Titanium Biocompatibility and Osseointegration
- Titanium is the most biocompatible metal due to its resistance to corrosion from bodily fluids.
- It is bio-inert and has a high capacity for osseointegration.
- Titanium implants have a high fatigue limit and last longer compared to alternatives.
- High energy surfaces induce angiogenesis during osseointegration.
- Titanium implants physically bond with bone, eliminating the need for adhesives.
- Surface properties of biomaterials play a crucial role in cellular response and osseointegration.
Surface Properties of Titanium
- Titanium's protective oxide film prevents reactions between the metal and the surrounding environment.
- The oxide film is strongly adhered, insoluble, and chemically impermeable.
- Titanium can have different standard electrode potentials depending on its oxidation state.
- The adsorption of hydroxyl groups, lipoproteins, and glycolipids on titanium changes its interaction with the body.
- Alloying elements in the passive layer add biocompatibility and corrosion resistance.
Surface Coating and Adsorption
- Cellular binding to a titanium oxide surface occurs naturally.
- Titanium alloys like Ti-Zr and Ti-Nb release zirconium and niobium ions, which are added to the passivation layer.
- The alloying elements in the passive layer improve biocompatibility and corrosion resistance.
- Surface coating optimization can enhance the wetting of titanium implants.
- Grafted polymers on the metal surface promote cell binding and increase the contact area for integration.
- Corrosion of the titanium oxide film increases with mechanical abrasion.
- Titanium and its alloys can undergo hydrogen absorption, leading to material failure.
- Hydrogen embrittlement and TiH formation can occur under fretting-crevice corrosion conditions.
Mechanical Properties of Titanium
- Titanium has excellent mechanical properties, including high strength and low density.
- It has a high tensile strength, allowing it to withstand significant mechanical stress.
- Titanium is highly resistant to fatigue and corrosion, making it suitable for long-term implantation.
- It has a low modulus of elasticity, which helps to reduce stress shielding and promote bone remodeling.
- Titanium alloys can be tailored to have specific mechanical properties.
Medical Applications of Titanium
- Titanium is one of the most commonly used metals in medical and dental applications.
- It is biocompatible and well-tolerated by the human body.
- Titanium implants have a high success rate, with long-term survival rates exceeding 95%.
- The use of titanium in medical devices and implants has revolutionized orthopedics and dentistry.
- Other metals, such as stainless steel and cobalt-chromium alloys, are also used in medical applications.
Titanium was first introduced into surgeries in the 1950s after having been used in dentistry for a decade prior. It is now the metal of choice for prosthetics, internal fixation, inner body devices, and instrumentation. Titanium is used from head to toe in biomedical implants. One can find titanium in neurosurgery, bone conduction hearing aids, false eye implants, spinal fusion cages, pacemakers, toe implants, and shoulder/elbow/hip/knee replacements along with many more. The main reason why titanium is often used in the body is due to titanium's biocompatibility and, with surface modifications, bioactive surface. The surface characteristics that affect biocompatibility are surface texture, steric hindrance, binding sites, and hydrophobicity (wetting). These characteristics are optimized to create an ideal cellular response. Some medical implants, as well as parts of surgical instruments are coated with titanium nitride (TiN).
