| Objectives:In this study,a unified and standardized resin curved root canal was used.By comparing the forming ability of three root canal preparation systems,Namely m3-L Blue,Pro Tpaer Next(PN)and Pro Taper Universal(PU),the forming effect of M3-L Blue on curved root canal was preliminarily evaluated,so as to provide preliminary experimental basis for clinical application.Methods:30 unified and standardized resin curved root canals(Schneider method:30°)were selected and randomly divided into 3 groups: M3-L Blue,PN and PU,10 for each group.Root canal preparation is performed according to the recommended preparation procedure,during which the time required for root canal preparation is recorded.The morphology of the curved root canal before and after preparation was recorded under the root canal microscope.The images recorded before and after preparation of the resin root canal were overlapping with the computer software Photoshop CS6,and the offset of the center point after preparation of the resin root canal was obtained by Digimizer,a two-dimensional image measurement software.A centrifugal tube was used to collect the solution containing the detritus from the device during root canal preparation,and the electrothermal vacuum drying was performed to collect and weigh the detritus.SPSS16.0 was used for statistical analysis.The offset data and the resin root canal preparation time data of the three groups of instruments were in accordance with the normal distribution and variance analysis was adopted;l SD-T test was used for paly-comparison;the root tip detrusion data of the three groups of instruments were not in accordance with the normal distribution and Kruskal-Wallis test was used.Set test level =0.05.Results:1.None of the three sets of instruments broke or deformed significantly during root canal preparation.No obvious steps or elbow excursion were observed in the resin root canal.2.Root canal migration: The root canal migration occurred to a certain extent in each site of the three groups of instruments.Compared with the three groups of instruments 2mm from the root tip,the root canal migration in the M3-L Blue group was the smallest,and the difference was statistically significant compared with the PU group(P<0.05);The offsets of M3-L Blue group and PN group at a distance of 3mm-6mm from the root tip were smaller than those of PU group.In the middle and upper part of the root canal(4mm-7mm away from the root tip),the deviation value of the three groups of niti instruments was the largest,and all of them tended to pull the root canal.3.Root canal preparation time of the three groups: the average time of the M3-L Blue group was 35.62 seconds(35.36±4.36 seconds),the average time of the PN group was 35.86 seconds(35.86±3.86 seconds),and the average time of the PU group was 58.40 seconds(58.40±7.05 seconds).Compared with the PU group,the preparation time of the M3-L Blue group and the PN group was significantly shortened,and the difference between the groups was statistically significan(P<0.05).4.Apical detrital output: the average weight of the M3-L Blue group was0.0030g(0.0030±0.0052g),that of the PN group was 0.0023g(0.0023±0.0024g),and that of the PU group was 0.0021g(0.0023±0.0024g).There was no statistically significant difference between the three groups(P>0.05).Conclusion:1.Both M3-L Blue and PN have better flexibility and root canal adaptability than PU.2.Root canal migration was observed in all the devices of m3-L Blue,PU and PN.The centrality of m3-L Blue at the root tip(2mm from the root tip)was better than that of PU and PN,and the migration of m3-L Blue and PN in the middle of the root canal(4mm-7mm)was better than PU.3.PU takes the longest time in root canal preparation,and there is no difference between M3-L Blue and PN.4.In terms of the amount of detritus released,there was no significant difference among the three instruments. |
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