ABSTRACT
Objective@#To evaluate the antimicrobial activity of nonequilibrium plasma against Enterococcus faecalis (Ef) biofilms in vitro and to obtain novel evidence of root canal disinfection with nonequilibrium plasma.@*Methods@#Sterile cover slips and single-rooted canals were filled with Ef and incubated to form 1-week-old and 3-week-old biofilms, respectively. The infected samples were subjected to nonequilibrium plasma, 2% chlorhexidine digluconate (CHX) and saline for 3, 10 and 30 minutes, respectively. After treatment, the killing effectiveness of nonequilibrium plasma was analyzed by using laser scanning confocal microscopy (LSCM) and colony forming unit (CFU) counting.@*Results@#The 3-dimentional reconstruction LSCM images showed that about 48.3%-79.8% of 1-week-old Ef biofilm cells and 40.0%-67.4% of 3-week-old biofilm cells were killed by nonequilibrium plasma and 2% CHX compared to saline (P<0.05). The proportion of killing activity was lower after 3 minutes (40.0%-50.9% killing) than after 10 minutes (65.3%-77.8% killing) and 30 minutes (66.4%-79.8% killing) (P<0.05). And the killing of biofilm bacteria was fastest during the first 3 minutes (13.3%-17.0% killing per minute) and slow down greatly after 10 minutes. Remarkably more bacteria were killed in 1-week-old Ef biofilms (48.3%-79.8% killing) than in 3-week-old biofilms (P<0.05).@*Conclusions@#The nonequilibrium plasma killed more Ef biofilm cells in infected root canals showed promotional as an additional approach against bacterial biofilms during root canal disinfection.
ABSTRACT
To evaluate amoebicidal efficacy of various disinfectants, we treated ten ocular isolates of Acanthamoeba with polyhexamethylene biguanide(PHMB), chlorhexidine and hexamidine. Acanthamoeba cysts were collected from axenic nonnutrient agar plates from 4 week culture. Cyst suspension(100microliter) was inoculated on 96-well microplate with concentration of 105 cys/ml. Each well was treated with two-fold diluted hexamidine, PHMB and chlorhexidine(100microliter each, 8 and 48hrs). Each well was examined under the inverted microscope until 7 days after treatment. Minimal cysticidal concentration(MCC) of each disinfectant qas measured after five experiments. MCC of hexamidine, chlorhexidine and PHMB against ten ocular isolates ranged 6.07-500microgram/ml, 3.12-12.50microgram/ml, 1.17-4.68microgram/ml respectively in 48hr treatment. In 8hr treatment, MCC of PHMB and chlorhexidine ranged 4.42-12.50microgram/ml and 4.67-17.71microgram/ml, but hexamidine did not demonstrate cysticidal effect. For proper disinfection of contact lens, disinfectants having cysticidal efficacy should be included in the composition of contact lens solution. Among the currently used topical amoebicidal agents, PHMB showed the greatest cysticidal activity on ten ocular strains of Acanthamoeba in invitro study.