RESUMO
ObjectiveTo monitor the microbes in urban drinking water in Jiangxi from 2016 to 2020， to analyze the change in microbial qualification rate， and to provide a scientific basis for government decision-making. MethodsAccording to the Standard Examination Method for Drinking Water （GB/T 5750‒2006） and the Standards for Drinking Water Quality （GB 5749‒2006）， the water samples were collected， tested and evaluated for hygienic safety. The chi-square test was used to compare the qualification rates among different water periods， water source types， water supply modes， water samples， treatment processes， and disinfection methods. ResultsA total of 10 584 water samples were collected and examined from 2016 to 2020，with a qualification rate of 97.72%. The qualified rate of the microbiological index increased gradually over the years. There was no statistically significant difference in the microbiological qualification rate of water samples monitored in different water periods （χ2=0.718，P=0.398）， and the qualification rates were 97.85% and 97.60% in dry and abundant water periods respectively. There was a statistically significant difference in the qualification rates of water samples monitored in different water source types （χ2=79.560，P=0.398）， with groundwater having a higher qualification rate of 98.83% than surface water （97.70%）. The microbiological pass rate of water samples differed among different water supply methods （χ2=201.836，P<0.001）. The microbiological pass rates of municipal centralized water supply， self-built centralized water supply and secondary water supply were 97.51%， 88.94% and 96.56% respectively. The microbiological pass rates of water samples differed among different treatment processes. There were differences in the qualification rates of the water samples between different treatment processes（χ2=855.034，P<0.001）， with 98.22%， 67.19%， 95.60% and 53.13% of the conventionally treated， precipitated filtered， disinfected only and untreated water samples， respectively. The differences in the microbiological qualification rates of the monitored water samples between different disinfection methods were statistically significant （χ2=904.993，P<0.001）. Chlorination disinfection， chlorine dioxide disinfection， other disinfection methods and non-disinfected water samples had the pass rates of 98.35%， 98.19%， 84.38% and 60.16%， respectively. ConclusionThe qualified rate of the microbiological index of drinking water in Jiangxi increases year by year， but there are still some drinking water without appropriate disinfectants and water quality treatment processes. There is still a need to strengthen the purification， disinfection and monitoring of drinking water.
RESUMO
OBJECTIVE: To investigate the root and canal morphology of permanent mandibular anterior teeth in a Chongqing population using cone-beam computed tomography (CBCT). METHODS: CBCT images of 1,725 patients in a Chongqing population were selected, and a total of 9,646 mandibular anterior teeth were analyzed. The number of root canals and the canal configurations were investigated. RESULTS: In total, 0.3% (11/3,257) of lateral incisors and 0.8% (26/3,014) of canines had double roots, and 3.8% (127/3,375) of central incisors, 10.6% (345/3,257) of lateral incisors, and 4.2% (127/3,014) of canines had multi-root canals. The difference in the incidence of multi-canals in lateral incisors between female and male was statistically significant. The frequency of multi-canals in the different age groups was 5.0% for central incisors for ages 21-30 years, 14.7% for lateral incisors for ages 41-50 years, and 8.1% for canines for ages 41-50 years. CONCLUSION: With the limitations of the current study, we found that a high percentage of mandibular anterior teeth had multiple canals in the studied Chinese Chongqing population. The current data may provide clinicians practicing in Chongqing with a more thorough understanding of root canal morphology.
