Objective: This study aimed to evaluate the effect of incorporating bioactive particles (montmorillonite loaded with chlorhexidine, MMT/CHX) and different concentrations of silica nanoparticles (0%, 3%, 5%, 7%, 10%, and 15 wt%) into a universal dental adhesive on its degree of conversion, bond strength, water sorption, solubility, and antimicrobial activity. Materials and Methods: A universal adhesive was modified with 1 wt% MMT/CHX and varying amounts of silica nanoparticles. Degree of conversion was analyzed by Fourier transform infrared spectroscopy (FTIR), and microtensile bond strength was evaluated at 24 h, 6 months, and 12 months after water storage. Water sorption and solubility were measured according to ISO 4049, and antibacterial activity was tested against Streptococcus mutans using the agar diffusion method. Results: All experimental adhesives containing ≥7% silica showed significantly reduced water sorption and solubility. The presence of MMT/CHX imparted consistent antimicrobial activity across all experimental groups. Degree of conversion remained stable across all groups and storage periods. Notably, after 12 months, only the experimental groups maintained or improved bond strength, while the control group showed a significant reduction. Failure mode analysis indicated increased mechanical integrity with higher filler content. Conclusions: Incorporating 1 wt% MMT/CHX and ≥7 wt% silica into a universal adhesive improved long-term bond strength, reduced degradation, and introduced antibacterial properties without compromising polymer conversion. These findings support the potential of developing durable, bioactive adhesive systems for restorative dentistry. Clinical Significance: The incorporation of bioactive and reinforcing nanoparticles into universal adhesives enhances bond durability and introduces antibacterial properties without compromising polymerization. This innovation may lead to longer-lasting restorations and reduced risk of secondary caries in clinical practice.
Brandt et al. (2025) studied this question.