Changes in retention of electroformed telescope crowns over long-term use

Abstract

We investigated the change in retentive force of electroformed telescope crowns over the long term by analyzing the retentive force curve during 10,000 cycles of vertical insertion and dislodgement of ten outer crowns using a tensile and compression testing machine. The peak retentive force, the peak pushing force and the duration of retentive force were measured. No significant differences were found during 10,000 cycles in the peak retentive force, the peak pushing force or the duration of retentive force. The retentive characteristics of electroformed telescope crowns did not change after the 10,000 cycles. Our results clarified that the electroformed telescope crown could be used as an effective retainer over the long term.