Objective To detect the sealing ability of iRoot as root end retrograde filling material in vitro experiment,and to compare it with mineral trioxide aggregate(MTA) in order to provide reference basis for clinical use of iRoot.Methods The dental crown was removed in 67 single root canal anterior teeth.The routine root canal preparation and filling were performed.The root end was resected by 3 mm for conducting root end retrograde preparation.Sixty-three teeth in the samples were randomly divided into 4 experimental groups.Then the different materials were used for root end filling:iRoot BP (group A,n=17),iRoot BP plus (group B,n=17),MTA (group C,n =17),and group D(iRoot BP + gutta percha,n =12),the residual 4 samples served as the control group.The apical microleakage of 10 teeth in each experimental group was detected by the fluid dynamics.The microleakage situation at the time points of 1,7,14,28 d was observed.In addition,2 teeth selected from each group were performed the filling material ultramicrostructure observation by SEM.Each 5 teeth were remained in the group A,B and C and performed the Micro CT scanning.The porosity rate of filling material was detected.Results No obvious edge gap was found between the filling materials and dentin surface in the group A,B and D by SEM,but obvious gap could be seen in various samples of group C.Micro CT scanning found that the porosity rates in the group A,B and C were 0.020 ±0.023,0.045 ±0.035 and 0.031 ± 0.011 respectively,but showing no statistical difference(P＞0.05).The fluid dynamic experiment showed that the microleakage detection value in each group had no statistical difference(P＞0.05).Conclusion The sealing ability of iRoot and MTA used in root end retrograde sealing has no obvious difference,But iRoot operability is superior to MTA.

Objective To understand the characteristics and regularity of child oral mucosal diseases in Chongqing by analyzing its related factors so as to provide a reference for its diagnosis and treatment.Methods A total of 3792 children with oral mucosal diseases in the stomatology department of our hospital from January to December 2015 were taken as the research subjects for analyzing the disease entities,gender,age,onset time.Results Among 3 792 cases,15 kinds of oral mucosal diseases were recorded.The top five places of prevalence rates were herpetic stomatitis (42.67 ％),oral candidiasis(23.36 ％),traumatic ulcer(14.82 ％),recurrent aphthous ulcer (8.81％) and migratory glossitis (8.65％).Conclusion The clinical characteristics of child oral mucosal diseases are complex and various,and the onset age and time have a certain rule,which indicates that early diagnosis and treatment are very important to prognosis.