The purpose of this multicenter study was to review the results of treatment and identify complications in edentulous patients who were treated with the transmandibular implant. A total of 190 patients were treated in four university departments. These patients presented for treatment with mandibular bone heights that ranged from 4 to 18 mm (mean, 10 mm). After postoperative periods that ranged from 3 months to 5 years, 182 of the 190 implants (95.8%) were stable and functional. Three implants were removed due to perioperative fractures in mandibles with 4 to 6 mm of bone height. Five were removed due to infection which occurred within the first 3 months after surgery. Reversible complications that developed in 22.2% of the patients were treated successfully. The 182 implants in function demonstrated no mobility and no infrabony pockets around any of the transmucosal posts. The results of this study demonstrate that the transmandibular implant has acceptable predictability and reliability for reconstruction of patients with severe atrophy of the mandibular alveolar process.