The Effect of Glass Ceramic Layering on the Marginal Leakage of Zirconia Supported Crowns

Objective: The purpose of this study was to evaluate the effect of veneering with lithium-disilicate glass-ceramic material on the marginal microleakage of zirconia-supported crowns. Methods: Ten freshly extracted human third molars were embedded in an acrylic mold from the roots. Crown preparation of each tooth half was handled differently. The distal half of each tooth was prepared with a chamfer-type margin (1.2 mm), while the mesial half was finished with a mini-chamfer (0.6 mm). Zirconia frameworks were designed and manufactured with computer-aided design/computer-aided manufacturing, and the frameworks were veneered on the distal surfaces of the framework using lithium-disilicate glass-ceramic. Specimens were thermocycled and immersed in a basic fuchsine dye solution for 24 hours. Four cross-sections were made from each specimen (n=40), and dye penetrations were recorded under a stereo microscope for microleakage measurements. The microleakage values were statistically analyzed with a Mann-Whitney U test (α=0.05). Results: Mean microleakage values were recorded for each group. The values for the ceramic veneered margin group were noted as 1.17±0.69 mm, while the values for the zirconia margin group were noted as 1.03±0.74 mm. The results did not show significant differences for the compared groups (p=0.102). Conclusion: Lithium-disilicate glass-ceramic veneering for zirconia-supported restorations did not enhance the marginal seal capability.