Abstract:

Objective　In order to compare the influence of casting and laser welding on magnetic retentive force, the magnetic retentive forces of laser-melted and cast post-keepers of the magnetic attachments were measuredin vitro.Methods　5 cast and 6 laser-melted post-keeper specimens (Magfit MD800) were formed, respectively. Using untreated keeper as control group, the vertical magnetic retentive forces were measured by a universal testing machine.Results　The average vertical mag- netic retentive force of the laser-melted post-keeper group and the cast post-keeper groupin vitrowere(4·223 3±0·217 0)N, (3·792 9±0·296 4)N, respectively. Compared with the cast post-keeper group, the average vertical magnetic retentive force of the laser-melted post-keeper group was much higherin vitro(P<0·05).Conclusion　Laserwelding had less influence on the magnetic retentive force of the magnetic attachments than casting.

Key words: laser-melted post-keeper, cast post-keeper, magnetic retentive force, magnetic attachments