Chair: Tetsuo Ohyama (Nihon University)

poster discussion


 Retentive forces and displacement of new stress breaking magnet attachment

 Mana Torii, Takuya Waki, Daisuke Ozawa, Yasunori Suzuki,  Chikahiro Ohkubo

 Dept. of Removable Prosthodontics, Tsurumi Univ. Sch. of Dent. Med.



 Numerous studies with reliable results on attachment systems for implant overdentures in the mandible and maxilla have been published. Most attachments allow for rotational change but cannot compensate for vertical displacement under functional forces. This study evaluated the retentive forces and displacement of stress-breaking attachments after repeated loads.

Seven types of stress-breaking attachments, namely, a self-adjustment type magnet attachment, a cushion type magnet attachment, a locator attachment, three types of SBB (Stress-Breaking Ball) attachments, and SBM(Stress-Breaking Magnet)were placed on the implants. To simulate the chewing cycles, a load of 5 kgf was repeatedly applied up to 50,000 using a loading apparatus. The retentive force was measured by tensile test. The vertical displacement of each female was measured under 5 kgf. These measurements were repeated for 10,000 cycles. The mean values were analyzed using 1-way ANOVA followed by the Tukey’s test at a significance level of α=0.05.

There were no significant differences of the retentive forces of both magnet and SBM attachments before and after loading (p>0.05).

The vertical displacement of the magnet and SBM attachments showed a slight decrease after loading. On other hand, Locator attachment had no vertical displacement, and cushion type magnet attachment showed significant decrease (p>0.05).