To contribute to the prefectural oral health policy, we examined individual factors associated with dental caries and regional differences. Analysis of secondary data from a survey of 3-year-old children conducted in the Kanagawa Prefecture Resident Survey on the Actual Health Situation in 2020 was performed. Data on self-reported dental caries, attributes, and dental health behaviors of 4,741 participants aged 3 years were analyzed. The associations among the presence, absence, or unknown status of dental caries and other survey items were examined by cross-tabulation. Multinomial logistic regression analysis was conducted with the presence, absence, or unknown status of dental caries as the objective variable and other items as the explanatory variables. A quantitative text analysis of open-ended responses regarding the sense of burden or difficulty in finishing-toothbrushing by parents was conducted. The multinomial logistic regression analysis revealed significant odds ratios of 1 or higher (p<0.05) in the presence of dental caries (reference category: no caries) for the following areas of residence: Sagamihara city, East Shonan, and western part of the prefecture (reference: Yokohama city). The analysis also showed significant odds ratios for the second and third child in birth order (reference: first-child), eating while watching TV (reference: none), daily consumption of sweet snacks and/or sweetened drinks (reference: none), not brushing teeth daily (reference: yes), burden or difficulty in finishing-toothbrushing by parents (reference: none), do not use fluoride-containing toothpaste daily (reference: yes), and yes or unknown answers for experience of visiting dentist (reference: no experience). The quantitative text analysis revealed many difficulties, such as reluctance in opening their mouths. In conclusion, late birth order, habit of eating while watching TV, frequent consumption of sweets and sweetened drinks, lack of daily tooth brushing, parents’ sense of burden and difficulty in finishing-toothbrushing by parents, lack of daily use of fluoride toothpastes, and unknown answers for experience of visiting dentist were associated with dental caries among 3-year-old children in Kanagawa Prefecture, and regional differences remained even after adjustment for these individual factors.

 Fluoride rinsing is very effective at preventing dental caries and reducing health problems. Although many studies have shown the caries-preventive effects of fluoride rinsing, few have demonstrated the effects of fluoride rinsing on changes in parents’ dental health awareness and behavior, and factors associated with continued fluoride rinsing. Therefore, we conducted a questionnaire survey of the parents of elementary school children in the fluoride rinsing program. We investigated the changes in the parents’ dental health behavior after introducing fluoride rinsing, and analyzed factors associated with the continuation of rinsing in junior high school. Many subjects in the group that wanted to continue rinsing understood the caries-preventive effects of fluoride. Many parents in the rinsing group showed positive changes in dental health behaviors, including caries prevention awareness and checking oral cavities in their children. Logistic regression analysis with continued rinsing as the objective variable showed a correlation between the understanding of the caries-preventive effect of fluoride (odds ratio 2.07, p<0.01) in all subjects, and the parents’ awareness of caries prevention for their children (odds ratio 2.48, p<0.05) in the subjects in the rinsing group. The results suggest that parents’ understanding of the caries-preventing effect of fluoride and improved caries prevention awareness is related to the continuation of fluoride rinsing.

 In recent years, there has been an increase in the use of artificial intelligence to predict the onset of disease using machine-learning models. In our study, we evaluated the accuracy of a machine-learning model using Prediction One^Ⓡ to predict an increase in the number of decayed, missing, and filled teeth (DMF teeth) after 5 years in adults. We enrolled 284 participants who underwent dental checkups at Asahi University Hospital in 2016 and 2021. Data on the 284 dental checkups were divided into training (200 participants) and validation (84 participants) data. A machine-learning model using Prediction One^Ⓡ Version 1.3 was created based on dental checkup training data in 2016 and number of DMF teeth in 2016 and 2021. Then, we examined the accuracy of the machine-learning model using the validation data. At the results, we showed a positive correlation between the predicted increase in the number of DMF teeth after 5 years by the machine-learning model and actual increase after 5 years, with a correlation coefficient value of 0.802. Furthermore, sensitivity and specificity between the presence or absence of an increase in the number of DMF teeth predicted by the machine-learning model and presence or absence of an actual increase in the true number showed values of 1.00 and 0.77, respectively. These results suggest that the machine-learning model created by Prediction One^Ⓡ can predict an increase in the number of DMF teeth after 5 years with high-level accuracy in adults.

 The aim of this study was to investigate the oral function status of individuals aged 40, 50, 60, and 70 years who were undergoing periodontal disease screening. In total, 137 participants (49 males and 88 females) undergoing periodontal disease screening were included in the study. The oral frailty questionnaire and oral function tests were performed in addition to dental checkups. Oral function was evaluated by assessing six sub-symptoms of poor oral function: low occlusal force, poor oral hygiene, low articulatory oral motor skill, poor chewing ability, low tongue pressure, and compromised swallowing function. Low occlusal force was evaluated by the number of remaining teeth, poor oral hygiene using the tongue coating index, low articulatory oral motor skill using oral diadochokinesis, poor chewing ability using color-changeable chewing gum, low tongue pressure using a tongue pressure measuring device, and compromised swallowing function using EAT-10. The relevant rates and number of applicable sub-symptoms for these factors were calculated and compared among the age groups. The median number of remaining teeth was 28 and median age was 60 years. Of all participants, 67.2% exhibited sub-symptoms of poor oral function, and the rates of sub-symptoms at the age of 70 were significantly higher than those at the age of 40. Regarding the number of applicable sub-symptoms, 32.8% had none, 42.3% of participants had one, and 24.8% had two or more. Among all participants, low articulatory oral motor skills were observed in 50.4%, low tongue pressure in 21.2%, poor chewing ability in 10.2%, poor oral hygiene in 8.8%, low occlusal force in 5.1%, and compromised swallowing function in 2.9%. The present study found sub-symptoms of poor oral function at age 40, and increase with age among participants in periodontal disease screenings.