Research Of Antimicrobial Effects Of Enterococcus Faecalis And One-time Root Canal Therapy Using Er:YAG Laser Combined With Sodium Hypochlorite Irrigants

Objective: To compare the antimicrobial effects and One-time root canal therapy of Er:YAG laser combined with different concentrations of Sodium hypochlorite irrigants on Enterococcus faecalis.Methods:For the in vitro study,75single-rooted teeth were selected for the experiment.Prepare the root canal using Nickel titanium instrument by crown-down technique.Recovery the Enterococcus faecalis in BHI culture dishes and take them into BHI liquid medium,adjust the concentration to 1.5×108CFU/m L.Put all sterilized teeth into the liquid medium for 4 weeks.Change the liquid medium every 4 days.The teeth were randomly divided into 5 groups: 5.25 % Na Cl O only(group A),Er:YAG laser +5.25 % Na Cl O(group B),1 % Na Cl O only(group C),Er:YAG laser + 1 % Na Cl O(group D),and untreated(group E).Use group E to evaluate the success of models and the baseline number in the root canal.The amount of bacteria in the root canal of all models after treatments were measured by counting the Colony-Forming Units(CFU)in the culture dishes and bacteria reduction were analyzed by means of Chi-square test.For the in vivo study,113 anterior teeth and premolars with acute pulpitis or dental pulp exposure caused by injury were selected and randomly divided into 2 groups.After root canal preparation,Group A were irrigated with Er:YAG laser combied with1% Na Cl O,Group B were irrigated with 1% Na Cl O separately,and were then filled.The patients were followed up at 3d,7d and 1 month after treatment.SPSS 19.0 software was used to analyze the data.Count data were analyzed by means of Chi-square test.The difference was significant at P <0.05.Results:In vitro study,Group A B D show great antimicrobial effects and reduce the Colony-Forming Units(CFU)to 0,all culture dishes are empty.But group C can not kill all Enterococcus faecalis.4 of 15 culture dishes of group C are empty and without any bacterial colony,but the rest are not.Every culture dishes of group E has a lot of bacterial colonies.The antimicrobial effects between group A B D were the same and significantly better than group C.In vivo study,54 of 56 in group A were success and the success rate was96.4%.While 51 of 57 in group B were success and the success rate was 89.4%.Group A was significantly better than group B.Conclusions: Low concentrations of Sodium hypochlorite don`t have ability to kill all Enterococcus faecalis but high concentrations of Sodium hypochlorite shows great antimicrobial effects.Er:YAG laser combined with low concentrations of Sodium hypochlorite irrigants has strong effects on disinfection of Enterococcus faecalis and One-time root canal therapy...