Sepiolite and Zirconia Nanoparticles Doped with Erythrosine: Adhesive Bond Strength and Antimicrobial Performance in Primary Carious Dentin.

OBJECTIVE: Antimicrobial effectiveness against Lactobacillus and micro tensile bond strength (μTBS) of etch and rinse adhesive (ERA) modified using Erythrosine (Ery), Ery-doped Zirconium oxide nanoparticles (ZrO2NPs), and Ery-doped Sepiolite Nanoparticles (SepNPs) bonded to caries-affected dentin (CAD) in primary dentition. METHODOLOGY: The present in vitro study was approved by the Institutional Review Board and Ethical Committee of Princess Nourah Binte Abdul Rahman University, IRB# 25-0063. The study duration was two months, November 20, 2025 - January 20, 2026. Primary CAD was removed. All the specimens were divided into four groups based on the application of ERA modification. Group-1 (Conventional ERA), Group-2 (Ery-modified ERA), Group-3 (Ery-doped ZrO2NPs modified ERA), and Group-4 (Ery-doped SepNPs modified ERA). Composite build-up was performed on all the specimens after adhesive application, and the specimens were exposed to μTBS testing and fracture analysis. All adhesives (modified and unmodified) were further tested for antimicrobial efficiency against Lactobacillus. The statistical analysis was conducted using a one-way analysis of variance (ANOVA) and a Tukey post hoc test. RESULTS: Group-4 (Ery-doped SepNPs-ERA) treated samples displayed the minimum survival of microorganisms (0.30 ± 0.04 CFU/mL) and the highest bond integrity (15.02±0.61MPa). However, Group-1 (Unmodified ERA) exhibited the highest bacterial survival count (0.65 ± 0.11 CFU/mL) and the lowest μTBS (10.95 ± 0.55 MPa). CONCLUSION: Ery-doped ZrO2NPs and Ery-doped SepNPs modified adhesive presented satisfactory antimicrobial activity against Lactobacillus and μTBS as compared to the unmodified adhesive when bonded to primary dentin.