Evaluation of Shear Bond Strength of Two Glass Ceramic Veneers Fabricated by CAD/CAM Technology (In Vitro Study)

Abstract

Background and objectives:The purpose of the study was to evaluate and compare shear bond strength of lithium disilicate and zirconia reinforced lithium silicate glass ceramics for fabrication of veneer restoration by CAD/CAM technology.

Materials and methods: Thirty sound human maxillary first premolars with comparable dimensions were used. The teeth were prepared in standardize way for bonding to laminate veneer. Prepared teeth were divided into two groups (n=15/group) according to fabrication of veneer restoration by two different glass ceramics block, group (1); Lithium disilicate glass ceramic, and group (2); Zirconia reinforced lithium silicate glass ceramic. Ceramic veneers of (1) mm in thickness and (5×4) mm in diameter were luted to the tooth surface by using light-curing (RelyX Veneer) resin cement. After cementation samples were subjected to thermal cycling then shear bond strength test was performed in a universal testing machine at 0.5 mm/min until bonding failure.

Results: (G2) Zirconia reinforced lithium silicate showed significantly higher bond strength than (G1) Lithium disilicate glass ceramics (P= 0.02). 

Conclusions: The bond strength of restorations depends on the chemical composition and micro structure of the glass ceramics.