The Influence Of Passive Ultrasonic And Photoacoustic Activation On Sodium Hypochlorite Penetration Into Dentine Tubules In Infected Teeth

Objective By comparing the penetration depth of ultrasonic and laser dynamic irrigation technology in infected root canals and clean root canals,the flushing efficiency of modern dynamic irrigation technology in infected root canals was judged and relevant factors affecting infiltration were found,so as to provide flushing strategies for clinical chemical preparation of infected root canals.Methods 72 root canals including 24 younger infected root canals,24 older infected root canal and 24 clean root canal were extracted from The Affiliated Stomatological Hospital of Anhui Medical University from September 2019 to October 2021.The canals were prepared to size 40.06 taper by the Pro Taper Universal system.The irrigation solution were heated 3% sodium hypochlorite and 17% EDTA.Group into ultrasonic group,laser group and manual group for activation irrigation.The penetration range of methylene blue was used as the penetration depth of sodium hypochlorite.Horizontal sections of root tip,root middle and crown were obtained with150 microns by EXAKT hard tissue cutting and grinding system.Computer photography was conducted.Images were imported into Image J software to measure the penetration depth of each section,including average penetration depth and maximum penetration depth,as well as the percentage of staining circumference/inner canal circumference.SPSS21.0 statistical software was used for data import.One-factor ANOVA was used for inter-group comparison and Bonferroni’s Post Hoc test was used for intra-group comparison.P<0.05 was statistically significant.Results The mean penetration depth of the older infected root canal group was20-233.5μm.The maximum penetration depth was 363μm obtained by laser irrigation in coronal level.The mean penetration depth of the younger infected root canal group was 38.87-319.5μm.The maximum penetration depth was 824μm obtained by laser irrigation in coronal level.The mean penetration depth of the clean root canal group was 167-845.5μm,The maximum penetration depth was 1225μm obtained by ultrasonic irrigation in coronal level.The percentage of penetration circumtance up to100 in older infected root canal was 5/72,2/36 in younger canals and 69/72 in clean roots.They showed a trend of increasing penetration depth from root tip to crown,and the penetration depth of buccoclination and linguoclination was higher than in mesial and distal direction.The penetration depth in older and younger root canals was lower than clean roots（P<0.05）while older lower than younger root canals（P>0.05）.Ages showed no significant effect to penetration in infected teeth.Conclusion The penetration depth of dentin tubules in infected root canal was much lower than clean root canal after laser and ultrasonic activation irrigation of sodium hypochlorite.Ages showed no significant effect to penetration in infected teeth.The penetration of apical was the lowest.