| Objective:The aim of this research is to study the occluding effect of diode laser and Duraphat alone and in combination on dentinal tubule,so as to provide the experimental reference for the selection of treatment of dentinal hypersensitivity.Methods:28 premolars were collected from orthodontic extraction and their crown dentin was extracted.A dentin slice was cut from each tooth.28 dentin slices were randomly divided into four groups.Each group consisted of 7 pieces.The preparation and process of cross-sectional samples of dentinal tubules:five pieces of dentin slices were randomly selected from each group and cut into two halves along buccal-lingual direction after treated with EDTA.Half of them were taken as control group samples and the other half as experimental group samples.The preparation and process of longitudinal section samples of dentinal tubules:the remaining two slices in group A,B,C and D were taken as the longitudinal section samples of dentinal tubules.The control group sample was broken into two halves by holding the mesial and distal edges with two needle holders.The other piece was taken as the experimental group sample,which was left for experimental treatment,and then broken into two halves.The open model of dentinal tubules was taken by 17%EDTA treatment for 2 minutes.The open effect of dentinal tubules was observed by scanning electron microscope in control groups.The experimental groups were treated as follows.Group A:treated in Duraphat for 2 minutes.Group B:blackened with 2B pencil and irradiated for 30 seconds by diode laser with parameters of 30Hz,1.5W and CW mode.Group C:treated in Duraphat(the same as Group A)and then irradiated by diode laser(the same as Group B).Group D:irradiated by diode laser(the same as Group B)and then treated in Duraphat(the same as Group A).The occluding effect of dentinal tubules was observed by scanning electron microscope Image-pro plus 6.0 was used to calculate the blocking rate of dentinal tubules and measure the blocking depth.And the changes of F content(weight percentage)were detected by energy spectrum analyzer.Results:1.The cross-sectional sealing of dentinal tubules:the complete opening situation of dentinal tubules treated with EDTA was observed by SEM.In group A,the dentinal tubules were partial closed,and the sealing material was slightly lower than the orifice of tubules.In group B,the dentinal tubules were partly closed with a crater-like and melted honeycomb appearance,and the molten sealing material around the orifice was slightly higher than the surface of dentin.In group C,most tubules were sealed,and the surface was covered with a layer of molten sealing material.In group D,few parts of the tubules were open,and some of the sealing material were granular.Image-pro plus 6.0 was used to calculate the closure rate of dentinal tubules(%).Group A:66.245±12.260.Group B:66.245±12.260.Group C:85.454±10.869.Group D:84.050±10.953.The differences between group C and group A,B were statistically significant(P<0.05).The differences between group D and group A,B were statistically significant(P<0.05).The difference between group A and group B was not statistically significant(P>0.05).The difference between group C and group D was not statistically significant(P>0.05)2.The longitudinal profile sealing of dentinal tubules:the dentinal tubules were empty and the walls were clear,and other tubules from the wall were visible after treated with EDTA.In group A,a thin layer of sealing material on the dentin was observed.In group B,a small amount of granular impurities was observed in the wall.In group C,the sealing material in the dentinal tubules was melted and dense.In group D,the sealing material on the dentin was thick and the blockages in the tubules were variable in thickness.Image-pro plus 6.0 was used to measure the closure depth of dentinal tubules(micron).Group A:5.32±0.94.Group B:5.58±0.84.Group C 8.25±1.06.Group D:8.12±1.07.The differences between group C and group A,B were statistically significant(P<0.05).The differences between group D and group A,B were statistically significant(P<0.05).The difference between group A and group B was not statistically significant(P>0.05).The difference between group C and group D was not statistically significant(P>0.05).3.The values of the Fluorine content of group A,C and D were 2.036±0.367,3.008±0.724 and 2.438±0.863.The difference between group C and group A was statistically significant(P<0.05).The difference between group D and group A was not statistically significant(P>0.05).Conclusion:There was no difference in the occluding effect of dentinal tubules between diode laser alone and Duraphat alone.The combined application of the two methods had better occluding effect than the single application,and the order of use had no effect on the occluding effect of dentinal tubules.Diode laser can promote the entry of Fluorine into dentinal tubules. |
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