Green-synthesized tricalcium silicate nanoparticles from Salvia officinalis for antimicrobial coating of clear aligners and prevention of enamel demineralization

Orthodontic treatment has evolved to include clear aligners, which offer better aesthetics and comfort compared to traditional fixed appliances. However, prolonged intraoral wear can promote bacterial adhesion and enamel demineralization. In this short communication, we report a plant‑mediated route to synthesize tricalcium silicate (C₃S) nanoparticles using Salvia officinalis (sage) extract and to apply them as an antimicrobial coating on transparent aligners via polyethylene glycol 400 dip coating. The nanoparticles were characterized by UV–Vis, FTIR, XRD, SEM, and EDX analyses, confirming calcium‑silicate formation at the nanoscale. Antibacterial screening against Streptococcus mutans and Acinetobacter showed measurable inhibition zones for nanoparticle suspensions and for C₃S‑coated aligners, compared with uncoated controls. The antibacterial effect is attributed (based on calcium‑silicate chemistry and prior reports) to hydroxyl‑ion–mediated alkalinity and calcium‑ion release; quantitative pH monitoring, coating thickness, durability under cleaning/wear, cytocompatibility, and direct enamel‑protection/remineralization assays were not evaluated in the present work and are required for translation.