To investigate the prevalence and dynamic changes of dental caries in primary teeth among 3- to 5-year-old children in Kashgar, Xinjiang, analyze its influencing factors, and provide a scientific basis for the prevention and control of dental caries in this region.

A random sampling method was employed to select children aged 3-5 from two kindergartens in urban and suburban areas of Kashgar City. A baseline survey was conducted in May 2021, followed by a follow-up survey one year later. Caries and oral hygiene status were assessed using the WHO diagnostic criteria for caries and the Debris Index, combining visual inspection and probing. Chi-square (χ²) tests and paired Wilcoxon signed-rank tests were used to compare differences between years and groups.

The baseline survey included 315 children aged 3-5, with a caries prevalence of 74.3% and a mean dmft of 2.51. One year later, the caries prevalence increased to 86.7% (χ² = 17.398, P<0.001), and the mean dmft rose to 2.83 (W = 12 759.0, P = 0.022). The caries prevalence significantly increased in both boys (χ² = 7.220, P = 0.007) and girls (χ² = 9.818, P = 0.002). The largest increase in caries prevalence was observed in 3-year-old children, rising from 65.8% to 83.6% (χ² = 13.796, P<0.001). The mean dmft for children aged 3-5 increased from 2.51 to 2.83 (W = 12 759.0, P = 0.022), with significant increases observed in girls (W = 1 926.0, P = 0.018), 3-year-old children (W = 1 940.5, P<0.001), and Uygur children (W = 3 633.0, P = 0.034). Additionally, the Debris Index for the 315 children increased from 4.95 to 5.43 (W = 5 479.0, P<0.001), with statistically significant changes in all subgroups except for 4-year-old children (W = 398.5, P = 0.249). The questionnaire results indicated that urban residence (χ² = 14.138, P<0.001), frequent dairy consumption (χ² = 4.700, P = 0.030), non-use of fluoride toothpaste (χ² = 4.310, P = 0.038), and lower parental oral health knowledge scores (χ² = 11.270, P<0.001) were significant influencing factors for childhood dental caries.

The prevalence of deciduous tooth caries is high among children aged 3-5 in Kashgar City. Over the course of one year, the severity of caries increased more significantly in 3-year-old children, girls, and Uygur children. Longitudinal surveys on caries incidence are of greater value and provide guidance for targeted prevention and control in key populations.