Effect of Aging and Pre-sintering Surface Treatment of Zirconia Cores on Chipping of Veneered Zirconia Crowns

Abstract

Abstract Aim: This study was conducted to study the effect of surface treatment of zirconia cores by nanosilica before sintering on veneers chipping and to evaluate the effect of aging in terms of thermocycling and cyclic loading on veneer chipping before and after surface treatment. Method: Model acrylic tooth was prepared for zirconia crown, twenty silicon impressions were recorded and epoxy resin dies were produced. Twenty zirconia cores were fabricated by CAD/ CAM system and divided into 2 groups (n=10) group I was the control which veneered with porcelain by hand layering technique while group II was subjected to treatment by nanosilica slurry before sintering then veneered and fired to produce crowns. The crowns were cemented by resin cement on their epoxy dies and they were subjected to 10000 thermocycles and 10000 cyclic loads. All crowns were loaded till chipping of veneer layer then the chipped surfaces were examined by SEM/EDX. Results: There was no significant difference in chipping resistance between group I and group II. Conclusions: Treatment of zirconia cores by nanosilica before sintering has no effect on chipping resistance of the veneer layer after subjecting to aging process (thermocycling and cyclic loading).