Femtosecond laser-induced micro/nanostructures loaded with silver nanoparticles on clear aligner prevent bacterial infection

Background: Controlling biofilm formation is crucial for maintaining aesthetically healthy teeth during clear alignertreatment. In this study, we use a femtosecond laser to prepare porous micro/nanostructures on the surface of invisible aligner for loading silver nanoparticles (AgNPs) to create an anticarie aligner. Methods: Femtosecond laser technology was used to fabricate Porous micro-nanostructures on invisible aligner, after which the micro-nanostructures were loaded with green synthesized silver nanoparticles. Physical properties, chemical properties, antimicrobial properties against S. mutans , and biocompatibility were evaluated. Results: Laser treatment significantly increased the wettability of the aligner (water contact angle reduced from 86.5°to 38.7° p < 0.05), while preserving salivary absorption rate and flexural elastic moduli. In addition, the results of in vitro antimicrobial tests showed that the laser/Ag group had a high inhibition rate of 62.89% against Streptococcus mutans. All treatment groups exhibited excellent biocompatibility with both mouse fibroblast (L-929) and human gingival fibroblast (HGF) cells. Significance: Our strategy provides a promising avenue for improving the antimicrobial properties of invisible orthodontic appliances. Laser treatment help aligners to load more silver nanoparticles while having no adverse effect on the physicochemical properties of clear aligner. This innovative drug delivery platform demonstrates versatile applicability with broad material compatibility for hydrophilic nano-antimicrobials, establishing a clinically translatable framework for orthodontic infection control.