Implant-Retained Mandibular Overdentures: Patient-Related Outcome Measurements after Seven Years of Function

Denture wearers often complain about jeopardized function and reduced quality of life due to lack of prosthesis' retention. Implant-retained mandibular overdentures, on two non-connected implants (2IOD) are well-proven solutions to overcome these issues. We prospectively assessed 69 patients and scrutinized clinical records until at least seven years of function. Thirty-six were retained on Locator^® Abutments (LA) and thirty-tree on Ball Abutments (BA). Both systems were compared regarding the type, amount, and total cost of required maintenance. One implant was lost, yielding 98.7% survival after seven years. In total, 438 technical issues occurred: 121 (27.35%) in BA and 317 (72.4%) in LA. Out of these, 343 events (78%) were solved chairside: 191 (43.6%) were replacements of retention caps, 113 (25.8%) were minor acrylic repairs, 26 (5.9%) pressure ulcers had to be relieved, and 13 (3%) were related to abutments. LA required 179 insert replacements compared to 12 in the BA group. The overall initial treatment cost was EUR 3850 (base year of the analysis: 2003). The average total maintenance cost in relation to the initial cost for the LA and BA groups was 19.11 (range 0-82.24%) and 18.91% (range 0-113.26%) respectively (p = 0.540). Conclusions: The seven-year maintenance costs for a 2IOD is acceptable when the patient is regularly checked and professionally maintained. Most events are easily solvable chairside, but a few patients required more expensive interventions, regardless of the type of attachment used.