AN IN VITRO COMPARISON OF OVERALL FIT OF COBALT-CHROMIUM COPINGS CASTED CONVENTIONALLY FROM INLAY CASTING WAX, PATTERN RESIN & 3D PRINTED RESIN EVALUATED BEFORE & AFTER CERAMIC FIRING CYCLES

Aim: To compare the overall fit of cobalt-chromium copings casted conventionally from inlay casting wax, auto polymerizing pattern resin & 3D printed resin evaluated before & after ceramic firing cycles.

Method: A stainless-steel master die assembly was fabricated which was used to fabricate the working models. 60 working dies (Group A Inlay Casting Wax n=20, Group B Pattern Resin n=20, Group C 3D Printed Resin n=20) simulating full crown preparations werestudied. The stainless-steel master die was duplicated using polyvinyl siloxane (PVS) elastomeric impression and poured in gypsum type IV die stone. Dieswere scanned using a digital scanner. 60 cobalt-chromium (Co-Cr) metal copings were fabricated using three different techniques: inlay casting wax, autopolymerising pattern resin& 3D printed resin. Each die was fired with conventional PFM ceramic. A standardized weightwas used to exert uniform pressure on the elastomeric impression material while recording the intaglio surface of the crowns (copings) fabricated before and after ceramic firings. It was thenscanned aiding in STL File. The STL files were later overlapped and evaluated on their respective working die STL file using the software. The overall fit was measured by colour surface mapping software viz before & after ceramic firing cycles.

Results: The copings obtained by 3D printed resin technique revealed the best overall fit before and after ceramic firing cycles amongst the three fabrication techniques.

Conclusion: 3D printed resin technique had the best overall fit before and after ceramic firing cycles followed by inlay casting wax technique and pattern resin technique.