margin fit related to margin types of glass infiltrated alumina core cabricated from aqueous-based alumina tape

STATEMETN OF PROBLEM: In-Ceram system is one of the all-ceramic crowns that can be used in anterior 3 unit fixed partial dentures and posterior single crowns. The alumina core used in In-Ceram system is manufactured using slip-casting technique. The slip-casting technique is difficult and technique sensitive. To improve this problem, tape-casting method was introduced into dentistry. There were no studies to examine the effect of margin design on the margin fit-ness of all-ceramic crowns fabricated from alumina tape. 0aPURPOSE: The purpose of this study was to compare the marginal fitness of glass infiltrated alu-mina core fabricated from aqueous-based alumina tape according to different margin types (90 .,110 ., 135 .shoulder margin). 0aMATERIAL AND METHOD: Three upper central resin incisors were prepared with 90 ., 110 .and 135 .shoulder margins for all-ceramic crowns, respectively. The resin teeth were duplicated and master die and special plaster die were made as usual. After alumina cores were fabri-cated from aqueous-based alumina tape, cores were cemented to each 15 epoxy dies replicated from three resin teeth with resin cement. These cemented cores were embedded in epoxy resin. Specimens were cut mesiodistally and buccolingually. Marginal gap and discrepancy were measured under microscope.0aRESULTS: The marginal gap and discrepancy of 90.marginal angle was 75.1 mu m, 86.6 mu m, 110 .marginal angle was 41.5 mu m, 50.7 mu m and 135 .marginal angle was 51.7 mu m, 54.2 mu m, respectively. The smallest value was seen in 110 (angle, which was statistically significant com-pared to that of 90 .angle (p