Biological and mechanical performance of TI-6AL-4V implant superplastically embedded with hydroxyapatite in animal / Hidayah Mohd Khalid

Hidayah , Mohd Khalid (2018) Biological and mechanical performance of TI-6AL-4V implant superplastically embedded with hydroxyapatite in animal / Hidayah Mohd Khalid. PhD thesis, University of Malaya.

	PDF (The Candidate's Agreement) Restricted to Repository staff only Download (1248Kb)
Preview	PDF (Thesis PhD) Download (4Mb) | Preview

Abstract

The bioactivity, biocompatibility and durability of two types of Ti-6Al-4V implants embedded with hydroxyapatite (HA), i.e. superplastic embedment (SPE) and superplastic deformation (SPD) implants are studied and compared with the as-received titanium. The samples were implanted subcutaneously on the backs of Sprague Dawley (SD) rat models for 1, 5 and 12 weeks. Wear tests were conducted to evaluate the durability of the HA layers. The HA layer thickness for the SPE and SPD samples increased from 249.1±0.6 nm to 874.8±13.7 nm, and from 206.1±5.8 nm to 1162.7±7.9 nm respectively, after 12 weeks of implantation. The SPD sample exhibited much faster growth of newly formed HA compared to SPE. The growth of the newly formed HA was strongly dependent on the degree of HA crystallinity in the initial HA layer. After 12 weeks of implantation, the surface hardness value of the SPE and SPD samples decreased from 661±0.4 HV to 586±1.3 HV and from 585±6.6 HV to 425±86.9 HV respectively. The decrease in surface hardness values was due to the newly formed HA layer that was more porous than the initial HA layer. However, the values were still higher than the substrate surface hardness of 321±28.8 HV. According to a histological evaluation, the SPD sample exhibited the best biocompatibility where the space left by the removed implant was almost completely filled with fibrous tissue. This suggests that more bioactive HA layer accelerated the body system’s response to the SPD sample. The wear test indicates that to some extent both SPE and SPD samples were able to withstand the durability test. The SPD sample adequately strengthened the newly-formed HA layer, indicating the best durability test result. This study confirms that the bioactivity, biocompatibility and durability results demonstrate the potential of the SPD sample for medical implant applications.

Actions (For repository staff only : Login required)