Nanoindentation of Peri-Implant Bone and Dentin

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Abstract

Advances in the field of medicine have extended the average human life expectancy worldwide. As a result an increasing number of people will suffer from problems associated with their mineralized tissues and will require orthopedic and dental implants to restore their quality of life. Ideally, implants should have mechanical and structural properties compatible with the original mineralized tissue, and should also promote faster and stronger implant fixation. An improved understanding of the properties of mineralized tissues can help with the improvements of implants. This thesis focuses on improving the understanding of two aspects related to mineralized tissues and implant systems: the mechanical properties of peri-implant bone, and the mechanical, composition and structural properties of dentin and jawbone.

Studies have shown that local delivery of alendronate, an anti-osteoporosis drug, enhances new bone formation; however, the effects of the drug on the elastic modulus of new formed bone are unknown. In this study, nanoindentation was used to evaluate and compare the elastic modulus of peri-implant bone with and without the presence of alendronate. To better understand the properties of dentin and jawbone, nanoindentation and qualitative backscattered electron imaging were used to measure their elastic modulus, mineral content and volume fraction, and regression analyses were used to establish correlation between the properties.

In this thesis, mineralized tissue samples were collected from an animal study. To study the effects of alendronate on the elastic modulus of peri-implant bone, porous tantalum implants with three different coating treatments were used: non-coated (Ta), calcium phosphate coated (Ta-CaP), alendronate-immobilized-calcium-phosphate coated (Ta-CaP-ALN). The calcium phosphate coatings, with or without alendronate, increased the elastic modulus of peri-implant Ingrown Bone by approximately 22% (3GPa). The addition of alendronate did not significantly increase the elastic modulus of peri-implant.

For the study of dentin and jawbone, regression analyses showed that the elastic modulus of dentin is strongly dependent on the porosity and to a lesser extent on the calcium content. The elastic modulus of jawbone and dentin were compared and the elastic modulus of jawbone was generally higher than that of dentin while the mineral content was lower.

Cited Works (18)

Year	Entry
1997	Bloebaum RD, Skedros JG, Vajda EG, Bachus KN, Constantz BR. Determining mineral content variations in bone using backscattered electron imaging. Bone. May 1997;20(5):485-490.
1998	Weiner S, Wagner HD. The material bone: structure-mechanical function relations. Ann Rev Mater Sci. August 1998;28:271-298.
1995	Roschger P, Plenk H Jr, Klaushofer K, Eschberger J. A new scanning electron-microscopy approach to the quantification of bone-mineral distribution: backscattered electron image grey-levels correlated to calcium kα-line intensities. Scanning Microsc. March 1995;9(1):75-88.
2003	Burr DB, Miller L, Grynpas M, Li J, Boyde A, Mashiba T, Hirano T, Johnston CC. Tissue mineralization is increased following 1-year treatment with high doses of bisphosphonates in dogs. Bone. December 2003;33(6):960-969.
1990	Boyce TM, Bloebaum RD, Bachus KN, Skedros JG. Reproducible methods for calibrating the backscattered electron signal for quantitative assessment of mineral content in bone. Scanning Microsc. September 1990;4(3):591-600.
2002	Currey JD. Bones: Structure and Mechanics. Princeton, NJ: Princeton University Press; 2002.
2007	Duan K. Bisphosphonate-Containing Coatings for Bone Implants [PhD thesis]. Vancouver, BC: University of British Columbia; August 2007.
2005	Gupta HS, Schratter S, Tesch W, Roschger P, Berzlanovich A, Schoeberl T, Klaushofer K, Fratzl P. Two different correlations between nanoindentation modulus and mineral content in the bone–cartilage interface. J Struct Biol. February 2005;149(2):138-148.
1997	Rho J-Y, Tsui TY, Pharr GM. Elastic properties of human cortical and trabecular lamellar bone measured by nanoindentation. Biomaterials. 1997;18(20):1325-1330.
1992	Oliver WC, Pharr GM. An improved technique for determining hardness and elastic modulus using load and displacement sensing indentation experiments. J Mater Res. 1992;7(6):1564-1583.
1998	Roschger P, Fratzl P, Eschberger J, Klaushofer K. Validation of quantitative backscattered electron imaging for the measurement of mineral density distribution in human bone biopsies. Bone. October 1998;23(4):319-326.
1986	Boyde A, Maconnachie E, Reid SA, Delling G, Mundy GR. Scanning electron-microscopy in bone pathology: review of methods, potential and applications. Scan Electron Microsc. 1986;1986(4):1537-1554.
1993	Skedros JG, Bloebaum RD, Bachus KN, Boyce TM. The meaning of graylevels in backscattered electron images of bone. J Biomed Mater Res. January 1993;7(1):47-56.
1999	Zysset PK, Guo XE, Hoffler CE, Moore KE, Goldstein SA. Elastic modulus and hardness of cortical and trabecular bone lamellae measured by nanoindentation in the human femur. J Biomech. October 1999;32(10):1005-1012.
1988	Currey JD. The effect of porosity and mineral content on the Young's modulus of elasticity of compact bone. J Biomech. 1988;21(2):131-139.
1999	Currey JD. What determines the bending strength of compact bone? J Exp Biol. September 1999;202(18):2495-2503.
1999	Rho J-Y, Roy ME II, Tsui TY, Pharr GM. Elastic properties of microstructural components of human bone tissue as measured by nanoindentation. J Biomed Mater Res. 1999;A45(1):48-54.
1997	Majumdar S, Genant HK, Grampp S, Newitt DC, Truong V-H, Lin JC, Mathur A. Correlation of trabecular bone structure with age, bone mineral density, and osteoporotic status: in vivo studies in the distal radius using high resolution magnetic resonance imaging. J Bone Miner Res. January 1997;12(1):111-118.