Implant failure occurs at three distinct times: (1) at the time of (or shortly after) stage II surgery, (2) approximately 18 months after stage II surgery, and (3) more than 18 months after stage JI surgery. A few implantswlll fail to integrate. This failure will be identified at the time of (or shortly after) stage II surgery. Failure in this period may be related to a variety of factors.
Overheating of the bone during placement or failure to achieve a precise implant fit with primary stability may lead to failure of integration. Postoperative infection, excessive pressure on the integrating implant (with
movement of the implant), or wound-healing problems may also jeopardize implant integration. After loadingwith a prosthesis, bone loss will occur for approximately 18 months after which time a steady state will be achieved. During this 18-month period, additionalimplant failure may occur. Failure in this period is often associated with excessive biomechanical forces on the
implant or compromised periimplant soft tissue health resulting from lack of attached tissue, poor hygiene, orboth. Smoking is also associated with increased failure in this period and later periods. Late failure (i.e., more than HLmontl}s after placement of the prosthesis) may also occur. This is rare, and frequently the cause is not identifiable. In general, these implants are identified as “ailing” during routine recall. Progressive bone loss in spite of rigorous hygiene measures is often seen. A combined prosthodohtic and surgical intervention can often restore health to these ailing implants. Once periimplant bone loss has been identified, effortsshould initially be focused on optimizing hygiene. This may even require removal of the prosthesis to facilitate access. If bone loss is severe or progressive, surgical intervention
js necessary. The implant must be exposed surgically and all soft tissue adjacent to the “implant surface removed. The surface of the implant is then cleaned with hydrogen peroxide, after which citric acid is used. etracycline
powder is placed along the implant surface and into the bony defect, and the defect reconstructed with a graft. Healing for a minimum of4 months is allowed, after which the implant is uncovered and the prosthesis replaced.