In Vitro Evaluation Of The Antibacterical Effectivess Of 17%EDTA Associate With 1%NaOCl On Enterococcus Faecalis Within Root Canals

Objective:For the purpose of looking for an ideal root canal irrigation in clinical, germicidal efficacy of 1% NaClO, associating with 17% EDTA, was investigated in vitro against Enterococcus faecalis (E.faecalis) within root canal, and compared with 5.25% NaClO, 2.5% NaClO, 1% NaClO and 17% EDTA.Methods :45 extracted human anterior teeth with a single root canal were selected for this experiment,their crowns were removed and roots were standardized to a length of 14 mm.All root canals were enlarged with K-file to size 30 and autoclaved at 121°C,1.5 atm,for 15min.Then,they were kept in an incubator at 37°C for 48 to check the efficacy of the sterilization treatment.Each root canal was completely filled with the E.faecalis suspension,the medium was changed erery 2 days and all samples were infected for 21 days.Then,5 samples were chosen to see how the dentinal tubule was infected by E.faecalis. The other forty infected teeth were divided into five groups randomly, with eight in each.All root canals were preparated chemomechaniacally with different root canal irrigation, that was 5.25% NaClO for group A, 2.5% NaClO for group B,1% NaClO for group C,17%EDTA for group D and 17%EDTA+1% NaClO for group E. Microbiological samples were collected from root canal at three time points ( before, immediately after, and 72 hours after irrigation).Results:1. The meidum containing all the samples kept transparent after a 48-hours incubation at 37°C,indicating samples had been sterilized fully.2.After a 21-day incubation,we could observe bacterial penetration into the dentinal tubules by using a light microscrope.3.The numbers of E.faecalis in root canal in all the five groups were effectively reduced after chemomechanical preparation(P<0.05),Group A was statistically more effective than group B, group C, group D and group E (P<0.05);Group B was statistically more effective than group C and group D (P<0.05) ,and there was no statistically difference betweem group B and group E(P>0.05); Group C was statistically more effective than group D and group E (P<0.05).Group D was statistically more effective than group E (P<0.05)4. There were no bacterial contamination after 3-day-incubation, but bacterial survival was still observed in all canals of each group.Conclusion:1. The antibacterial efficacies of chemomechaniacal preparation with five irrigations were different and could be ranked from the strongest to the weakest solutions as follows: 5.25% NaClO,2.5% NaClO,17%EDTA+1% NaClO,1% NaClO and 17%EDTA .2. The antibacterial efficacies of chemomechaniacal preparation with NaClO were different, and could be ranked from the strongest to the weakest solutions as follows: 5.25% NaClO,2.5% NaClO and 1% NaClO .3. The antibacterial efficacy of chemomechaniacal preparation with 17% EDTA+1% NaClO was super to 1% NaClO or 17%EDTA,but similar to 2.5% NaClO.4. The antibacterial efficacy of 17%EDTA was the weakest among five irrigantions.5.The E.faecalis could not be eliminated completely even by chemomechaniacal preparation with antimicrobial irrigation.