The aims of this study were to synthesize highly positively charged chitosan nanoparticles (Ch-Np) using the electrospraying technique, and to test their antimicrobial activity against endodontic pathogens, and cytotoxicity against fibroblast cells. Ch-Np were synthesized from low molecular weight chitosan (LMW-Ch) using the electrospraying technique, and characterized. The antimicrobial activity was evaluated against Streptococcus mutans, Enterococcus faecalis, and Candida albicans in their planktonic state using a Time-Kill Test performed by using broth micro-dilution technique, and against biofilm biomass using a microtiter plate biofilm assay. The cytotoxicity was evaluated using Balb/c 3T3 fibroblast cells with the standard MTT assay. Electrospraying of LMW-Ch produced Ch-Np with an average size of 200 nm, and a surface charge of 51.7 mV. Ch-Np completely eradicated S. mutans and E. faecalis in the planktonic state and showed fungistatic activity against C. albicans. Furthermore, it significantly reduced the biofilm biomass for all the tested microbial species [S. mutans (p = 0.006), E. faecalis (p < 0.0001), and C. albicans (p = 0.004)]. When tested for cytotoxicity using 3T3 cells, Ch-Np showed no cytotoxicity. In conclusion, the highly positively charged, colloidal dispersion of Ch-Np are effective as a biocompatible endodontic antimicrobial agent.

There has been an increased demand for dental bleaching globally irrespective of age and gender. Main drawbacks associated with conventional tooth bleaching agents have been compromised strength and mineral-content of tooth enamel which results in sensitivity, discomfort, roughness, and structure loss of human teeth. Currently, nanoparticles synthesized by green synthesis have gained popularity especially in medical and dental applications because of their versatile and beneficial nano-scaled features. Titanium dioxide nanoparticles (TiO₂Nps) in this study were prepared from green ecofriendly source using the aloe vera plant extract and were then characterized via dynamic light scattering (DLS), scanning electron microscope (SEM), X-ray diffraction spectroscopy (XRD), and energy dispersive X-ray (EDX), for size, shape, composition and true-phase. These TiO₂ Nps were incorporated in commercial bleaching gel containing hydrogen peroxide to form a novel TiO₂-bleaching gel which was used to bleach extracted anterior teeth belonging to four different age groups: 20–29 years, 30–39 years, 40–49 years and ≥50 years. These teeth were investigated for micro-hardness (Vickers microhardness tester) and mineral-content (EDX spectroscopy) including sodium, magnesium, phosphorus, calcium in an in-vitro environment both before and after bleaching. Results revealed that TiO₂ Nps prepared by aloe vera plant were nanos-sized of about 37.91–49 nm, spherical shape, true anatase phase with pure titanium and oxygen in their composition. The values of Vickers micro-hardness and mineral-content (Na, Mg, P, Ca) of enamel specimens belonging to different age groups enhanced in a linear pattern before bleaching with the increase in age (p value < 0.05). There was negligible reduction observed in Vickers micro-hardness and mineral-content elements (Na, Mg, P, Ca) of all enamel specimens belonging to different ages after the bleaching (p value > 0.05). The novel TiO₂-bleaching gel prepared was effective enough in preventing the declination in Vickers micro-hardness strength and mineral-content of all the enamel specimens belonging to different age groups even after the bleaching procedure which makes it a promising biomaterial.

Objectives To synthesize a bioactive nanocomposite intra-canal medicament using chitosan nanoparticles (Ch-Np), loaded into Zeolite-Y as a carrier, and evaluate its antimicrobial activity in the presence and absence of tissue inhibitors. Also, to evaluate its cytotoxic activity against fibroblast cells. Materials and methods A concentration of 3% (w/v) electrosprayed Ch-Np was mixed with Zeolite-Y in a concentration of 53.3 (w/v) and characterized using Scanning Electron Microscopy (SEM), and Energy Dispersive Spectroscopy Analysis (EDS). The antimicrobial activity was evaluated against Streptococcus mutans and Enterococcus faecalis using the agar diffusion test, and Time-Kill Test performed by using the broth micro-dilution technique in presence of tissue inhibitors. The cytotoxicity was evaluated against Balb/c 3T3 mouse fibroblast cells using the standard MTT assay. Results The mixture resulted in a white paste with a crystalline-like structure under SEM. EDS analysis showed a reduction in the anatomical percentage of Zeolite-Y, indicating cation exchange with Ch-Np. A mean diameter inhibition zones of 9.57 mm for S. mutans and 7.85 mm for E. faecalis were observed, indicating antimicrobial activity. S. mutans and E. faecalis were completely eradicated in the presence of tissue inhibitors. The Ch-Np-Zeolite nanocomposite promotes the growth of 3T3 fibroblast cells significantly (p = 0.00). Conclusions Zeolite-Y loaded chitosan nanoparticle nanocomposite completely eradicated S. mutans and E. faecalis even in the presence of tissue inhibitors while maintaining its biocompatibility. Clinical relevance: The novel Ch-Np-Zeolite nanocomposite exhibits antimicrobial activity against endodontic pathogens while maintaining its biocompatibility, providing the potential to be used as a novel intra-canal medicament.