Morphologicalvariations of the root canalsystem of C-shaped roots in mandibular second molars of young Japanese patients (aged 20 to 29 years old) were analyzed by using multidetector row computed tomography (MDCT) in order to clarify the entire picture from the orifice to the apex. CT images were reconstructed so that the axialimage was inclined perpendicular to the long axis of teeth. C-shaped roots were more frequently found in females (54.0%) than in males (36.7%) (p<0.01). One root canal was most frequently found on the coronalside, and the root canalnumbers increased to the apex. Thus, in many cases at the coronallevelthe canalformed letter “C”, but it ramified into increasingly smaller canals towards the apex. The complex configuration of the root canals may be related to various degree of fusion in the roots. The results of this study might be used for understanding the nature of C-shaped root canals.

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Dental implant is an effective treatment modality to restore esthetic loss and masticatory dysfunctions. However, at least three to six months healing period following implant surgery is necessary. This healing period is burden for the patients, especially with a broad edentulous area and may decrease their quality of life. Therefore, shortening the healing period and accelerating prosthetic rehabilitation is clinically important. We speculate periimplant bone may be improved by systematic approaches such as use of osteoporosis supplement promoting bone metabolism. As a preliminary step, an animal pilot study was conducted to confirm whether intake of the synthetic bone mineral (SBM) is effective in bone formation.
To confirm whether intake of a supplement developed for osteoporosis, SBM, is effective in bone formation.
Twelve female Wister rats, 20-week-old were randomly assigned to receive a　 standardized diet with SBM (n=6) or without SBM (n=6, control).
After 8 weeks, right and left femur were extracted form the rat under CO₂ inhalation and bone mineral density (BMD) and bone flexure strength were determined. Between group differences in bone mechanical strength and BMD at 28 weeks old were analyzed by Mann‒Whitney Utest.
BMD was significantly higher for the Diet with SBM group at compared to the Diet without SBM group (P<0.05). Pull-out strength was also significantly increased than the Diet without SBM group (P<0.05).
Within the imitations, this study indicates that SBM could be effective in bone formation.

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We elucidated the effects of orexin-A in dorsal root ganglion (DRG) neurons. Immunohistochemical staining was performed to compare changes in N-methyl-daspartate receptors (NMDARs) and orexin-A in the DRG between the carrageenaninduced neuropathic pain rat model (CA) and non-algetic rats (Control). We also evaluated the inhibitory effects of orexin-A by measuring [Ca²⁺] i. Using immunohistochemistry, orexin-A expression was observed in both the posterior and anterior horns of the spinal cord. No major difference was observed between the groups. Using immunohistochemistry, orexin-A expression was also observed in neurons in the DRG, and no major difference was observed between the groups. NMDAR expression levels in the posterior horn of the spinal cord and the DRG were not quantitatively determined, but the overall staining intensity of NMDAR was higher in CA than in control rats. Also, in the DRG neurons of the CA rats, administration of orexin-A significantly suppressed the increase in [Ca²⁺] i due to depolarization stimulation caused by high K⁺. Thus, the anti-nociceptive effect was due to an increase in orexin-A. Furthermore, orexin-A may have specifically acted on L-type calcium channels.

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　Lactobacillus crispatus KT-11, which was originally isolated from the feces of healthy infants, has been reported to show multiple immunoregulatory effects. However, there have been no reports about the effect of the Lactobacillus　 on periodontal disease, a chronic destructive inflammatory disease of the tissues supporting the teeth. We used a model of periodontal disease in which mice were infected with Porphyromonas gingivalis.　As　we report here, oral　 ingestion of KT-11 exerted inhibitory effects on alveolar bone resorption in this model, suggesting potential preventive activity of the Lactobacillus in periodontal disease.
　Mice were given free access to feed containing dead Lb. crispatus KT-11 over 6 weeks, and were then orally infected with P. gingivalis 10 times for 2 weeks from 4 weeks later of Lb. crispatus KT-11 administration. The results showed a marked attenuation of alveolar bone resorption in mice that ingested the Lb. crispatus KT-11-containing feed. Induction of total IgG in plasma and total secretory IgA in saliva was observed. A specific plasma IgG antibody response to P. gingivalis also was induced.
　Based on the immune response to P. gingivalis infection induced by ingestion of Lb. crispatus KT-11, this study suggests that oral administration of Lb. crispatus KT-11 is effective in preventing chronic periodontitis.

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　Ameloblastoma is a slow-developing benign odontogenic tumor, but it has relatively large number of local recurrence. Ameloblastoma was classified on the basis of the morphology that predominates in the tumor itself into plexiform type, follicular type, and other subtypes, and there have been comparative histological and clinical studies that include prognosis predictions for the different types. However, there are no conclusions regarding histological patterns and tumor activities have been reached.
　The purpose of the present study was to perform a detailed investigation of the progressive front of solid/multicystic type ameloblastoma in order to search for possible prognostic factors.
　For this study, 22 cases were chosen, in whom solid/multicystic type of a ameloblastoma. Progressive fronts of the solid/multicystic type ameloblastoma were morphologically classified into six types; plexiform, follicular, basaloid cell, sheet, trabecular and polycystic types, and immunohistochemical and morphometrical comparative studies were performed.
　Proliferative activity of columnar cells was highest in basaloid cell type at 1.9%. Periostin showed moderate to strong positive reaction in columnar cells of plexiform and basaloid cell types. Columnar and stellate-reticulum-like cells of basaloid cell type showed strong positive reaction for VEGF. The highest microvessel density and microvessel area using CD105 in basaloid cell type were 48.2±24.2 and 11.4±8.6%, respectively.
　The result of this study suggested with resection of solid/multicystic type ameloblastoma, it is important the prognosis observation to base judgment on the morphology of cells in the progressive front or in the vicinity of the resected surface.

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　In this study, we first investigated the expression of wnt5a in tension sites during experimental tooth movement in rats in vivo. We then assessed the effects of wnt5a on the expression of　bone marker from human periodontal ligament (hPDL) cells.
　Twelve male 6-week old Wistar rats were subjected to an orthodontic force of 10g in order to induce the mesial tipping movement of the upper first molars for 7 days. The expression levels of wnt5a proteins in the alveolar bone were determined using an immunohistochemical analysis. Furthermore, the effects of wnt5a on the gene expressions of alkaline phosphatase (ALP) and type I collagen (COL1) were investigated using hPDL cells in vitro.
　Under the conditions ofexperimental tooth movement in vivo, the immunoreactivity for wnt5a was detected in the tension side on day 7 in the PDL tissue ofrats subjected to the orthodontic force (10g). In the in vitro study, wnt5a treatment increased the gene expression ofALP and COL1 from the hPDL cells in a time-dependent manner.
　These results suggest that the wnt5a stimulates the alveolar bone formation in the tension side during orthodontic tooth movement.

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We report a case of impacted tooth in the maxillary sinus. The frequency of ectopic impacted tooth is higher with permanent teeth than with deciduous teeth, and the mandibular third molars are the most commonly impacted teeth. The most common site of ectopic impacted teeth is the maxillary canine area, followed by the mandibular molar area and ramus. However, impaction in the nose or maxillary sinus has rarely been reported. We encountered a patient with an impacted tooth located in the maxillary sinus. This case was coincidentally found on panoramic radiography and computed tomography (CT) for assessment of the alveolar bone with dental implantation. CT showed a marginal highabsorption area with clear and smooth boundaries of the longaxis 18 mm in size, located in the floor of the left maxillary sinus. We confirmed the tooth as the second premolar impacted in the maxillary sinus from imaging findings of panoramic radiography and CT.

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