人类和猪磨牙尖折断处的牙釉质微观结构与微应变

Enamel microstructure and microstrain in the fracture of human and pig molar cusps.

作者信息

Popowics T E, Rensberger J M, Herring S W

机构信息

Department of Oral Biology, University of Washington, Seattle, Washington, DC 98195, USA.

出版信息

Arch Oral Biol. 2004 Aug;49(8):595-605. doi: 10.1016/j.archoralbio.2004.01.016.

DOI:10.1016/j.archoralbio.2004.01.016

PMID:15196977

Abstract

The role of microstructure in enamel strain and breakage was investigated in human molar cusps and those of the pig, Sus scrofa. Rosette strain gauges were affixed to cusp surfaces (buccal human M3, n=15, and lingual pig M1, n=13), and a compressive load was applied to individual cusps using an MTS materials testing machine. Load and strain data were recorded simultaneously until cusp fracture, and these data were used to estimate enamel stresses, principal strains, and stiffness. Fractured and polished enamel fragments were examined in multiple planes using scanning electron microscopy (SEM). Human cusp enamel showed greater stiffness than pig enamel (P=0.02), and tensile stress at yield was higher (17.9 N/mm2 in humans versus 8.9 N/mm2 in pigs, P=0.06). SEM revealed enamel rod decussation in both human and pig enamel; however, only pig enamel showed a decussation plane between rod and inter-rod crystallites. Human inter-rod enamel was densely packed between rods, whereas in pig enamel, inter-rod enamel formed partitions between rows of enamel rods. Overall, human enamel structure enabled molar cusps to withstand horizontal tensile stress during both elastic and plastic phases of compressive loading. In contrast, pig cusp enamel was less resistant to horizontal tensile stresses, but appeared to fortify the enamel against crack propagation in multiple directions. These structural and biomechanical differences in cusp enamel are likely to reflect species-level differences in occlusal function.

摘要

在人类磨牙尖和猪（野猪）的磨牙尖中研究了微观结构在牙釉质应变和破损中的作用。将玫瑰花结应变片粘贴在牙尖表面（人类颊侧M3，n = 15；猪舌侧M1，n = 13），并使用MTS材料试验机对单个牙尖施加压缩载荷。同时记录载荷和应变数据，直到牙尖断裂，这些数据用于估计牙釉质应力、主应变和刚度。使用扫描电子显微镜（SEM）在多个平面上检查断裂和抛光的牙釉质碎片。人类牙尖牙釉质比猪牙釉质表现出更大的刚度（P = 0.02），屈服时的拉伸应力更高（人类为17.9 N/mm²，猪为8.9 N/mm²，P = 0.06）。SEM显示人类和猪的牙釉质中都存在釉柱交叉；然而，只有猪牙釉质在釉柱和柱间质微晶之间显示出一个交叉平面。人类的柱间质牙釉质在釉柱之间紧密堆积，而在猪牙釉质中，柱间质牙釉质在釉柱排之间形成分隔。总体而言，人类牙釉质结构使磨牙尖在压缩载荷的弹性和塑性阶段都能承受水平拉伸应力。相比之下，猪牙尖牙釉质对水平拉伸应力的抵抗力较弱，但似乎能增强牙釉质抵抗裂纹向多个方向扩展的能力。牙尖牙釉质的这些结构和生物力学差异可能反映了物种在咬合功能方面的差异。