ABSTRACT
The success of implant supported overdentures depends on the retention capacity of their retainers to maintain their long term function. The aim of this study is to evaluate the retentive force of metal clips and to compare the strength of the fixed clips with two types of resins. A metal clip (MP-Clip®, Ackermann Bar®) was fixed in fourteen PMMA blocks with MegaCryl N and Quick-Up®. Another block presents a metal bar screwed to two parallel implants. Using a testing universal machine, a fatigue test up to 1080 cycles and a pull test were performed. The mean retentive force registered for the clip retained with MegaCryl-N is 33.85 N, which is lower than the one registered with Quick Up® (49.33 N). In the traction test, a mean force of 240.72 N is necessary to pull the metal clip from the MegaCryl N resin, while in the Quick-Up® resin it is 154.02 N. No fracture of the attachments occurred, but there was fracture of the Quick-Up® samples. It can be concluded that a metal clip fixed with Quick-Up® has more retentive force than a clip fixed with MegaCryl N. Most likely due to the composition differences between the two materials, the force required for pulling a clip is much lower with Quick-Up®.
