• Homepage
• Research

  • Research Group
  • Photo Gallery
  • Projects
  • Thesis
  • Scientific Meetings
  • Publications
• Facilities
  • Electron Microscope Investigations
  • X-Ray Fluorescence and Diffractometer Analysis
  • Molecular Bond Characterization
  • Powder and Bulk Materials Characterizations
  • Thermal Analysis
  • Colour Measurements
  • Refractometer
  • Microscopes
  • Microdardness Test
• Courses

  • Materials Science I
  • Biomaterials
  • Bioceramics
• Contact
• Photo Gallery

THE IMPROVEMENT OF TITANIUM REINFORCED HYDROXYAPATITE FOR BIOMEDICAL APPLICATIONS

When a defect occurs in a biological system, it may not be able to resolve some of the pathologies by using traditional surgical methods or leaving it to it’s natural healing process. Thus, biomedical implants could be used to undergo the function of resolving similar problems.

Bone is a natural composite material made up of collagen fibers threading through hydroxyapatite [Ca10(PO4)6(OH)2]. Hydroxyapatite (HA) makes up about 70 % of bone structure and essentially all of the enamel in teeth. Materials that are ideal to be used as implant materials should withstand physiological and mechanical loads without the formation of any substantial fracture or toxic reaction. There shouldn’t be an interaction with the material that will cause a toxic reaction in the body. That is why, in order to satisfy criteration’s successful implant materials, composites could be developed.

Ceramics preferably used at medical applications as an implant material are mostly HA based. HA, the main mineral component of natural bone is form of a calcium phosphate. It is a material stiffer than bone having lover fracture toughness and is highly attractive for hard tissue implants. Applications of HA are restricted to areas free of dynamic load bearing because HA is known for its weakness and brittleness. Titanium by being most biocompatitable metal, when added to HA could improve mechanical properties. Moreover, titanium and it’s alloys have been extensively preferred as implant materials for over 30 years due to their excellent mechanical properties and high corrosion resistance. There has not been any evidence gained to suggest that titanium causes hypersensivity effects. Biocomposite materials lend themselves to long term hard tissue implants because of their perfect chemical stability, mechanical strenght, wear, corrosion resistance and biocompability. As a result of very limited supply of autograph material and potential health risks associated with use of allografts, HA and their composites have become increasingly important as bone implant materials.

The objective of this study is; reinforcing hydroxyapatite with titanium in order to obtain a structure that is both biocompatible and has high mechanical properties suitable for load bearing areas in the body. First of all, freshly extracted human teeth were calcinated at 850 º C to obtain hydroxyapatite from the dentine matter of teeth. Dentine derived HA were wet milled with acetone and zirconia balls only powders between 100-150 µ were mixed by 5, 10 and 15 wt % with titanium powders having particle sizes between 45-100 µm. After mixing the powders, they were compacted under 350 MPa and subjected to sintering at 1100, 1200 º C and 1300 º C for three hours. The Vickers micro hardness, Archimedes density and compression tests were carried out the materials were characterized by scanning electron microscopy and X-Ray analysis.

The specimen which demonstrated optimum results were subjected to an in-vitro experiment for 5 weeks. This experiment revealed that HA-Ti containing 5-10 % Ti sintered at 1300 º C, when kept in a simulated body fluid, develop a β-Ca3(PO4)2 phase improving bone bonding characteristics of the composite.