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.

Objective:Based on the forgetting curve principle to construct a model for the popularization of cardiopulmonary resuscitation among college students and validate its effectiveness, providing reference for the promotion of cardiopulmonary resuscitation.Methods:A randomized controlled trial was conducted. In October 2021, a multistage random sampling method was used to select 262 freshmen and sophomores from the School of Mathematics and Physics at Leshan Normal University as the control group, and 262 freshmen and sophomores from the School of Electronic Information and Artificial Intelligence as the experimental group.The control group received conventional training, while the experimental group, in addition to conventional training, received cardiopulmonary resuscitation retraining based on the Ebbinghaus forgetting curve at three time intervals: within 1 week, within 1 month, and within 1 to 6 months after training. The retraining included online self-learning, on-site observation reinforcement, and social practice sublimation. The cardiopulmonary resuscitation knowledge awareness rate and cardiopulmonary resuscitation skill assessment of the two groups were compared before training, immediately after training, and 6 months after training.Results:The final number of participants was 256 in the control group (126 males and 130 females) and 224 in the experimental group (110 males and 114 females). There were no statistically significant differences in cardiopulmonary resuscitation knowledge awareness rate and cardiopulmonary resuscitation skill scores between the two groups before and immediately after training (both P>0.05). Immediately after training, the average cardiopulmonary resuscitation knowledge awareness rate in the experimental and control groups were 91% (1 626/1 792) and 88% (1 806/2 048), respectively, which were significantly higher than the pre-training rates of 55% (989/1 792) and 55% (1 129/2 048) ( χ2=8.46, 7.30, both P<0.01). The cardiopulmonary resuscitation skill scores were (42.00 ± 3.55) and (41.68 ± 3.40), respectively, higher than the pre-training scores of (15.41 ± 4.85) and (15.92 ± 4.66) ( t=84.47, 45.56, both P<0.05). Six months after training, the awareness rates of determination of consciousness and cardiac arrest judgment, cardiopulmonary resuscitation steps, chest compression location, frequency, depth, and the ratio of chest compressions to artificial ventilation in the experimental group in college students were 90% (201/224), 93% (208/224), 92% (206/224), 93% (208/224), 89% (200/224), and 94% (210/224), respectively, higher than those in the control group, which were 62% (158/256), 71% (182/256), 77% (198/256), 73% (186/256), 70% (178/256), and 69% (176/256) ( χ2 values were 4.21-7.03, all P<0.01). The cardiopulmonary resuscitation skill score in the experimental group was (49.77 ± 3.68), higher than the control group′s (34.95 ± 4.79) ( t=38.25, P<0.01). The proportion of students confident in using cardiopulmonary resuscitation to save others was 92% (206/224) in the experimental group, higher than 58% (148/256) in the control group ( χ2=7.68, P<0.01). Six months after training, the cardiopulmonary resuscitation skill score in the experimental group was (49.77 ± 3.68), higher than the immediate post-training score of (42.00 ± 3.55), whereas the control group's cardiopulmonary resuscitation skill score was (34.95 ± 4.79), lower than the immediate post-training score of (41.68 ± 3.40) ( t=22.74, 18.33, both P<0.01). Conclusions:The cardiopulmonary resuscitation popularization model for college students based on the forgetting curve is conducive to mastering cardiopulmonary resuscitation knowledge and skills among trained college students, enhancing their confidence in using cardiopulmonary resuscitation techniques to rescue others. Moreover, it helps save the human, financial, and material resources required for cardiopulmonary resuscitation training to a certain extent and is worthy of promotion.