Objective To analyze the incidence characteristics and pathogen epidemic characteristics of respiratory tract children in Chongqing Kaizhou area. Methods A total of 5 328 children admitted to our hospital from January 2019 to December 2022 were selected as the research subjects. Indirect immunofluorescence method was used to detect 8 common respiratory pathogens in the serum of the children; Using SPSS 22.0 software, analyze the incidence characteristics and pathogen prevalence of 8 pathogens in respiratory tract children. Results (1) The highest detection rate was MP (χ²=12.141, P<0.05); (2) The detection rate of PM and PIV in the infant group was lower than that in the infant group and large group, The difference was statistically significant (χ²=7.923, P<0.05); (3) Eight pathogens IgM had the highest detection rate in the spring, Opposite in winter (χ²=1.872, P<0.05); (4) A total of 3 817 IgM antibody positive cases were detected in 5328 sick infants, The positive rate was 71.64%, There was a statistical difference between the sexes (χ²=3.928, P<0.05). Conclusion The detection rate of respiratory pathogens varies in age and sex, which is highest in spring, so pay attention to the respiratory tract infection in spring, focusing on the prevention and treatment of mycoplasma pneumoniae.

Objective To analyze the correlation between intestinal flora changes and neonatal necrotizing enterocolitis (NEC)through 16S rRNA metagenomic sequencing and bacterial culture. Methods From September 2018 to March 2019, 10 NEC cases and 6 controls were randomly selected in the neonatal ICU ward of Nanjing maternal and child health care hospital to analyze the 16S rRNA metagenomic diversity of the for intestinal flora. The fecal samples and corresponding environmental samples were corrected from 51 cases of NEC children and their case controls to isolate and culture Clostridium. Results The dispersion of samples within the case group was smaller than that of the control group, and the sample diversity was higher than that of the control group. In the isolation and culture of Clostridium, the overall detection rate of Clostridium in the case group was 43.14% (22/51), and the detection rate of Clostridium butyricum was the highest (19.61%, 10/51). There was a statistical difference between the two groups (χ²=5.85, P=0.015 58). All Clostridium strains did not carry the A, B and E type neurotoxin genes. Conclusion: Increased intestinal flora diversity, intestinal flora abundance and changes in the abundance of Clostridium may be closely related to the intestinal environment of children with NEC; Clostridium, especially Clostridium butyricum, may be related to the occurrence of NEC.

Objective: To evaluate the effect of 3D-printed oval root canal preparation by using small field-of-view cone beam CT (CBCT) combined with computer-aided technologies. Methods: An extracted tooth with a suitable single oval canal was selected by small field-of-view CBCT scanning. Three-dimensional (3D)-printed resin teeth were obtained based on the CBCT data after data conversion and processing. 50 general dentists were selected to prepare the oval root canal of the resin teeth with X-Gold rotary Ni-Ti instruments. Small field-of-view CBCT was applied to scan the oval root canals before and after preparation. Then, computer-aided technologies were used to calculate and compare these CBCT data, analyzing the effects of oval root canal cleaning as well as the root canal deviation by 3D reconstruction and rendering of the images. Results : Among the 50 cases, the mean unprepared area of the oval root canal wall was（56.20 ± 11.91）% and the mean maximum deviation distance of the root canal was（0.140 ± 0.041）mm. There was no correlation between root canal cleanliness and deviation (r=0.18, P=0.212). Conclusion Combined with small field-of-view CBCT and computer-aided technology, we can effectively quantitatively evaluate the root canal preparation effect.