osteointegration

Osteointegration (often spelled osseointegration) is the direct structural and functional connection between living bone and the surface of an implant, with no intervening fibrous tissue. This integration enables load transfer from implant to bone and provides long-term stability for dental and orthopedic devices.

Historically, the concept emerged in the 1950s through work by Per-Ingvar Brånemark on titanium implants in bone. The term describes the formation of a tight bone-implant interface, resulting from bone remodeling around an implant surface.

Mechanistically, bone responds to implant surfaces through protein adsorption, osteoblast recruitment, and new bone deposition that fills interfacial gaps and bonds to the implant. Surface characteristics such as roughness, porosity, and coatings influence the extent of bone-implant contact and osseointegration rate. Titanium and its alloys are most commonly used due to biocompatibility, corrosion resistance, and favorable modulus. Zirconia and other ceramics are alternatives.

Common surface strategies include roughening (eg, sandblasted/acid-etched), coatings (hydroxyapatite), and nanoscale features, which aim to enhance initial stability and long-term integration. Design, surgical technique, loading protocols, and patient factors (bone quality, smoking, diabetes, osteoporosis) also affect outcomes.

Applications span dental implants and orthopedic devices such as joint arthroplasties and spinal instrumentation. Evaluation methods include radiographs, removal torque testing in research, histology showing bone-implant contact, and noninvasive measures such as resonance frequency analysis to assess implant stability.

Healing times vary by site but dental implants typically require several months before loading; early stability is followed by ongoing remodeling to maintain integration. A failure to achieve or maintain tight bone-implant contact can result in fibrous encapsulation and loss of stability.