Influence of marginal configuration and porcelain addition on the fit of In-Ceram crowns

The fit of In-Ceram copings and crowns was investigated in a laboratory study. Two methods were used, one a direct sectioning technique and the other a cement analogue technique using additioncured polyvinylsiloxane impression material. The former method involved 40 crowns cemented and sectioned on their respective electroformed silver dies. For the second method, 80 analogues were embedded and sectioned. All measurements were made using a Reflex microscope. This showed In-Ceram crowns and copings to fit well with marginal openings and ranging from 1 to 63 μm and a mean of 19 μm. No significant difference in fit was found between chamfer margins and shoulder margins. The addition of porcelain to the In-Ceram coping and repeated firing cycles involved in building a crown did not alter the fit. It is concluded that In-Ceram crowns fit well in comparison to other crown types.