Controlled failure mechanisms toughen the dentino-enamel junction zone.
Controlled failure mechanisms toughen the dentino-enamel junction zone.
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DOI：
10.1016/j.prosdent.2005.08.013
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发表时间：
2005-10
期刊：
影响因子：
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通讯作者：
Shane N. White;V. G. Miklus;P. Chang;Angelo A. Caputo;H. Fong;Mehmet Sarikaya;Wen Luo;M. Paine;Malcolm L. Snead
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文献类型：
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作者：
Shane N. White;V. G. Miklus;P. Chang;Angelo A. Caputo;H. Fong;Mehmet Sarikaya;Wen Luo;M. Paine;Malcolm L. Snead
牙本质-牙釉质结合部（DEJ）持久地结合不同的硬脆牙釉质和坚韧柔韧的牙本质。与牙本质和牙本质之间的人工粘合相反，DEJ很少失败，除非它受到遗传性疾病的影响。DEJ增韧机制的知识对于理解遗传性疾病、人工修复体和牙齿之间连接的仿生工程，本研究的目的是鉴定特异性的DEJ-材料与方法在10名人体DEJ区的3个部位制作断裂韧性压痕，门牙使用光学显微镜和断裂韧性（MPa·m1/2）确定的失效模式进行了计算后，维氏显微压痕。然后使用单因素方差分析（α= 0.05）计算并比较现场平均值。DEJ没有发生灾难性的界面分层;相反，损伤分布在一个广泛的区域。主要的损伤模式涉及破裂和损伤分散在专门的第一次形成的釉质接近DEJ。多个，有些曲折，有时分支，裂纹蔓延和扩散的损害在一个广泛的区域相邻的釉质，而不是产生灾难性的界面故障。其他次要机制包括DEJ邻近牙本质中的短微裂纹（可能存在裂纹桥接）以及DEJ的塑性变形（无分层）。DEJ区断裂韧性约为0.8 ~ 0.9MPa·m1/2。结论DEJ区损伤主要发生在特化的第一次形成釉质的邻近层内，光学DEJ界面抵抗分层。
STATEMENT OF PROBLEMThe dentino-enamel junction (DEJ) durably unites dissimilar hard brittle enamel and tough flexible dentin. In contrast to artificial bonds between restorations and dentin, the DEJ rarely fails except when it is affected by inherited disorders. Knowledge of DEJ toughening mechanisms is important in understanding inherited disorders, in biomimetic engineering of junctions between artificial restorations and teeth, and in tissue-engineering a DEJ.PURPOSEThe purpose of this study was to identify specific DEJ-zone failure mechanisms and to survey the fracture toughness of the human DEJ zone.MATERIAL AND METHODSFracture toughness indentations were made at 3 sites across the DEJ zone of 10 human incisor teeth. Failure modes identified using optical microscopy and fracture toughness (MPa·m1/2) were calculated following Vickers microindentation. Site mean values were then calculated and compared using 1-way analysis of variance (α=.05).RESULTSThe DEJ did not undergo catastrophic interfacial delamination; instead, damage was distributed over a broad zone. The primary damage mode involved cracking and damage dispersion in the specialized first-formed enamel close to the DEJ. Multiple, somewhat convoluted and sometimes branching, cracks spread and diffused damage over a wide area of adjacent enamel rather than producing catastrophic interfacial failure. Other secondary mechanisms included short microcracks in the DEJ adjacent dentin with possible cracked bridging, as well as plastic deformation of the DEJ without delamination. A DEJ-zone fracture toughness of approximately 0.8 to 0.9 MPa·m1/2was calculated.CONCLUSIONDEJ-zone damage occurred primarily within the adjacent layer of specialized first-formed enamel, and the optical DEJ interface resisted delamination.