Analysis of Shear Bond Strength and the Quality of the Interface Between Composite Resin and Novel Hybrid Calcium Silicate Cements

Hybrid calcium silicate cements (HCSC) are new bioactive materials of the fourth generation with the main application as pulp capping agents and/or as liners in indirect pulp capping. The aim is to analyze the shear bond strength and the quality of the interface between a composite restorative material and a new bioactive material and other hybrid cements at the same conditions. The used pulp-capping hybrid materials: TheraCal and the new hybrid biomaterial BioCal-Cap. In this study only one type of adhesive system (Scotchbond 3M, St. Paul, MN, US) and resin-based composites (Filtek Ultimate 3M, USA) were used. For this purpose, 60 molds were prepared and divided into 4 groups. Half of them were filled with TheraCal and the other 30 with BioCal-Cap. The shear bond strength between calcium-silicate cements and the composite material was investigated. Mann-Whitney test and Wilcoxon Signed Ranks Test were used for statistical analysis of the results. In both of the materials there was no statistically significant difference in the results after the immediate and postponed placement of the composite material. Nevertheless, in both of them there was a tendency for a slight increase in shear strength in the samples which delayed the application of the restorative material. The novel hybrid material BioCal-Cap was reported to have higher shear strength values (18.06 – 20.25 MPa) at both time periods in comparison to the values for TheraCal (13.71 – 15.58 MPa). The data clearly showed that the time of the composite material placement did not affect the shear bond strength in each of the observed groups. The median value was shifted higher after the immediate composite placement, which supported one-step treatment approach to the novel hybrid material BioCal-Cap, while the TheraCal LC exhibited the opposite tendency. The adhesive layers in both hybrid cements were homogeneous, properly structured, without the presence of microcracks and gaps, and had different thicknesses at different recovery times.