Síntese de suspensões de micropartículas de quitosana/fluoreto de sódio e efeito no esmalte dental após desafio cariogênico

Abstract

The use of sodium fluoride (NaF) present in mouthwashes is considered an auxiliary method for the control of caries disease. However, the antimicrobial potential of fluoride is still questioned, and its use can be associated with antimicrobial agents for the prevention of caries. Chitosan (Quit) is a polymer with antimicrobial potential, but few studies have evaluated the association of Quit with NaF to prevent the development of enamel caries. Thus, the aim of this study was to synthesize two suspensions of chitosan particles loaded with sodium fluoride (Quit/NaF) at 0.05% and 0.2% to evaluate in vitro their effects on dental enamel after cariogenic challenge with pH cycling. . The Quit/NaF particle suspensions were synthesized by the ionic gelation method and characterized by titration using the dynamic light scattering method (particle size measurements by hydrodynamic diameter - Dh and zeta potential analysis - ZP) and absorption spectroscopy in the infrared region (FTIR). The stability of suspended particles was evaluated by means of ZP and Dh for one month, with an interval of one week between measurements. The cariogenic challenge was performed on human enamel blocks (4 x 4 mm) by the pH cycling method (3 h in the demineralizing solution and 21 h in the remineralizing solution) for 7 days, with application of the tested solutions and suspensions of particles (n = 10 /group): 1) Chitosan 0.2% (Quit 2); 2) 0.2% NaF (NaF 2); 3) Chitosan/NaF 0.2% (Quit/NaF 2); 4) Control 0.2% (C 2); 5) Chitosan 0.05% (Quit 05); 6) 0.05% NaF (NaF 05); 7) Chitosan/NaF 0.05% (Quit/NaF 05); 8) Control 0.05% (C 05). Before and after the acid challenge, Knoop microhardness (KHN) measurements were performed on the surface of the samples. Statistical analysis was performed by repeated measures ANOVA and Tukey's post-hoc h results showed that chitosan interacted with NaF, suggesting the formation of microparticles (1100 ± 91.7 nm). A reduction in Dh values was observed when NaF was titrated in chitosan and positive values of ZP (+ 30 mV ± 0.8). Quit/NaF 0.05% and 0.2% showed stability in size and ZP for 30 days. The FTIR spectra showed interaction between Quit-NaF, evidencing the formation of microparticles. The Quit/NaF 2 group presented the highest hardness value (213.0 ± 23.1) and the lowest % KHN value (41.7 ± 6.5) after the cariogenic challenge, being statistically different from the other groups. The suspension of chitosan microparticles loaded with 0.2% sodium fluoride reduced enamel demineralization after cariogenic challenge, demonstrating potential to be used as an anti-caries agent.