Background A nomogram is a tool that transforms complex regression equations into simple and visual graphs and enables clinicians and patients to conveniently compute output probabilities without needing medical knowledge and complex formulas. The aim of this study was to develop and validate a predictive nomogram to screen for severe caries among 12-year-old children based on risk factors in Sichuan Province, China. Methods A cross-sectional study of 4573 12-year-olds was conducted up to May 2016 in middle schools from three districts and three counties in Sichuan Province, China. All the children underwent oral examinations and completed questionnaires to assess general information, oral impacts on daily performance, dietary habits, subjective health conditions, history of dental trauma, frequency of toothache, dental visits, and knowledge, attitudes, and behaviours toward oral hygiene. Univariate analysis and multivariate logistic regression analysis were used to determine which variables were significantly associated with severe caries (operationalized as DMFT ≥ 3). A nomogram was developed and validated by using the ‘rms’ package and two cross-validation methods. Results Severe caries was found in 537 of the 4573 children (11.74%). Multivariate logistic regression analysis revealed that the following variables predicted a higher risk of severe caries: ‘female’ [odds ratio (OR) = 1.985, 95% confidence interval (95% CI): 1.63–2.411], ‘urban’ (OR = 2.389, 95% CI: 1.96–2.91), ‘non-only child’ (OR = 1.317, 95% CI: 1.07–1.625), ‘very poor self-assessment of oral health status’ (OR = 2.157, 95% CI: 1.34–3.467) and ‘visited a dentist less than 6 months’ (OR = 1.861, 95% CI: 1.38–2.505). Multivariate logistic regression analysis also indicated that the following variables predicted a lower risk of severe caries: ‘middle level of urbanization’ (OR = 0.395, 95% CI: 0.32–0.495) and ‘high level of urbanization’ (OR = 0.466, 95% CI: 0.37–0.596). Both the fivefold and leave-one-out cross-validation methods indicated that the nomogram model built by these 6 variables displayed good disease recognition ability. Conclusions The nomogram was a simple-to-use model to screen children for severe caries. This model was found to facilitate non-dental professionals in assessing risk values without oral examinations and making referrals to dental professionals.

Background Research on the predictors of oral health-related quality of life (OHRQoL) in Tibetan adolescents is limited. The aim of this study was to investigate the OHRQoL of Tibetan adolescents in Ganzi, Sichuan, and to determine whether the region-specific lifestyle, subjective perception and objective conditions of oral health could predict Tibetan adolescents’ OHRQoL. Methods A cross-sectional survey of Tibetan adolescents aged 11–15 years was conducted in Ganzi, Sichuan. Relevant data was collected via a self-reported questionnaire and a complete oral examination. The OHRQoL was measured using the standardized Child Oral Impacts on Daily Performances (sC-OIDP) scores. Binary logistic regression was used to explore the association between region-specific lifestyle, subjective perception, objective conditions and OHRQoL. Results Four hundred and eighty-five Tibetan adolescents participated in the study. The sC-OIDP ranged from 39.44 to 99.70 (mean55.41 ± SD11.19) with 288 (59.38%) adolescents reported an sC-OIDP above 50. It was revealed that Tibetan adolescents living at a higher altitude of 3300m than 1400m were more likely to report a poorer OHRQoL (OR = 1.880, 95%CI 1.101–3.209, P = .021). Also, buttered tea consumption by adolescents (OR = 2.284, 1.200-4.348, P = .012) or by mother (OR = 2.278, 1.171–4.432, P = .015) and boarding student (OR = 1.761, 1.180–2.626, P = .006) were significantly associated with poorer OHRQoL. Regarding the subjective perception, adolescents that rated a bad or very bad oral health (OR = 4.360, 2.341–8.120, P < .001) was more likely to have poorer OHRQoL compared to those with good or very good oral health. Furthermore, self-reported dental pain was significantly related to poorer OHRQoL (OR = 2.836, 1.836–4.382, P < .001). Interestingly, objective conditions, such as BOP, DC and DMFT were not related to OHRQoL. Conclusion Region-specific lifestyle and subjective perception on oral health were the key predictors affecting the OHRQoL of Tibetan adolescents. To improve OHRQoL, it is recommended to weigh the pros and cons of buttered tea and take moderate consumption among adolescents and their mothers and improve communication of students in boarding school with their parents can boost self-confidence. Additionally, developing good oral hygiene habits and keeping more healthy teeth to prevent dental pain is equally important for improving OHRQoL.