Thirty seven people were provided with mandibular overdentures stabilized by Astra Tech implants. Thirteen people were provided with ball attachments, 12 with magnet attachments and 12 with bar attachments. The patients were followed for 3 years and detailed records were kept of the extent of maintenance required after placement of the dentures. The bar attachment mechanism required 9 episodes of maintenance, compared to 38 for the ball attachment mechanism and 23 for the magnet attachment mechanism. There was no difference between the three groups for the amount of maintenance required by the overdentures. The design of the ball attachment changed during the study from a two piece to a one piece abutment. It is likely that had this "all in one" attachment been available from the beginning of the study, the amount of maintenance required by the ball attachment mechanism would have been considerably less.