Background and Objectives: Failure of extra coronal restorations from secondary caries and periodontal problems are quite common. Intact marginal adaptation or marginal accuracy is essential to prevent oral fluid entry in between the restoration and abutment tooth causing luting cement dissolution and failure of the restoration. Even though manufacturers advice single use of base metal casting alloys; due to the increased demand and economy, reusing of cast alloy is practiced by many dental laboratories.
Materials and Method: A master die was fabricated in brass and a wax pattern for complete cast crown was carved over it. These patterns was duplicated to fabricate 72 identical wax samples using a custom made duplicating mold and were randomly distributed into six groups (A to F). These groups were then cast with different percentage of new and once cast alloy. The cast crowns were held in position over the master die with the help of a custom made holding device and each surface was examined for marginal gap under a stereomicroscope. The marginal gap values were recorded in microns and subjected to statistical analysis using One way ANOVA, Independent samples ‘t’ test and Scheffe’s post hoc test.
Results: The mean marginal gap values obtained for groups A, B, C, D, E and F were 48.55µ, 49.12µ, 61.63µ, 63.97µ, 67.77µ and 70.34µ respectively. Significant difference was observed between the groups.
Conclusion: Increase in mean marginal gap was observed with increase in the amount of once cast alloy, but these values were within the clinically acceptable range. Intergroup comparisons showed statistically highly significant difference in marginal gap in an ascending order from group A to group F. No statistical difference was observed among the four surfaces of same sample of any test groups.
Impact Factor
2022: 6.012
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