Photodynamic inactivation (PDI) combined with chitosan has been shown as a promising antimicrobial approach. The purpose of this study was to develop a chitosan hydrogel containing hydroxypropyl methylcellulose (HPMC), chitosan and toluidine blue O (TBO) to improve the bactericidal efficacy for topical application in clinics. The PDI efficacy of hydrogel was examined in vitro against the biofilms of Staphylococcus aureus (S. aureus) and Pseudomonas aeruginosa (P. aeruginosa). Confocal scanning laser microscopy (CSLM) was performed to investigate the penetration level of TBO into viable S. aureus biofilms. Incorporation of HMPC could increase the physicochemical properties of chitosan hydrogel including the hardness, viscosity as well as bioadhesion; however, higher HMPC concentration also resulted in reduced antimicrobial effect. CSLM analysis further demonstrated that higher HPMC concentration constrained TBO diffusion into the biofilm. The incubation of biofilm and hydrogel was further performed at an angle of 90 degrees. After light irradiation, compared to the mixture of TBO and chitosan, the hydrogel treated sample showed increased PDI efficacy indicated that incorporation of HPMC did improve antimicrobial effect. Finally, the bactericidal efficacy could be significantly augmented by prolonged retention of hydrogel in the biofilm as well as in the animal model of rat skin burn wounds after light irradiation.

The objective of this study was to evaluate the antibacterial efficacy against Enterococcus faecalis and Streptococcus mutans and in vivo toxicity using embryonic zebrafish assays of sodium hypochlorite (NaOCl) and electrolyzed oxidizing (EO) water (containing hypochlorous acid (HOCl))-based root canal irrigating solutions. Methodology: Using 100 μL microbial count of 1 × 10⁸ cfu/mL Enterococcus faecalis to mix with each 10 mL specimen of NaOCl or HOCl for designed time periods. The above protocol was also repeated for Streptococcus mutans. The concentration of viable microorganisms was estimated based on each standardized inoculum using a plate-count method. Zebrafish embryo assays were used to evaluate acute toxicity. Results: All the HOCl or NaOCl treatment groups showed > 99.9% antibacterial efficacy against Enterococcus faecalis and Streptococcus mutans. Zebrafish embryos showed almost complete dissolution in 1.5% NaOCl within 5 min. Both survival rates after being treated with 0.0125% and 0.0250% HOCl for 0.5 min or 1.0 min were similar to that of E3 medium. Conclusions: Both NaOCl and HOCl revealed similar antibacterial efficacy (> 99.9%) against Enterococcus faecalis and Streptococcus mutans. While 1.5% NaOCl fully dissolved the Zebrafish embryos, both 0.0125% and 0.0250% HOCl showed little in vivo toxicity, affirming its potential as an alternative irrigation solution for vital pulp therapy.

In this study, the effects of sodium lauryl sulfate and various amino acids (DL-aspartic acid, dodecanedioic acid, and suberic acid) on the formation of calcium-deficient hydroxyapatite via hydrolysis of α-tricalcium phosphate (α-TCP) were investigated; moreover, a combined effect of these additives and ethylene glycol as a synthesis medium was also estimated. The hydrolysis reaction was performed in solutions containing different concentrations of additives in aqueous and mixed aqueous–organic media under solvothermal conditions. It was demonstrated that the nature and the concentration of organic additives influence the phase purity and morphology of the final product. Higher concentrations of sodium lauryl sulfate and dodecanedioic acid induced the formation of impurities in addition to hydroxyapatite, while aspartic and suberic acid did not affect the phase purity. The morphology of the samples varied from plate- to rod-like depending on the concentrations of specific organic additive.

Bismuth oxide (Bi₂O₃) is an effective additive used to enhance radiography resolution for dental materials. However, there are potential concerns regarding its biocompatibility and connection to tissue discoloration. In the present study, we modified the radiopacity properties of Bi₂O₃ with zirconium oxide (ZrO₂) using a sol-gel process and investigated the composition, as well as the effects of heat treatment temperature using Thermogravimetry analysis (TGA), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), and X-ray diffraction (XRD). The harvested Bi_2−xZr_xO_3+x/2 particles showed that the dominant phase transferred from α-Bi₂O₃ to β-Bi_7.38Zr_0.62O_12.31 after a heat treatment of over 750 °C for 2 h. As the x values of Bi_2−xZr_xO_3+x/2 increased from 0.2 to 1.0, more zirconium oxide precipitated onto the particle surface, thus enhancing the surface roughness of particles. For sol-gel Bi_1.8Zr_0.2O_3.1 powders (x = 0.2), the radiopacity values became 4.90 ± 0.23 and 5.83 ± 0.22 mmAl after a heat treatment of 500 °C and 750 °C, respectively.