Relaxin is a short circulating peptide hormone, and the major stored and circulatory form in humans is relaxin-2, generally known to have hormogenic functions and to act as an antifibrotic factor during childbirth in females. Relaxin is also expressed in mammary gland tissue and its tumors, suggesting association with tumorigenesis and development in exocrine tissues. In addition, leucine-rich repeat containing G protein-coupled receptors（LGR）7 and LGR8 are known to be receptors for relaxin. To understand the biological role of relaxin, it is necessary to determine the distribution pattern of both relaxin and its related receptors. Therefore, we performed a preliminary immunohistochemical analysis of relaxin and the receptors in salivary gland tumors comprising pleomorphic adenomas, Warthin tumors, adenoid cystic carcinomas, mucoepidermoid carcinomas and submandibular gland tissues.
The immunohistochemical findings showed positive immunoreactivity for relaxin-2 in the ductal, myoepithelial and/or basaloid cells in pleomorphic adenomas, Warthin tumors, adenoid cystic carcinomas, mucoepidermoid carcinomas, and in duct, myoepithelial and serous acinar cells in the submandibular glands.
These results suggest that localization and binding of relaxin-2 and receptors such as LGR7 and LGR8 are associated with ductal and tubular growth of the tumors, as well as the maintenance of duct formation, in salivary gland tumors and submandibular gland tissues.

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Among the genus Rothia, Rothia dentocariosa and Rothia mucilaginosa are found in oral cavity and pharynx of humans. Furthermore, there is only one report that Rothia aeria,which is capable of causing serious systemic infections, has been also detected in the mouths of healthy individuals. A suitable selective medium for the isolation of R. aeria is necessary to assess the veritable prevalence of this organism in the oral cavity. To examine the bacterium population in the oralcavity, a novelselective medium, designated RASM,was developed for the isolation of R. aeria. RASM consists of sodium gluconate, tryptone,lablemco powder and aztreonam. Average growth recovery of R. aeria on RASM was 96.1％ compared with that on BHI-Y agar. Growth of other representative oral bacteria including R. dentocariosa, R. mucilaginosa, genera Actinomyces, Neisseria, and Corynebacterium were remarkably inhibited on the selective medium. Though the inhibitions of certain strains of streptococci were not complete, they formed small or pin colony on RASM and could be distinguished from R. aeria colony. Clinical efficacy was evaluated by the recovery of R. aeria on RASM from the stimulated saliva samples of ten volunteers. R. aeria was detected at 3.1（range: 0.5-14.4)％ to totalbacteria of 7.0×10⁷ CFU/ml on BHI-Y agar in their oral cavities. The new selective medium, RASM, was usefulfor the isolation of R. aeria. Moreover, we examined the antibiotic susceptibility of twenty isolates from four subjects. The bacterium was susceptible to most antibiotics;however R. aeria isolates from one subject were highly resistant to erythromycin, lincomycin, and clindamycin.

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We previously reported a primer design for the identification of oral Rothia dentocariosa and Rothia mucilaginosa, using multiplex polymerase chain reaction（PCR）. There is only one report of Rothia aeria, which is capable of causing serious systemic infections, being detected in the mouths of healthy individuals. Thus, if R. aeria is part of the normal flora in the oral cavity, a suitable identification method is necessary to assess the veritable prevalence of Rothia species, including R. aeria, in the oral cavity.
In this study, five PCR primers were designed based on partial sequences of the 16S rDNA genes of the above-mentioned known oral rothia and R. aeria. These primers react to R. dentocariosa, R. mucilaginosa and R. aeria, respectively, and did not react to other nonoral rothia. Moreover, representative non-Rothia oral bacteria displayed negative reactions to these primers. These results indicate that these primers are useful for identifying R. dentocariosa, R. mucilaginosa and R. aeria. We also developed a simple multiplex PCR procedure using the five PCR primers designed in the present study as a rapid and reliable method of identifying known oral rothia and R. aeria.

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Fermented foods are widely accepted health products and are considered to be important components of the daily diet. The health-promoting effects of fermented foods may be attributed to both the beneficial effects of probiotics and the immunostimulatory functions of food components. In this study, we evaluated the immunostimulatory effects of fermented foods. Mice were orally administered fermented soybeans（natto）or yogurt twice a day for 7 consecutive days. One day after the last oral administration, mononuclear cells were isolated from the spleen and Peyerʼs patches（PP）, and were analyzed by flow cytometry to elucidate the frequency of natural killer（NK）cells. The results showed increased frequencies of NK cells in PP, but not spleen, of mice given natto or yogurt, as compared with mice given phosphate-buffered saline. These results suggest that ingestion of fermented foods, e.g., natto and yogurt, may stimulate innate immunity in the intestinal immune system.

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High molecular weight compounds have been widely used in the field of dentistry. Although preparation of the tooth abutment and contamination by metal fragments are known to cause discoloration and injury in the periodontal tissues in the field of crown and bridge prosthodontics, the changes due to metal and composite resin fragments have not been fully comparatively studied and clarified to date.
In addition, as patients with diabetes are more frequently encountered in dental clinics, the present study conducted histopathological, histochemical and immunohistochemical analyses in order to comparatively elucidate the changes in periodontal tissues after injection of metal（silver group）or composite resin fragments（resin group）. The histopathological reactions of the periodontal tissues in both healthy（m+/m+）and diabetic（db/db）mice were also compared at 28 days after injection.
Histopathologically and immunohistochemically, inflammatory cell infiltration and CD68- and MMP-2-positive macrophages were observed around the silver and resin fragments,and the fragments were decreased during fibrosis up to 28 days; these findings were more marked in the resin group than in the silver group. In addition, accumulation of the macrophages and subsequent fibrosis showed a delay in db/db. Furthermore, the number of mast cells was higher degree in the resin group than in the silver group, and was higher in db/db than in m+/m+, indicating that resin induces an allergic reaction in db/db.
These results suggest that resin fragments are more readily excised than silver fragments due to the higher level of phagocytosis and antigen-presenting activity of macrophages. Furthermore, critical changes against precipitation were delayed in db/db as compared to m+m+.

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The purpose of this study was to investigate the influence oftaper angle on the dynamic behavior of the taper joint in a dental implant system under two different loading conditions using transient dynamic finite element analysis（FEA）. The taper joint dental implant model was prepared with seven different taper angles. The analysis was performed using three-dimensional FEA. To simulate an in vitro pull-out test, compressive loading was first applied to the dental implant systems as a preload, corresponding to the installation load. In addition, two types of pull-out load were applied: vertical tensile loading and rotational tensile loading. During the preload, in all taper angles, the movement oftooth direction increased with increasing preload force. And the movement decreased with increasing taper angles of abutment. On applying a pull-out load after preload, the resistances for both vertical and rotational tensile loads also decreased with increasing taper angle. For all taper angles, the movement increased with increasing load. This indicates that the connection force between the abutment and the implant decreases with increasing taper angle. Within the limits ofthe study, the relationship between the taper angle and the dynamic behavior of a taper joint abutment under two different pull-out loadings was clarified using transient dynamic FEA. Our results suggest that the taper angle significantly affects the dynamic behavior ofthe abutment in a taper joint implant. Therefore, dentists should take into consideration the characteristics ofthe taper angle when selecting the taper joint implant systems.

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Eating sweets and chewing gum are often said to lead to tooth decay. This study investigated whether gum is a cause of caries by measuring the pH of the reflex （stimulated）saliva secreted in large amounts as a result of chewing various commercially available brands of gum that are marketed as being good for teeth. Four brands of gum were used: Green Gum, which contains sugar, and Xylitol, Poscam, and Recaldent, which are sugar-fee. The control was a gum base. Experimental subjects were seven adult men and women. The pH of saliva rose at the start of gum chewing, but had largely returned to pre-chewing levels within 5min. Subsequently, with sugar-containing gum, pH decreased gradually until 40min, after which it showed a recovery trend. With the other types of gum,there was almost no change in pH after 5min.

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The head and neck region is one of the most common sites for malignant lymphoma;however, pediatric oral lymphoma is very rare. We discovered a case of a malignant lymphoma that developed in the right mandibular molar region of a child and we are now reporting the summary. A 3 and a half year old boy came in to the Nihon University Hospital in Matsudo with a chief complaint of swelling of the right mandibular gingiva. The biopsy results revealed a malignant lymphoma by an H-E stain. Afterwards, we informed the parents of the necessity of systemic treatment and referred them to a comprehensive medical care center.

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