Impact of surface treatment of different reinforced glass-ceramic anterior crowns on load bearing capacity.

This study investigated the influence of different surface treatments on fracture load (FL) of canine crowns fabricated from two different pressable lithium-disilicate ceramics: A (HS10PC, estetic ceram, n=180) and B (IPS e.max Press, IvoclarVivadent, n=120). The standardized specimens were divided into groups of six different surface treatments and two glazing temperatures. A-group specimens were additionally assigned two glazing pastes with various thermal expansion coefficients (TEC). FL was measured and TECs were determined. Data were analyzed using three/one-way ANOVA followed by post-hoc Scheffe's test. B showed comparable or higher FL than A (B: 503-876 N; A: 375-734 N). Lithium-disilicate crowns show higher FL when not grinded but only polished or glazed. Glazing pastes affected FL depending on their TECs, firing temperature and crown treatment. TEC of A and B was 10 ppm/K, glazing pastes for A presented TECs of 7.5 ppm/K and 10 ppm/K and for B of 9 ppm/K.