Dental implants replace missing teeth, functioning as surgical components that integrate with the jawbone to provide a stable foundation for a prosthetic tooth. The success of this replacement relies heavily on the advanced materials used in their construction. These materials must be strong enough to withstand biting forces while also being completely compatible with the human body. The right material choice ensures a secure, lasting anchor that mimics the function of a natural tooth root.
The Foundation: Titanium and Osseointegration
The part of the implant surgically placed into the jawbone, known as the fixture, is most commonly made from titanium or a titanium alloy. Titanium is the material of choice due to its exceptional strength-to-weight ratio, high corrosion resistance, and remarkable biocompatibility. The metal does not degrade in the mouth and is well-tolerated by the body’s tissues.
The primary advantage of titanium is its ability to achieve osseointegration—the direct structural connection between the living bone and the implant surface. When the fixture is placed, bone cells attach directly to its surface, fusing the implant to the jawbone over three to six months. This fusion is supported by a stable, protective oxide layer that minimizes immune response and encourages bone growth.
The most widely used forms are commercially pure (CP) titanium and the Ti-6Al-4V alloy, which includes aluminum and vanadium. This alloy offers greater strength and durability, making it suitable for the high mechanical demands of tooth replacement. Surface modifications, such as roughening or specialized coatings, are often applied to the fixture to enhance the bone connection.
Connecting and Restoring: Abutment and Crown Materials
Above the fixture are the abutment and the crown, requiring materials chosen for mechanical strength and aesthetic appearance. The abutment serves as the connector, bridging the submerged implant post to the visible prosthetic tooth (crown). For areas requiring maximum durability, such as back molars, abutments are frequently made from titanium due to its proven strength.
When aesthetics are a concern, especially in the front of the mouth, other materials are selected for the abutment. Zirconia (zirconium dioxide) is increasingly used because its white color provides a natural look, preventing the gray shadow sometimes associated with metal showing through thin gum tissue. Gold is another metal option, chosen for its malleability, though it is less common today.
The crown, the final prosthetic tooth, is designed to look and function like a natural tooth. Common crown materials include porcelain fused to metal (PFM) and all-ceramic options. All-ceramic crowns, such as lithium disilicate or monolithic zirconia, offer superior aesthetics, closely matching the color and translucency of natural teeth. Zirconia crowns are popular for combining high strength and excellent aesthetics.
Zirconia and Other Emerging Options
While titanium remains the standard for the implant fixture, Zirconia has gained traction as a metal-free alternative. Zirconia (Y-TZP) is a high-performance ceramic whose color eliminates the aesthetic concern of a dark metal post showing through the gums. It is highly biocompatible and achieves osseointegration comparable to titanium, appealing to patients with metal sensitivities or those desiring a completely ceramic restoration.
Zirconia implants are often designed as a one-piece system, where the fixture and abutment are a single unit, simplifying the structure. However, zirconia’s mechanical properties, such as a higher elastic modulus and potential for low-temperature degradation, mean that its long-term clinical performance is still being monitored.
Beyond zirconia, researchers are exploring Polyether Ether Ketone (PEEK), a high-performance polymer. PEEK has an elastic modulus closer to that of natural bone, which could theoretically reduce stress on the surrounding jawbone compared to stiffer materials. While PEEK shows promise for biocompatibility, substantial modifications are needed before it can be widely used as a load-bearing fixture.