| OBJECTIVE:Root canal treatment is a conventional method for the treatment of pulpitis and periapical periodontitis.However,conventional root canal treatment requires the establishment of a unobstructed access to the upper 1 / 3 of the root canal to uncover the top of the medullary chamber.This will inevitably grind away part of the healthy tooth tissue and peri cervical dentin(PCD).Minimally invasive root canal treatment has come into our view in recent years.In order to ensure the effect of accurate minimally invasive pulpotomy under computer-mediated and improve the removal effect of bacteria in the root canal system.To obtain an efficient and simple root canal disinfection method based on minimally invasive root canal treatment by comparing the different root canal irrigation methods between minimally invasive root canal treatment and conventional root canal treatment.METHODS:Sixty-six removed intact maxillary first molars were randomly divided into experimental group(computer-guided precision minimally invasive root canal treatment)and control group(conventional root canal treatment).All teeth were prepared to Pro Taper universal F2.After sterilization with high temperature and high pressure(121 ℃,30min),take 3 samples from each group for scanning electron microscope(SEM)observation and bacterial culture respectively,which proves that the sterilization is successful.The other samples were cultured to establish the Enterococcus faecalis infection model.Three samples from each group were observed by scanning electron microscope and bacterial culture respectively,which proved that the Enterococcus faecalis infection models were established.On this basis,each group was randomly divided into three subgroups,sodium hypochlorite + EDTA root canal irrigation(A),sodium hypochlorite + EDTA + ultrasonic(B)and sodium hypochlorite + EDTA + Er:YAG laser(C),9 in each group,a total of 6subgroups,for root canal irrigation respectively.After irrigation,1 sample of each subgroup was observed by scanning electron microscope,and the other 8 samples were cultured for24 hours by paper-tip method,and CFU values of each sample were calculated.Then palatal roots were prepared with Pro Taper universal F3 nitinol file and collect dentin debris about 50 μm under the dentin wall.After being diluted and cultured,the CFU value was calculated.Statistical analysis was performed by SPSS 26.0 software package.RESULTS:Through the observation of scanning electron microscope,it is proved that on the premise of the success of high temperature and high pressure sterilization,the Enterococcus faecalis infection model is successfully established without miscellaneous bacteria infection.Comparison of the amount of bacterial inner wall of root canal,the results of the control group and the experimental group showed that there was a significant interaction effect between the different invasive access and irrigation measure(F=3.394,P=0.043).The results of interaction effect analysis revealed a significant antagonism.The bacterial CFU counts of group B and group C were significantly less than that of group A(P<0.05),and there was no significant difference between group B and C(P>0.05).Additionally,group 2A was better than group 1A(P<0.05),there was no significant difference between group 1B and group 2B,group 1C and group 2C(P>0.05).Although the minimally invasive pulpotomy makes the bacterial residue more,the bacterial residue is significantly reduced with the assistance of ultrasound and Er:YAG laser,and there is no significant difference between the two.Comparison of the bacterial CFU counts in dentin debris after irrigation,the results revealed a significant antagonism(F=7.224,P=0.002),and group C had the least.The results showed that ultrasound and Er:YAG laser were also effective in removing bacteria from deep dentin.CONCLUSIONS:The disinfection effect of Er:YAG laser or ultrasound assisted computer-guided precision minimally invasive root canal treatment is similar to conventional root canal treatment,and Er:YAG laser is better than ultrasound in removing bacteria from dentinal tubules,which is more suitable for minimally invasive root canal treatment. |
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