On the R-curve behavior of human tooth enamel.
On the R-curve behavior of human tooth enamel.
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DOI：
10.1016/j.biomaterials.2009.04.017
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发表时间：
2009-08
期刊：
影响因子：
14
通讯作者：
Arola, Dwayne D.
中科院分区：
文献类型：
--
作者：
Bajaj, Devendra;Arola, Dwayne D.
本研究采用增量裂纹扩展方法和常规断裂力学方法对牙釉质的抗裂纹扩展行为和断裂韧性进行了定量研究。结果表明，随着裂纹由外向内扩展，牙釉质的抗裂纹生长能力增加（r曲线上升），韧性的上升与牙本质-釉质交界处（DEJ）的距离有关。外牙釉质的表观韧性最低（0.67±0.12 MPa·m0.5），内牙釉质的生长韧性从1.13 MPa·m0.5/mm增加到3.93 MPa·m0.5/mm。断裂时最大裂纹扩展阻力（即断裂韧性Kc）为1.79 ~ 2.37 MPa·m0.5。内牙釉质的裂纹生长伴随着从微观到纳米尺度的一系列机制。内牙釉质的讨论促进了裂纹的偏转和扭转，导致裂纹尖端局部应力强度的降低。此外，外部机制如未断裂的组织韧带和有机基质的桥接促进了裂缝的闭合。由于棱镜松动引起的微裂纹也被认为是能量耗散的一个积极来源。综上所述，牙釉质独特的微观结构促进了裂纹生长韧性，其韧性大约是牙本质的三倍，是骨骼的十倍以上。
In this study the crack growth resistance behavior and fracture toughness of human tooth enamel were quantified using incremental crack growth measures and conventional fracture mechanics. Results showed that enamel undergoes an increase in crack growth resistance (i.e. rising R-curve) with crack extension from the outer to the inner enamel, and that the rise in toughness is function of distance from the Dentin Enamel Junction (DEJ). The outer enamel exhibited the lowest apparent toughness (0.67 ± 0.12 MPa·m0.5), and the inner enamel exhibited a rise in the growth toughness from 1.13 MPa·m0.5/mm to 3.93 MPa·m0.5/mm. The maximum crack growth resistance at fracture (i.e. fracture toughness (Kc)) ranged from 1.79 to 2.37 MPa·m0.5. Crack growth in the inner enamel was accompanied by host of mechanisms operating from the micro- to the nano-scale. Decussation in the inner enamel promoted crack deflection and twist, resulting in a reduction of the local stress intensity at the crack tip. In addition, extrinsic mechanisms such as bridging by unbroken ligaments of the tissue and the organic matrix promoted crack closure. Microcracking due to loosening of prisms was also identified as an active source of energy dissipation. In summary, the unique microstructure of enamel in the decussated region promotes crack growth toughness that is approximately three times that of dentin and over ten times that of bone.
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影响因子：
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作者：
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通讯作者：
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