Assessment of the influence of selected electrolytic polishing process parameters on the surf ace roughness of casts made of the CoCrMo alloy

Background. To fabricate some prosthetic restorations, such as metal alloy frameworks for removable partial dentures (RPDs), casting techniques must be used. The penultimate stage of the cast finishing procedure is electropolishing. Objectives. The aim of the study was to assess the influence of selected electrolytic polishing process parameters on the resulting surface smoothness of the cobalt-chromium-molybdenum (CoCrMo) alloy. Material and methods. The CoCrMo alloy, 3 experimental and 2 name-brand electrolytes, were used in the study. A total of 25 samples, 63 mm x 10 mm x 1 mm in size, were cast using the Nautilus (R) equipment. The cast samples were shaped using metal cutters and carborundum stones and separators, and were sandblasted. The prepared samples were placed in an electrolysis cell as an anode. For each sample, measurements were made by changing the potential of the electrode by 0.2V in the range from 1.2V to 7.0V. The surface of the samples was analyzed using a profilometer. An optical microscope and a scanning electron microscope (SEM) were used to examine the structure of the surface. Results. An analysis of the obtained results showed no statistically significant differences between the BEGO Wirolyt (R) electrolytic polishing liquid (WB) and experimental electrolytes K15, K8 and K13, all of which were significantly better than the Dentaurum Electrolyt (R) polishing solution (ED). The microscope images indicated differences in the surface structure of the samples; in the SEM images, inclusions were also visible. Conclusions. The experimental electrolytes did not differ in quality from one of the name-brand electrolytes and were even better than the other one. The obtained surface roughness values (Ra) did not differ significantly from those achieved by other researchers.