Session 2 Chair: Hideki Aita (Health Sciences University of Hokkaido)




Development of Implant Magnetic Keepers

 – Study on the screw loosening by repeated load-


H. Nagai, T. Iwai, Y. Nakamura, H. Kumano, K. Yoshihara, K. Hayashi,

Y. Takada1, Yu. Ohno, Y. Tanaka


Department of Removable Proshodontics, School of Dentistry Aichi-Gakuin University

1Division of Dental Biomaterials, Tohoku University Graduate School of Dentistry




 Implant materials and techniques have markedly improved in recent years. An implant overdenture with magnetic attachments has excellent retention mechanism, and has been drawing attention as one of the implant treatments.

 We previously devised an ideal keeper for the implant based on the basic research, and investigated attractive force and surface treatment methods.

 A three-dimensional finite element method has been introduced, and stress-bearing ability of this implant system has been investigated for further optimization of a keeper.

 Another challenge is loosening of a keeper. The present implant system is used as a magnetic attachment of an overdenture. External force is applied to an implant keeper during mastication due to the characteristics of an implant overdenture. The abutment was fixed to a fixture using an abutment screw, and the implant keeper was fixed at the top. Since a prototype implant keeper is fixed to an abutment by a screw structure of a keeper, one turn of a screw may result in loosening of a screw. Loosening of a keeper during functioning may cause impairment in function, and increase a risk of accidental ingestion and aspiration of a keeper.