Narrow implants (2.75 and 3.25 mm diameter) supporting a fixed splinted prostheses in posterior regions of mandible: one-year results from a prospective cohort study

BACKGROUND Can multiple splinted narrow-diameter implants be used as definitive implants in patients with insufficient bone ridge thickness in posterior regions of the mandible? With this aim, we evaluated their outcomes in this set up to 1 year after loading. METHODS Forty-two patients with a mean age of 61.3 years old (range 49-73) in need of fixed prosthetic implant-supported rehabilitations in the posterior region of the mandible, presenting a thin alveolar crest, were selected. One hundred twenty-four narrow-diameter implants (2.75 and 3.25 mm diameter) were placed and splinted with a bridge. One implant for each missing tooth was requested to be inserted. Outcomes measured were implant survival, complications, and marginal bone level changes up to 1 year after loading. RESULTS At the 12-month follow-up, three implants failed. Two 2.75 mm diameter implants and one 3.2 mm diameter implant failed. The implant survival rate was 97.6%. Peri-implant bone resorption was 0.20 mm (CI 95% 0.14: 0.26) after 6 months and 0.47 mm (CI 95% 0.29; 0.65) after 12 months of loading, not different between 2.75 and 3.25 mm diameter groups (p = 0.786). Of the 42 cases, three had an episode of peri-implant mucositis (7.1%). CONCLUSIONS Within the limits of this study, preliminary short-term data (1 year post-loading) suggested that narrow-diameter implants (2.75 to 3.25 mm) can be successfully used as a minimally invasive alternative to horizontal bone augmentation in the posterior mandible. However, larger and longer follow-ups of 5 years or more are needed.