BackgroundRecent 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.Methods482 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.ResultsThe 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).ConclusionThe 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.

BackgroundThe 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.MethodsA three-part questionnaire was used to gather demographic data and evaluate the knowledge of students at Kyushu Dental University.ResultsQuestionnaire data were collected from 121 (53 first-year, 68 sixth-year) students. Regarding the immediate emergency management of a case in which a 9-year-old girl had fallen down the stairs and lost a maxillary incisor but remained conscious, 55.9% of sixth year students and 28.3% of first-year students suggested the immediate transportation of the tooth to a dentist. The answer selected by the largest number (50.9%) of first-year respondents was “sideline the injured girl and get her to bite on a tissue paper for several hours”. In a case in which a boy had an avulsed tooth after falling down on a road, only 13.2% of first-year students suggested the transportation of the tooth in his mouth to the clinic. Most the largest number of respondents believed that the best way to transport an avulsed tooth to the dental clinic was to “wrap it in dry tissue paper”.ConclusionsThese results suggest that education in first aid for accidents that occur outside dental clinics or hospitals is insufficient. Japanese dentists and dental educations must immediately improve the utilization of the guidelines for dental trauma and the education of undergraduate students and patients in the management of dental trauma using an integrated approach.

BackgroundThe 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.MethodsMale 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.ResultsIn 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.ConclusionsThese results suggest that HFD-induced obesity during growth not only triggers mandibular osteoporosis but also increases the risk of spontaneous periodontal disease.

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p130Cas, Crk-associated substrate (Cas), is an adaptor/scaffold protein that plays a central role in actin cytoskeletal reorganization. We previously reported that p130Cas is not tyrosine-phosphorylated in osteoclasts derived from Src-deficient mice, which are congenitally osteopetrotic, suggesting that p130Cas serves as a downstream molecule of c-Src and is involved in osteoclastic bone resorption. However, the physiological role of p130Cas in osteoclasts has not yet been confirmed because the p130Cas-deficient mice displayed embryonic lethality. Osteoclast-specific p130Cas conditional knockout (p130Cas DOCL-) mice exhibit a high bone mass phenotype caused by defect in multinucleation and cytoskeleton organization causing bone resorption deficiency. Bone marrow cells from p130Cas DOCL-mice were able to differentiate into osteoclasts and wild-type cells in vitro. However, osteoclasts from p130Cas DOCL-mice failed to form actin rings and resorb pits on dentine slices. Although the initial events of osteoclast attachment, such as b3-integrin or Src phosphorylation, were intact, the Rac1 activity that organizes the actin cytoskeleton was reduced, and its distribution was disrupted in p130Cas DOCL-osteoclasts. Dedicator of cytokinesis 5 (Dock5), a Rho family guanine nucleotide exchanger, failed to associate with Src or Pyk2 in osteoclasts in the absence of p130Cas. These results strongly indicate that p130Cas plays pivotal roles in osteoclastic bone resorption.