Purpose: The aim of this study was to ascertain whether simplifying mandibular overdenture treatment by using single-stage surgery and immediate prosthetic loading of a single implant will achieve acceptable implant success rates, functional improvement, and increased patient satisfaction. As part of this study, the Mk III Brånemark implant with an oxidized surface was compared to the classic machined Mk III Brånemark implant. Materials and Methods: Thirty-five patients (mean age: 68 years) with problematic mandibular dentures were treated. The primary complaints among the patients referred to the clinic for treatment were poor retention of the mandibular denture, instability, denture sores, and phonetic problems. Initially, patients were placed randomly into the "machined surface" or "oxidized surface" groups. A single implant was placed in the mandibular midline with high initial stability. A ball attachment was placed and the retentive cap incorporated into the existing denture. Reviews took place at 3, 12, and 36 months posttreatment. Clinical assessments, radiographs made with custom film holders, and stability measurements by both manual and resonance frequency analysis methods were recorded. All complications, failures, maintenance, and reasons for dropout were noted. Visual analog scale questionnaires were used to record patient satisfaction (analysis of variance: P .05). Results: Three of eight machined-surface implants failed, representing an unacceptably high failure rate (37.5%). The machined surface was therefore discontinued for this study. One machined and two oxidized-surface implants did not achieve sufficient primary stability to be immediately loaded, so they were treated with a two-stage delayed loading protocol. The 25 immediately loaded oxidized-surface implants were all classified as surviving at the 36-month recall. Patient satisfaction was very high with a significant increase in all comfort and functional parameters. Conclusions: Within the limitations of this study and research design, it appears that over a 3-year observation period, the immediately loaded single implant-retained mandibular overdenture, using an oxidized-surface implant and the existing prosthesis in a small group of prosthetically maladaptive patients, can provide a beneficial treatment outcome with a minimal financial outlay.