In vitro retention force changes of prefabricated attachments for overdentures

Abstract

Changes in the retention force of six prefabricated spherical and cylindrical attachments were examined in vitro under continuous loading. The testing machine permitted insertion-separation cycles to be tested under reproducible conditions while a calibrated measuring device determined the insertion and retention forces. At the beginning, during the so-called run-in period, all anchoring elements showed a very unstable behaviour characterized by a varying marked increase and subsequent decrease in the retention force. During the ensuing functional period, the retention force followed a more stable course. In this phase, the frictional attachments having lamellae for activation proved more stable than did the spring-loaded retention attachments. Furthermore, in two of five cylindrical anchors by Gerber, the spring broke. This provides support to the concept that prefabricated attachments should be constructed as robust elements composed of as few individual parts as possible. This would help to ensure that service and repairs remain at a minimum. Frictional attachments with lamellae for activation are to be preferred for use in matrices and patrices over attachments having spring-loaded retention.

Wear simulation effects on overdenture stud attachments

“…Different authors tried to relate simulated insertion-removal cycles with in vivo service years. According to Besimo and Guarneri 10,000 insertion-removal cycles in vitro corresponds with a time in use of about 9 years 21) . Gamborena et al considered that 5,500 placement-removal cycles can simulate 3 years of in vivo wear based on an average of five placements and removals daily 22) .…”

“…Many studies have addressed wear mechanisms of precision attachments 20,21) . Rapid loss of retentive force was accompanied by pronounced wear of metal surfaces.…”

Stability of Mandibular Overdentures Before and After Attachment Wear. An in vitro Study

“…The mean value of MRF was higher than that reported elsewhere. 15 Before wear simulation, MSF and SE of an overdenture with E3 were higher than those with E4. Both values showed greater reductions for E4.…”

The Evaluation of Changes in Retention Force Values in Three-Element Telescopic Crown Systems using Simulated Load Cycles

“…In publications, it is stated that a range of 10 thousand cycles of load corresponds to 10 years of using the prosthesis in clinical conditions, provided that the prosthesis fitted and removed three times a day [40][41][42]. When fitted and remove twice a day, it corresponds to 13-14 years [43].…”