A 3-year post-loading report of a randomised controlled trial

gennaio 1, 2011 in Articoli, Impianti Corti

A 3-year post-loading report of a randomised controlled trial on the rehabilitation of posterior atrophic mandibles: short implants or longer implants in vertically augmented bone?

Marco Esposito, Gioacchino Cannizzaro, Elisa Soardi, Gerardo Pellegrino, Roberto Pistilli, Pietro Felice

  • Objectives: To evaluate whether 6.3mm-long implants could be a suitable alternative to longer implants placed in vertically augmented atrophic posterior mandibles.
  • Materials and methods: Sixty partially edentulous patients having 7 to 8mm of residual crestal height and at least 5.5mm thickness measured on CT scans above the mandibular canal were randomised according to a parallel group design either to receive 1 to 3 submerged 6.3 mm-long implants or 9.3 mm or longer implants (30 patients per group) placed in vertically augmented bone. Bone was augmented with interpositional anorganic bovine bone blocks covered by resorbable barriers. Grafts were left to heal for 5 months before implant placement. Four months later, provisional acrylic prostheses were delivered, and were then replaced after another 4 months by definitive metal-ceramic prostheses. Outcome measures were prosthesis and implant failures, complications, and radiographic peri-implant marginal bone level changes. All patients were followed up to 3 years after loading.
  • Results: Four patients dropped out, two from each group. The augmentation procedure failed in two patients and only 6.3 mm-long implants could be inserted. There were no statistically significant differences for prosthesis and implant failures. Three prostheses could not be placed or had to be remade in the short implant group versus 4 prostheses in the augmented group. Two short implants failed versus 3 long implants, all in different patients. There were statistically significantly more complications in augmented patients (22 complications in 20 augmented patients versus 5 compli- cations in 5 patients of the short implant group). Both groups gradually lost peri-implant bone in a statistically significant way at 4 months, and 1 and 3 years after loading. Three years after loading, patients of the short implant group lost an average of 1.24 mm of peri-implant bone compared with 1.76 mm in the long implant group. Short implants experienced statistically significantly less bone loss (0.52mm; CI 95% 0.20 to 0.83, P = 0.002) than long implants.
  • Conclusions: When residual bone height over the mandibular canal is between 7 and 8mm, 6.3mm short implants could be an interesting alternative to vertical augmentation since the treatment is faster, cheaper and associated with less morbidity. Longer follow-ups are needed to confirm these results.
  • Conflict-of-interest statement: Biomet 3i, manufacturer of the implants used in this investigation, partially supported this trial. However the data belonged to the authors, and Biomet 3i by no means interfered with the conduct of the trial or the publication of the results.