Purpose: This clinical trial aimed to evaluate the outcomes of implant-supported mandibular overdentures (ISMOs) using 2 different loading protocols. Materials and Methods: Two groups of 10 edentulous patients each were selected for the study. Each patient received 2 implants placed in the mandibular canine sites. After 1 week, ISMOs were delivered to the 10 patients in the test group, while conventional mandibular dentures were delivered to the 10 patients in the control group. The conventional prostheses were converted to ISMOs after 3 months. Treatment outcomes for the ISMOs were evaluated 1 year after implant surgery. Results: The number of appointments and time needed for fabrication of ISMOs revealed statistically significant differences between the patient groups. The requirements for prosthodontic maintenance of ISMOs in the test group were higher than those in the control group; however, these differences were not statistically significant. The mean marginal bone resorption for each group was 0.3 mm after 1 year. Conclusion: The results of this clinical trial suggest that early loading of a specific length of implants used to support mandibular overdentures does not jeopardize treatment outcomes during the first year of service.