Objective: To clinically evaluate the behavior of BioHorizons® implants (BIOHORIZONS INTERNAL IMPLANT SYSTEM®) of 3,8 x 15mm or 3,8 x 12mm. They were immediately loaded and restored with O-ring abutment overdentures in the lower jaw. The behavior of the overdenture in terms of retention, stability, occlusion, cracks, fractures and defects in the attachments was also assessed. Materials and Methods: This pre-experimental study focused on the population of fully edentulous adults in the lower jaw, who attended the dental service clinics of a university. The sample was selected by convenience and consisted of 15 fully edentulous adults in the lower jaw. Subjects received two implants each and met the inclusion criteria for this research project. Results: A total of 30 implants were placed with 15 overdentures. An implant was lost due to the fact that the implant length and diameter was not suitable for the remaining bone available. The peri-implant evaluation showed no significant changes in the modified plaque index, gingival bleeding and gingival contour change or peri-implantitis. The results indicated the absence of fractures, cracks or changes in retention, occlusion or stability of the overdenture prosthesis. A satisfaction level of 100% was obtained during the controls undertaken. Conclusion: Despite the short observation period and the study limitations, the used implants were successful in the clinical and radiographic behavior during the immediate load of O-ring abutment overdentures. Therefore, the applied rehabilitation process could be a valid option in the treatment of edentulous patients in the lower jaw.