Dental caries is an infectious and transmissible disease, in which many genetic, environmental and behavioral risk factors interact. The mutans streptococci (MS), mainly Streptococcus mutans and Streptococcus sobrinus are the microorganisms most strongly associated with this disease. The main virulence factors associated with MS cariogenicity include adhesion, acidogenicity and acid tolerance. These properties work together to modify the physico-chemical properties of the biofilm, resulting in ecological changes in the form of increased proportions of S. mutans and other acidogenic and aciduric species. In addition, reports of higher numbers of S. mutans genotypes with increased virulence in caries-active subjects suggest the importance of microenvironmental factors in increasing the risk of caries. This review focuses on the transmission and establishment of different genotypes of S. mutans and the role they play in the development of dental caries. (J. Oral Sci. 47, 59-64, 2005)

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We examined the anatomical connections of trigeminal neurons between the trigeminal subnuclei interpolaris/caudalis (Vi/Vc) transition and caudal subnucleus caudalis/upper cervical dorsal horn (Vc/C_1,2) zones in rats, using the fluorogold (FG) retrograde tracing method combined with Fos expression, a marker of neuronal activation, following temporomandibular joint (TMJ) inflammation. The head withdrawal threshold was also measured in rats 3 days after complete Freund's adjuvant (CFA)-induced TMJ inflammation. The head withdrawal threshold on the inflamed side was significantly decreased after CFA injection into the TMJ. FG was injected into the Vi/Vc transition zone and retrogradely labeled FG-positive cells were observed in the Vc/C_1,2 region. Numerous Fos protein-expressing cells were present both in the Vi/Vc transition zone and in the laminated Vc/C_1,2 zone. A population of cells was double-labeled with Fos and FG in the Vc/C_1,2 zone. Fos/FG cells were only observed in the deep laminae of the Vc/C_1,2 zone. These findings suggest that Vi/Vc transition zone activity is modulated by activation of the caudal laminated zone after orofacial tissue injury. (J. Oral Sci. 47, 65-69, 2005)

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Some oral cancers are known to develop from dysplastic oral epithelium. In the present study, the expression of c-Jun, c-Fos, and cyclin D1 proteins in oral epithelial lesions with different degrees of dysplasia, and in oral squamous cell carcinomas (OSCCs) was evaluated. Eighteen cases of mild dysplasia, 23 cases of moderate to severe dysplasia and 24 OSCCs were studied immunohistochemically. Additionally, 15 sections of oral mucosa without any evidence of dysplasia were included in the study. Results: c-Jun expression increased according to the degree of oral dysplasia, with the greatest expression found in OSCC. c-Fos expression was intense in normal mucosa, reduced in mild dysplasia and high in moderate to severe dysplasia and in OSCCs. Cyclin D1 was expressed in only a few cases of moderate to severe dysplasia and in most of the OSCCs. Statistical analysis showed a correlation between the three proteins and the degree of epithelial alteration. The present results indicate a possible role of c-Jun and c-Fos in malignant transformation of oral mucosa. (J. Oral Sci. 47, 71-76, 2005)

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The incidence of mucous and ciliated cells in epithelial linings was examined among odontogenic inflammatory cysts (radicular cysts) and developmental cysts (dentigerous and primordial cysts). Mucous cells were found in 20.8% of all cysts examined, while ciliated cells were found in 11.4%; however, ciliated cells were always accompanied by mucous cells. The incidence of mucous cells in radicular cysts and dentigerous cysts and that of ciliated cells in radicular cysts was higher in the maxilla than in the mandible, while the incidence of mucous cells in primordial cysts and that of ciliated cells in dentigerous cysts and primordial cysts was higher in the mandible than in the maxilla. The present results regarding mucous cells and ciliated cells in the epithelial linings of intraosseous odontogenic cysts indicate a metaplasic origin, but the cause and biological significance of this phenomenon is not known. Mucous cells were present in the surface layer of epithelial linings, and intra-epithelial gland-like structures lined with mucous cells were observed in the hyperplastic regions of epithelial linings of several radicular and dentigerous cysts. Such gland-like structures lined by mucous cells in the thickened epithelial lining, which have not been demonstrated previously, resembled the glandular structures of “glandular odontogenic cysts”. (J Oral Sci 47, 77-81, 2005)

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The cephalometric features of class III malocclusion in Saudi adult females were investigated and compared with reference data for Japanese females. The sample consisted of 30 standardized pre-treatment cephalometric radiographs of adult Saudi females diagnosed as having skeletal class III malocclusion. The radiographs were traced and digitized. Linear and angular variables were obtained for comparison of cranial base, maxilla, mandible, intermaxillary and dentoalveolar measurements. The method error in identifying and locating the anatomical landmarks was small and acceptable. Student's t-test was used for comparing the measurements. The results showed that Saudi females had a larger anterior cranial base, a smaller posterior cranial base, a smaller cranial base angle, smaller anterior and posterior facial heights, downward tipping of the maxilla, a retruded chin, a less steep mandibular plane, an increased joint angle, a smaller ramus, body and total mandibular length, and less retroclined mandibular incisors. The null hypothesis of no difference between the two groups was rejected. These results appear to suggest real differences in skeletal features between Saudi and Japanese adult females. (J. Oral Sci. 47, 83-90, 2005)

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The present study uses structural equation modeling to explore the structural relationship of child behavior type and its evaluation during dental treatment. The study population consisted of 33 children at their first visit to a pediatric dentist at the Dental Hospital of Tsurumi University. Child behavior was evaluated by the Frankl Behavior Rating Scale and the behavior evaluation scale developed by Kurosu. Factor analysis extracted 3 behavior types: escape, self-defense, and facial expression. The path diagram of structural relationships between child behavior and the Frankl Behavior Rating Scale indicated that facial expression had the strongest correlation to the Frankl Behavior Rating Scale. (J. Oral Sci. 47, 91-96, 2005)

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The aim of this study was to investigate the relationship between dental clinic credibility and patient satisfaction with regular dental check-ups, to compare the level of satisfaction of patients who had regular check-ups with those who did not, and to identify factors associated with regular dental check-ups. Thirty-nine private dental clinics in 17 prefectures throughout Japan participated in this study. A total of 9024 questionnaires were distributed to the patients at these clinics, and patients returned the questionnaires using a pre-paid envelope (response rate 56.8%). The questionnaires consisted of items related to patient demographics and 11 items concerning the level of patient satisfaction with the dental clinic. Using multiple logistic regression analysis, the strongest correlation was found between dental clinic credibility in regular check-ups and the technical competence of the dentist. The responses to those items concerning making an appointment, and the cleanliness and neatness of the waiting room were different between patients who had regular check-ups and those who did not. To investigate the factors that encourage regular dental check-ups, correlation of factors with regular check up experience were analyzed. Multivariate-adjusted odds ratios indicated a strong association between regular dental check ups and both the technical competence of the dental hygienist and the cost of treatment. (J. Oral Sci. 47, 97-103, 2005)

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The effect of nifedipine and interleukin-α (IL-1α) on the cell proliferation and DNA synthesis was studied in human gingival fibroblasts derived from 5 patients who developed gingival overgrowth (nifedipine responders) and 5 patients who did not develop gingival overgrowth (nifedipine non-responders) in response to nifedipine. Epidermal growth factor was used as a positive control. The fibroblasts derived from nifedipine responders tended to have a numerically greater rate of cell proliferation and DNA synthesis (³H-thymidine incorporation) than those from nifedipine non-responders in the presence of nifedipine and IL-1α. Fibroblasts derived from nifedipine responders showed significantly higher cell proliferation rate in the presence of nifedipine and IL-1α, than nifedipine or IL-1α alone on both the second and the fourth day of incubation (P < 0.05). A combination of IL-1α and epidermal growth factor also showed significantly greater cell proliferation than IL-1α alone on the second day (P < 0.05). The DNA synthesis rate with a combination of nifedipine and IL-1α was higher than that for nifedipine alone on the second day (P < 0.01), and IL-1α alone on the fourth day (P < 0.05) in gingival fibroblasts originating from nifedipine responders. These results suggest that the interaction between nifedipine and gingival inflammation might play an important role in the pathogenesis of nifedipine-induced gingival overgrowth. (J. Oral Sci. 47, 105-110, 2005)

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Experimental animal models of diabetes induced either by alloxan or streptozotocin have been used to study aspects of the pathophysiology of this disease. The purpose of this study was to examine the metabolism of glycogen in the submandibular and parotid salivary glands of diabetic rats. Diabetes was induced by an intraperitoneal injection of streptozotocin. Eight weeks after the induction of diabetes, the animals were sacrificed and the submandibular and parotid salivary glands were removed. The glands were analyzed for glycogen concentration, and activities of glycogen synthase and phosphorylase. Although the diabetic rats consumed more food than controls, they had a lower body weight eight weeks after diabetes induction. Glycogen concentration in the submandibular and parotid glands increased by about 27% and 130%, respectively. Glycogen phosphorylase a in the submandibular gland of diabetic rats showed a reduction of between 75% and 68% compared with controls. In parotid glands, phosphorylase a was reduced by between 84% and 79% compared with controls. The increase in the activity of glycogen synthase a (active) varied from 64% to 130% for the submandibular glands and from 75% to 110% for the parotid compared with controls. These results suggest that the diabetic state influences glycogen metabolism in the submandibular and parotid salivary glands of rats. (J. Oral Sci. 47, 111-116, 2005)

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