| Objective:This experiment compares the killing effect of Nd:YAG laser on the biofilm formation of Streptococcus mutans(变形链球菌)cultured in vitro when using different light guide systems.By measuring the OD value of the biofilm formed by Streptococcus mutans,the effect of the two systems on the biofilm forming ability of Streptococcus mutans was studied.The killing effect of the two systems on the biofilm of Streptococcus mutans was detected by plate colony counting method and Confocal Laser Scanning Microscopy method.The effect of the two systems on the temperature change of the medullary cavity was measured by a K-type thermocouple temperature measuring instrument.Through the study of the sterilization effect and safety of the two light guide systems,the optimal power of sterilization is explored,in order to provide a new and effective caries prevention method for the clinic.Methods:1.The effect of two light guide systems on the film forming ability of Streptococcus mutansThe standard strain of Streptococcus mutans was activated and the bacterial solution was prepared.After dilution,the bacterial solution was placed in a 96-well plate and divided into traditional direct-emitting quartz optical fiber groups(Group 1to Group 4).Traditional direct-emitting quartz with Nd:YAG laser Fiber irradiated Streptococcus mutans bacterial liquid,power is 1.6w,1.8w,2.0w,2.2w,4 samples per group;side-emitting fiber group(Group 5 ～ Group 8)irradiated Streptococcus mutans biofilm with side-emitting fiber Bacterial liquid,power is 1.6w,1.8w,2.0w,2.2w,4 samples per group;the control group(Con group)is not treated.After treatment in each group for 24 hours,the OD value of each group was measured by the crystal violet staining method to quantitatively analyze the effect of the two light guide systems on the film forming ability of Streptococcus mutans.2.The killing effect of two light guide systems on Streptococcus mutans biofilmActivate the standard strain of Streptococcus mutans and prepare the bacterialsolution,construct a biofilm model of Streptococcus mutans on a 14mm*14mm cell slide,and divide it into traditional direct-emitting quartz optical fiber groups(group 1to group 4)with Nd:YAG laser Traditional direct light-emitting quartz optical fiber irradiates streptococcus mutans biofilm with powers of 1.6w,1.8w,2.0w,and 2.2w,4samples per group;the side-emitting fiber group(group 5 to group 8)is illuminated with side-emitting fiber Streptococcus mutans biofilm with power of 1.6w,1.8w,2.0w,2.2w,4 samples per group;control group(Con group).After treatment of each group,plate colony count was performed.Quantitative analysis of the killing effect of two light guide systems on Streptococcus mutans biofilm.Use the live dead bacteria staining kit to stain the laser-treated samples and the control group samples,observe the staining results with a laser confocal microscope,and collect and process the images.Qualitative analysis of the killing effect of two light guide systems on Streptococcus mutans biofilm.3.Evaluation of the safety of two light guide systemsAn isolated tooth crown was prepared,and a K-type thermocouple thermometer was used to measure the temperature change of the pulp cavity when the two light guide systems irradiated the crown at 1.6w,1.8w,2.0w,and 2.2w.Analyze and evaluate the safety of the two light guide systems.Results:1.Crystal violet staining results show:When the power is 1.6w,there is no statistical difference between the two light guide systems and the control group OD value(p>0.05),while at 1.8W,2.0w,2.2w,the two light guide systems and the control group There is a significant difference between the OD values ??of the two,with statistical significance(p<0.05).Comparing the two light guide systems,the difference in OD values ??was not statistically significant at 1.6w,1.8w,2.0w,and 2.2w(p>0.05).2.plate colony coun and Confocal Laser Scanning Microscopy displayCompared with the blank control group,both light guide systems(Group 1 to Group 8)showed a reduction in the number of colonies,the difference was statistically significant(p<0.05).In the traditional direct-emitting quartz optical fiber group,the greater the power,the better the sterilization effect,and the difference isstatistically significant(p<0.05);in the side-emitting fiber group,the 2.0w sterilization effect is better than 1.8w,1.8w The sterilization effect is better than 1.6w,and the difference is statistically significant(p<0.05).There is no statistical difference between the sterilization effect of 2.0w and 2.2w(p>0.05).Compared with the two light guide systems,when the power is 1.6w and 1.8w,the sterilization effect of the traditional direct-emitting quartz fiber group is better than that of the side-emitting fiber group,and the difference is statistically significant(p<0.05).The sterilization effect of the traditional direct-emitting quartz optical fiber group is better than that of the side-emitting optical fiber group when the power is 2.0w and 2.2w(p>0.05).According to the laser confocal image,when the two light guide system groups are at 2.0w and 2.2w,a large area of red signal can be seen,and the green signal is less.The green signal increases obviously at 1.8w and the green signal at 1.6w And the orange signal continues to increase.The saline group showed more green and yellow signals and less red signals.According to the analysis of laser confocal information,compared with the control group,both light guide systems showed a significant reduction in the proportion of viable bacteria,the difference was statistically significant(p<0.05).In the traditional direct-emitting quartz optical fiber group,when the power is 1.6w,1.8w,2.0w,as the power increases,the proportion of live bacteria gradually decreases,the difference is statistically significant(p<0.05);and the power 2.0w and 2.2 When compared with w,there was no significant difference in the proportion of viable bacteria and no statistical significance(p>0.05).When the power of the side-emitting fiber group is 1.6w,1.8w,2.0w,as the power increases,the proportion of viable bacteria decreases,the difference is statistically significant(p<0.05);while the power is 2,0w and 2.2w,The proportion of viable bacteria was significantly different and did not have statistical significance(p>0.05).Compared with the two light guide systems:at 1.6w,the proportion of viable bacteria in the traditional direct-emitting quartz optical fiber group is significantly lower than that of the side-emitting fiber group,which is statistically significant(p<0.05),while at 1.8w,2.0w,At 2.2w,there was no significant difference in the proportion of live bacteria between the two light guide systems,and no statistical significance(p>0.05).3.Temperature test displayIn the two light guide system groups,with the increase of power,the temperature change of the medullary cavity in each group also increased.However,the temperature of the medullary cavity of each power group of the traditional direct-emitting quartz optical fiber group is larger than that of the side-emitting optical fiber group.The temperature of the medullary cavity changes more than 5℃at 2.2w in the traditional direct-emitting quartz optical fiber group.Conclusion:The experimental results show that both light guide systems can inhibit the film forming ability of Streptococcus mutans.Both light-guiding systems have a killing effect on Streptococcus mutans biofilm,and the power can meet the safe and effective principle at 2w.When the power is 2w,there is no significant difference between the two sterilization effects,but the safety of the side-emitting fiber group is higher. |
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