A strontium isotope analysis on the relationship between ritual tooth ablation and migration among the Jomon people in Japan

patterns can be discerned in the extensive ritual tooth ablation found among the human skeletal remains of the Late-Final Jomon period (ca. 3200-2800 cal BP) in Japan. Based on comparative observations of sex and grave patterns in the skeletal remains, two major patterns in ritual tooth ablation, termed type 4I and type 2C, have been assigned to locals and immigrants, respectively. In order to test this hypothesis, strontium (Sr) isotope (87Sr/86Sr) analyses were performed on human skeletal remains from the Yoshigo shell mound in Aichi Prefecture, central Japan. Plants in the surrounding area were also examined to illustrate the geographic 87Sr/86Sr distribution. The Sr isotopic variation in human tooth enamel (87Sr/86Sr = 0.70868-0.71028) was greater than that in human bones (87Sr/86Sr = 0.70871-0.70943). Individuals with higher Sr isotope ratios in their tooth enamel than seawater Sr values of 0.7092 can be identified as immigrants (36% of population). The presence of these isotopically identified immigrants between both type 2C and type 4I individuals does not support the previous hypothesis. The intra-population 87Sr/86Sr distribution of tooth enamel of type 2C individuals showed a significantly higher mean ratio than that of type 4I individuals, suggesting a higher proportion of immigrants among the former

Number of teeth and masticatory function are associated with sarcopenia and diabetes mellitus status among community-dwelling older adults: A Shimane CoHRE study.

ObjectivesWe aimed to examine the number of teeth and masticatory function as oral health indices and clarify their roles in the pathogenesis of sarcopenia and diabetes mellitus in community-dwelling older adults.Subjects and methodsThis cross-sectional study was conducted with 635 older adults in Ohnan, Shimane Prefecture, in rural Japan. The number of teeth and masticatory function (measured by the number of gummy jelly pieces collected after chewing) were evaluated by dental hygienists. Sarcopenia status was assessed using handgrip strength, skeletal muscle index, calf circumference, and a possible sarcopenia diagnosis based on the Asian Working Group for Sarcopenia 2019. Diabetes mellitus status was defined as a hemoglobin A1c level ≥6.5% or self-reported diabetes. A multivariable logistic regression model was used to analyze the association between oral health, sarcopenia, and diabetes mellitus after adjusting for confounders.ResultsAfter adjusting for all confounders, logistic regression analysis showed that the number of remaining teeth was negatively associated with a low level of handgrip strength (odds ratio [OR], 0.961; 95% confidence interval [CI], 0.932-0.992) and possible sarcopenia (OR, 0.949; 95% CI, 0.907-0.992). Higher levels of masticatory function were also negatively associated with a low level of handgrip strength (OR, 0.965; 95% CI, 0.941-0.990) and possible sarcopenia (OR, 0.941; 95% CI, 0.904-0.979). Logistic regression analysis showed that the number of remaining teeth and a higher level of masticatory function were negatively associated with diabetes mellitus (OR, 0.978; 95% CI, 0.957-0.999; OR, 0.976; 95% CI, 0.960-0.992, respectively).ConclusionOur findings suggest that improvement in oral health, including the maintenance of masticatory function and remaining teeth, may contribute to the prevention of sarcopenia and diabetes mellitus in older adults