In a randomized prospective study, two implant systems were compared in forty consecutive patients treated for mandibular edentulism. The patients were randomly allotted for treatment by the Brånemark two-stage (submerged) system (BRS), or the ITI(R) one-stage (non-submerged) system. In all, 102 Brånemark selftapping implants and 106 ITI hollow screw implants were installed and all patients were treated with full bridges. Biological and prosthodontic parameters, complications, success rates, clinical efficacy, patient satisfaction and resource requirements were evaluated. No differences were found in plaque accumulation, bleeding or complications during the follow-up period. The BRS group showed deeper periimplant sulcus, less attached mucosa, larger bridge-mucosa distance and higher Periotest values. Prosthetic complications were not related to the configuration of the implant systems. After 3 years, the cumulative success rates were 97.9% and 96.8% for the Brånemark and ITI systems, respectively (difference not statistically significant). One implant in the BRS group had failed to osseointegrate at the time of abutment connection, and another was lost after 2 years due to progressive breakdown of bone. In the ITI group, three implants showed progressive bone loss after 1-3 years associated with periimplant infection. All 40 bridges were intact and remained stable throughout the study. There was general patient satisfaction, but about half the Brånemark patients reported difficulty in coping with the surgical procedures. Treatment time was similar for the two systems. It is concluded that both systems meet the current requirements for dental implant systems in the treatment of mandibular edentulism.

Fourteen Swedish teams outside the University of Gothenburg, each with minimally three years' experience in the Nobelpharma osseointegrated implant participated in a retrospective multiclinic study. The total number of consecutively inserted implants at the 14 clinics was 8139. The outcome of every implant was reported and all implant failures, irrespective of when they occurred, were published. The success criteria included absence of implant mobility, absence of radiolucent zones on x-rays, and an annual bone loss after the first year of less than 0.2 mm. In the mandible 334 implants were followed for five to eight years, with only three failures, for a success rate of 99.1%. In the maxilla 106 implants were followed for five to seven years, with a success rate of 84.9%. In irradiated and grafted mandibles, 56 implants were inserted and none was lost during a follow-up of up to five years. In the irradiated maxilla there were 16 implants inserted with three reported failures and in the grafted upper jaw 71 implants were inserted with 12 failures. The proportions of mandibular and maxillary sleeping implants were 0.8 and 0.3%, of patient drop-out implants 0.3 and 0.6%, and of patient death implants 0.9 and 1.2%, respectively. It was concluded that the osseointegrated implant, if inserted according to the guidelines of Brånemark, results in a very high degree of clinical success, thereby meeting any published oral implant success criteria.

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Soft tissues surrounding Brånemark titanium implants and single crystal sapphire implants were studied by conventional light- and transmission electron microscopy and by immunohistochemical markers for cytokeratin, protein S-100, Factor VIII and KP1. Histological sections of biopsies obtained from clinically healthy peri-implant mucosa were separated into a keratinized outer implant epithelium and an inner, non-keratinized epithelium, both immunoreactive towards cytokeratin. The inner implant epithelium terminated in a junctional epithelium, apically not a few cell layers thick. The cells adjacent to the implant showed a condensed cytoplasm, resembling hemidesmosomes. In the underlying connective tissue, rich in fibroblasts and factor VIII immunoreactive blood vessels, the bundles of collagen ran in different directions. S-100 immunoreactive nerve structures were more frequently found beneath the outer than the inner implant epithelium. Inflammatory cell infiltrates, some KP1 positive, were observed in the apical parts of the inner implant epithelium. S-100 positive Langerhans' cells were present mainly within the the outer implant epithelium. For the two implant systems, the techniques disclosed no qualitative structural differences in the adjacent soft tissues.

From January 1992 to March 1997, a total of 30 ITI hollow cylinder implants were installed to replace lost single maxillary incisor teeth. Conical abutments with cemented all-ceramic crowns were used in 10 cases and the Octa-abutment with screw-retained metallo-ceramic crowns in 19 cases. One implant failed due to postoperative infection, and was extracted a month after installation. After a mean observation time of 3.4 years, the cumulative success rate is 96.7%. Only minor bone loss has occurred around the implants, and there have been no other complications to date. The implant system fulfills the requirements for good function and esthetics.