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PNAS:珐琅质如何拯救牙齿

已有 4046 次阅读 2009-4-16 23:21 |个人分类:生物力学|系统分类:科研笔记

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科学家发现,牙齿珐琅质的显微结构能够防止常年咀嚼形成的张力所产生的破坏,同时提供自我愈合能力,从而防止小的裂痕毁掉整颗牙齿。
 
据美国《科学》杂志在线新闻报道,在压力下,一枚牙齿会沿着较为脆弱的位面或簇——随着牙齿的生长形成于珐琅质中——产生裂纹。而复杂的簇网络能够有助于分散这些压力,同时防止任何一条裂缝长得过大。当研究人员将牙齿浸泡在水中达一周之久从而模拟湿润的口腔环境后,这些牙齿上的裂缝被富含蛋白质的液体所填满。这种像胶水一样的物质有助于稳固裂缝,防止更大的损伤,从而保证牙齿能够在未来几十年的使用中依然坚固。研究人员在4月13日的美国《国家科学院院刊》(PNAS)网络版上报告了这一发现。
 
《科学时报》 (2009-4-17 A3 国际)
 
更多阅读

Remarkable resilience of teeth

  1. Herzl Chaia,
  2. James J.-W. Leeb,c,
  3. Paul J. Constantinob,
  4. Peter W. Lucasb and
  5. Brian R. Lawnc,1

+Author Affiliations

  1. aSchool of Mechanical Engineering, Tel Aviv University, Tel Aviv 69978, Israel;
  2. bDepartment of Anthropology, George Washington University, Washington, DC 20052; and
  3. cCeramics Division, National Institute of Standards and Technology, Gaithersburg, MD 20899-8520
  1. Communicated by John W. Hutchinson, Harvard University, Cambridge, MA, March 5, 2009 (received for review November 20, 2008)

Abstract

Tooth enamel is inherently weak, with fracture toughness comparable with glass, yet it is remarkably resilient, surviving millions of functional contacts over a lifetime. We propose a microstructural mechanism of damage resistance, based on observations from ex situ loading of human and sea otter molars (teeth with strikingly similar structural features). Section views of the enamel implicate tufts, hypomineralized crack-like defects at the enamel–dentin junction, as primary fracture sources. We report a stabilization in the evolution of these defects, by “stress shielding” from neighbors, by inhibition of ensuing crack extension from prism interweaving (decussation), and by self-healing. These factors, coupled with the capacity of the tooth configuration to limit the generation of tensile stresses in largely compressive biting, explain how teeth may absorb considerable damage over time without catastrophic failure, an outcome with strong implications concerning the adaptation of animal species to diet.

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