[Retention of Pt-Co magnet for dental prosthesis]

Though Pt-Co magnet is inferior to rare-earth magnet in magnetic properties, the magnet is much superior to the corrosional resistances in oral fluids. The purpose of this investigation was to determined the retentive characteristics of Pt-Co magnet. The break away force between the magnet and XM27 stainless steel keeper were measured. The retention of phi 4x 1.5 mm Pt-Co magnet was 49 g. This retention could be increased to 172 g by using stainless steel cup type yoke. These retention were rather small, but if 3 or more couples of attachments or larger Pt-Co magnet attachment were fixed in denture, the retention level approach that of clasp or mechanical precision attachments.