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Hydroxyapatite degradation and biocompatibility

Wang, Haibo
http://rave.ohiolink.edu/etdc/view?acc_num=osu1087238429

Abstract Details

2004, Doctor of Philosophy, Ohio State University, Materials Science and Engineering.
Hydroxyapatite (HA) is widely used as a bioactive ceramics since it forms a chemical bonding to bone. The disadvantage of this material is its poor mechanical properties. HA can be degraded in body, which is the reason for its bioactivity, but too fast degradation rate could cause negative effects, such as macrophage present, particle generation, and even implant clinical failure. HA degradation rate will be greatly changed under many conditions: purity, HA form (i.e. bulk form, porous form, coating, or HA/polymer composites), microstructure, implant site, body conditions, etc. Although much work has been done in HA properties and application areas, the HA degradation behavior and mechanism under these different conditions are still not clear. In this research, three aspects of HA degradation have been studied: 1) Two very common impurities—Tri-Calcium Phosphate (TCP) and Calcium Oxide and their influences on HA degradation in vitro and in vivo, 2) influence of HA/polymer composite form on HA degradation, 3) HA material particle generation and related mechanism. From the in vitro and in vivo tests on bulk HA disks with various Ca/P ratios, HA degradation can clearly be found. The degradation level is different in different Ca/P ratio samples as well as in different test environments. In same test environment, non-stoichiometric HA samples have higher degradation rate than stoichiometric HA. HA/PMMA composite design successfully intensifies HA degradation both in vitro and in vivo. Grain boundary damage can be found on in vivo test samples, which has not been clearly seen on bulk HA degraded surface. HA particle generation is found in in vitro and in vivo HA/PMMA composite surface and in vivo bulk HA surface. Sintering temperature and time does affect HA grain size, and this affect HA degradation rate. Intergranular fracture is found in a several micron zone close to the Ca/P ratio 1.62 and 1.67 sample degraded surfaces. At Ca/P ratio greater than 1.667, after HA degradation in water, solution pH increases because of CaO presence.
John Lannutti (Advisor)
HA; HYDROXYAPATITE; implant; bone; Grain; ceramics; TCP

Recommended Citations

Citations

  • Wang, H. (2004). Hydroxyapatite degradation and biocompatibility [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1087238429

    APA Style (7th edition)

  • Wang, Haibo. Hydroxyapatite degradation and biocompatibility. 2004. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1087238429.

    MLA Style (8th edition)

  • Wang, Haibo. "Hydroxyapatite degradation and biocompatibility." Doctoral dissertation, Ohio State University, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=osu1087238429

    Chicago Manual of Style (17th edition)

osu1087238429
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© 2004, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.