The Study For The Sterilisational Effect Of Photodynamic Therapy On Periodontal Pathogens

[Objectives]This study was to observe the sterilisational effect of different light dose and different TBO concentration on Prevotella melaninogenica(Pm), Porphyromonas gingivalis(Pg) and Aggregatibacter actinomycetemcomitans(Aa).EspeciaIly the endogenous photosensitizer was investigated to choose a special light dose which have the best sterilisational effect. To provide experimental and academic evidences on the clinical application of photodynamic therapy(PDT) on the treatment of periodontitis.[Methods]Part1:In the exogenous photosensitizer group,we chose standard strains of Prevotella melaninogenica (Pm), Porphyromonas gingivali (Pg) and Actinobacillus actinomycetemcomitans (Aa) for the experiment. And we chose toluidine blue oxygen (TBO) as photosensitizers.A home-made LED portable light source which provided a red light, wavelength630nm,40mW/cm2was picked. All the plates had the processing of semi-shade.The opaque part belonged to the experimental group while the shading part was the control group. The culture medium in the plates contained different TBO concentrations (TBO concentrations of Pm group were1μg/ml,2.5μg/ml,5μg/ml,7.5μg/ml,10μg/ml; TBO concentrations of Pg group were10μg/ml,20μg/ml,30μg/ml,40μg/ml,50μg/ml; TBO concentrations of Aa group were10μg/ml,20μg/ml,30ug/ml,40μg/ml,50μg/ml). Bacterias were spreaded on the plate.Red light was irradiated at different times (light doses of Pm group were J/cm2,3J/cm2,9J/cm2; light doses of of Pg group were3J/cm2,9J/cm2,12/cm2; light doses of of Aa group were3J/cm2,9J/cm2,12J/cm2).The bacterias were to be cultured in48to72hours.The bacteria colonies were to be counted. The t test was used for analysis the data which had been standardized. Part2:In the endogenous photosensitizer group,we chose standard strains of Prevotella melaninogenica (Pm), Porphyromonas gingivali (Pg) and Actinobacillus actinomycetemcomitans (Aa) for the experiment.A home-made LED portable light source which provided a blue light, wavelength415+10nm,40mW/cm2was picked.All the plates had the processing of semi-shade.The opaque part belonged to the experimental group while the shading part was the control group. Bacterias were spreaded on the plate.Red light was irradiated at different times (light doses of Pm group were10J/cm2,20J/cm2,30J/cm2,40J/cm2; light doses of of Pg group were10J/cm2,20J/cm2,30J/cm2,40J/cm2,50J/cm2; light doses of of Aa group were10J/cm2,20J/cm2,30J/cm2,40J/cm2,50J/cm2).The bacterias were to be cultured in48to72hours.The bacteria colonies were to be counted. The t test was used for analysis the data which had been standardized.[Results]1. Exogenous photosensitizer group, when the light dose was3J/cm2and the TBO concentration was5μg/mL, the survival rate of Pm was at the minimum,and there was significant difference between the experimental group and control group (P=0.01).When the light dose was9J/cm2and the TBO concentration was40μg/mL, the survival rate of Pg was at the minimum, and there was significant difference between the experimental group and control group (P=0.0005). When the light dose was9J/cm2and the TBO concentration was of40μg/mL, the survival rate of Aa was at the minimum, and there was significant difference between the experimental group and control group (P=0.001).2. Endogenous photosensitizer group, when the light dose was20J/cm2, Pm had the minimum survival rate, and there was significant difference between the experimental group and control group (P<0.05). When the light dose was20J/cm2, Pg had the minimum survival rate70%, but P>0.5.There was no significant difference between the experimental group and control group.When the light dose was40J/cm2. Aa had the minimum survival rate. and there was significant difference between the experimental group and control group (P=0.001).[Conclusions]1. The optimal sterilization effect of light dose and photosensitizer concentration have been received preliminary in the exogenous photodynamic therapy on Pm,Pg and Aa. 2. The sensitivity of Pm to th exogenous photodynamic therapy is higher than Pg and Aa.3. Even without exogenous photosensitizer endogenous photodynamic therapy still have showed sterilisational effect obviously while just rely solely on the endogenous photosensitizer and our homemade light on Pm and Aa.And the light dose have been received preliminary. The sterilization effect of endogenous photodynamic therapy on a single Pg strains had no statistical difference.4. It is suggested that the anaerobic bacteria are more sensitive to endogenous photodynamic therapy than aerobic bacteria.