Long-Term Follow-Up of 2.5-mm Narrow-Diameter Implants Supporting a Fixed Prostheses

Background: The use of narrow-diameter implants (NDIs; <3.75 mm) constitutes an alternative to bone augmentation procedure. Long-term evaluation of NDIs with a diameter <3.0 mm is still lacking. Purpose: Analyze the long-term outcomes of 2.5-mm NDIs splinted to regular-sized implants for supporting partial and complete fixed prostheses. Materials and Methods: Patients charts were retrospectively analyzed to select patients treated by the insertion of at least one 2.5-mm two-piece implant before July 2005. The study was based on the available charts (no patient was recalled). Patient's demographic data were described. The known implant length was used as a reference to calibrate the linear measurements of marginal bone loss on digital periapical radiograph. Implant details, survival and prosthetic complications were analyzed. Results: Thirty-seven 2.5-mm implants placed in 20 patients (mean age at surgery: 54.05 +/- 9.7 years) in maxilla and mandible were included and evaluated. The implants' mean follow-up time since insertion was 6.5 +/- 3.2 years (range 0 to 9.7 years). The follow-up time was more than 7 years for 22 implants. One implant failed due to lack of osseointegration. Two prosthetic complications (connector and porcelain fracture) occurred. The survival rate was 97.3% for implants and 92.0% for prostheses. The mean marginal bone loss at the mesial and distal aspect was 0.70 +/- 0.55 and 0.72 +/- 0.56 mm, respectively. Conclusions: When dental implants of 2.5 mm in diameter are splinted by a fixed prosthesis, long-term favorable outcomes could be obtained.