Efeito da incorporação de nanopartículas metálicas em propriedades antimicrobianas, físicas e mecânicas de materiais dentários restauradores

Abstract

The modification of dental restorative materials may be promising for microbial control, resulting in biofilm reduction around dental restoration margins, without compromising mechanical properties of materials. The use of nanoparticles was introduced to improve the effectiveness of materials, acting on their chemical, mechanical, physical, electrical and/or optical properties. Thus, the present dissertation is composed by two chapters, which aim, respectively: 1) to perform a systematic review with meta-analysis, evaluating the antimicrobial effects of dental restorative materials modified by incorporating metallic nanoparticles and 2) to investigate the antimicrobial effect of adding copper/silver nanoparticles (CuAgNP) in a chemically activated glass ionomer cement (GIC) in Streptococcus mutans-and-Candida albicans biofilms, as well as on physical properties of the cement. In study 1, an electronic search was performed using 7 databases and the gray literature. The initial search identified 1,072 articles. After removing duplicates and screening eligibility criteria, 39 articles were eligible for this review, leaving 29 articles for metaanalysis. In study 2, GIC specimens were made (n=9), according to the groups: 1- unchanged GIC; 2- GIC + 0.01% CuAgNP; 3- GIC + 0.05% CuAgNP and 4- GIC + 0.1% CuAgNP. Duo-species biofilms were formed on specimens in tryptone casein soy culture medium supplemented with yeast extract and 1% sucrose for 72 h. The experiment was repeated 3 times with 3 experimental units in each group. Then, the biofilms were collected and seeded in selective media and the colony forming units (CFU) were counted and the dry weight was analyzed. Physical tests assessed surface roughness, color variation and setting time. Statistical analyzes were performed using Kolmogorov-Smirnov, ANOVA and Tukey test. In study 1, the incorporation of Ag and Cu reduced CFU in primer and GIC. In terms of mechanical properties, Ag in GIC reduced microhardness and diametral tensile strength, increasing only the shear and compression strengths. Ag-incorporation significantly increased shear strength in adhesive and Ti and Ag showed no change in conversion degree. In the experimental study, the incorporation of CuAgNP into the GIC did not present a significant antimicrobial effect and significant changes in physical properties of the CuAgNP-dopped material, such as an increase in setting time, roughness and color change were observed. Incorporation of metallic nanoparticles in the material composition does not guarantee effectiveness in antimicrobial and physical properties of materials. In situ and clinical studies need to be carried out to assess efficacy and safety of using materials modified by the incorporation of metallic nanoparticles.