| ObjectiveTo investigate the sterilization effect of Er:YAG laser Photon-initiated photoacoustic streaming(PIPS),Shock wave enhanced emission(SWEEPS)in straight and curved root canals of multiple teeth.MethodsAfter recovery,the Enterococcus faecalis strains were inoculated in agar dishes of bovine heart brain infusion using the plate scribing method,and a suspension of Enterococcus faecalis was made with BHI liquid enrichment medium after 24 h and its OD value was adjusted to 0.6 using a spectrophotometer.One hundred and fifty isolated teeth meeting the inclusion criteria of this experiment were selected,pulp chamber opened,root canals negotiated with 15#k files,autoclaved and then all isolated teeth were placed in bottles containing 100ml of the above bacterial solution and incubated for 4w under aerobic conditions at 37℃.The BHI solution was changed once every 3d to establish a root canal model of E.faecalis infection.Determine the placement position and parameter settings of the PIPS tip through preliminary experiment 1 and preliminary experiment 2.Seventy-five straight root canals and seventy-five curved root canals of multiple teeth were selected and randomly divided into 8 groups of 15 cases each.15 cases each of straight and curved root canals were randomly selected and the number of bacteria in the root canals was tested as a baseline.After preparing the root canal in each group using M3 nickel-titanium files to 06/25,the following treatments were performed.Group A:PIPS-Er:YAG+1%NaOCL irrigate straight root canals of multiple teeth.Group B:PIPS-Er:YAG+1%NaOCL irrigate curved root canals of multiple teeth.Group C:SWEEPS-Er:YAG+1%NaOCL irrigate straight root canal of multiple teeth.Group D:SWEEPS-Er:YAG+1%NaOCL irrigate curved root canals of multiple teeth.Group E:ultrasound+ 1%NaOCL irrigate straight root canals of multiple teeth.Group F:ultrasound+1%NaOCL irrigate curved root canals of multiple teeth.Group G:1%NaOCL irrigate curved root canals of multiple teeth.Group H:1%NaOCL irrigate curved root canals of multiple teeth.15 cases of multiple teeth with straight and curved root canals were taken as blank control.After treatment,the bacteria in the root canals of each group were collected by reaching into the root canals with a tip of dental absorbent point dipped in saline,diluting the specimens,coating the plates,incubating for 24 h,counting the colonies and calculating the sterilization rate,using SPSS 21.0 statistical software to analyse the results by ANOVA and LSD-t test for two-way comparison,and taking P<0.05 as statistically different.Two cases of each group were randomly selected for scanning electron microscopy to observe the effect of smear layer removal,and five cases were used for laser confocal observation of sterilization depth.ResultsThe overall sterilization rate of the laser group(A,B,C,D)is higher than that of the PUI(E,F)and CI(G,H)groups.The sterilization rate of PIPS(A)group in straight root canal group was higher than that of PUI(E)group and CI(G)group,and higher than that of CI(H)group in curved root canal group,and that of straight root canal(A)group was higher than that of curved root canal(B)group.The difference is statistically significant(P<0.05).PIPS(A and B)groups could remove a large number of smear layers in the middle and upper part of root canals,there was no obvious advantage in apical of root.The sterilization rate in straight root canal in SWEEPS(C)group was higher than that in PUI(E)group and CI(G)group,and the result in curved root canal was higher than that in PIPS(B),PUI(E)and CI(G)groups.The sterilization rate in straight root canal(C)group was higher than that in curved root canal(D)group.The difference is statistically significant(P<0.05).A large number of smear layers could be removed in all parts of the root canal in SWEEPS(C,D)groups.The laser confocal results showed that in the upper part of the root canal,the maximum sterilization depth in the curved root canal of the chemical irrigation group was less than 100 μm,while the average sterilization depth of the other groups was 100 μm.The average sterilization depth of the laser group in the middle part of the root canal was 200 μm 400 μm,and the maximum sterilization depth was 600 μm,while the sterilization depth of SWEEPS was 200～300 μm,which was much higher than that of ultrasound(30 μm)and chemical irrigation group(30 μm).The effect of SWEEPS group was the best,the average sterilization depth was about 100um,and the maximum depth was 300 μm.When ultrasonic and chemical irrigation were used on the lower part of root canal,the sterilization depth in curved root canal(10 μm)was much lower than that in straight root canal(100～200μm),while PIPS and SWEEPS could achieve ideal sterilization depth even in curved root canal.Compared with traditional root canal irrigation methods,Er:YAG laser PIPS and SWEEPS can effectively improve the efficacy of sterilization.ConclusionThe Er:YAG laser PIPS and SWEEPS demonstrated good smear layer removal and higher depth of sterilization both in the straight and curved root canals.Compared with traditional root canal irrigation methods,it can effectively improve the sterilization effect.What is more significant is that SWEEPS shows better cleaning results in the apical 1/3 of the root canal compared to PIPS. |
PDF Full Text Request