Osteocytes are considered to be a candidate for key cells regulating bone metabolism, which consists of bone formation by osteoblasts and bone resorption by osteoclasts; however, the role of the osteocyte remains unclear. Osteocytes are released from the osteocytic lacunae when osteoclasts resorb the bone matrix during bone metabolism, bone modeling and remodeling; and a variety of proposals for the fate of the released osteocytes have been made. This variety suggests that osteoclasts can react differently to individual osteocytes during bone resorption and that this difference may provide a clue as to the role of osteocytes in the regulation of bone metabolism. So we recently conducted a precise investigation of the reaction of osteoclasts to osteocytes when these cell types encounter one another during bone resorption in the course of bone modeling, including the fate of the released osteocytes. Morphological observations made by LM and TEM revealed that osteoclasts engulfed some osteocytes but did not engulf others when releasing osteocytes from the osteocytic lacunae during bone modeling and suggested that the 3-dimensional relationship between osteocytes and osteoclasts when they encounter each other might be a key to decide the reaction of osteoclasts to osteocytes. This article reviews the reaction between osteoclasts and osteocytes when they encounter each other at the bone resorption surface during bone modeling based on our present study and previously published studies.

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ING1 gene, the founding member of the ING tumor suppressor family, was originally identified through subtractive hybridization between normal mammary epithelial cells and breast cancer cell lines, and subsequent in vivo selection of genetic suppressor element that displayed oncogenic features. The four additional members of the ING family (ING2-5) were recently identified and all the gene products contain a highly conserved plant homeodomain (PHD) finger motif in the carboxy (C)-terminal end. Although exact functions of ING family genes have not been clarified, the gene products are involved in transcriptional regulation, apoptosis, cell cyle, angiogenesis and DNA repair through p53-dependent and -independent pathways and constituting complexes with histone acetyltransferases (HAT) and histone deacetylases (HDAC). This review summarizes the known biological functions of the ING tumor suppressors and signaling pathways that they involve.

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The trigeminal somatic stimulation has been reported to evoke a parasympathetic reflex vasodilatation in the various orofacial areas such as lip, tongue, salivary glands (submandibular and parotid glands) and palate. The vasodilatations in the lip, tongue, and salivary glands occurred predominantly in the ipsilateral side to the stimulation, however, the vasodilatation in the palate was observed in the both (ipsilateral and contralateral) sides. This review is to describe the possible neural network within the brain stem A) of the ipsilateral parasympathetic reflex vasodilatation in the lower lip, and B) of the contralateral reflex vasodilatation in the palate when the central cut end of the lingual nerve was electrically stimulated for the trigeminal somatic stimulation.

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The transcriptional factors nuclear factor-κB (NF-κB) and signal transducer and activator of transcription-1 (STAT1) play crucial roles in the initiation and development of innate and acquired immunity by inducing transcription of many genes that are essential for host defense mechanisms. Although NF-κB and STAT1 are activated by distinct extracellular stimuli, such as tumor necrosis factor and interferon gamma, respectively, these transcription factors often interact to regulate the expression of inflammatory genes at the transcriptional level. The cross-talk between NF-κB and STAT1 is orchestrated by transcriptional coactivator CREB binding protein (CBP) and p300, which integrate distinct extracellular signals in the nucleus for gene expression in the context of control of immune responses. This review focuses on the cross-talk between NF-κB and STAT1 in the regulation of inflammatory gene expression and the mechanisms involved in the regulation of transcriptional synergy between NF-κB and STAT1.

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A previous report has revealed that dental caries is an infectious disease caused by a localized infection with specific oral streptococci. Dental-caries-associated oral streptococci are called the mutans streptococci (MS), with Streptococcus mutans and Streptococcus sobrinus being the most prevalent caries-associated organisms in humans. When searching for a control method against caries, effective measures are required at each of the following three phases of infectious disease: (1) eliminating the source of contagion, (2) blocking the infection route, and (3) lowering host susceptibility. In order to eliminate the source of contagion, we conducted a follow-up clinical test using a passive immunization method in which teeth were coated with anti-S. mutans specific antibodies. A subsidiary finding was made during the course of the test, in that physicochemical control methods were more effective than specific antibodies. Based on this finding, we have adopted a new caries-control method designated as the dental drug delivery system (3DS), and we have released an associated clinical manual (3DS unit).
In order to effectively eliminate MS from the oral cavity, however, we need to inhibit its initial adhesion as well as eliminating the source of contagion. Antibodies may be effective in the prevention of recolonization of MS.

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The representation of the oral structures in the postcentral somatosensory cortex (areas 3b, 1 and 2) was studied in conscious Japanese monkeys (Macaca fuscata) by recording single neuronal activity. Neuronal receptive fields (RFs) were examined by manually applying simple tactile stimuli such as light touching or pressing, and moving tactile stimuli. A large body of data was collected from eight hemispheres of six male animals. A total of 3,435 neurons responded to tactile stimuli. Most of them (96%, 3,297/3,435) responded to simple tactile stimuli (simple tactile neurons), whereas the rest (4%, 138/3,435) responded exclusively to moving tactile stimuli (movement-specific neurons). The relative incidences of movement-specific neurons among the total sample were 1.2% in area 3b and increased gradually with statistical significance upon moving caudally toward area 1 (4.4%) and area 2 (7.2%). Ninety percent of the neurons had ordinary uninterrupted RFs (continuous RFs) and the remaining 10% had RFs composed of several discrete RF-portions, e. g., the tongue dorsum and palate (discontinuous RFs). The relative incidences of neurons with discontinuous RFs in area 3b or 2 were significantly higher in movement-specific neurons than in simple tactile neurons. This suggests that the spatiotemporal integration to represent motion proceeds across the postcentral oral region and tends to be accompanied by the convergence of inputs from discrete but functionally related oral portions.

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Previously, bio-mechanical studies on the temporomandibular joint have concentrated mainly on the mandibular condyle while the articular eminence has been largely overlooked. Furthermore, research on the mechanical properties of bone using finite element analysis has focused on cortical bone in preference to cancellous bone. In this study, morphological changes in the internal structure of the articular eminence, as related to child growth, were examined using micro-computerized tomography (Micro-CT). Morphometric analysis of cancellous bone, representing both deciduous and early mixed dentitions, showed an increase in the bone volume fraction and trabecular thickness in the early mixed dentition. Finite element analysis indicated a directional transmission of stress. These results suggest that the morphology of the trabecular bone alters to adapt to the functional growth change from deciduous to early mixed dentition.

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The presence or absence of 17 non-metric tooth crown traits was examined to investigate the intra- and interregional variation of five tribes in Myanmar (Burma). In this study, we elucidated dental traits at five other sites in Myanmar: Kalaw and Peinnebin located in the central Part of Myanmar, Tiddim located near India, Thandwe facing the Bay of Bengal and Myitkyina located near China. The Shans, the Chins, the Rakhines, the Palaungs, and the Kachins were identified from plaster models by using the Arizona State University Dental Anthropology System. The incidences of the five tribes were compared with other Mongoloid populations in various regions. According to multidimensional scaling based on Smith’s Mean Measures of Divergence, all five tribes in Myanmar belong to Sundadonty. The prehistoric Burmars had more Sundadont elements than contemporary Myanmar populations. Myanmar was established by waves of human migration from neighboring regions. The biological divergence in the five tribes was not found to be associated with geographical distances and did not correlate with the traditional linguistic classification. Myanmar populations should be categorized taking into consideration a genetic influence from China as well as the theory of local evolution.

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The immunological responses induced by Porphyromonas gingivalis (Pg) and Fusobacterium nucleatum (Fn) in mice were compared. SPF ICR immune mice were obtained by 3 injections with either Pg or Fn. Two weeks later each bacteria was administered to immunized mice and mice were assayed for cell numbers in exudates, antibody titer, cytokine production, expression of cytokine receptors, and the elimination of the bacteria. The total cell numbers in Fn immunized, then Fn challenged, mice were 1.6 times that of mice challenged with Pg. High IgG antibody titers were detected in Pg immunized mice and IgM antibody predominated in Fn immunized mice.
TNFα production was higher in the abdomen of Pg immunized mice than in serum. IL-1β levels were the same in both Fn and Pg challenged mice. IFNγ production was significantly higher in Fn than Pg-immunized mice. Expression of CXCR-1 and CXCR-3 mRNA was significantly higher in Fn than Pg-immunized mice. The elimination effect of the bacteria in the abdominal cavity was remarkable after Fn but not in Pg immunization. Fn immunized mice were more effective in eliminating Pg in the abdomen, suggesting the macrophage activation via Th1 may play a part in protection from periodontitis.

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A palatoplasty via the push-back method is applied for the patients with cleft palate. Disturbances such as impaired growth of maxilla, narrowing of the maxillary dental arch, malalignment, and lingual slanting of teeth occasionally occur as poor prognosis of this surgical method. The etiology of these complications has not been fully elucidated. In this research, mucoperiosteal scraping was experimentally performed at the palate, and the influence of the surgery on the early reparative processes of the palate was explored for 2 weeks postoperatively, both with histopathological and multiple fluorescence labeling approaches. The findings acquired were as follows:
1. At three days after surgery, inflammatory infiltrates and bone resorption were observed at the surface and medial side of the molar alveolar bone. A calcein (CA) labeling line produced by fluorescent pigments immediately before surgery disappeared at the medial area of the palate around the molars, while an alizarin red S (AR) line formed by the third postoperative day, and was generally thin and irregular, unlike those of the control.
2. At 1 week after surgery, the analysis of the CA line disclosed that bone resorption progressed at the medial area of the palatal bone around the molars, and subsequently the height of the palate was lowered. In these areas, sequester-like free bone fragments that showed both fluorescent CA and AR lines existed in the palatal mucosa and inflammatory granulation tissue formed around the bone fragments.
3. Free bone fragments (sequesters) were observed in the palatal mucosa at 2 weeks as well as 1 week after surgery. The height of the palatal bone lowered at the molar areas by progressive bone resorption, having a slightly concave appearance.
4. In combination with analyses of fluorescent CA and AR lines, free bone fragments were formed at both 1 week and 2 weeks after surgery, and the height of palatal bone was subsequently lowered. It is conceivable that these changes could be a plausible cause of the impaired growth of maxilla, the narrowing of maxillary dental arch, malalignment and lingual slanting of teeth after surgery.

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