Immediate Loading of Brånemark System® TiUnite™ and Machined‐Surface Implants in the Posterior Mandible: A Randomized Open‐Ended Clinical Trial

Abstract

Background: Immediate loading of osseointegrating implants shortens the treatment time and makes it possible to give the patient an esthetic appearance during the whole treatment period. A previous retrospective clinical study showed a success rate of 94.2% after 1 year of immediate loading of fixed partial constructions in the maxilla supported by machined-surface implants. The recently introduced Brånemark System® TiUnite™ (Nobel Biocare AB, Gothenburg, Sweden) surface has been shown to better maintain primary implant stability and to help achieve secondary stability earlier compared with the machined surface. Purpose: The aim of the present study was to compare TiUnite and machined-surfaced Brånemark System implants when applying immediate loading of partial fixed bridges in the posterior mandible. Materials and Methods: Forty-four patients were randomized for test and control therapy. In the test group, 22 patients received 66 Brånemark System TiUnite surface implants supporting 24 fixed partial bridges, all of which were connected on the day of implant insertion. In the control group, 22 patients received 55 Brånemark System machined-surface implants supporting 22 fixed partial bridges, which also were connected on the day of implant insertion. All constructions were two- to four-unit bridges. Bone quality and quantity were assessed. Radiographic examinations were performed on the day of surgery/loading and at the 1-year follow-up visit. Results: Three TiUnite and eight machined-surface implants failed during the first 7 weeks of loading. This resulted in a cumulative success rate of 95.5% for TiUnite surface implants after 1 year of prosthetic load in the posterior mandible. The corresponding cumulative success rate for machined-surface implants was 85.5%. When using the machined-surface implants, the number of failed implants was significantly higher in smokers and in bone quality 4 sites. Such findings were not seen with the use of TiUnite implants, despite the fact that there were more smokers and more implants placed in bone quality 4 in this group. The marginal bone resorption after 1 year of loading was on average 0.9 mm (SD 0.7 mm) with the TiUnite implants and 1.0 mm (SD 0.9 mm) with the machined implants. Conclusions: The present study demonstrated a 10% higher success rate following immediate loading of partial fixed bridges in the posterior mandible supported by TiUnite surface implants compared with success with machined implants. When using the machined implants, the number of failed implants was significantly higher in smokers and in bone quality 4 sites. Such findings were not seen following the use of TiUnite implants.