Engineered functional doped hydroxyapatite coating on titanium implants for osseointegration

Abstract

Titanium (Ti) and its alloys are commonly used implant materials in orthopedics due to their good corrosion resistance, mechanical properties, and biocompatibility. However, the inherent biological inertness of the Ti surface leads to insufficient osseointegration and antibacterial ability, which may result in implant failure. Hydroxyapatite (HA) is currently the most widely used material in the biomedical field. It is one of the bioactive coating materials because of its chemical and structural similarity to natural bone. At present, many techniques are used to deposit HA as a coating material on Ti implants. The stability of the HA coating is the most important factor in determining the success of the implant. In addition, biofunctional ions have been introduced into HA coatings to enhance functional performance. This article aims to present the crystal structure and characteristics of HA and the principle of doping ions into HA. The preparation methods for the deposition of HA functional coatings on Ti and its alloys are introduced and discuss its advantages and limitations. In addition, the coating of doped HA on the surface of Ti and its alloys to improve their surface properties for bone integration is also reviewed.