Purpose: This randomized clinical trial examined implant overdenture (IOD) fabrication and maintenance time and costs, adjustment and repair incidence, and patient satisfaction after 1 year. Materials and Methods: Sixty-four patients received 2 mandibular implants and an IOD with either a bar with 2 clips or 2 ball attachments for denture retention. Results: Fabrication time, number of appointments, and chair time for adjustments were similar for the 2 denture designs. The most common adjustments for both types were to the IOD contours. Ball-attachment dentures required about 8 times longer for repairs than bar-clip prostheses. Approximately 84% of patients with ball-attachment dentures needed at least 1 repair, versus 20% of those with a bar-clip mechanism. The most common repairs were replacement of the cap spring or cap for the ball-attachment IOD and replacement of a lost or loose clip for bar-clip dentures. Discussion: Patients were equally and highly satisfied with the improvements in function, comfort, and appearance with both types of IOD compared to their original conventional dentures. Conclusions: Given equivalent levels of patient satisfaction with either method of retention and a much higher repair rate for the ball attachment, it is suggested that a bar-clip design be used rather than the particular ball attachment utilized in this study.