The clinical effectiveness of 6 mm diameter implants

Background: Five- and 6 mm diameter screw-type endosseous implants have been used for the last decade. While some studies have reported very promising results (94% to 98% success rate), others have demonstrated survival rates below those clinically acceptable (75% to 87%). Moreover, such implants have been associated with increased cervical bone resorption and thread exposure. Methods: Between June 1999 and July 2003, 43 patients received treatment with 6 mm diameter tapered hydroxyapatite (HA)-coated implants. A total of 45 implants were placed. All patients were recalled annually after implant exposure. One patient was lost to follow-up after I year. Forty-four implants were evaluated at the recall examinations. All implants supported a fixed prosthesis; in the majority of patients (35 implants), it was a single-tooth fixed prosthesis. The mean loading time was 23.4 months (range, 1 to 54 months). Results: No implants were lost during the loading period. The overall survival rate was 100%. Crestal bone remodeling was examined using periapical radiographs. After a mean of 23.4 months in function, only one implant presented bone loss beyond the first thread. Conclusions: This study showed that high survival rates can be obtained after prosthetic treatment with 6 mm-wide tapered HA-coated implants. Long-term prospective studies are needed to confirm these results.