Background: Although childhood cancer accounts for a small percentage of total cancer cases globally, it remains a critical public health issue. Studying the incidence of childhood and adolescent cancer in Ulaanbaatar, where nearly half of Mongolia's population resides, is essential for improving diagnosis and treatment quality. Objective: To investigate the patterns and trends of new childhood and adolescent cancer cases in Ulaanbaatar from 2015 to 2024. Material and Method: A descriptive cross-sectional study was conducted. Based on statistical data from the Center for Health Development, incidence rates per 100,000 population were calculated and analyzed using STATA 14.2 software. Results: A total of 516 new cases were recorded during the study period, with an average incidence rate of 9.0 per 100,000 population. The incidence increased by 35.2%, rising from 8.8 in 2015 to 11.9 in 2022. Regarding cancer types, hematological and lymphoid malignancies dominated (50%). The highest incidence was observed in the 0–4 age group (12.5). The male-to-female ratio was 1.4, showing a male predominance. By district, the highest overall incidence rates were observed in Bayangol (10.3 per 100,000), Songinokhairkhan (9.6), and Bayanzurkh (9.4), while the lowest rates were observed in Nalaikh (4.7) and Bagakhangai (0.0). Conclusion The incidence of childhood cancer in Ulaanbaatar has shown an increasing trend over the last decade. The patterns of cancer types, age, and sex distribution are consistent with international and Asian regional trends.

Background: Conventional methods for assessing exposure to environmental tobacco smoke rely mainly on questionnaires and biomarkers with short half-lives, such as urinary cotinine. In contrast, oral mucosal pigmentation may represent a visible, non-invasive biomarker of chronic exposure. However, its clinical and policy relevance, as well as its validity for screening purposes, remain insufficiently established. Aim: To summarize the evidence on the association between exposure to environmental tobacco smoke and oral mucosal pigmentation and to assess some confounding factors. Materials and Methods: We synthesized findings from observational studies that examined the association between environmental tobacco smoke exposure and oral mucosal pigmentation across all age groups. International electronic databases, including PubMed, Embase, Web of Science, and Scopus, were searched. Data were extracted on exposure–response relationships, measurement instruments, anatomical distribution of pigmentation, confounding by physiological pigmentation, and biochemical validation. The quality of included studies was assessed using the Mixed Methods Appraisal Tool (MMAT). A narrative synthesis was conducted, focusing on the biological plausibility of the biomarker, standardization of measurement, and its potential implications for screening and tobacco control policy. Results: Thirteen observational studies from seven countries, involving a total of 3,284 participants, met the inclusion criteria. Four studies reported a statistically significant association between duration of exposure and severity of pigmentation, while one cohort study showed that urinary cotinine levels increased with age among children. The Gingival Pigmentation Index and the Dummett Oral Pigmentation Index were the most commonly used assessment tools; however, methodological heterogeneity limited direct comparability across studies. The anterior gingiva was the most frequently affected anatomical site. Only a limited number of studies adequately controlled for physiological pigmentation, and skin color was identified as an important confounding factor. The pooled odds ratio was 2.35; however, the certainty of evidence was low due to the observational nature of the included studies. Conclusion Oral mucosal pigmentation may serve as a potential biomarker of long-term exposure to environmental tobacco smoke. Nevertheless, standardized assessment protocols, adequate control for physiological pigmentation, and validation against “gold-standard” biomarkers are required. If validated, this marker could be used for rapid identification of high-risk groups and incorporated into tobacco control policies.

Background: Passive smoking among children remains a serious public health concern, particularly because children’s ability to avoid household environmental tobacco smoke exposure is limited when parents smoke. In recent years, increasing scholarly attention has been given to oral mucosal pigmentation as a potential clinical sign of long-term passive smoking in children. However, no previous study has synthesized the available evidence on this topic. Aim: This systematic review and meta-analysis aimed to evaluate the association between passive smoking and oral pigmentation in children. Materials and Methods: A systematic search was conducted in international electronic databases, including PubMed, Scopus, Web of Science, and the Cochrane Library, in accordance with PRISMA guidelines. Observational studies assessing the association between passive smoking and oral pigmentation among children aged ≤18 years were included. Methodological quality was assessed using the Mixed Methods Appraisal Tool (MMAT). A random-effects meta-analysis was performed, and pooled odds ratios (ORs) with 95% confidence intervals (CIs) were calculated. Between-study heterogeneity was assessed using the I² statistic, and the certainty of evidence was evaluated using the GRADE approach. Results: Seven studies involving a total of 1,582 participants met the inclusion criteria. The meta-analysis demonstrated that passive smoking was significantly associated with an increased risk of oral pigmentation in children, with a pooled OR of 2.58 (95% CI, 1.35-4.95; p=0.004). Compared with children without exposure to passive smoking, those exposed to environmental tobacco smoke had an absolute risk increase of 17% (95% CI, 6.3%-23.9%). Subgroup analysis by assessment method showed a consistent effect among studies using the Gingival Pigmentation Index (GPI) (OR, 2.12; 95% CI, 1.58-2.84), whereas studies using the Dummett Oral Pigmentation Index (DOPI) showed a wider confidence interval (OR, 3.26; 95% CI, 0.68-15.54). According to the MMAT assessment, the included studies demonstrated adequate participant selection in 100% of cases, appropriate outcome measurement in 76.9%, and adequate control of confounding factors in 46.2%. Owing to the observational nature of the included studies, moderate heterogeneity, and the potential risk of confounding by physiological pigmentation, the certainty of evidence was rated as low according to GRADE. Conclusion Children exposed to environmental tobacco smoke had a significantly higher likelihood of oral mucosal pigmentation than unexposed children. These findings suggest that screening for oral mucosal pigmentation during pediatric oral examinations may serve as a non-invasive marker of passive smoking exposure and may provide visible clinical evidence to support counseling parents on smoking cessation and smoke-free household environments.

Background: The capital city of Mongolia, Ulaanbaatar is not only one of the coldest capitals in the world but has also become one of the most polluted cities in recent years due to the prolonged effects of severe cold. According to the World Health Organization (WHO), the most harmful air pollutant to human health is PM2.5. These fine particulate matters can penetrate the human body through the respiratory tract, causing various changes in the body and the oral cavity. Aim: Relationship between dental caries, gingivitis and periodontal status and PM2.5 air pollutant levels among 12 years old children in different areas of Ulaanbaatar. Materials and Methods: The study population consisted of 190 children aged 12 years old, who were selected from high and low level areas with air pollutant PM2.5 in Ulaanbaatar city, Mongolia. We obtained informed consent No.24-25/10-1 of the Ethical Committee, MNUMS. The oral examination of every child was done according to WHO recommendation (2013). We determined the prevalence of dental caries and mean DMFT score, and the prevalence of gingivitis, and CAL score. Statistical analysis was done by the SPSS 29 software. Results: The prevalence and mean DMF/t score of dental caries were 96% аnd 5.37±2.75 among children living in the high level area of the PM2.5 air pollutant; and 91% and 5.39±3.95 in the low level area, respectively (p<0.01). The prevalence of gingivitis was 23.2% among all children; 25.2% among children living in the high level area of the PM2.5 air pollutant and 20.5% in the low level area. The CAL score was 1.89±0.89 mm in the high polluted area and 1.94±0.77 mm in the low polluted area (p<0.001). Conclusion The prevalence of dental caries and gingivitis and the mean DMFT and CAL score among children living in air polluted areas were higher than low polluted areas.