Effect of nanoparticle incorporation on antimicrobial activity and shear bond strength of orthodontic adhesives: a scoping review.

Nanoparticle incorporation into orthodontic adhesives has emerged as a strategy to enhance antimicrobial properties, improve mechanical performance, and prevent enamel demineralization during fixed appliance therapy. This scoping review aimed to synthesize evidence on the effectiveness of nanoparticle-modified orthodontic adhesives. A systematic search and independent screening process were conducted by two reviewers across multiple databases following the PRISMA-ScR guidelines. Among the 153 initially identified records, 25 studies met the inclusion criteria. Most studies (72%) were in vitro, whereas only 12% used in situ models. Preclinical studies are scarce (4%), emphasizing the gap between laboratory findings and clinical application. Silver nanoparticles (AgNPs), which demonstrate strong antimicrobial activity against S. mutans, E. coli, and S. aureus while maintaining acceptable bond strength at moderate concentrations, have been the most frequently investigated. Other nanoparticles, such as titanium dioxide (TiO₂), β-AgVO₃, mesoporous bioactive glass nanoparticles (MBNs), calcium phosphate compounds, and calcium phosphate compounds, also show promising antimicrobial and remineralization properties. However, variations in study designs, nanoparticle concentrations, and adhesive formulations hinder direct comparisons. Despite promising laboratory findings, the clinical application of nanoparticle-modified orthodontic adhesives remains uncertain due to the lack of standardized methodologies and long-term clinical validation. Further well-designed clinical trials are essential to confirm their efficacy, safety, and impact on orthodontic bonding performance under real-world conditions. Standardization of nanoparticle formulations and biocompatibility assessments are crucial to ensure their practical integration into orthodontic practice, promoting safer and more effective treatments.