Purpose: To quantify the rate of maintenance interventions of mandibular prostheses: complete dentures and overdentures retained by two implants, with either internal hex or external hex connections. Materials and Methods: This study analyzed patients with edentulous mandibles treated with distinct treatment protocols: a control group received complete dentures; a second group received Locator-retained overdentures supported by two external hex connection implants; and a third group received overdentures supported by internal hex connection implants. All of the maintenance interventions associated with the prosthetic treatment after delivery were recorded (starting from 2000 until the final assessment in 2012). Moreover, patient satisfaction was assessed using a 0 to 10 visual analog scale. Results: The final sample was composed of 136 patients: 56 in the control group, 31 in the hex implant overdenture group, and 49 in the internal connection overdenture group followed over a period of 60 months (ranging from 3 to 144 months). Prosthetic adjustment was the most frequent intervention carried out, particularly within the control group (a mean rate of 1.1 ± 1.9 times/subject/year) in comparison with the internal connection (0.6 ± 0.8 times/subject/year) and hex implant overdenture groups (0.3 ± 0.2 times/subject/year). Relining was also frequently required, occurring on average every 4 years in the control group and every 7 years in the overdenture groups. Abutment loosening was more frequent in the hex implant overdenture group than in the internal connection overdenture group (8/31 versus 8/49), as well as abutment wear (5/31 versus 5/49). Gingival inflammation was significantly more common in the hex implant overdenture group (19/31 patients), as compared with the controls (16/56 subjects), and satisfaction was higher in patients in the two overdenture groups (mean Oral Satisfaction Scale [OSS] score of 8.1 ± 1.9 for external and 8.4 ± 1.6 for internal connections) than in the control group (5.3 ± 3.3). Conclusion: Locator-retained overdentures needed less than half the number of maintenance interventions when compared with the control group, and maintenance was required every 2 to 4 years. Keywords: gerodontology, Locator system, overdentures, prostheses complication, prostheses maintenance