Rationate: In recent years, global warming, climate change, environmental pollution driven by human activities, expansion of settlement areas, and mining operations within the Tuul river basin have been increasingly recognized as major factors affecting the river’s water quality, pollution levels, and flow regime [1, 3].
In particular, air and soil pollution in Ulaanbaatar, the quality and composition of effluent from the central wastewater treatment plant, water use by thermal power plants and boilers, as well as increasing domestic and industrial water consumption, continue to exert pressure on the Tuul river system [4, 6]. In addition, gold mining activities in the Zaamar area further contribute to the deterioration of water quality.
These combined pressures highlight the growing vulnerability of the Tuul river ecosystem and underline the need for detailed, spatially differentiated assessment of water quality along its course, especially within and downstream of urbanized areas. Objective: The objective of this study is to assess and evaluate the level of pollution in the Tuul river by spatially dividing the river into zones based on the results of chemical analysis. Materials and Methods: This study utilized water quality data obtained from laboratory analyses of Tuul River water samples conducted by the Information and Research Institute of Meteorology, Hydrology and Environment between 2022 and 2024. The data were accessed and used with official permission from the relevant authority.
The study was designed as a descriptive cross-sectional analysis. The research area was divided into three zones and 14 monitoring sites. A total of 373 water samples were analyzed based on 15 chemical parameters. Ethics: Before initiating the study, the research methodology and procedures were reviewed and approved by the Ethics Committee of Ach Medical University. An official request was submitted to the National Agency for Meteorology and Environmental Monitoring to obtain permission for the use of research data, and the data were used upon receiving approval.
To assess the water quality of the Tuul river, a statistical analysis was conducted on 15 key parameters across Zones 1, 2, and 3 using SPSS and Microsoft Excel. The study calculated arithmetic means and standard deviations to evaluate the data. A total of 373 samples, collected from 14 monitoring points within these three zones over a three-year period, were included in the analysis. Results: The three-year average concentrations of water quality indicators differed across Zones 1, 2, and 3. In Zones 2 and 3, key indicators including dissolved oxygen, biochemical oxygen demand (BOD), chemical oxygen demand (COD), ammonium nitrogen, mineral phosphorus, and chromium corresponded to Class IV and V levels of surface water quality classification, indicating heavy to extreme pollution. Conclusion
1. The chemical indicators reflecting the water quality and pollution level of the Tuul River show clear spatial variation along its course. The upper reach entering the city is relatively unpolluted, the central urban section experiences noticeable contamination, and the downstream section accumulates the highest level of pollution.
2. The main surface water pollution indicators in Zones 2 and 3 fall within heavily polluted (IV) and very heavily polluted (V) categories, indicating a strong influence of human activities and urbanization.
3. The average fluoride concentration in all zones exceeds the permissible limit defined by relevant standards by 2.5–3.9 times. Consumption of surface water with elevated fluoride levels may lead to fluorosis in humans, while livestock drinking water along the Tuul River may experience reduced productivity and disruption of normal bone structure development.

Background: According to the World Health Organization’s 2022 Global Oral Health Status Report, approximately 3.5 billion people worldwide - nearly half of the global population - suffer from some form of oral disease, among which dental caries is the most prevalent, affecting close to 2 billion people in permanent teeth (global average prevalence of 29%) and 514 million people in primary teeth (global average prevalence of 43%). In Mongolia, the prevalence of dental caries also remains high: a 2017 survey of 1,754 individuals from six provinces and five districts found caries prevalence of 82.9% among children under 5 years of age, 80.9% among those under 12, 97.8% among the population aged 35-44, and 99.1% among those aged 65-74. A 2010 study among Mongolian preschool and school-age children found a caries prevalence of 87.8-90%, with S. mutans identified alone in 75% of culture-positive plaque samples and together with S. sobrinus in the remaining 25%. Given the persistently high global burden of dental caries, preventing the disease rather than merely treating it - for example through “replacement therapy,” in which a less cariogenic strain of S. mutans is used to colonize the oral cavity - requires a reliable rat model in which standard and clinical strains of S. mutans can reproducibly induce dental caries, so that the efficacy of such preventive strategies can be properly evaluated. Untreated dental caries is also estimated to impose an annual global economic burden of approximately US$387 billion in direct costs and US$323 billion in indirect costs, underscoring the growing importance of research into new preventive approaches. Aim: Development of a dental caries model caused by Streptococcus mutans infection in rat teeth. Materials and Methods: This study used an experimental research design. It was conducted from March 30 to April 14, 2021, at the Core Laboratory and the Education Laboratory of the Department of Microbiology and Infection Prevention Control of the Mongolian National University of Medical Sciences (MNUMS). Ethical approval was obtained from the Medical Ethics Review Committee under the Ministry of Health (meeting No. 02, March 18, 2019). Five 8-week-old Wistar rats were divided into four experimental groups - differing by bacterial strain (S. mutans ATCC 25175 standard strain versus a clinical isolate) and by drinking-water composition (with or without sucrose) - plus one negative control group, with one rat assigned to each group. A bacterial suspension was applied to the rats’ molar teeth with a sterile cotton swab three times daily at two-hour intervals for 28 consecutive days. Rats were lightly sedated with midazolam during application, and the suspension was applied during the daytime, when salivary flow is naturally reduced in rodents, in order to promote bacterial colonization of the tooth surface. Result: On day 28, microscopic examination of each rat’s maxillary and mandibular teeth revealed carious spots and cavities in all groups except the sucrose-free negative control. Cavities were deeper in the groups that received sucrose-supplemented drinking water, whereas the sucrose-free groups showed comparatively milder lesions, indicating that bacterial infection alone was sufficient to induce caries. Conclusion Infection of 8-week-old Wistar rats with either the standard or a clinical strain of S. mutans for 28 days successfully induced dental caries, and sucrose intake increased the severity of the lesions. This baseline model can be reproduced within a relatively short time frame and at low cost, and may be applied in future studies evaluating the efficacy of replacement-therapy strains or probiotic products against dental caries.

Background: Mongolia ranks first in the world for liver cancer incidence and mortality, with more than 95% of cases associated with hepatitis B virus infection. Healthcare professionals are considered a priority group for vaccination. Aim: To investigate the level of hepatitis B virus immunization among dental specialist physicians. Materials and Methods: This retrospective, observational, analytical cross-sectional study was conducted with approval from the Research Ethics Committee of the Mongolian National University of Medical Sciences (MNUMS). We analyzed serum test data from 76 dentists officially registered in the Dentistry residency program during the 2025–2026 academic year, assessing hepatitis B virus infection status and immunization levels. Statistical analysis of quantitative data was performed using SPSS version 27. Results: Data from 76 dentists were analyzed. The mean age was 28.5±6.2 years; by age group, 70% (n=53) were aged 20–29 years, 22.3% (n=17) were 30–39 years, and 7.8% (n=6) were over 40 years (p<0.05). By sex, 13.2% (n=10) were male (p>0.05). Among the study participants, 97.4% were HBV-negative with a mean age of 28.2±5.3 years (Median: 27.0, IQR: 24.0–31.0), whereas 2.6% were infected; the mean age of infected physicians was 43.5±2.1 years (Median: 43.5, IQR: 42.0–45.0), indicating a high and statistically significant occurrence of HBV infection in the age group over 40 years (Fisher’s exact test, p=0.05). When classified by immunity level, 29.2% (n=19) had anti-HBs levels below 10 mIU/mL (insufficient), 24.6% (n=16) had anti-HBs levels of 10–99 mIU/mL (weak), and 46.2% (n=30) had anti-HBs levels above 100 mIU/mL (adequate immunity); however, no statistically significant association was observed between age groups and protective antibody levels (Fisher’s exact test, p=0.892). Conclusion Among participants, the prevalence of hepatitis B virus infection was 2.6%, vaccination coverage was 85.5%, and anti-HBs antibody titers were adequate in 46.2%.

BACKGROUND In recent years, the new treatment and technology developing quickly however, the disease prevention therapy necessary investigate in preventive dentistry. Oil pulling is a traditional Indian folk remedy and Researchers et al previously first time investigated this method. Asokan S, Emmadi P, Chamundeswari et al have indicated the antibacterial activity of sesame oil against on oral microorganisms and found the bacterial growth decreased 20%. In our country, this has not been investigated thus . AIM The aim of this study to assess the antimicrobial efficacy of sunflower oil for reducing micro bacterial count in the oral cavity. METHODS The present study was a parallel design, double-blind, randomized clinical trial with two groups which collected from 162 dental students at the MNUMS, School of Dentistry. The participants rinsed a mouth by 10 ml oil 5 min twice a day after meal and all participants used the same teeth paste during the study period. Oral health status and plaque index were obtained and assessed at baseline and after 30 days of oil therapy . RESULTS However, the Oral health status index not reduced after 30 days. The baseline bacterial count mean of treatment group: a) 0-15 colons subgroup increased from 40.4% to 55.4%, b) 16-200 colons subgroup reduced from 33.3% to 28.6% and c) >201 colons subgroup reduced from 26,3% to 16.1%. In the control group no differences the bacterial count means on baseline and after therapy. CONCLUSION The oil rinse therapy can be used as valuable preventive agents in maintaining and improving oral health furthermore reduced plaque formation and bacterial colonization 15%.

Background and Aim: The traditional herbal formulation of “Sendeng- 4”have been used to treat ulcers. The wound healing activity of traditional herbal formulations (Sendeng-4) containing Acacia catechu Willd (FamilyFabaceae), Terminalia chebula Retz, Terminalia bellarice (Family Combretaceae), Gardenia jasminoides (family Rubiaceae). We were prepared lotion of “Sendeng-4” was evaluated for its wound healing potential of incision wound models in mice’s. Material and Methods: Healthy inbred white mice’s were weighing 20-22 used for the study. The animals were randomly divided into two groups(n= 10) in all the models. The mice’swere anesthetized ketamine (12mg kg–1bodyweight) of the experimental wounds. We used comparable to that of lotion of thestandard drug and standard solution used for comparison in this present investigation. The results were also comparable of wound contracting ability, epithelization period, regeneration of tissues at the wound area. On Day 14-16th lotion of “Sendeng-4” treated animals exhibited 100% reductionin the wound area when compared to controls. The increased rate of woundcontraction, skin breaking strength and of “Sendeng-4” in wound healing. Conclution:The lotion of traditional herbal formulation of “Sendeng-4” have facilitateswound healing in the experimental animal model.

Objectives: To study of the effects on traditional drug Sendeng 4 for papain-induced osteoarthritis in rats. Methods: The rats were divided into three equal groups in number and were sacrificed under high-dose ether anesthesia after one, two, and four weeks of the last papain injection, respectively. Osteoarthritis was experimented in Wistar rats. Total 21 rats were injecting an admixture of 4% papain and its activator 0.03 M cycteine into the right knee joints on the first, fourth, and seventh days. The same volume of sterile saline solution was injected into the left knees as controls. Result. Pre sacrifice, measured with the artritis scoring evalution and X ray analysis, after cartilage from femorel condyles and tibial plateaus was macroscopically and histophatologically evaluated. The artritis scoring evalution were significantly lower at Sendeng 4 groups (2.2±0.16) compared to the control (3.7±0.25) groups. (p