Effectiveness Of Three Rotary Instrumentation On Remove Enterococcus Faecalis From Root Canals

Objective:Compare the removal effectiveness of Enterococcus faecalis within root canalrelated to different rotary instrumentation systems on remove Enterococcus faecalisfrom root canals. It will provide a theoretical and experimental basis for the selectionof a ideal rotary system.Methods:Forty-four extracted human maxillary first permanent molar teeth were selectedfor this experiment,their crowns were removed and distobuccal root canals werestandardized to a length of12mm.The working length was11mm. All root canalswere enlarged with K-file to size20#,and then the apical foramens were sealed byepoxy resin. All root canals were autoclaved at121℃,1.5MPa,for15min.Then,theywere kept in CO2incubator at37℃for48h to check the efficacy of the sterilizationtreatment.Each root canal was completely filled with the E. faecalis suspension, andincubated in CO2incubator at37℃.The medium was changed every2days.Bacteriology characterization approaches were used to make sure that there were noliving contaminants. All samples were infected for21days. Four samples werechosen to evaluate how the dentinal tubule was infected by E.faecalis in the scanningelectron microscope. The other forty infected canals were randomly and evenlydivided into A,B,C,D four groups,which underwent different rotary instrumentation,and each group with10samples. Group A applied Safe Sider, Group B used BLx,Group C employed ProTaper and Group D was control group, using the conventionalstainless steel K file. Then, each group was divided into two subgroups according todifferent root canal irrigation,marked as A1,A2,B1,B2,C1,C2,D1,D2,that was17%EDTA+1%NaOCl for group A1,B1,C1,D1,saline water for A2,B2,C2,D2.In theexperiment,each tiome replace of the larger size instrumentation needed the specifiedirrigation.All of the canals were prepared to35#. Microbiological samples werecollected from root canal at three time points (before,prepared to35#).Aliquots wereplated onto agar plates and incubated in CO2incubator at37℃for48hours. The colony forming units (CFUs) were counted and analyzed.Results:1. After a21-day incubation, bacterial colonization could be observed on rootcanal walls, and Enterococcus faecalis were into the dentinal tubules by using ascanning electron microscope. The root canal infection model could be successfullyestablished in vitro.2. Before root canal preparation, the numbers of Enterococcus faecalis in rootcanals were no statistically significant diference between each of groups (P>0.05).3. After preparation,the numbers of Enterococcus faecalis in root canals were nostatistically significant diference in group A1,B1,C1,however,all the three groups hadsignificant difference when compared with the control group (D1group)respectively;the numbers of Enterococcus faecalis in root canals were nostatistically significant diference in group A2,B2,C2.however,all the three groups hadsignificant difference when compared with the control group (D2group)respectively.4. After preparation，the bacteria reduction in A2,B2,C2and D2groups weremuch more than that in A1,B1,C1and D1groups, and bacteria reduction in theexperimental groups were also greater than that in the control group, but the value ofbacteria reduction between the experimental groups had no significant difference.onremove Enterococcus faecalis from root canals.Conclusions:1. The model for root canal invaded by Enterococeus faecalis can beestablished successfully in vitro.2. When the canals prepared to35#,the three rotary instrument had nosignificant difference in the abilities of removing Enterococcus faecalis from rootcanals with the same irrigation.3. When the canals prepared to35#,the antibacterial efficacy of1%NaOCl+17%EDTA was better than saline water using the same rotary instrumentation.