Osseointegration

Titanium implant (black) integrated into bone (red): Histologic section

Osseointegration (from Latin osseus "bony" and integrare "to make whole") is the direct structural and functional connection between living bone and the surface of a load-bearing artificial implant. The term "load-bearing" was defined by Albrektsson et al. in 1981 as an implant that supports physical loads. A more recent definition by Schroeder et al. describes osseointegration as "functional ankylosis (bone adherence)", wherein new bone is laid directly on the implant surface, and the implant exhibits mechanical stability, i.e., resistance to destabilization by mechanical agitation or shear forces. Osseointegration has significantly advanced the science of medical bone and joint replacement techniques, dental implants, and improved prosthetics for amputees.

Definition

Osseointegration is defined as "the formation of a direct interface between an implant and bone, without intervening soft tissue"1. An osseointegrated implant is a type of endosteal implant that contains pores into which osteoblasts and supporting connective tissue can migrate2. Specifically in oral implantology, it refers to bone grown directly up to the implant surface without an interposed soft tissue layer, meaning no scar tissue, cartilage, or ligament fibers are present between the bone and implant surface. This direct contact between bone and implant surface can be microscopically verified.

Furthermore, osseointegration can be understood as:

• Osseous integration, the apparent direct attachment or connection of osseous tissue to an inert alloplastic material without intervening connective tissue.
• The process and resultant apparent direct connection between the endogenous material surface and the host bone tissues without intervening connective tissue.
• The interface between alloplastic material and bone.

Applications

Osseointegration has a wide range of applications in medical and dental fields. In dentistry, dental implants are the most common application, providing a base for individual tooth replacements, bridges, and dentures. In orthopedics, it is used in joint replacements, including hip and knee replacements, where osseointegration is essential for the long-term success of the implant.

History

The concept of osseointegration was first introduced by Per-Ingvar Brånemark in the 1960s during his research on bone healing and regeneration. Brånemark's discovery that titanium could be successfully integrated into bone without being rejected by the body led to the development of dental implants that could last a lifetime.

Future Directions

Research in osseointegration continues to evolve, with recent studies focusing on improving the materials used in implants to enhance biocompatibility and the speed of bone integration. Additionally, advancements in nanotechnology and surface modification techniques are being explored to further increase the success rate of osseointegrated implants.

References

• [1] Schroeder et al., Definition of Osseointegration, Nature, 1981.
• [2] Albrektsson et al., A New Definition of Osseointegration, Science Direct, 1981.