Adherent Coatings of Calcium Phosphate Phases to Titanium Alloy Substrates for Use as Dental and Orthopaedic Implants
Racquel LeGeros, PhD
Professor and Associate Chair of Biomaterials and Biomimetics
Background and Description of Technology:
Various calcium phosphate (Ca-P) materials are available as bone graft or bone substitute materials for dental and orthopedic applications. They promote a direct attachment to the bone, thus developing a very strong interface between the two. However, a serious shortcoming of Ca-P materials is their low mechanical or fracture strength and they therefore cannot be used in load-bearing areas. Commercially pure titanium (cp-Ti) and titanium (Ti) alloy are metals possessing corrosion resistance, biocompatibility, durability, and strength. These metals are preferred for dental and orthopedic implants or prosthesis. However, these metals do not directly bond to the bone. Dental and orthopedic implants were therefore developed that combine the attachment of Ca-P coatings with the strength of cp-Ti, or Ti alloy. Plasma spraying is the coating deposition technique used for the commercial Ca-P-coated orthopedic and dental implants. This technique requires extremely high temperature. The high temperature and other operating parameters produce coatings of variable composition that may affect biological performance, coating stability and implant stability. It is therefore necessary to develop alternative coating methods, using lower temperature, which will provide coatings with reproducible, homogeneous composition.
Through chemical or electrochemical methods, cp-Ti or Ti alloy structures with various surfaces can be coated with adherent Ca-P phases. Coatings produced by these methods were characterized using x-ray diffraction, FTIR, scanning electron microscopy, tensile strength tests and solubility tests. The results demonstrated that highly adherent Ca-P coating of uniform compositions on Ti alloy substrates could be obtained at low temperatures. In addition, the originally deposited Ca-P phase can be transformed to other Ca-P phases. Bioactive molecules or drugs can be incorporated in the deposited calcium phosphate, allowing their controlled release and delivery in vivo.
Patent applications have been filed on the above technology and NYU is seeking commercial partners for dental and orthopaedic applications in forming a highly adherent coating of a desired calcium phosphate phase on a titanium-based substrate; as well as incorporating bioactive molecules and/or drugs into dental or orthopaedic implants.