Titanium Alloys in Biomedicine Introduction 2
In dentistry, titanium has been used in post, screw, abutment, braces, instruments, and temporary devices. The devices used in dentistry and orthodontics are subject to less mechanical demands than those in orthopedics, but the oral cavity is a more hostile environment from a chemical and biological perspective. Constant changes in pH, the release of aggressive chemicals from food and beverages, the presence of tartar/plaque, and the proliferation of pathogens such as bacteria can significantly reduce the chances of clinical success and the expected life span of biomaterials. In most cases, the chemical inertness of titanium has proven to be up to the task, but there are occasional concerns about the potential release of harmful alloying elements, and allergic reactions have also been reported, especially for titanium-nickel alloys.
Like orthopedic devices, trauma devices such as screws, plates, and intramedullary nails are subject to such extreme stresses that surgeons prefer more durable stainless steel to titanium. In addition, unlike most components used in joint replacements, which are typically not removed until the healing process is complete, perfectly osseointegrated titanium devices are difficult to remove without damaging surrounding tissue.
Although spinal implants are technically a subset of orthopedic implants, they have unique characteristics and will be considered a separate category in this article. Spinal implants that can use titanium or titanium alloys include pedicle screws, rods, intervertebral implants, artificial discs, and all hooks and wires used to correct spinal deformities such as scoliosis, so depending on the application, the device can be articulating (artificial discs) or locking (intervertebral implants), holding the bones in place and behaving like a joint prosthesis or a trauma device. Although in most cases spinal implants are subject to relatively low mechanical stresses, they face complex anatomy, great variability between