NARROW-DIAMETER IMPLANTS SUPPORTING FIXED PROSTHESES IN THE POSTERIOR MANDIBLE: 5-YEAR REPORT ON A PROSPECTIVE SINGLECOHORT STUDY

PURPOSE. To assess the 5-year post-loading outcomes of narrow-diameter implants supporting fixed prostheses in the posterior mandible of patients with horizontal bone atrophy.

MATERIALS AND METHODS. A total of 42 partially edentulous patients who needed a fixed implant-supported prosthesis in a posterior mandible presenting a thin alveolar crest were enrolled in this study. One hundred and twenty-four narrow-diameter implants (2.75 and 3.25 mm) were placed and splinted with a fixed prosthesis. One implant was required to replace each missing tooth. Patients were followed-up for a period of 5 years. Outcomes considered were: implant failures, any complications, and marginal bone level changes.

RESULTS. Of the 42 patients, three dropouts were recorded (3/42, 7.1%). At the 5-year follow- up, five implants had failed in 4 patients: two 2.75 mm diameter implants and three 3.25 mm diameter implants. The implant survival rate was 90.5% at the patient level and 95.9% at the implant level. Peri-implant bone resorption was 0.47 mm (95% CI: 0.29; 0.65) one year after loading and 1.19 mm (95% CI: 0.81; 1.58) five years after loading. The marginal bone level changes were not significantly different between the two diameters used (P = 0.579). Of the 42 patients, eight (19.04%) experienced complications during the follow up.

CONCLUSIONS. Five years after loading, both narrow-diameter implants (2.75 to 3.25 mm) placed in posterior mandibles showed high survival and low complication rates, so can be considered a valid alternative to horizontal bone augmentation. However, longer follow- ups on a larger sample are needed.