Dental Caries in Children Under Five Years of Age in Mongolia.

During the Japan International Cooperation Agency (JICA) partnership program in Mongolia, six times between October 2017 and October 2019, education for caries prevention, a questionnaire of daily oral health behavior, and an oral examination for parents and children aged 0-5 years old were done. The target parent population were middle socio-economic class families. In total, there were 2223 participants. The caries prevalence measured in October 2017, January, April, and October 2018, and April and October 2019, was 78.0% (95% CI: 74.2-81.4); 79.4% (73.7-84.4); 80.8% (76.2-84.9); 76.4% (70.1-82.0); 89.3% (85.3-92.6); and 82.6% (79.3-85.6), respectively. Compared to October 2017, in October 2019, the deft of three years old was significantly decreased (p < 0.01) and that of four years old was also decreased (p = 0.085). For the prevention of early childhood caries (ECC), daily oral health behaviors are important. In 2019, compared with the percentage of 0-5 years old in 2017, the frequency of tooth cleaning per day, parents cleaning after children, and parents watching during children's tooth cleaning were significantly increased (p < 0.01). Unfortunately, the frequency of sugary-snack intake per day showed an increased tendency (p < 0.05). The baby teeth decayed, extracted and filled (deft) index at three and/or four years old in October 2019 was correlated with the childrens' background characteristics, such as parent educational attainment, frequency of sweets intake, frequency of daily tooth cleaning, and parental cleaning of children's teeth. The effects of the JICA program were recognized.

Comparison of mesiodistal tooth crown diameters and arch dimensions between modern Mongolians and Japanese.

The purposes of this study were to establish normative data for mesiodistal tooth crown diameters and arch dimensions in Mongolian adults and to compare them with those of Japanese adults. The study materials comprised dental casts of 100 modern Mongolian and 100 Japanese subjects (50 males, 50 females for each) with Angle Class I normal occlusion. The mean ages were 20 years 8 months for the Mongolian subjects and 20 years 0 months for the Japanese subjects. On the dental casts, the mesiodistal tooth crown diameters (excluding wisdom teeth) and dental arch dimensions were measured. The following arch dimensions were measured: inter-canine lingual, inter-premolar lingual, inter-molar lingual, inter-molar central, coronal arch length, basal arch length, and basal arch width. In the Mongolian samples, significant sex differences were noted, and most of the items were significantly larger in males than in females. Significant differences between the Mongolian and Japanese samples were mainly noted in the premolar and molar regions, rather than in the anterior region, and were significantly smaller in the Mongolian samples. In the Mongolian samples, the molar section widths and basal arch width and length were significantly larger in males and females compared with the Japanese samples. These results suggest that the tooth crown size and arch dimensions in the Mongolian samples differed from those in the Japanese samples, and that establishment of the clinical norm for Mongolian adults might be helpful in formulating treatment plans for Mongolian patients, given that these parameters are the basic tools for diagnosis.

Influence of environmental factors on tooth displacement.

An analysis of static occlusion including occlusal force and occlusal contact area in intercuspal position may be helpful but a dynamic analysis of occlusion should be regarded as more important for analyzing the stomatognathic system. Anthropological research has shown that the Japanese and the Mongolian populations share morphological and genetic similarities, although their dietary lives are not the same. The purpose of this study was to evaluate the relationship between environmental factors such as dietary life and stomatognathic function with a dynamic analysis of physiological tooth displacement. Ten clinically healthy subjects were recruited (mean age 24.8 +/- 1.0 years). The subjects were divided into two groups 1) Mongolian group: five Mongolians grown with a more or less natural texture diet and 2) Japanese group: five Japanese grown with a relatively soft diet. The displacement of the upper left first molar was measured during function using a three-dimensional tooth displacement transducer Type M-3. The tooth displacement in the Japanese group occurred mostly in an apicopalatal direction, but intruded basically parallel to the tooth axis in the Mongolian group. The stress-strain curve revealed that elastic socket deformation and viscous elements were more pronounced in the Japanese group. It was concluded that environmental factors such as dietary life could influence tooth displacement during function.