In search of reasons for regional differences in the death rate from stroke, an extensive factfinding project was carried out in Yamagata Prefecture. Out of the total 44 municipalities in the prefecture, we picked out four townships; two are noted for their high standard mortality rate from cerebrovascular disease and the other two have a low mortality from the disease. In these four townships, a thorough investigation was conducted on the incidence of stroke, along with health examination for cardiovascular disease. The findings are as follows;
1. Despite the fact that Yamagata Prefecture has a high rate of stroke, blood pressure levels stood on a par with, or even lower than, the national average.
2. There were no correlations between the standard mortality rates and blood pressure levels, ECG readings, funduscopic observations, and total serum cholesterol levels.
3. By occupation, white-collar workers showed higher values than blue-collar workers and farmers in diastolic blood pressure, obesity, and cholesterol levels in the blood serum. The occupational difference was observed in each and every one of the four townships.
4. The standard mortality rate and other fatality indices were not correlated with the incidence rate of stroke among the middle-aged and the rate of detection in the health examination for the conditions that might lead to stroke. Interesting to note is the fact that the incidence rate among the middle-aged was parallel with the detection rate. This finding suggests that further study of the incidence rate and the prevalence rate in necessary.

BACKGROUND: Systemic and local factors may lead to disruption of craniofacial growth and development, causing an imbalance between the orofacial skeleton, muscle and soft tissue, dental occlusion, and the dental arch during growth periods. We aimed to reveal whether the prevalence of incompetent lip seal (ILS) varies with age and region, as well as to clarify the factors related to an ILS, in a national, large-scale epidemiological study. METHODS: We surveyed 3399 children, from 3 to 12 years of age, visiting 66 pediatric dental clinics throughout Japan. For this survey, we employed a questionnaire consisting of 44 questions regarding daily health conditions and lifestyle habits. We evaluated the differences in ILS prevalence by age and region (using a Cochran-Armitage test for trend and a Kruskal-Wallis test), and the relationship between ILS and factors investigated in the questionnaire (using Spearman's rank correlation coefficient). RESULTS: We observed that 30.7% of Japanese children exhibited an ILS and that the ILS rate increased with age (p < 0.001). There were no regional differences in the rate of ILS in Japanese children (p = 0.506). We revealed that 12 of 44 survey items exhibited a statistically significant correlation with ILS (p < 0.001), using Spearman's rank correlation coefficient. These items involved orofacial morphology, mouth breathing, and possibly, allergic rhinitis. CONCLUSION The rate of ILS seems to increase with age in children, throughout Japan. Therefore, this disorder may not self-correct during the growth periods in these children. Guidelines are required for pediatric dentists to recognize ILS among children aged 3-12 years.
Child ; Child, Preschool ; Cross-Sectional Studies ; Female ; Humans ; Japan/epidemiology* ; Lip/abnormalities* ; Male ; Prevalence