Posterior non-atrophic jaws rehabilitated with 4x4 mm or by longer implants- 3-year RCT results

15798 Oral Communication Clinical Research – Surgery

Background

The fixed rehabilitation of atrophic edentulous jaws is challenging because of inadequate bone volumes. It has been shown by several RCTs that short implants can be successfully used as an alternative to more invasive bone augmentation procedures. A more recent clinical question is whether to use short implants also in those situations where long implants could have been used and how short could an implant be in order to be able to provide a good long-term outcome.

Aim/Hypothesis

To evaluate whether 4.0 x 4.0 mm dental implants could be an alternative to implants at least 8.5 mm-long, which were placed in posterior jaws in the presence of adequate bone volumes.

Material and Methods

One-hundred-fifty patients with posterior (premolar and molar areas) jaws having at least 12.5 mm bone height above the mandibular canal or 11.5 mm below the maxillary sinus, were randomised according to a parallel group design, in order to receive one to three 4.0 mm-short implants or one to three implants which were at least 8.5 mm long, at three centres. All implants had a diameter of 4.0 mm. Implants were loaded after 4 months with definitive screw-retained prostheses. Patients were followed up to 3 years after loading and outcome measures were prosthesis and implant failures, any complications and peri-implant marginal bone level changes.

Results

Seventy-five patients were randomly allocated to each group. At the 3-year post-loading evaluation five patients dropped-out from the long implant group and three from the short implant group. Up to 3-year post-loading, three patients lost one 4.0 mm-short implant each in comparison to two patients who lost one long implant each (P = 1). All failures occurred before loading, the failed implants were replaced and the delivery of two prostheses in each group was delayed of some months (P = 1). Five short-implant patients experienced six complications versus three complications in three long-implant patients (P = 0.719). There were no statistically significant differences in prosthesis failures, implant failures and complications. Patients with short implants lost on average 0.55 mm of peri-implant bone while patients with longer implants lost 0.61 mm. There were no statistically significant differences in bone level changes up to 3 years between short and long implants (P = 0.221).

Conclusion and clinical implications

Three-year after loading 4.0 x 4.0 mm-short implants achieved similar results as 8.5 x 4.0 mm-long or longer implants placed in posterior jaws in the presence of adequate bone volumes, however 5 to 10 years post-loading data are necessary before reliable recommendations can be made.