Propriedades físico-químicas e antibacterianas da incorporação de micropartículas poliméricas carregadas com clorexidina em cimento ionômero de vidro

Abstract

Chlorhexidine (CHX) is the most investigated antimicrobial agent in dental caries control and its incorporation in glass ionomer cement (GIC) has been proposed to reduce the microorganism number in patients with high caries activity. Thus, the aim of this study was to evaluate the effect of adding CHX salts in their free forms (diacetate - DA or digluconate - DG) and incorporated in polymeric microparticles of poly (lactic-co-glycolic acid) (PLGA), in the physicochemical properties and antibacterial action of a chemically activated GIC. Materials and Methods: PLGA microparticles containing CHX diacetate (MPDA) or digluconate (MPDG) were obtained by the spray drying technique. The experimental groups were prepared with the addition of 1% CHX in their free or microencapsulated forms into GIC, and the control group had no CHX incorporation, constituting the following groups: GIC (control), DA, DG, MPDA and MPDG. Stability of CHX, Fourier transform infrared spectroscopy, CHX cumulative release (%) and scanning electron microscopy (SEM) analysis were performed, followed by physic testing of setting time, flowability and compressive strength. For antibacterial effect determination, S. mutans was inoculated in culture medium tryptone soy broth supplemented with yeast extract and 1% sucrose by forming biofilms over the specimens up to 5 days. After 24 h of initial adhesion and subsequent 1-day intervals, the number of colony forming units (CFU/ml) of the biofilm formed on freshly prepared samples (after 24 h of setting time- immediate group) and samples aged in water at 37 °C for 15 days (aged group) was determined. Statistical analysis for physicochemical tests and antibacterial effect were performed by analysis of variance (ANOVA) and Mann Whitney test, both followed by post-hoc tests at a pre-set 5% significant level. Results: DG in solution in GIC presence was more stable at room temperature and at 37 °C when compared to DA. FTIR analysis didn’t indicate chemical reaction between GIC and CHX in tested concentrations. Microencapsulated formulations have increased setting time, while DG decreased it (p<0.05). DG inclusion increased compressive strength (p<0.05) and flowability was reduced by CHX free forms inclusion (p<0.05). MPDA and MPDG showed a later and gradual releasing profile when compared to DA and DG groups. Incorporating CHX showed significant antibacterial effect when compared to pure GIC, but without statistically significant differences when comparing groups with free or microencapsulated forms, as well as immediate and aged GICs. Conclusion: The incorporation of CHX resulted in glass ionomer cements with antibacterial effect and appropriate physical properties for clinical use.