The mandibular two-implant overdentures have been shown to be a highly successful treatment. However, for patients who desire a fixed prosthesis, overdentures may not satisfy their needs. This prospective study is aimed to compare (1) prosthetic outcome, (2) patient satisfaction, and (3) survival rates of Astra Tech implants between two-implant overdentures (2IOD) and three-implant fixed dentures (3IFD). Twenty complete edentulous patients were randomly and equally assigned to two groups. The implants were immediate loaded with a relined denture right after denture delivery and implant surgery. Ball attachments were inserted at 8 weeks and 3IFD delivered at 16 weeks. Patient satisfaction and panoramic radiographic survey were investigated at 6 and 12 months. Both treatments had significant and positive effect in patient satisfaction and quality of life. None of the fifty implants had failed at 6 months follow-up; therefore, implant survival rate was 100%. Prosthetic complications were generally few and easily manageable.