Published Paper Details:

Objective: This study evaluated the marginal fit of CAD/CAM copings milled from Cercon HT blocks. It also evaluated the effect of firing on the marginal fit of zirconia copings. Materials and method: A stainless steel master die was fabricated using CNC-lathe of dimensions with crown length of 6mm, width of 7mm having 1mm rounded shoulder finish line with 50 taper on each side with occlusal diameter of 5mm. It also had a orientation groove of 0.5mm. Impressions were made and were poured in type IV die stone. Each die was scanned with a Dentsply Sirona inEos X5 scanner to produce the copings. The copings were seated on the master die with approx. load of 50N. A stereomicroscope was used for direct viewing of the marginal gap. Image analysis software was used to measure the marginal gaps in micrometers. For zirconia copings the measurements for marginal gap were made before and after firing. Data was analyzed by paired t-test. Results: There was no significant difference between marginal fit of zirconia copings before and after porcelain firing (p<0.05). Conclusion: The marginal fit of the copings before ceramic firing was lesser than marginal fit after ceramic firing, but the difference between the two margins after firing was not significant. Both marginal configurations showed marginal gaps that were within a reported clinically acceptable range of marginal discrepancy.