Impact of Capping Materials on Bond Strength

Objectives: The purpose of this in vitro study was to investigate the effect of three different pulp capping materials on the shear bond strength (SBS) of a universal adhesive system in deep dentin.
Methods: Thirty two molars were sectioned perpendicular to the long axis of the tooth to form flat occlusal sound deep dentin surfaces. A long fissur bur was used to remove dentin up to 0.5 mm from the pulp chamber to ensure accessing deep dentin (within 0.5 mm of the highest pulp horn), and teeth were embedded in PVC tubes using self-cured acrylic resin. Then teeth were randomly assigned to four groups according to the capping materials used: (1) Control; no pulp capping material; (2) Dycal; (3) Theracal LC; (4) Biodentin. After the application of capping materials (1*1 mm) , a universal adhesive was applied in self etching mode. Buildups (d:3mm, h:4 mm) were made over the deep dentin surfaces by a resin composite and the SBS values of the specimens were determined. The maximum shear bond strengths were noted at the time of the fracture. Fracture types were evaluated using a stereomicroscope.
Results: Regarding SBS values, there was a statistically significant difference between the pulp capping materials (P.05). Therecal's SBS (18,42 MPa) was significantly higher than Dycal's SBS (14,41 MPa) and Biodentin's SBS (9,66 MPa), while the control group showed the highest SBS value (30,39 MPa).
Conclusions: Application of pulp capping materials used in this study (Dycal, Therecal LC and Biodentin) in sound deep dentin lowered the SBS value of a universal adhesive. However the results obtained with Therecal LC showed clinically acceptable results.