AN EVALUATION OF THE MARGINAL ACCURACY AND SURFACE ROUGHNESS OF NICKEL CHROMIUM COPINGS FABRICATED BY CONVENTIONAL AND ACCELERATED CASTING TECHNIQUES

Prof (Dr)Chethan Hegde; Prof(Dr)Krishna Prasad D; Dr Ambar Ojha

Volume : VII, Issue : V, May - 2017

AN EVALUATION OF THE MARGINAL ACCURACY AND SURFACE ROUGHNESS OF NICKEL CHROMIUM COPINGS FABRICATED BY CONVENTIONAL AND ACCELERATED CASTING TECHNIQUES

Prof Dr Chethan Hegde, Prof Dr Krishna Prasad D, Dr Ambar Ojha

Abstract :

Purpose: A study was carried out to measure the marginal discrepancy and surface roughness of nickel chromium castings faicated by conventional and accelerated casting techniques. Methodology: A total of 30 patterns were prepared using inlay casting wax patterns to obtain a uniform thickness of 0.5mm as recommended. All the patterns were subjected to casting procedures.15 castings were invested using conventional casting and 15 were invested using accelerated casting. The cast copings were devested, sandblasted and steam cleaned. The faicated cast copings were grouped as Group I, Group II. The vertical and marginal gap of the cast copings were evaluated microscopically and measured at 4 predetermined reference points using a stereo optical microscope at 32x magnification. The surface roughness was also measured using a contact profilometer on the castings obtained from the both the conventional and accelerated casting techniques. The data was subjected to descriptive statistics and independent sample ’t’ test. A p value < 0.05 was considered as statistically significant. Results: Statistical comparison of the mean marginal discrepancy and surface roughness between the groups was done. The values of the samples obtained were statistically analysed using independent sample ’t test’. There was significant difference between the study groups in marginal discrepancy of conventional and accelerated castings..A significant difference was noted in surface roughness values between these two groups. Copings faicated by conventional casting techniques had lower values of marginal discrepancy and surface roughness as compared to copings faicated by accelerated castings but these values were within the clinically acceptable range. Conclusion: Within the limitation of the study, it is concluded accelerated casting offers us a time saving technique which is beneficial for the patient, lab technician and the dentist.