Effect of Different Casting Techniques on the Castability of Nickel-Chromium Alloy

Statement of Problem: Castability plays an important role in success and failure in the field of restorative and prosthetic dentistry. Recasting of base metal alloys can alter its castability value and some of its physical properties.

Aim: To evaluate the castability of new and recasted Ni-Cr alloy using conventional ring and ringless casting system and compare the results.

Place and Duration of Study: Department of Prosthodontics and crown and bridge, KLE V.K. Institute of Dental Sciences, Belagavi, KLE University, between August 2016 and February 2017.

Materials and Methods: Thirty identical mesh - runner bar - sprue patterns were prepared and divided into 2 different groups of 15 each, namely; Group 1 – Metal ring casting system and Group 2 – Ringless casting system. Each group was further divided into 3 sub-groups based on weight percentage of new-recasted Ni-Cr alloy; Group 1A and 2A – 100% new Ni-Cr alloy, Group 1B and 2B – 50% new and 50% recasted Ni-Cr alloy, and Group 1C and 2C – 100% recasted Ni-Cr alloy. Castability of the alloy was tested using modified Whitlock’s method.

Results: The results of this study revealed that the mean castability values ranged from 99.64% – 99.86%, and there is no significant difference (p > 0.05) between the castability of new alloy and recasted alloy using ring and ringless casting techniques.

Conclusions: Ring and ringless casting techniques have comparable accuracy and can produce clinically acceptable castings.