In the past decade, the technique of osseointegration has elicited three general responses in the dental profession. The first and major response has been an enormous clinical satisfaction to resolve difficult prosthetic problems, as well to expand the scope and range of routing prosthetic therapy. A second, if minor, response has been an attempt to deny the documented apparent superiority of the osseointegrated method. The third response has been a very active marketing one, which led to the rapid proliferation of a large number of implant systems, all claiming osseointegration and comparable success to the originally introduced Swedish system. The purpose of this paper is to describe and analyze those clinical criteria which can be used by dentist and researcher to determine the long term success or failure of functioning dental implants. Some attempts had been made to identify criteria which reflected sound scientific consideration of long term host acceptance of functioning implants. However, these criteria where a reflection of the state of the art information as perceived by the authors at the time. It is therefore fair to add that the principle of osseointegration did not feature in our colleagues recommendations. Since it is an axiom that host response must be analyzed and understood if a clinical technique is to be successfully prescribed, we regarded our own and other's published data on clinical results with osseointegration as pivotal in the grouping of criteria which would comprise a reliable yardstick, easy to identify and apply, and which reflected assessment experiences in dental practice and research, mainly in the disciplines of periodontics and prosthodontics.(ABSTRACT TRUNCATED AT 400 WORDS)