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. 2013 May:21:178-84.
doi: 10.1016/j.jmbbm.2013.02.020. Epub 2013 Mar 14.

Indentation damage and crack repair in human enamel

C Rivera  1 , D Arola, A Ossa
Affiliations

Indentation damage and crack repair in human enamel

C Rivera et al. J Mech Behav Biomed Mater. 2013 May.

Abstract

Tooth enamel is the hardest and most highly mineralized tissue in the human body. While there have been a number of studies aimed at understanding the hardness and crack growth resistance behavior of this tissue, no study has evaluated if cracks in this tissue undergo repair. In this investigation the crack repair characteristics of young human enamel were evaluated as a function of patient gender and as a function of the distance from the Dentin Enamel Junction (DEJ). Cracks were introduced via microindentation along the prism direction and evaluated as a function of time after the indentation. Microscopic observations indicated that the repair of cracks began immediately after crack initiation and reaches saturation after approximately 48 h. During this process he crack length decreased up to 10% of the initial length, and the largest degree of reduction occurred in the deep enamel, nearest the DEJ. In addition, it was found that the degree of repair was significantly greater in the enamel of female patients.

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Figures

Figure 1
Figure 1
Schematic diagram of a sectioned molar embedded in cold cured epoxy for the indentation analysis. Note that this is a portion of the tooth crown that is mounted to permit the axis of indentations to be parallel to the enamel prism axes.
Figure 2
Figure 2
Indentation of the enamel for determination of the apparent fracture toughness and crack repair.
Figure 3
Figure 3
Effect of indentation load on the Vickers hardness of enamel. a,b) indentations at 0.1 N and 3 N, respectively, and viewed after etching to reveal enamel prisms. Note that the relative size of the indent at loads of 0.1 μN (a) is on the order of the prism diameter, whereas those at larger loads (b) span a group of prisms. c) indentation size effects on the hardness distribution
Figure 4
Figure 4
Properties related to the indentation fracture resistance of enamel. The distributions are shown from the occlusal surface (x/d = 0) to the DEJ (x/d = 1).
Figure 5
Figure 5
Crack length and repair efficiency of enamel from male and female patients depending on time after introduction of the indent and depth.
Figure 6
Figure 6
SEM image of a selected indentation crack. Arrows point towards organic ligaments spanning the crack faces which help on the crack repair process.
See this image and copyright information in PMC

References

    1. Ang SF, Schulz A, Pacher Fernandes R, Schneider GA. Sub-10-micrometer toughening and crack tip toughness of dental enamel. J Mech Behav Biomed Mater. 2011;4(3):423–32. - PubMed
    1. Arola D, Bajaj D, Ivancik J, Majd H, Zhang D. Fatigue of Biomaterials: Hard Tissues. Int J Fatig. 2010;32(9):1400–1412. - PMC - PubMed
    1. ASTM C 1327–96a. Standard Test Method for Vickers Indentation Hardness of Advanced Ceramics. American Society of Testing and Materials; West Conshohocken, Pennsylvania:
    1. Bajaj D, Arola D. On the R-curve behaviour of human tooth enamel. Biomaterials. 2009;30:4037–4046. - PMC - PubMed
    1. Bajaj D, Arola D. Role of prism decussation on fatigue crack growth and fracture of human enamel. Acta Biomater. 2009;5(8):3045–56. - PMC - PubMed

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