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TEM study of calcium phosphate precipitation on bioactive titanium surfaces
1Department of Mechanical Engineering, Hong Kong University of Science and Technology, Kowloon, Hong Kong.
Biomaterials
|January 24, 2004
Summary
Alkali- and heat-treated titanium forms octacalcium phosphate (OCP) and calcium titanate in simulated body fluid. OCP nucleates directly from amorphous calcium phosphate on titanium surfaces.
Area of Science:
- Biomaterials Science
- Materials Chemistry
- Surface Science
Background:
- Titanium is a widely used biomaterial for implants.
- Surface modification of titanium aims to enhance its bioactivity.
- Understanding calcium phosphate formation on treated titanium is crucial for osseointegration.
Purpose of the Study:
- To investigate the initial stages of calcium phosphate formation on alkali- and heat-treated titanium surfaces.
- To identify the specific calcium phosphate phases formed.
- To elucidate the nucleation and growth mechanisms.
Main Methods:
- Transmission electron microscopy (TEM) for high-resolution imaging.
- Electron diffraction for phase identification of precipitates.
- Immersion of treated titanium in revised simulated body fluid (R-SBF) mimicking physiological conditions.
Main Results:
- Octacalcium phosphate (OCP) was identified as the primary nucleating phase, not hydroxyapatite (HA).
- OCP crystals grew directly on the titanium surface without prior transformation.
- Amorphous calcium phosphate was observed as an intermediate phase.
- Calcium titanate was also detected on the treated surfaces.
Conclusions:
- Alkali and heat treatment promotes the direct nucleation of OCP on titanium surfaces.
- The formation pathway involves amorphous calcium phosphate and subsequent OCP growth.
- The role of calcium titanate in the bioactivity of these calcium phosphate layers requires further investigation.