Immediate loading of Brånemark implants: a 24-month follow-up of a comparative prospective pilot study between mandibular overdentures supported by Conical transmucosal and standard MK II implants.

The purpose of this prospective study is to compare the long-term outcome of immediately loaded implant-retained mandibular overdentures supported by four screw-type one-piece transmucosal implants with that of four screw-type two-piece implants inserted in the interforaminal area of the mandible and rigidly connected by a U-shaped curved A prospective pilot study was conducted with 10 patients receiving an implant-supported overdenture in the mandible. The patients were randomly assigned to two groups. In the control group (five patients), four standard Brånemark implants (MK II; Nobel Biocare AB, Gothenburg, Sweden), 3.75 mm large and at least 10 mm long, were sited anterior to the mental foramina, and four standard abutments (Nobel Biocare AB) for bar construction were immediately screwed to the implants. In the test group (five patients), four conical transmucosal implants (Nobel Biocare AB), 3.75 mm large and at least 9 mm long in the threaded part, were sited anterior to the mental foramina. Immediately after implant placement, a U-shaped gold or titanium bar was fabricated and implants were immediately loaded (within 24 h) in both groups with an implant-retained overdenture. The patients were followed up for a minimum of 24 months. Implants were evaluated at the time of immediate loading and at 12 and 24 months after prosthetic loading, with the following parameters: modified plaque index (MPI), modified bleeding index (MBI), and probing depth (PD). Periimplant bone resorption was evaluated on panoramic radiographs taken 12 and 24 months after the beginning of prosthetic loading. No significant differences were found between the two groups with regard to MPI, MBI, PD, and periimplant bone resorption at 12 and 24 months. The cumulative success rate of implants according to the criteria proposed by Albrektsson and colleagues was 100% in both groups after 2 years of functional loading. Results from this study demonstrated that the success rate for immediately loaded mandibular implants is similar to that obtained in cases of delayed loading and that there are no significant differences between results with two-piece implants and one-piece transmucosal implants.