RESUMEN
objective: To study the properties of keepers treated with different methods. Methods: Eighteen Z 3 magnetic attachments were divided into three groups at random. Cobalt chromium alloy was used for root cap. The keepers in the first group were cast to the caps, those in the second group were welded to the caps by Nd:YAG laser welding apparatus. Keepers in the third group were untreated. Universal testing machine was adopted to measure the breakaway retention of the attachments. The roughness of keeper surfaces was measured by roughness tester. Results: No statistical difference was observed as to the breakaway retention between magnetic attachments and laser welded coping keeper or between those and cast coping keepers. But retention of the keepers in the two groups was slightly lower than that of untreated keepers. Defects of pits were found on the surfaces of the cast coping keepers. The surface smoothness of the cast coping keepers was inferior to that of the laser welded coping keepers. Conclusion: Laser welded keepers and cast coping keepers can meet clinical demands for the use of magnetic attachments.