Abstract:

Objective　In order to introduce the laser welding technology into root-cap making, this study compared the surface characters and internal structures of laser-melted and cast post-keeper to provide experimental data for clinical application of the technique.Methods　Using untreated keeper as the control group, the surface characters and metallographic structures of the keepers were examined by stereomicroscope, metallographic microscope and SEM, and element analysis were conducted with EPMA.Results　The laser-melted post-keeper basically keptthe original smooth and the internal structure of the keeper, the heat reaction zone was extremely small and elements diffused mutually around the fusion zone obviously. While in the cast post-keeper, the surface was rough and had an oxide-layer. The internal structure changed and a fusion band formed between the base alloy and the keeper, but element diffusion was limited to the fusion zone.Conclusion　Compared with casting, laser welding technique demonstrated less influence on the surface and internal structure of the keepers.

Key words: laser-melted post-keeper, cast post-keeper, micro-structure, heat reaction zone