An in-vitro study of the shear bond strength of four resin core build-up materials.

Objectives: The aim of this study was to evaluate and compare the shear bond strength of four resin composite core materials, namely Filtek Supreme Plus, Surefill SDR Flow, CoreXflow and ParaCore.

Methods: 40 extracted maxillary central incisor teeth, randomly divided into 4 groups of 10, that were restored with the resin composite core materials. The teeth were mounted parallel into PVC pipes with acrylic resin and secured in a jig in order to apply the load at an angle of 90°. The specimens were subjected to a load at a crosshead speed of 0.5mm/min to the dentine and restorative material interface until fracture (universal testing machine).

Results: The mean Shear Bond Strength (SBS) was highest for CoreXflow followed by Paracore. The mean SBS of CoreXflow, ParaCore, Filtek Supreme XTE, SDR Surefill, obtained was 164.27N, 112.65N, 108.51N and 91.06N respectively. A significant difference in SBS was observed between the materials (One-way ANOVA and post hoc Tukey’s test (p < 0.05). CoreXflow yield the highest mean SBS and have shown a significant difference when compared to Filtek and SDR (p<0.05, Tukey’s test). No significant difference in SBS was found when comparing Filtek with SDR; Filtek and ParaCore; and ParaCore and SDR (p>0.05, Tukey’s test). No significant difference was also observed when comparing ParaCore and CoreXflow (p>0.05, Tukey’s test). SDR had the lowest mean SBS compared to all material tested.

Conclusions: CoreXflow had the highest SBS compared to the other materials. The results also revealed that the shear bond strenght of materials specifically indicated as a core build up materials like CoreXFlow and ParaCore, showed a higher shear bond strenght. The practitioner is therefore advised to use these materials specific designed for core build up instead of the traditional composite materials.