Effect Of Carboxymethyl Chitosan On Chemical Preparation Of Oval Root Canals In Vitro

Objective:Root canal therapy is the first choice for dental pulp disease and periapical disease.Chemical preparation is one of the key links.Carboxymethyl chitosan increases the water solubility of chitosan and retains the antibacterial properties and the ability to adsorb metal ions.In this experiment,the feasibility of using carboxymethyl chitosan as a root canal irrigating solution was investigated by studying the removal effect of the root canal smear layer and the bactericidal effect of Enterococcus faecalis.methods: The E.faecalis suspension cultured to the logarithmic growth phase was diluted in BHI medium at a volume ratio of 1:10,and then the diluted bacteria suspension was inoculated into a 96-well plate,and the experimental group was added at a concentration of 1mg/ml,5mg/ml,10mg/ml and 30mg/ml of CMC,the positive control group was 0.2% CHX,and the negative control group was BHI.The OD600 value,is used to draw the growth curve of the bacterial suspension.The diluted bacterial suspension was inoculated into a 96-well plate,added the above 6 reagents,and cultured for 48 hours,and the OD570 was measured by a microplate reader.The 48 h E.faecalis bacterial biofilm was constructed in a 96-well plate,and the above 6 reagents were added respectively.After 2h,the OD570 was measured.Collect single canal premolars,truncated crown,the standard working length is 11 mm,and the samples were divided into 4 groups randomly according to different irrigation schemes: negative control group,saline;positive control group,1% Na OCl+17% EDTA;30 mg/ml CMC;30 mg/ml CMC+17% EDTA,10 samples per group,Protaper mechanical preparation,split longitudinally,and fixed.Dehydrated,dried,and the upper,middle and lower sections of the root canal were scanned by electron microscope,Observe the debris and smeared layers at 200 and 1000 times,respectively,and score according to the classification criteria.All data were analyzed statistically using SPSS 25.0 software,the optical density values were using one-way analysis of variance and SNK method.Mann-Whitney U test was used to compare the score data under electron microscope,and Kruskal-Wallis H was used to compare within the group.Inspection standard is 0.05.Result:1.Different concentrations of CMC can inhibit the growth of suspended E.faecalis,and the better the antibacterial effect with the increase of CMC concentration.5mg/ml,10mg/ml and 30mg/ml CMC can achieve similar antibacterial effect to 0.2% CHX in the first hour(P> 0.05).2.The inhibitory effect of CMC of 3.5mg/ml,10mg/ml and 30mg/ml on 48 h E.faecalis biofilm is the strongest,and it is statistically different from 1 mg/ml CMC and 0.2% CHX(P <0.05),1mg/ml There was no statistical difference between the CMC and 0.2% CHX groups(P> 0.05).3.30mg/ml CMC has the strongest bactericidal effect on E.faecalis biofilm,which is not statistically different from the 0.2% CHX group(P> 0.05),and has statistical difference with the CMC group at 1 mg/ml,5 mg/ml and 10 mg/ml.(P <0.05).4.The ability of CMC+17% EDTA group to remove debris and smeared layer is better than that of CMC alone(P<0.05),there is no statistical difference between CMC group and negative control group(P> 0.05).Conclusion:1.Different concentrations of CMC can inhibit the growth of suspended E.faecalis,and the better the antibacterial effect with the increase of CMC concentration.2.Different concentrations of carboxymethyl chitosan can effectively inhibit the formation of E.faecalis faecalis biofilms,and 30 mg/ml carboxymethyl chitosan has the strongest bactericidal effect on mature E.faecalis faecalis biofilms.3.The use of CMC alone has no obvious effect of removing debris and stains in the root canal,and it is better to use it in combination with 17% EDTA.