Enhancing Bond Strength and Sealing Ability? Impact of Nanoparticle Incorporation on Micro tensile Bond Strength and Microleakage in 5th Generation Adhesive Systems

Purpose: This study aimed to evaluate the combined effects of 2% graphene oxide (GO) and 5% hydroxyapatite (HA) nanoparticles on both the micro-tensile bond strength (µTBS) and microleakage characteristics of a fifth-generation adhesive system. Materials and Methods: A total of 120 extracted human molars were utilized. For µTBS testing, 84 teeth were randomly divided into four groups (n=21): Group 1 (control), Group 2 (2% GO), Group 3 (5% HA), and Group 4 (2% GO + 5% HA). Flat mid-coronal dentin surfaces were prepared, followed by adhesive application and composite resin build-up. Specimens were stored for 24 hours at 37°C, sectioned into beams, and subjected to µTBS testing. For microleakage evaluation, 36 samples were prepared per ADA and ISO standards and divided into two groups: control and 2% GO. Samples were stored in deionized water for 24 hours, stained with dye, and examined using confocal laser scanning microscopy. Data were analyzed using One-Way ANOVA and Paired T-tests at a 5% significance level. Results: The µTBS analysis demonstrated that GO significantly improved bond strength compared to the control, HA showed no significant difference, and the GO + HA group exhibited the highest bond strength, indicating a synergistic effect. Microleakage analysis revealed greater dye penetration in control samples, whereas the GO group exhibited minimal, localized leakage at the adhesive–dentin interface, suggesting enhanced sealing ability. Conclusion: Incorporation of 2% GO nanoparticles into a fifth-generation adhesive improved both the mechanical (µTBS) and sealing (microleakage) properties, while 5% HA contributed additional bioactivity. The combination of GO and HA yielded the most promising enhancement in bond strength, attributed to GO’s reinforcing capacity and HA’s remineralizing potential. These findings support the potential of nanoparticle-modified adhesives in improving clinical performance. However, further in vivo and long-term studies are warranted to confirm their clinical efficacy.