Investigation of Marginal Fit and Surface Roughness of Crowns, Due to Different Bench Set and Different Burnout Temperature Using Base Metal Alloy

The conventional investing technique is used most commonly for casting. Inspite of the popularity of this technique, it is very time consuming. To save time of the patient, dentist and dental laboratory technician, accelerated casting technique can be used. This study uses different bench set and different burnout temperatures and has been carried to investigate their effects on marginal fit and surface roughness. A total of 40 wax patterns were made simulating the artificial crown from the first master die and 20 rectangular wax patterns were made from the second master die. Twenty castings simulating the crown and 10 castings of rectangular plates were obtained by short protocol represented as Group A and C, similarly the remaining castings were obtained by standard protocol and represented as Group B and D. Marginal discrepancy of both Group A and B were determined by using Travelling microscope, whereas Perthometer was used for quantitative evaluation of average surface roughness of both Group C and D. Scanning electron microscope evaluated the surface roughness qualitatively for the specimens of both Groups C and D. The obtained values of Group A and C and Group C and D were subjected to statistical analysis. Qualitative analysis of Group C and D were done. Accelerated/short protocol gives similar results in terms of marginal fit and surface roughness as compared to the conventional/standard protocol and is definitely a time saving procedure.