Abstract - The aim of this in vitro study was to compare the resistance to separation (breakaway force) of flat (Magï¬tâ„¢-IP-BF) and domed (Magï¬tâ„¢-IP-BD) implant magnet attachments subjected to non-axial forces. The separating forces were applied by an Instron Universal Testing Instrument to single magnet attachments at angles of 0°, 2°, 5°, 10°, and 20° from the axial line of the components (angle of pull) and at crosshead speeds of 0.5mm/min and 50 mm/min. The breakaway forces were signiï¬cantly (p<0.0001) inversely related to the angle of pull for both flat magnets and for domed magnets. At the slow crosshead speed, the breakaway forces recorded for the domed magnets were signiï¬cantly greater than those recorded for the flat magnets for angles of pull greater than 5°. At the faster crosshead speed, the breakaway forces recorded for the domed magnets were signiï¬cantly greater than those recorded for the flat magnets for angles of pull greater than 2°. This apparent superiority of domed magnets under non-axially directed separating forces could influence the choice of magnet attachment for implant overdentures as intraoral displacing forces are multidirectional. Domed magnets may also be advantageous where implants are not parallel.
KEY WORDS: Breakaway force, angle of pull, implant magnet attachments, flat magnets, dome magnets, overdentures
V. Chopra, B. J. Smith, H. W. Preiskel, R. M. Palmer, R. Curtis