The human EDAR 370V/A polymorphism affects tooth root morphology potentially through the modification of a reaction-diffusion system.

Morphological variations in human teeth have long been recognized and, in particular, the spatial and temporal distribution of two patterns of dental features in Asia, i.e., Sinodonty and Sundadonty, have contributed to our understanding of the human migration history. However, the molecular mechanisms underlying such dental variations have not yet been completely elucidated. Recent studies have clarified that a nonsynonymous variant in the ectodysplasin A receptor gene (EDAR 370V/A; rs3827760) contributes to crown traits related to Sinodonty. In this study, we examined the association between the EDAR polymorphism and tooth root traits by using computed tomography images and identified that the effects of the EDAR variant on the number and shape of roots differed depending on the tooth type. In addition, to better understand tooth root morphogenesis, a computational analysis for patterns of tooth roots was performed, assuming a reaction-diffusion system. The computational study suggested that the complicated effects of the EDAR polymorphism could be explained when it is considered that EDAR modifies the syntheses of multiple related molecules working in the reaction-diffusion dynamics. In this study, we shed light on the molecular mechanisms of tooth root morphogenesis, which are less understood in comparison to those of tooth crown morphogenesis.

Oral health behavior of children and guardians' beliefs about children's dental caries in Vientiane, Lao People's Democratic Republic (Lao PDR).

Dental caries is considered a major health problem among schoolchildren in Lao People's Democratic Republic (Lao PDR). According to Health Belief Model (HBM)-based research, children's oral health behavior can be determined by their guardians' beliefs. This study aimed to describe children's oral health behavior and its association with childhood dental caries, as well as to assess associations between children's tooth-brushing behavior and guardians' beliefs in an urban area of Lao PDR, using HBM. Data were collected from ten primary schools in the Sisattanak district, the Vientiane capital, between 2013 and 2014. Ten dentists with the help of dental hygienists and schoolteachers conducted dental health check-ups at the schools that diagnosed dental caries based on visual inspection. They also conducted a questionnaire-based survey with the schoolchildren's guardians to collect data including socio-economic and demographic information, their children's oral health behavior, and guardians' beliefs derived from HBM, including perceived susceptibility to and perceived severity of child dental caries, perceived benefit of and perceived barrier to child's tooth brushing, and self-efficacy in making their children brush their teeth twice daily. A mixed-effects logistic regression model assessed the association between dental caries and children's oral health behavior and between children's tooth-brushing behavior and guardians' beliefs. Data from 1161 of 1304 (89.0%) children registered at the schools were used. The prevalence of dental caries was 82%. Children who brushed their teeth ≥ twice/day were significantly less likely to have dental caries than those brushing once or seldom (OR: 0.64, 95% CI: 0.45 to 0.91). The number of children who brushed twice daily also significantly increased with the increased level of guardians' self-efficacy (OR: 2.14, 95% CI: 1.91 to 2.41). In conclusion, childhood dental caries was associated with daily tooth brushing. Children's tooth-brushing behavior was associated with guardians' self-efficacy in making their children brush twice daily.

Triple primary cancer of the head and neck, skin and prostate: A case report and literature review.

Second primary cancer (SPC) is an important prognostic factor for patients with head and neck cancer (HNC); therefore, the association between the prognosis and development of SPC has been well-reported. The use of 2-[18F]-fluoro-2-deoxy-D-glucose-positron emission tomography (FDG-PET) is valuable to examine cancer stage, evaluate treatment responses and investigate suspected relapses or metastases. In the present study, the case of a male patient who was diagnosed with three primary cancer types, including well to moderately differentiated squamous cell carcinoma (SCC) of the mandible, axillary cutaneous poorly differentiated SCC and prostate adenocarcinoma, was described. Among these, mandible cancer was the first diagnosed when the patient was 70 years of age. Synchronous skin and prostate cancer (PRC) types then developed 3 years later. To the best of our knowledge, this is the first report of the aforementioned combination of cancer types. Postoperative FDG-PET was not performed as no lesions of recurrence or metastases of mandible cancer were found. Three years later, the PRC was asymptomatic and was incidentally detected by FDG-PET performed for a preoperative evaluation of skin cancer. It was indicated that FDG-PET could be utilized in patients with HNC due to there being no accurate FDG-PET protocol to detect SPC over a long-term follow-up.

Triple primary malignancies of surface osteosarcoma of jaw, myelodysplastic syndrome and colorectal cancer as a second primary cancer detected by PET2-[18F]-fluoro-2-deoxy-D-glucose positron emission tomography: A case report.

Second primary malignancy (SPM) is a severe issue for cancer survivors, particularly for osteosarcoma (OS) survivors. To date, the associations between subsequent SPM and OS have been well reported. Hematogenic and solid malignancies tend to occur following OS treatment. Reportedly, 2-[18F]-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) is mainly used in OS patients for initial cancer staging, to evaluate the response of neoadjuvant chemotherapy, and when recurrence or metastasis is clinically suspected. The present case report describes a 70-year-old man diagnosed with three primary malignancies: jaw OS, myelodysplastic syndrome and colorectal adenocarcinoma. To the best of our knowledge, this combination of malignancies has not been reported previously. Until now, there is no specific protocol of postoperative FDG-PET for OS patients. Few studies have described OS follow-up methods; therefore, there is no consensus on proper follow-up methods. In the present case report, the colorectal early-stage SPM was observed, without any symptoms, by FDG-PET/computed tomography. To avoid overlooking solid SPMs, it is suggested that FDG-PET should be performed in the long-term follow-up of OS patients.

Topographic analysis of the maxillary premolars relative to the maxillary sinus and the alveolar bone using cone beam computed tomography.

OBJECTIVE: The purpose of the present study was to elucidate the anatomic characteristics of the maxillary premolars for the planning of dental treatment using cone beam computed tomography (CBCT). STUDY DESIGN: CBCT images were obtained for 150 maxillary premolars in 68 patients. The internal angle formed by the long axis of the maxillary premolars and the long axis of the alveolar bone was evaluated on the cross-sectional images. The vertical relationships between the maxillary premolars and the maxillary sinus were classified into 5 categories. The bone width and internal angle were compared among the images classified into the 5 categories. RESULTS: The internal angle was 25.5 ± 6.9° at the maxillary first premolars. The incidence of Type I in the maxillary first premolars was 46.7%. In the maxillary second premolars, the incidence of Type I (14.7%) was significantly lower than the total incidence of Types II, III, IV, and V (85.3%). Type I had the significantly largest internal angle (28.0 ± 7.7°) among all types for the maxillary first premolars. CONCLUSION: When considering dental treatment in the maxillary premolars, one should observe the inclination of the maxillary premolars to the alveolar bone as well as the position of the inferior wall of the maxillary sinus.