Avaliação da ação antimicrobiana da sílica nanoparticulada utilizada como medicação intracanal em canais radiculares infectados com enterococcus faecalis

Abstract

Some species of bacteria, such as Enterococcus faecalis (E. faecalis), present greater resistance to endodontic therapeutic procedures, and can survive in the root canal system even after the use of intracanal medications, such as calcium hydroxide (HC). Nanoparticulate silica (SN) has been recently researched because of its biological properties and, in particular, for a possible antimicrobial action. This study aimed to evaluate the antimicrobial action of nanoparticulated silica (NS) as an intracanal medication in human root canals infected with E. faecalis. Methods: Twenty-five teeth with a single canal and extracted for therapeutic reasons had the crown cut close to the cementoenamel junction. The root canals were infected with an E. faecalis strain (ATCC 29212) and incubated for 14 days at 37°C. After root canal preparations, the teeth were randomly allocated into four groups: PC - positive control (no medication, n=4); NC - negative control (no contamination, n=6); CH - calcium hydroxide (n=7); NS - nanoparticulated silica (n=8). The intracanal medications remained in the root canals for 15 days at 37C. Microbiological testing was performed to count the colony forming units (CFU). Statistical analysis was carried out by Kruskal-Wallis test for comparison of CFU between all groups, followed by the Mann-Whitney test for comparisons between groups (NS X CH; NS X PC; CH X PC), with =5%. Results: After 15 days as intracanal medication, both CH and NS groups showed a significant decrease in the CFU count compared to the PC (p<0.05). The NS group presented the lower mean of CFUs (4.0 ± 7.3 x 104 cell/mL), but with no significant differences compared to the CH (5.3 ± 1.3 x 105 cell/mL) group. Conclusion: Present findings suggest that both NS and CH had similar antibacterial effect against E. faecalis. NS has potential to be used as an intracanal medication, but further studies are required to validate the clinical use of NS in root canal therapy.