RETENTION OF PREFABRICATED ATTACHMENTS FOR IMPLANT STABILIZED OVERDENTURES IN THE EDENTULOUS MANDIBLE - AN IN-VITRO STUDY

Statement of problem. Bar and stud attachments are widely used to stab ilize overdentures on implants in the mandible. There is strong eviden ce that retention of the attachment is an important factor for a patie nt's satisfaction. Purpose. This study describes retentive forces and wear of commercially available attachments of 4 implant systems (3I, I MZ, Nobel Biocare, ITI Straumann) and 2 magnets (Steco). Methods. Forc es while removing the keyway portion of an attachment in its path of i nsertion were measured with a platform load cell. A total of 15,000 re movals were performed to simulate fatigue. Results. Retentive forces r anged between 5 and 85 N. The fatigue test revealed an initial increas e of forces with some attachments. After 15,000 cycles, most of the at tachments showed little loss of retention compared with the initial re tentive: forces. It is suggested that conventional fatigue tests with application of axial loads do not simulate clinical fatigue adequately .