The purpose of this study was to investigate the retentive force distribution of the upper overlay denture with magnetic attachments.The magnetic attachment used in this study consisted of a magnetic assembly and a magnetizable metal commonly refered to as a keeper.The keepers were attached to the bilateral canine and/or second molar regions on the upper edentulous model, while magnetic assemblys were attached to the upper denture which was made of an acrylic resin.The retentive force was measured by pulling at eight locations on the denture vertically with a tensile testing machine.
The results were as follows:
1.The retentive force was greater at locations near the magnetic attachments and decreased at locations further away from magnetic attachments.
2.In the case with two magnetic attachments, the retentive force distribution was more influenced by the arrangement of attachments than other cases.
3.The denture with three or four attachments showed stable retentive force distribution.
4.The maximum retentive force was smaller than the total attractive force, which was 40-70%.
