In this prospective study, 46 edentulous patients who had undergone traditional denture optimization therapy without success were treated with osseointegrated implants according to the surgical protocol described by Dr. P.I. Branemark. Two hundred seventy-four implants were placed in 49 dental arches--43 mandibles and six maxillae. At the time of writing, 4 to 9 years after insertion of the implants, 244 or 89.05% remained osseointegrated. Of the 262 implants in place more than 5 years, 232 or 88.55% were still integrated. The implant success criteria developed in this clinical study endorsed the predictably favorable outcome of the Branemark technique.