Background: Currently, dental impressions are captured using both conventional and digital methods. Numerous studies worldwide have assessed conventional impression techniques in both clinical and in vitro settings. While most studies have evaluated the factors affecting error rates during impression taking, few have examined error rates by impression material type. Proper evaluation of working models and clarification of the causes of impression errors and the factors influencing them form the basis for effective restoration of patients’ oral health. In appliance fabrication, the material properties, technology, and techniques used directly influence the final outcome. Therefore, this study was conducted to examine the causes of impression errors and the related factors that have not been fully investigated in previous studies, including impression-taking technique, impression material type, the size of the area requiring restoration, and other related factors. Aim: To investigate the factors influencing clinical errors in working models used in fixed prosthodontics. Materials and Methods: This cross-sectional observational study was conducted from May 2025 to November 2025 and included 80 working models prepared for fixed prosthesis fabrication. The models were collected from the Central Hospital Laboratory of the MNUMS School of Dentistry, Changed Goods Dental Laboratory, and Suld Dental Laboratory in Ulaanbaatar. After disinfection and drying, the models were analyzed using a Model MD-ID0400 digital 3D scanner to evaluate factors potentially contributing to impression errors. Result: Of the 80 cases included in the study, 67.5% (n=54) were male and 32.5% (n=26) were female, with a mean age of 35.2±3.5 years. Data were collected from working models prepared from impressions submitted by dental clinics for fixed dental restorations and evaluated digitally. All impressions were made using addition silicone impression material. The mean number of working models presenting impression errors among the received cases was 8.00±3.53. Conclusion 1. In the practice of dentistry, the impact of material properties on the quality of the material is not enough to make better impressions of the teeth without additional silicone. The total number of impressions taken was 8.00±3.53. 2. The error rate of the impression taking method was 7.78±3.9 in one stage and 8.03±3.51 in two stages (p<0.843).

Background: Mastication is a biomechanical process that involves the jaws and teeth working together to effectively break down food through the contraction of masticatory muscles. The efficiency of this process is influenced by factors such as bite force, the integrity of the dental arch, and individual characteristics, including age, gender, and body weight. Previous research has investigated the bite force of natural teeth, comparing the differences between removable and fixed denture teeth. For instance, Gibbs et al. estimated the bite force of Eskimo individuals to be 348 lbs (138 kg), while Al-Zarea et al. reported a bite force of 580.9 N for fixed partial dentures. Additionally, J. Urangua estimated the bite force of first permanent molars to be 472 N. Although studies have explored the bite force of Mongolian individuals with removable dentures, there has been no investigation into the bite force of fixed partial dentures, highlighting a significant gap in the literature that the current study aims to address. Aim: This study aims to assess the bite force following the restoration of teeth with Zirconia and Porcelain-Fused-to-Metal crowns. Materials and Methods: The study involved 20 individuals aged 18 to 34 years, each of whom had their mandibular molars restored with Zirconia and Porcelain-Fused-to-Metal (PFM) crowns on one side, while the other side retained their natural teeth, which had not undergone root canal treatment and exhibited no significant alveolar bone loss. A single-instance design was employed to measure occlusal force using the Occlusal Force Meter GM10. Statistical analysis was conducted using SPSS 26.0 software, with results considered statistically significant at a probability level of p < 0.05. Results: The cohort comprised 20 subjects aged 18 to 34 years, with 65% (13) male and 35% (7) female, yielding a mean age of 28.2 ± 3.5 years. The mean bite force for teeth covered with crowns was (393.2±0.3 N), compared to (445.5±70 N) for natural teeth. Notably, the bite force of the Zirconia crown (407.0±0.7 N) was higher than that of the Porcelain-Fused-to-Metal (PFM) crown 367.7±0.9N. When analyzed by gender, the bite force of natural teeth in men averaged 484.1±46.2N, while that of crowns was 445.3±43.7N. In women, the bite force of natural teeth averaged 373.7±15.4N, compared to 296.4±19.6 N for crowns. Conclusion 1. The bite force of zirconia porcelain crowns was 407.0±76N, while the bite force of metal porcelain crowns was 367.7±97N. 2. When determining the bite force of crowns and natural teeth, the bite force of crowns and natural teeth was 296.4±19.6N, and the bite force of uncoated teeth was 445.5±70N, respectively. 3. When compared by gender, the bite force of uncoated teeth in men was 484.1±46.2N, the bite force of coated teeth was 445.3±43.7N, and the bite force of uncoated teeth in women was 373.7±15.4N, and the bite force of coated teeth was 296.4±19.6N, and the bite force was significantly related to gender (p<0.0001).

Background: Treatment of adult tibiofibular fractures, especially severely comminuted fractures, is technically challenging due to the lack of reduction markers and difficulty in restoring the alignment. Fixation of the fibula can facilitate reduction of the tibia fracture and restoration of the lower extremity alignment. Methods: Between 2018-2019 we have operated on 50 patients who have lie on the same plane of tibiafibular fractures. Measures of angulation were obtained from radiographs taken immediately after the surgery, a second time 3 months later, and at 3-month follow-up. The analysis was performed with STATA. Results: Fixating fractures of tibia and fibula at same level were not shown to have complications on the development of nonunion including fibular shortening, hindfoot alignment, slow process of nonunion and unstableness. Conclusions We recommend fibular fixation in all 50 distal fractures when both fractures lie on the same plane and the tibial fracture is relatively stabilized.

BACKGROUND. Congenital Cleft Lip and/or Palate (CL/P) is a common craniofacial birth defect and occurs 1 per 500-700 live births in average. Children with CL/P at a higher risk for speech/language problems due to the anatomical and structural differences in the oral and nasal cavities, Velopharyngeal Insufficiency causing speech disorders with articulation, phonation, and resonance, respectively. It leads to long-lasting adverse outcomes, influencing quality of life and causes obstacles in child’s socialization. Speech in 2007 Therapy team of School of Dentistry ( G. Ariuntuul , B. Bulgan, U. Azzaya, B. Batsukh, M. Bat-Erdene), Mongolian National University of Medical Sciences (MNUMS) (former Health Sciences University of Mongolia) established and successfully conducted a first clinical speech therapy sessions for children with clefts in Mongolia based on the Department of Oral and Maxillofacial Surgery (G. Ayanga et al.) of National Maternal and Children’s Health Center (NMCHC). Since 2012 the speech therapy team of School of Dentistry, officially transferred the equipped operating speech room to NMCHC and speech pathologist B. Bulgan, supervised and trained by Ariuntuul G. recruited by NMCHC for a full time position and working as a member of multidisciplinary team till present. OBJECTIVES. To assess and analyze registry data of children with clefts, visited speech therapy sessions of speech pathology team of School of Dentistry, MNUMS during 2007 through 2012. MATERIAL AND METHODS. Registry based retrospective study was conducted to obtain demographic and speech disorder related data of children with clefts, visited speech therapy sessions between 2012-2017 at the NMCHC. RESULTS. In total 203 participants are attended the speech therapy sessions: 103 male (51%), 100 female (49%). Out of total 203 children 144 (71%) had Cleft Lip and Palate (CLP), 44 had cleft palate only (22%), 15 had cleft lip (7%), respectively. Average age for primary cleft surgery was 1y13m, where as for secondary was 4y22m. CONCLUSION. For speech therapy session for children with clefts boys were dominant compared to girls (1:1.03). By the types of clefts children diagnosed with Cleft Lip and Palate was prevalent to attend treatment classes. There is a need in early CL/P diagnosis, using birth screening and furthermore, traning of speech therapists/pathologists are important for development of multidisciplinary team, surgery outcome and improvement of quality of life of children with clefts.