Effect of Blood Contamination Using Self-Etching Self-Adhesive Flowable Composite and Nanohybrid Composite on the Shear Bond Strength to Dentin – An in-Vitro Study

Background: Shear bond strength (SBS) is a key factor in the success of restorative materials, reflecting their adhesion to dentin. Blood contamination can interfere with resin infiltration and compromise bonding. Self-etching self-adhesive flowable composites offer ease of application, while nanohybrid composites provide superior mechanical properties. Comparing their SBS under uncontaminated and contaminated conditions helps assess their clinical performance. Aim: To compare and evaluate the shear bond strength (SBS) of self-etching self-adhesive flowable composite and nanohybrid composite to dentin under uncontaminated conditions and after contamination with blood. Materials and Methods: Sixty extracted human premolars were prepared with standardized Class V cavities and divided into two groups: uncontaminated, and blood-contaminated. Each group was subdivided into two subgroups (n = 15): self-etching self-adhesive composite and nanohybrid composite. SBS was measured using a universal testing machine. Data were analysed using independent t-test, one-way ANOVA, two-way ANOVA, Tukey post-hoc test, and Levene’s test. Results: Under uncontaminated conditions, nanohybrid composite showed significantly higher SBS than self-etch composite (p < 0.001). Blood contamination caused the greatest reduction in SBS, with self-etch composite performing significantly better than nanohybrid composite (p < 0.001). Significant differences were observed among subgroups and between factors (p < 0.001). Conclusion: Nanohybrid composite performs best under ideal conditions, while self-etch composite shows greater resistance to contamination. Blood contamination has the most detrimental effect on dentin bonding.