The Effect of Veneering Porcelain on the Marginal Fit of Cercon Zirconia Copings

MastersThe review of the literature reflects variable results regarding the effect of veneering porcelain on the marginal fit of the crown coping in metal ceramic and all-ceramic restorations in relation to different finish lines, materials and systems. As the zirconia material is gaining popularity these days due to its exceptional strength and fracture toughness combined with promising esthetic results achieved by the application of its recommended veneering porcelain, the purpose of the study was to reveal the effect of Cercon® Ceram Kiss veneering porcelain (DeguDent/ Germany) on the marginal fit of Cercon® zirconia coping (Cercon® Smart Ceramic System/ DeguDent/ Hanau/ Germany) in relation to 1mm shoulder and chamfer finish lines. Two master stainless steel models of a single posterior full-crown preparation were machined for the shoulder and chamfer finish line preparations. Then duplicated into stone models that were scanned by Cercon® Smart Ceramic System to produce thirty Cercon zirconia copings for each finish line preparation which were veneered later with Cercon® Ceram kiss veneering porcelain. The assessment of the marginal fit of the specimens was performed on the stainless steel master models in relation to 31 defined points secured with the specimen positioning device (SPD) using the direct view technique with the aid of the Traveling Measuring Microscope in relation to 1mm shoulder and chamfer finish lines before and after the addition of the veneering porcelain. The data were statistically analyzed using Student paired and independent ttests to compare the marginal fit of Cercon® zirconia coping before and after adding the veneering porcelain for the shoulder and chamfer finish lines separately and the marginal fit of the final crowns of both the shoulder and chamfer finish lines respectively. The results indicated that the addition of veneering porcelain significantly affected the marginal fit of both finish lines preparations (P