| Objectives: 1.To provide theoretical support for photodynamic therapy promoting enamel remineralization,innovation of this experiment using surface light emitting optical fiber combined with PDT in anti-caries,detecting the content of calcium(Ca)and phosphorous(P)in enamel after four time laser irradiation.2.Study on the pathological changes of pulp tissue using side glowing optical fiber irradiation under different power of PDT.3.Whether there will be changes or no change of pulp mineralization and pain related cytokines after once or fourth treatment with side glowing optical fiber,it will be provided theoretical support for further demonstration of the safety and efficacy of photodynamic therapy in animal models.Methods:Rats molars were infected by S.mutans suspension to establish the rat caries models.60 rats were divided into five groups.17 mW PDT?34 mW PDT?and 68 mW PDT groups were used as the experimental groups,and the positive control group was treated with 2% sodium fluoride solution,and the negative control group treated with 0.9% saline.650 nm semiconductor laser connected with side glowing optical fiber with different laser power.40 ?g/mL Hematoporyrin monomethy Ether(HMME)was used as photosensitizer.The rats teeth were irradiated after using HMME in the dark to incubate.The experiment lasted for four weeks.Using inductively coupled plasmaoptical emission spectroscopy(ICP-OES)to test the contents of calcium and phosphorus in enamel of rats molars after fourth treatments.After fourth treatment,the pulp tissue of rats was extracted under microscope,stained with hematoxylin and eosin.To observe the pathological changes of pulp.Pulp was separated from molars of 34 mW PDT under the microscope,grinded and centrifugal.Using Enzyme-linked immunosorbent assay(ELISA)to measure related cytokines CGRP and Substance P changes of pulp after one and four times of PDT with different time nodes.Results: 1.The content of Ca in each group before and after experiment:There was not statistically different in each group before experiment(P>0.05).The contents of Ca both B group and C group after experiment were significantly higher than those before experiment.There had significant difference(P<0.05).The contents of Ca in D group after experiment was significantly higher than before experiment.There had significant difference(P<0.05).Comparison of the content of Ca(35)value of each group: The Ca(35)value of A group was significantly less than B and C groups.There had significant difference(P<0.05).There was no statistically different of the Ca(35)value between B group and C group(P>0.05).The Ca(35)value between B and C groups were significantly higher than D group.There had significant difference(P<0.05).The content of P in each group before and after experiment:There was not statistically different in each group before experiment(P>0.05).The contents of P both B group and C group after experiment were significantly higher than those before experiment.There had significant difference(P<0.05).The contents of P in D group after experiment was less than before experiment.There was no significant difference(P>0.05).Comparison of the content of P(35)value of each group:The contents of P(35)value of A group was significantly less than B and C groups.There had significant difference(P<0.05).There was no statistically different of the contents of P(35)value between B group and C group(P>0.05).The P(35)value between B and C groups were significantly higher than D group.There had significant difference(P<0.05).2.Histopathological examination showed that the pulp tissue of the average of 68 mW fourth time treatment occurred telangiectasis and congestion,but there was no infiltration of inflammatory cells.There were no inflammatory cells,edema,hyperemia,necrosis in 17 mW group?34 mW group?2% Sodium fluoride solution group and saline group.3.Results of pulp cytokines showed: The result of CGRP:The expression of experimental group at 1,3,7,14 days significantly higher than control group of single treatment(P<0.05).The expression of experimental group at 1,3,7,14 days significantly higher than control group of four time treatment(P<0.05).The result of Substance P:There were no difference of expression between experimental group and control group of single treatment(P>0.05).There were no difference of expression between experimental group and control group of four time treatment(P>0.05).Conclusions: 1.Side glowing optical fiber connected with 650 nm diode laser to anti-caries,34 mW PDT group and 68 mW PDT group promoted contents of Ca and P.The ability of HMME-PDT with different power to promote the trace elements of rat molar was different.Based on the principle of low energy treatment,the best energy was 34 mW.2.17 mW PDT group?34 mW PDT group did not cause damage after four time treatment(once a week,four consecutive).However,the 68 mW PDT group could lead to histopathological change of pulp.3.No matter once or four times treatment,it could promote the expression of neuropeptide CGRP under 34 mW(90 s)irradiation.It may trigger the endogenous remineralization of dental pulp.There was no obvious of the expression of substance P after one and four treatments.Within the range of this experimental parameters,PDT promoted remineralization without causing dental pulp pain. |
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