The relationship between high-fat food consumption and obesity is well-established. However, it is as yet unclear whether high-fat diet (HFD)-induced obesity in childhood and adolescence determines age-related changes in jaw bone health. The aim of this study is to examine the age-related influence of HFD-induced obesity on mandibular bone architecture and the structure of the periodontium in growing mice. Male C57BL/6 J mice (6-weeks-old) were divided into two groups (n = 6 each): the control group received a control diet and the experimental group a HFD. After treatment for 4, 8, or 12 weeks, trabecular and cortical bone architecture was assessed using micro-computed tomography. The periodontium and alveolar bone structure were evaluated by histopathology. In HFD mice, body weight, serum total cholesterol, and serum leptin levels were significantly higher than those in age-matched control mice (p < 0.05, all comparisons). Reductions in trabecular bone volume and in cortical bone growth (measured as the thickness and cross sectional area) in HFD mice were significant compared with the control mice after 4 weeks of treatment (p < 0.05, both comparisons). Significant decreases in cortical bone density in HFD-fed vs. age-matched control mice were determined after 12 weeks (p < 0.05). In the HFD mice, the periodontal ligament fibres were disrupted, having lost their orientation with respect to the bone surface, and constriction of the periodontal ligament space was inhibited. These results suggest that HFD-induced obesity during growth not only triggers mandibular osteoporosis but also increases the risk of spontaneous periodontal disease.

Background: Recent studies suggest that tonsilloliths are clinically related to halitosis and tonsillar abscess. Based on our empirical knowledge, tonsilloliths are relatively commonly encountered in daily clinical practice. It has been reported that the detection rate of tonsilloliths was under 24% in previous reports, although experience suggests otherwise. The purpose of the study was to evaluate the prevalence and characteristics of tonsilloliths using computed tomography (CT). In addition, the possible causes of low detection rates on panoramic radiographs were evaluated based on comparisons between CT images and panoramic radiographs in order to elucidate the limitations of visualizing the area around the palatine tonsils on panoramic radiographs. Methods: 482 pairs of CT images and panoramic radiographs were retrospectively assessed with respect to the presence and characteristics of tonsilloliths. In addition, the causes in cases of disagreement between the two modalities were analyzed. Results: The detection rate of tonsilloliths was 46.1% using CT scans, unlike previous reports. The characteristics of tonsillolith were dot-like figures with about 300-500 Hounsfield units within the palatine tonsil under the soft palate. The most common length of tonsilloliths was about 3 or 4 mm. As the subjects aged, the detection rate increased gradually. A significant difference in the tonsillolith detection rate was found between the over and under 40-year-old groups (p < 0.0001). However, the detection rate of tonsilloliths was only 7.3% on panoramic radiographs. A significant correlation was observed between the detection rate of tonsilloliths on panoramic radiographs and CT number (Spearman r = 0.429), size, (Spearman r = 0.318), and number of tonsilloliths (Spearman r = 0.333). Conclusion: The present results suggest that tonsilloliths are relatively more common than previously suggested. However, panoramic radiographs detect only a small percentage of palatine tonsilloliths. The low detection rates on panoramic radiographs might be related to the degree of calcification, size, and number of tonsilloliths.

The management of the avulsion of deciduous and permanent teeth in children is well outlined in the guidelines of the International Association of Dental Traumatology and the American Academy of Pediatric Dentistry. However, little information is available about the level of knowledge in the management of dental trauma among undergraduate dental students in Japan. The objective of this study is to explore dental students’ level of educational knowledge in the management of avulsed teeth.

In recent decades, the eating habits of children and adolescents have undergone many changes due to the diversification of lifestyles worldwide. Reduced masticatory function in growing animals results in changes in the mandible, including a decrease in bone mass. However, the influence of different eating behaviors on jaw bone metabolism (e.g., the palatal palate) during the growth period is not fully understood. In addition, recent clinical studies reported that masticatory performance is positively related to tongue pressure in adults, but no consensus has been reached regarding whether tongue pressure is related to masticatory performance in children. This review summarizes current findings related to these issues, focusing on the influence of different feeding behaviors on jaw bone metabolism, including the development of tongue pressure. Consumption of a soft diet had a negative impact on jaw bone metabolism in the maxilla and mandible of rats; however, mastication of a hard diet recovered the collapsed equilibrium of bone turnover caused by a soft diet during growth. Tongue pressure is closely associated with an increase in masticatory performance in children. Peak maximum tongue pressure is reached earlier in women than in men. Before reaching adulthood, women require intervention to increase their peak tongue pressure.

Smoking is a major risk factor for cancer and cardiovascular disease. However, mental stress leads to smoking in dental students. We believe that dentists, as health professionals, should set an example for the public. Therefore, this study determined the prevalence of and factors associated with regular smoking among Japanese dental students. We also surveyed their attitudes regarding smoking cessation and how to counsel smokers about quitting. We collected demographic and behavioral data from 453 students at Kyushu Dental University, and evaluated their mental health with the 12-item General Health Questionnaire (GHQ 12). We also asked them nine questions related to their intentions to counsel smokers about quitting. A multivariate binary logistic regression analysis was used to identify factors associated with smoking. Fifty-two (11.5%) of the dental students smoked. Univariate analyses indicated that male gender, higher academic year, greater number of times eating out per day, alcohol consumption, prevalence of skipping breakfast, poor health, and poor sleep habits were significantly associated with regular smoking. Regular smokers were less likely to have GHQ 12 scores ≥4. On multivariate analysis, male gender (OR = 5.449, 95% CI = 1.851–16.040), sixth year students (OR = 21.971, 95% CI = 1.686–286.290), eating out two or more times a day (OR = 2.492, 95% CI = 1.165–5.331), drinking alcohol three or more times per week (OR = 9.484, 95% CI = 3.335–26.970), and GHQ 12 score ≥ 4 (OR = 0.339, 95% CI = 0.136–0.845) were significantly associated with regular smoking. Overall, 50.1% of the non-smokers and 71.2% of the regular smokers responded that patients’ chances of quitting smoking are not increased when a dentist advises them to quit. Regular smoking was strongly associated with male gender, higher academic year, alcohol consumption, and higher frequency of eating out per day. Mental health status among regular smokers was better than that among non-current smokers. Furthermore, we found that more than half of dental students have inadequate attitudes to advise their patients to quit smoking. It is necessary to develop educational programs regarding smoking for dental students.

The aims of the present study were to the determine changes in, and factors related to, masticatory performance and swallowing threshold according to dental formula development. A total of 120 subjects, ranging in age from 4 to 19, and 21 to 29 years, were included in the present study. Grip strength and maximum occlusal force were measured in all subjects. Masticatory performance and swallowing threshold (including the number of chewing cycles and chewing time), were determined according to the concentration of dissolved glucose obtained from gummy jellies. The 12-item General Health Questionnaire (GHQ-12) was used to assess mental health status in participants 21 to 29 years of age. In the primary dentition, masticatory performance and glucose concentration before swallowing were the lowest in all dentition groups. Masticatory performance was the highest in subjects 21-29 years of age. In children with mixed and permanent dentition, glucose concentration levels before swallowing were similar to those in individuals aged 21-29 years. Multiple regression analysis revealed that maximum occlusal force was significantly and positively correlated with glucose concentration before swallowing in children, and the GHQ-12 score was significantly and negatively correlated with glucose concentration before swallowing in young adults. Changes in swallowing threshold did not coincide with masticatory performance according to dental formula stage. Maximum occlusal force was the variable most strongly associated with swallowing threshold in children, while in young adults, better mental health status was closely associated with a higher swallowing threshold.