Retentive characteristics of overdenture attachments during repeated dislodging and cyclic loading.

The retentive and morphologic changes of overdenture attachments were evaluated independently after repeated insertion and sinusoidal loading on implant abutments. Stud and magnetic attachments were embedded in overdenture housing (n = 5). The overdentures were subjected to either repeated insertion and removal for 5,400 cycles or sinusoidal cyclic loading for 100,000 cycles. A 67.8% decrease in retentive force was observed after 100,000 loading cycles (P < .05), and a 73.9% decrease of retentive force occurred after 5,400 insertion-removal cycles (P < .05). Stud attachments showed more loss of retention and physical deterioration than magnetic attachments tested under identical conditions.