Evaluation of retentive force of attachment systems for overdentures retained by one or two implants

Abstract

Objective: Single implant-retained overdentures are an appealing option for rehabilitation, but the retentive force of attachments in this setting has yet to be determined.

Methods: Three attachment systems (ERA, O-Ring, and Ball Attachment), using components made from different materials (plastic and metal), were tested under two different support conditions (single-implant or two-implant). Under irrigation, the systems were subjected to a series of simulated insertion-removal cycles. Maximal retention values were obtained before testing and after 3,240 cycles on a universal testing machine (cross-head speed of 0.5 mm/min). Student’s t-test for independent samples was used for statistical analysis (P < 0.05).

Results: Tensile strength of the O-Ring and Ball Attachment systems did not show significant changes after mechanical cycling (with one or two implants), while the ERA system showed significant reductions at cycles 2,160 and 3,240 (in the single-implant and in the two-implant specimens) as compared with the other cycles.

Conclusion: Single-implant support for mandibular overdentures can be an alternative for the oral rehabilitation of fully edentulous patients, providing greater simplicity, lower costs, and similar retentive strength as compared to two-implant overdentures, improving the user’s quality of life. The tested systems meet the retentive needs of removable prosthodontic appliances, regardless of the number of supporting implants.