When working with experimental oral implants at our bio-materials unit in Gothenburg during the 1960s, Brånemark et al.1 observed that there seemed to be a direct bone anchorage of the metallic devices. At that time proper methods were not available to verify the presence of direct bone anchorage, which is why the osseointegration of metal implants was not generally recognized until well into the 1980s.1 In Bråne-mark's early concept, osseointegration was a feature of c.p. titanium alone and characterized by an almost complete cortical bone encapsulation of the foreign material. This is in contrast to our present knowledge when, in fact, many look upon bone anchorage of metallic implants to be a primitive foreign body reaction that is observed to occur with numerous metals of varying biocompatibility.3 Furthermore, it is now understood that in reality the osseointegrated interface consists of a mixture of bone and soft tissue.4 The reason osseointegration (which at present is best defined as a stability concept)5 has survived as a relevant important contemporary term is related to the clinical superiority of osseointegrated craniofacial implants compared to soft tissue anchored devices that have a high failure rate. There is substantial evidence that a biocompatible metal such as c.p. titanium shows a stronger bony interface response than other metals, which lends support to the early concept.6 The osseointegrated, clinical implant, which is similar to the experimental version, does not have complete encapsulation in bone. With retrieved c.p. titanium oral implants, an average bony interface of about 80% has been reported.7 [ABSTRACT FROM AUTHOR]