Abstract
Magnetic attachments are considered to be a type of stud attachment. Due to the phenomenon of magnetic attraction, magnetic attachments provide retention which has different characteristics than that of other mechanical attachments or retainers. Unlike the retention which results from male/female fitting in mechanical attachments, magnetic attractive (retentive) forces occur when surfaces of the keeper and magnetic assembly are in close proximity or contact. The attractive force between keeper and magnetic assembly remains virtually uniform. Magnetic attractive forces provide guidance during denture insertion, thus the denture is always guided to the same position. Also, magnetic attachments protect abutments from excessive loading. However, retentive force depends on the direction of withdrawal (magnetic flux) and gap between keeper and magnetic assembly, and decreases as both increase. Conic telescopes also possess the property of constant retention which is similar to that of magnetic attachments. Still, dislodgment in the oblique direction like with magnetic attachments is impossible because of the fit of inner and outer crowns. This limitation is applicable to all mechanical attachments. Thus magnetic attachments allow various unrestricted paths of insertion and removal energy is low. Having the unique feature of “retention without bracing, ” magnetic attachments can be indicated for teeth with damaged crowns, short roots and maxillary anterior teeth abutments susceptible to lateral forces.
