underwent incremental extension under cyclic stresses that were 40% lower than those required in peripheral dentin. The average fatigue crack growth rates increased significantly with tubule density, indicating the importance of microstructure on the potential for tooth fracture. Molars with deep restorations are more likely to suffer from the cracked-tooth syndrome, because of the lower fatigue crack growth resistance of deep dentin.

Degradation in the Fatigue Resistance of Dentin by Bur and Abrasive Air-jet Preparations

“…Dentin exhibits spatial variations in apparent brittleness, i.e., it increases with proximity of the pulp, due to an increasing mineral-to-collagen ratio and microstructure (Ryou et al, 2011). There is also a reduction in the resistance to fatigue crack growth with depth (Ivancik et al, 2011). That raises the potential for degradation in the fatigue strength of coronal dentin via cavity preparations when deep preparations are cut, where dentin is most brittle.…”

On the Mechanics of Fatigue and Fracture in Teeth

“…Nevertheless, constraints in tissue volume have limited this configuration to studies of dentin from the tooth crown e.g., Refs. [64][65][66]. A schematic description of the more common specimen configurations that have been adopted is presented in Fig.…”

Fracture resistance of bleached teeth restored with different procedures

“…The results showed a standard deviation within the normal range. Although the teeth have been selected previously, which are reported in Table 1, the human teeth have different levels of mineralization that occurs deposition of tertiary reactionary dentin in their lifetime due to the stress absorbed by the tooth 20 . In addition, the fracture resistance of the endodontically-treated teeth are dependent on the amount of retained residual dentin 21,22 .…”