| Objective:To evaluate the effect of semiconductor laser irradiation on root canal sealing after routine root canal therapy(RCT).Methods:Sixty freshly extracted single-rooted human teeth were used,roots with resorption,fractures or open apices were discarded.Immediately after extraction the teeth were stored in 0.5% chloramine at 4 8C up to1 month.,randomly divided into six groups(n=10).The anatomic crowns were sectioned at the cementoenamel junction.All of the root canals were prepared with Wave-one rotary nickel titanium instruments to an apical size of 40,0.06 taper using 1% sodium hypochlorite and17%EDTA as the irrigant.The canals were irrigated with 1% sodium hypochlorite and17%EDTA between each file size,and were lubricated with EDTA.After canal preparation,specimens were rinsed with water,then a final flush of 1% Na OCl and finally dried with absorbent paper points.And then the remaining roots were prepared endodontically with conventional RCT methods.Groups A and B were irradiated with 1W semiconductor laser for 20 seconds;Groups C and D were ultrasonically rinsed for 60 seconds as control group;Groups E and F without treatment of root canal prior to RCT as blank group.Root canal sealing of Groups A,C and E were evaluated by measurements of apical microleakage.The teeth from Groups B,D and F were sectioned,and the micro-structures were examined with scanning electron microscope(SEM).One way ANOVA and LSD-t test were used for statistical analysis(?=.05).Results: 1.Apical microleakage detectionThe length of the root canal was infused into the root canal of the magenta solution.The E group of the blank control group was 4.56 ± 2.72 mm,the group A was the shortest 1.70 ± 0.82 mm in the laser irradiation group,The group C was 2.02 ± 0.40 mm.There was significant difference between group E of laser control group and group A in laser irradiation group(p<0.05).There was also significant difference between group E of blank control group and group C of ultrasonic swing group(p<0.01).There was no significant difference between group A and group C(p>0.05),group A of blank control group,group A of laser irradiation group and ultrasonic dishwashing There was no significant difference between the three groups(p>0.05).The results showed that there was no significant difference in the apical sealing ability between the root canal and the root canal,but the laser irradiation group had a significant difference compared with the blank group.2.Observation of dentin tubule occlusionThe results of scanning electron microscope in this study showed that: Most small dentinal tubules in the laser irradiation group were melted and closed,the number of tubules was reduced,the edge was blunt and thickened,and some molten crystals were embedded on the surface.Some dentin tubules were sealed by molten dentin;In the ultrasonic cleaning group,the dentin tubule was clearly visible,and most of the dentin tubules showed gutta-percha or paste.In the blank group,small dentinal tubules were clearly visible,and some dentin tubules showed debris coverage.Conclusion: 1.After root canal preparation with the semiconductor laser root canal irradiation or root canal ultrasonic flushing compared with the conventional root canal preparation can significantly reduce the apical microleakage,improve the root tip after the sealing performance.2.Root canal preparation after the use of laser irradiation or ultrasonic swing to wash a different treatment,apical microleakage for the ultrasonic wash group is greater than the laser irradiation group,but the apical sealing effect was no significant difference. |
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