Shear Bond Strength of E. Max Ceramic Restoration to Hydraulic Calcium Silicate Based Cement (Biodentine): An In Vitro Study

Objective: The purpose of this study was to evaluate the shear bond strength (SBS) of hydraulic calcium silicate (Biodentine) as a core material to the e.max ceramic restoration. Methods: Forty discs (6 mm diameter; 2 mm thickness) were fabricated from each core material, Hydraulic calcium silicate [Biodentine™, Septodont], resin composite [Filtek™Z250 XT, 3M ESPE], and resin-modified glass ionomer cement (RMGIC) [GC Fuji II LC, GC Corporation]. Dentine surfaces of 40 extracted human permanent molars were exposed and used as a control group. All specimens were mounted in self-curing acrylic resin. One hundred sixty IPS e.max discs were fabricated (4 mm diameter; 2 mm thickness) and cemented to the core specimens with Variolink N (IvoclarVivadent). After storage in distilled water (37oC; 24h), the specimens were thermocycled 1.500 times. SBS was tested using a universal testing machine at 0.05 mm/min crosshead speed. The fracture modes were determined by a stereomicroscope at ×20 magnification. Data were analyzed using one-way analysis of variance followed by Tukey's test (P=0.05). Results: The mean SBS values of four tested groups showed statistically significant differences (P<0.05). The resin composite group exhibited the highest SBS value (36.17±6.08 MPa), while the Biodentine had the lowest SBS value (21.86±3.18 MPa). Mixed failure mode was the most common failure type in all tested groups except in the Biodentine group, which had a predominantly cohesive failure. Conclusion: The SBS of e.max ceramic restorations cemented with resin is affected by the type of core material. Biodentine core material had the lowest SBS to e.max restoration. However, when Biodentine is indicated to be used as core material for pulp preservation, it is recommended to be covered with a layer of resin composite material to enhance its bonding strength to the e.max restoration.