Over the past thirty years, clinicians have been restoring aesthetics and function in edentulous patients with implant-supported overdentures using different retention systems. The choice of prosthesis retention has significant economic implications but it is not well known if there are specific clinical implications, particularly with regard to treatment's success as well as patient satisfaction therefore is critically important to determine whether there are meaningful differences in outcomes, based on the type of retention used. The purpose of this study was to evaluate subjects\' satisfaction correlated with total costs during a four years randomized clinical trial of implant-retained mandibular complete dentures attached by Retentive Anchors (Balls - B), Magnets (M) or Locator System (L) to Straumann endosteal dental implants.The 69 patients enrolled in the study were followed every 6 month for 4 years and detailed records were kept of costs, extent of maintenance required after placement of the dentures, general satisfaction as well as comfort, stability, masticator efficiency, speech, aesthetic and cleaning ability. All three groups had less oral health related quality of life problems than before treatment. The Magnet group has the highest cost for the components but less maintenance requirements.The Ball and Locator groups scored higher rating on comfort, stability and ability to chew comparing to the Magnet group. Although the retention force of the Magnet attachment is smaller, patient satisfaction is high at all groups. Keywords: mandible, implant, overdenture, locator, retentive anchor, magnet