A dental implant system replaces a missing tooth from the root up. The system has three main components: the prosthetic crown, the abutment, and the post. The post, often called the fixture, is the cylindrical screw surgically placed into the jawbone to act as the artificial tooth root. This foundational component must withstand significant chewing forces and integrate seamlessly with the living bone tissue. The material composition of the post determines the long-term success and stability of the restoration.
The Primary Material: Titanium and Alloys
The vast majority of dental implant posts are made from titanium, a metal valued for its unique combination of strength and low density. This material is used either in its commercially pure (CP) form or as a specialized alloy. Commercially pure titanium (grades 1 through 4) is generally softer and less resistant to mechanical stress.
The material of choice for many modern implants is a titanium alloy known as Ti-6Al-4V, which corresponds to Grade 5 titanium. This alloy is composed of approximately 90% titanium, 6% aluminum, and 4% vanadium. The addition of aluminum and vanadium significantly increases the material’s hardness, tensile strength, and fatigue resistance compared to CP titanium. This enhanced mechanical integrity is beneficial in areas experiencing high biting forces, ensuring the implant endures the stresses of chewing.
Osseointegration and Biocompatibility
Titanium is widely used in medical devices due to its exceptional biocompatibility, meaning it interacts with the body without causing an adverse reaction. When exposed to air or bodily fluids, titanium spontaneously forms a thin, dense layer of titanium dioxide (TiO2) on its surface. This oxide layer, typically 5 to 10 nanometers thick, is chemically inert and protects the underlying metal from corrosion in the mouth.
This stable oxide layer facilitates the process known as osseointegration. Osseointegration is the direct, structural connection between the living bone and the surface of the implant. The surrounding bone tissue fuses with the implant surface because the titanium dioxide layer is recognized favorably by the body. This direct fusion anchors the post securely in the jaw, providing the necessary stability for the final restoration. The surface characteristics of the implant, such as texture and roughness, are often modified to enhance the speed and quality of this bone-to-implant contact.
The Metal-Free Option: Zirconia
While titanium is the standard, zirconia has become an increasingly popular metal-free alternative for implant posts. Zirconia is a high-performance ceramic material, specifically Zirconium Dioxide (ZrO2), which possesses a white, tooth-like color. This aesthetic quality is a major advantage, as it eliminates the risk of a dark gray hue showing through thin gum tissue, which can occur with titanium posts.
Zirconia is highly valued for its biocompatibility and is an excellent option for patients with known sensitivities or allergies to metals. Like titanium, zirconia is corrosion-resistant and capable of achieving osseointegration with the jawbone. Although titanium exhibits superior mechanical strength, modern zirconia implants are engineered to be highly fracture-resistant, offering comparable clinical survival rates to titanium posts. Surface treatments on zirconia posts are often employed to promote hard and soft tissue integration.