INFLUENCE OF MARGINAL CONFIGURATION AND PORCELAIN ADDITION ON THE FITOF IN-CERAM CROWNS

The fit of In-Ceram copings and crowns was investigated in a laborator y study. Two methods were used, one a direct sectioning technique and the other a cement analogue technique using addition-cured polyvinylsi loxane impression material. The former method involved 40 crowns cemen ted and sectioned on their respective electroformed silver dies. For t he second method, 80 analogues were embedded and sectioned. All measur ements were made using a Reflex microscope. This showed in-Ceram crown s and copings to fit well with marginal openings and ranging from 1 to 63 mu m and a mean of 19 mu m. No significant difference in fit was f ound between chamfer margins and shoulder margins. The addition of por celain to the In-Ceram coping and repeated firing cycles involved in b uilding a crown did not alter the fit. It is concluded that In-Ceram c rowns fit well in comparison to other crown types. (C) 1996 Elsevier S cience Limited