Is Marginal Bone Loss around Oral Implants the Result of a Provoked Foreign Body Reaction?

Abstract

When a foreign body is placed in bone or soft tissue, an inflammatory reaction inevitably develops. Hence, osseointegration is but a foreign body response to the implant, which according to classic pathology is a chronic inflammatory response and characterized by bone embedding/separation of the implant from the body. The aim of this paper is to suggest an alternative way of looking at the reason for marginal bone loss as a complication to treatment rather than a disease process. The present paper is authored as a narrative review contribution. The implant-enveloping bone has sparse blood circulation and is lacking proper innervation in clear contrast to natural teeth that are anchored in bone by a periodontal ligament rich in blood vessels and nerves. Fortunately, a balanced, steady state situation of the inevitable foreign body response will be established for the great majority of implants, seen as maintained osseointegration with no or only very little marginal bone loss. Marginal bone resorption around the implant is the result of different tissue reactions coupled to the foreign body response and is not primarily related to biofilm-mediated infectious processes as in the pathogenesis of periodontitis around teeth. This means that initial marginal bone resorption around implants represents a reaction to treatment and is not at all a disease process. There is clear evidence that the initial foreign body response to the implant can be sustained and aggravated by various factors related to implant hardware, patient characteristics, surgical and/or prosthodontic mishaps, which may lead to significant marginal bone loss and possibly to implant failure. Admittedly, once severe marginal bone loss has developed, a secondary biofilm-mediated infection may follow as a complication to the already established bone loss. The present authors regard researchers seeing marginal bone loss as a periodontitis-like disease to be on the wrong track; the onset of marginal bone loss around oral implants depends in reality on a dis-balanced foreign body response.