A multi-stage, whole-group, random sampling method was used. Based on the Fourth National Oral Epidemiological Survey, the prevalence of gingivitis among 12-year-old children in Jinzhou, China is approximately 58%.15 The sample size was increased by 10%, considering issues such as missed visits and individual samples that did not meet the inclusion criteria. A total of 2,880 children aged 6–12 years were sampled from all counties and districts in Jinzhou, China. The specific demographic characteristics are presented in Table 1. This epidemiological investigation was approved by the Ethics Committee of the Second Hospital of Jinzhou Medical University, China. A signed informed consent form was obtained from the family of the child before the children participated in the study.
The inclusion criteria were (1) age 6–12 years, (2) no other systemic diseases, (3) have been informed of the study details and have signed a consent form, (4) have lived in Jinzhou City for more than 6 months, and (5) eruption of the first molar.
The exclusion criteria were (1) people with congenital oral diseases, (2) people with incomplete or inaccurate oral examination data, (3) children who were unable to cooperate with the examination after behavioral and psychological induction, (4) children undergoing orthodontic treatment, and (5) children whose first molar had not yet erupted.
On-site inspections occurred between September 2021 and 2021. Examination was performed in the sitting position under LED light. Intra-oral examination was performed using conventional oral examination instruments including plane mouth mirror, CPI probe, instrument cassette (one for sterilized instruments and the other for used instruments), disposable cap, mask, and gloves. The WHO Oral Health Assessment Form, which is a modified version of clinical examination, was used to obtain the clinical examination report. The oral cavity of each participant was assessed by a clinical examiner who was assisted by a recorder (the recorded the results of the examination results). The clinical examiner is a practicing dentist with at least 3 years of experience.
When the clinical examination was completed, teachers distributed the questionnaire to the parents with reference to the 4th National Oral Epidemiological Survey. The questionnaire covered general information about the respondents, their oral health behavior, dietary habits, poor oral habits, and family oral health awareness. The questionnaires were collected, quality checked, and filled in by the auditors. All examination and questionnaire results were inputted into an electronic computer to create a database for statistical processing and analysis of data, which was used to calculate the prevalence and risk factors of gingivitis, respectively, in children aged 6–12 years in Jinzhou, China.
Using the GI as a screening standard for gingivitis, a probe-based examination was combined with visual examination. The CPI probe was gently inserted into the gingival sulcus, and the entire area of the gingival sulcus was probed with the probe being parallel to the long axis of the tooth and close to the root, making short up and down quivering movements. In addition, we assessed for bleeding gums and scored the gum condition with not more than 20 g of force. Record the scores of all stages, including 1 score (red and swollen gums but no probing bleeding), where 2 and 3 are indicators of positive probing bleeding gingivitis (with probing bleeding). The fraction of each tooth in the mouth, the non-eruption of permanent teeth, and the fraction of milk teeth in the same position were recorded, and the second and third molars were not recorded. Gingivitis was defined as children with ≥ 10% positive teeth for gingival bleeding and with no AL or PD (≥ 4 mm), which was further categorized into localized gingivitis (30%number of teeth positive for gingival bleeding ≥ 10%) and generalized gingivitis (number of positive teeth for gingival bleeding > 30%).10 No other diagnostic methods or equipment were used, including oral radiography. The Löe-Silness plaque index, a visual inspection standard, has also been chosen and used to classify plaques into four classes: none, light, medium, and heavy. Several risk factors that may affect gingivitis, including tartar, number of decayed fillings, BMI, deep coverage, and crowding, were also examined. In addition, to avoid examiner bias and training of six physicians who participated in the field survey, 20 children were selected for examination prior to the survey for standard consistency tests, and all the kappa values were greater than 0.87. To further reduce examiner bias, the examination was repeated in the groups by 2 physicians.
The data from this survey were double-entered using Epidata, and all statistical processing of the data was performed using SPSS 25.0. Percentages were used to describe categorical data, showing the prevalence of each factor. Two-factor analysis using Pearson's chi-square test was performed, and statistically significant variables were further included in the binary logistic regression analysis and in the calculation of dominance ratios (OR) and 95% confidence intervals (CI) to identify risk factors. The statistically significant level was α = 0.05, and P < 0.05 was considered statistically significant.