Title: Posterior atrophic jaws rehabilitated with prostheses supported by 5×5 mm implants with a novel nanostructured calcium-incorporated titanium surface or by longer implants in augmented bone. Preliminary results from a randomised controlled trial.

Journal: Eur J Oral Implantol 2012;5(2):149-161

Authors: Pietro Felice, Roberto Pistilli, Maurizio Piattelli, Elisa Soardi, Valeria Corvino, Marco Esposito


Purpose: To evaluate whether 5×5 mm dental implants with a novel nanostructured calcium-incorporated titanium surface could be an alternative to at least 10×5 mm long implants placed in bone augmented with bone substitutes in posterior atrophic jaws.

Materials and Methods: Forty patients with atrophic posterior (premolar and molar areas) mandibles having 5-7 mm bone height above the mandibular canal and 40 patients with atrophic maxillas having 4 to 6 mm below the maxillary sinus, were randomised according to a parallel group design to receive one to three 5×5 mm implants or one to three at least 10×5 mm long implants in augmented bone at 2 centres. Mandibles were vertically augmented with interpositional bovine bone blocks and resorbable barriers and implants were placed after 4 months. Maxillary sinuses were augmented with particulated porcine bone via a lateral window covered with resorbable barriers and implants were placed simultaneously. All implants were submerged and loaded after 4 months with provisional prostheses. Four months later, definitive screw-retained of provisionally cement metal-ceramic or zirconia prostheses were delivered. Outcome measures were: prosthesis and implant failures as well as any complication.

Results: Patients were followed to 4 months post-loading with the exception of one patient subjected mandibular augmentation who had a multiple complications at and after grafting and subsequent graft failure who did not want to go ahead with the treatment. This case was considered a complete failure. There were no statistically significant differences in prostheses and implant failures. In mandibles, apart the complete graft failure, one 10×5 mm implant, failed at placement of the provisional prosthesis. In maxillas one 5×5 mm implant failed with its provisional crown 3 months after loading. All complications occurred before loading. Significantly more intra- and post-operative complications occurred at both mandibular and maxillary grafted sites: 16 augmented patients were affected by complications versus 8 patients treated with short implants in the mandible and 5 sinus lifted patients versus none treated with maxillary short implants.

Conclusions: Short-term data (4 months after loading) indicate that 5×5 mm implants with achieved similar results than longer implants placed in augmented bone. Short implants might be a preferable choice to bone augmentation especially in posterior mandibles since the treatment is faster, cheaper and associated with less morbidity, however 5-10 years post-loading data are necessary before making reliable recommendations.

Key words: inlay graft, bone substitutes, short dental implants, sinus lift, vertical augmentation