Despite the achievements of modern periodontology, partially or completely edentulous mouths are unavoidable. The rehabilitation of such patients is a great challenge in oral health care. The state of the art of osseointegrated implants according to Brånemark is described. Both full dentures and fixed partial dentures are discussed, with special emphasis on microbiological issues. The hypotheses are supported by substantial published evidence, and the problems discussed are further exemplified by a number of clinical case reports. The authors conclude that osseointegration according to Brånemark is an effective long-term method for oral rehabilitation, and that the failure rate is low. One reservation that has to be made is that we are still waiting for the results of long-term studies on patients who are edentulous due to advanced adult periodontitis. This is the only way to evaluate in more detail the robustness of the tissues around the implantation site.