Hard and soft tissue reactions to ITI screw implants: 3-year longitudinal results of a prospective study

Between November 1988 and July 1992, a total of 320 ITI screw implants were consecutively placed in 109 patients. The patients were observed in a prospective longitudinal study focusing on implant success and clinical proof. Radiologic and clinical parameters were established at specific time intervals to examine hard and soft tissue reactions. Clinical parameters and the measured bone resorption were analyzed for possible correlation. Seventy-five percent (n = 82) of patients were edentulous, and 16% (n = 17) had distal extensions or extended edentulous spaces. Nine percent (n = 10) of the implants were for single-tooth replacement. During the follow-up period, a total of 10 patients with 29 implants dropped out, and 6 implants were lost as a result of failed osseointegration. The cumulative implant survival rate was 98.1%, and the cumulative implant success rate, using strict criteria for success, was 97.1% after 3 years. The mean bone loss between implant placement and prosthetic restoration was 0.8 mm. For the period between prosthetic treatment and the 3-year examination, a mean annual bone resorption of approximately 0.1 mm was observed. The periodontal parameters indicated a healthy soft tissue response during the time of observation. The statistical correlation analysis showed a definite relationship between the crevicular fluid volume and bone resorption. The results of this 3-year study indicate that ITI screw implants, with their nonsubmerged healing characteristic, can serve as a reliable foundation for implant-supported restorations.