Delivery of Low-Diluted Toothpaste during Brushing Improves Enamel Acid Resistance.

Toothpaste viscosity decreases rapidly when diluted with saliva during brushing, potentially causing premature washout of high-risk caries areas and reducing the uptake of dental fluoride ions. However, no reports have examined the acid resistance of enamel from the perspective of the toothpaste's physical properties. This study aimed to elucidate the impact of toothpaste dilution on the acid resistance of the enamel, using bovine enamel as the subject. Five diluted toothpaste groups were created: a control group without toothpaste, and 100% (1.00×), 67% (1.50×), 50% (2.00×), and 25% (4.00×) dilution groups. Acid resistance was evaluated through pH cycling after toothpaste application. The results revealed a significant increase in substantial defects, compared to 67% (1.50×) at dilutions of 50% (2.00×) or higher, accompanied by a decrease in Vickers hardness. Moreover, the mineral loss increased with dilution, and a significant difference was observed between 67% (1.50×) and 50% (2.00×) (p < 0.01). This study revealed that the acid resistance of the enamel decreased when the dilution of toothpaste during brushing exceeded 67% (1.5×). Therefore, delivering toothpaste with a lower dilution to high-risk caries areas, including interproximal spaces and adjacent surfaces, could maintain a higher concentration of active ingredients in the toothpaste, thereby enhancing its medical effects.

Relationship between Obesity and Oral Health Behavior in Primary and Junior High School Students: A Cross-sectional Study.

It has been reported that people who brush their teeth frequently might be more health-conscious and maintain healthier lifestyle habits. The relationship between obesity and oral health behavior in childhood is unknown, however. The aim of the present study was to fill this gap by investigating obesity and factors associated with oral health behavior in Japanese primary and junior high school students. A total of 475 primary school students (fifth-grade, age 10-11 years) and 408 junior high school students (first-grade, age 12-13 years) were included. All the participants underwent a regular health check-up and completed a self-reported questionnaire. The data thus obtained were subjected to multiple logistic regression analyses to identify the relationship between obesity and factors associated with oral health behavior. In primary school students, a dislike of physical activity was the only factor showing a significant association with obesity (p<0.05). In addition, however, tooth brushing <2 times per day and a lack of regular clinical dental care showed a significant association with obesity in junior high school students (p<0.05). The present results suggest a significant association between regular clinical dental care and tooth brushing and obesity in junior school students.