Aim: The aim of this 1-year prospective cohort study was to evaluate the outcomes and complications of immediately loaded mini dental implants used for stabilizing mandibular overdentures in edentulous patients wearing conventional complete dentures. Materials and methods: Thirty patients received mandibular conventional complete dentures that were subsequently retained by 4 immediately loaded mini dental implants placed in the interforaminal region. Overdenture success, implant success and biological and prosthetic complications were evaluated after the first year of service. Quality of life using the Oral Heath Impact Profile (OHIP)- EDENT test, satisfaction with dental prosthesis and chewing efficiency using questionnaires and a Visual Analogue Scale (VAS) were evaluated twice: after they had received mandibular complete dentures, and again after they had received mandibular overdentures. Results: After 1 year, no overdenture failed and 2 implants did not osseointegrate, resulting in a 98.3% success rate for loaded implants and 95.9% for total implants used (3 out of 123 were not loaded due to fracture). A flap surgical approach was performed in 7 patients, 3 implants fractured during insertion, 3 overdentures fractured, occlusion balancing was necessary for 11 dentures and relining for 8. Implant rehabilitation provided significant improvement in quality of life, stability, comfort, chewing and speaking ability while no significant differences were found in quality of maintenance of hygiene and for aesthetics. Conclusions: Mini dental implant retained overdentures can be a successful therapeutic procedure for treating mandibular edentulism that improves quality of life, patient satisfaction and chewing ability in patients wearing maxillary dentures. Longer follow-ups are needed to validate this therapy in the medium and long-term. Keywords: lower complete denture, lower overdenture, mini dental implants, patient satisfaction, quality of life