Marginal gap width of a new refractory porcelain system

This study was conducted to determine whether matching the physical properties of refractory die material to porcelain could increase the marginal accuracy of porcelain inlays. Restorations made with a matched Fortune refractory porcelain system were compared with restorations made with unmatched Vita porcelain and Polyvest refractory material. Thirty addition-silicone impressions were made of a master mesioocclusodistal inlay preparation. Fifteen refractory dies were made for each of the refractory materials. The dies were prepared and the porcelain applied according to the manufacturer's specifications. Three measurements of marginal gap were recorded adjacent to premarked points on each proximal box by use of a Unitron microscope with micrometer adjustment. The mean marginal gap was 51.24 +/- 20.84 microns for the matched material and 100.43 +/- 17.30 microns for the unmatched material. A Student's t-test was performed, which showed a significantly greater mean gap for the unmatched system compared with the matched system (t[28] = 7.03, p < 0.005). The results indicate that a matched refractory porcelain system can produce restorations with significantly improved marginal accuracy.