| Objective: To detect and quantify the endotoxin content of infected root canal before and after treatment and evaluate the effectiveness of clearing root canal endotoxin by conventional hand instrument preparation, hand instrumented followed ultrasonic irrigation as well as hand instrumented followed Nd:YAG laser irradiation. To provide practical foundation for the improvement of root canal treatment.Methods: (1) Patient selection:Included in our study were 30 single root canal human teeth,diagnosed clinically and radiographically as chronic periapical periodontitis due to pulp necrosis.The teeth were randomly divided into three groups as hand instrumented group; ultrasonic treatment group ;and Nd:YAG laser treatment group. Each group was composed of ten teeth. (2)Treatment procedure: The root canal of teeth in group A were prepared and cleaned conventionally by hand instrument ,followed FC root canal dressing for 1 week. The teeth in group B first prepared by hand instrument as in group A,then cleaned by ultrasonic irrigation for 1 minute, followed by FC root canal dressing. The root canal of teeth in group C were irradiated byNd:YAG laser for 1 minute with the energy of 50mj 15Hz after hand instrumented as in group A, then dressed by FC for 1 week. (3) Detection of endotoxins:samples were taken before and after 3 different ways of root canal treatment,and after disinfection. Then the samples were assayed for the endotoxin content by dynamic turbidity method.(4)Statistical treatment: Statistically detect to see if there was significant difference intra- and inter-group. Results: (1) The contents of endotoxin in the root canals of 3 groups before treatment were55.658 EU/ml,52.350 EU/ml ,51.621 EU/ml respectively.(2)Hand instrument group: the endotoxin content in the root canals of group A reduced evidently from 55.658 EU/ml to 6.223EU/ml after traditional preparation and irrigation; and after root canal dressing by FC for 1 week ,the endotoxin was descended to 2.313EU/ml.There was great statistical difference among the three assays.(P<0.001 and P<0.01). (3)Ultrasonic irrigation group : in group B, the endotoxin content decreased dramatically from 52.350 EU/ml to 1.222EU/ml after hand instrumented followed ultrasonic irrigation for 1 minute and the reduction was statistically significant(P<0.001);but after the root canal dressing the endotoxin content rose to 5.177 EU/ml,but this increase was not statistically significant(P>0.05).(4) Nd:YAG laser irradiation group: the endotoxin content in the root canals of group C drastically decreased from 51.621 EU/ml to 0.323 EU/ml,there beingsignificant difference between the two assays(P<0.001);but after disinfected by FC for 1 week,the endotoxin recovered to 1.996 EU/ml, however the increase was not statistically significant(P>0.05).(5) The difference between the three groups after the second assay: with 3 different methods of treatment, the endotoxin contents in the root canal of the 3 groups were as follows: hand instrumented group the highest, ultrasonic treatment group the moderate ,and Nd:YAG laser treatment group the lowest. The difference between group A and B was significant,so was that group A and C(P<0.05,P<0.05);While there was not significant difference between group B and C (P>0.05). (6) the difference after the treatment: After statistical analysis,there found no obvious difference between the three groups after the 3 assay(P>0.05).A certain amount of LPS was detected after the root canal treatment and dressing.Conclusions: (1) Endotoxin can be detected in all the infected root canals .The mean content of the endotoxin in the root canals of teeth with chronic periapical periodontitis was 53.209EU/ml. (2) After the traditional hand instrument and irrigation, the endotoxin in the root canal reduced apparently.The conventional root canal therapy was an effective method for endotoxin clearance.(3)The mass of the root canal endotoxin can be cleaned after hand instrumented followed ultrasonic irrigati... |
