Clinical Evaluation of the Marginal Fit of a new Experimental All-Ceramic System

Objectives: This in-vivo-study evaluated the marginal fit of inlay and full-crown abutments for fixed partial dentures (FDPs) made from a new all-ceramic-material. Methods: After abutment preparation (for crowns 90° shoulder margin) impressions were made with a simultaneous, dual-mix-technique (Permadyne, Espe, Seefeld, FRG) and master dies were fabricated (Fujirock-EP, GC, Tokyo, J). Then FPDs were made with the experimental heat pressed lithium-disilicate-glass-ceramic (Ivoclar-Vivadent, Schaan, FL) following the manufacturer's recommendations. The marginal fit of the abutments was checked intraorally with a silicone indicator paste (Fit-Checker, GC) and a probe. Adjustments were done if necessary. At random one abutment of each FPD was chosen for evaluation (11 crown and 8 inlay abutments). Impressions of the restoration margins (President, Coltène, Altstätten, CH) were taken before and after adhesive cementation (Syntac & VariolinkII, Ivoclar-Vivadent). Using epoxy die (Ivoclar-Vivadent) replicas of the abutment margins were cast and investigated in a scanning-electron-microscope (XL30CP, Philips, Eindhoven, NL). The marginal discrepancies were evaluated in sections of 200 µm (magnification 1000 x). The highest value of each section was applied. The mean of all sections of each replica was used as the result for one abutment. Results: The mean marginal discrepancies before cementation were for crowns 105.8 ± 34.5 µm and for inlays 93.0 ± 32.6 µm. After adhesive cementation the means increased for crowns to 130.9 ± 31.8 µm and for inlays to 104.4 ± 30.0 µm. The Wilcoxon test showed a statistically significant (p<0.05) increase in the marginal discrepancies caused by cementation for crowns but not for inlays. The U-Test showed no significant differences between the discrepancies of full-crowns and inlays before or after cementation. Conclusions: The marginal discrepancies found in this study were within biologically acceptable standards. Adhesive cementation caused a statistically significant increase of the marginal discrepancies for crown but not for inlay abutments. Supported by Ivoclar-Vivadent, FL.