Nonsubmerged implants in the treatment of the edentulous lower jaw: a 5-year prospective longitudinal study of ITI hollow screws.
BACKGROUND: Although most implant systems have been designed for a two-stage surgical technique, a one-stage surgical technique has always been advocated for the ITI Dental Implant System (Straumann AG, Waldenburg, Switzerland). A new generation of ITI implants was presented in 1988 and included a hollow cylinder, a hollow screw, and a solid screw. PURPOSE: The goal of this study was to evaluate the one-stage surgical technique in connection with the ITI hollow screw in a longitudinal study over 5 years. MATERIALS AND METHODS: Forty-six patients with edentulous lower jaws were supplied with ITI hollow-screw implants. Patients who requested an overdenture (n = 18) had four implants inserted; those who requested a fixed bridge (n = 28) had five to six implants. The patients have been followed annually for 5 years. There was a dropout of three patients (6.5%); one patient did not want to cooperate, one moved from the area, and one was deceased. The clinical examinations included bridge removal for evaluation of the individual implant stability in connection with the 1-, 3-, and 5-year examinations. Radiographic examinations were performed with intraoral radiographs and the long-cone technique. RESULTS: The survival rate after 5 years was 95.7%. The success rate (in which implants undergoing treatment of peri-implantitis were not counted as successes) was 91.4%. The mean marginal bone loss between the baseline and the 1-year examination was 0.1 mm and between the 1- and 5-year examinations was 0.1 mm. These changes in marginal bone level were not significant. CONCLUSIONS: The success rate of ITI hollow-screw implants in the edentulous mandible was 91.4% after a 5-year observation period. There was no significant change in mean bone level between the loading of the implants and the 5-year examination. Peri-implantitis was diagnosed in three patients with poor oral hygiene, and it affected six implants. Five of these failed in spite of treatment.