The development of the open magnetic-circuit type magnetic attachment and magnetic shielding system for dental...

In a super-aging society, there is an increasing number of bedridden and partially or completely edentulous patients, presenting a challenge for conventional dental treatment. While closed magnetic-circuit attachments for implant overdentures are clinically established, an open magnetic-circuit attachment system that generates an attractive force by interposing alveolar mucosa between a denture-embedded magnet and a submucosal keeper has not yet been developed. This study aimed to develop a new open magnetic-circuit type magnetic attachment and a magnetic shielding system to mitigate magnetic-field leakage. A prototype of an open-circuit N55 neodymium magnet (φ4 × 2 mm) has been developed. To reduce magnetic-field leakage, shielding devices were fabricated from high-permeability soft-magnetic materials: Sendust and Permalloy B. A 3-spatial magnetic field analyzer was used to measure the spatial distribution of the magnetic field. The results showed that the shielding devices effectively reduced magnetic-field leakage. For the N55 magnet, the maximum magnetic field on the shield surface was 67.6 mT with Sendust and 79.7 mT with Permalloy B, representing a significant reduction relative to the magnet surface values of 389.0 mT and 392.6 mT, respectively. This study demonstrated the effectiveness of the developed open magnetic-circuit magnetic attachment/magnetic shielding system, paving the way for its application in overdentures for dental implants.