Teeth have been extensively used as a source of information in human identification, especially when the soft tissue cannot provide reliable information. Dental enamel is the most mineralized tissue, and resists post-mortem changes. The enhanced probability of personal identification from histological stress markers is said to be due to the pattern being specific to an individual. The timing of birth preserved in enamel, termed the neonatal line is a predictable consequence of the birth process and occupies a characteristic position and can be used in the assessment of pathological striae and has medico-legal implications. Though Amino acid racemization in dentin is extensively studied, enamel also offers certain advantages. Enamel can be used for sex determination based on AMEL gene using molecular biology. These highlight the importance and potential of enamel in forensic dental identification.

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The present study demonstrated collagen nanofiber deposition onto titanium and partially stabilized zirconia, yttria-stabilized zirconia (Y-TZP), using an electrospray deposition (ESD) technique. Type I collagen was dissolved into 1,1,1,2,2,2-hexafluoro-2-propanol at different concentrations. The effects of the flow rate of the collagen solution and the applied voltage on collagen nanofiber deposition were investigated. For titanium substrates, a collagen concentration of 50 mg/ml, a flow rate of 5.0 μl/min, and an applied voltage of 16 kV were found to be suitable for the deposition of uniform collagen nanofibers. Collagen nanofibers could be sprayed onto Y-TZP, which is not an electrically conductive substrate, although nanofibers fused during ESD. To avoid the fusion of nanofibers, titanium sputter-coating was performed on Y-TZP. Less fusion of collagen fibers occurred. A collagen concentration of 50 mg/ml, a flow rate of 5.0 μl/min, and an applied voltage of 25 kV were found to be appropriate for the deposition of uniform collagen nanofibers onto titanium sputter-coated Y-TZP. The ESD technique was shown to be effective for the deposition of collagen nanofibers.

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Using Waldo's method in mice, we examined the immunohistochemical expression of Runx2 and alkaline phosphatase (ALP) appearing in dental pulp cells, especially in odontoblasts, just after receiving experimental orthodontic mechanical stress, using Waldo's method in mice. The examination results demonstrated that some dental root pulp cells, especially some odontoblasts, expressed the Runx2 and ALP in a comparatively short time after receiving the stress. The results suggest that the stress may cause odontoblast activity up-regulation.

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The purpose of the current research is to elucidate of gene expression of the tooth germ. Fresh permanent incisor and molar teeth germs were extracted from mandibles of 6-month-old pig. Extracted human premolars for orthodontic reasons were used as sample of the completed tooth root. Apical and central samples were prepared from pulp tissue. mRNA expression by RT-PCR and protein expression of BMP in the pulp tissue were detected. DMP1, BMP2 expressions were similar in all samples. OP expression was weaker in centrum of the molar tooth as compared to the other parts. OC was not expressed. BMP4 expression was strong at the incisor apical part, though it was not expressed at the molar central area. BMP5 was weakly expressed at the incisor central and molar apical areas. Though BMP7 expression was remarkably detected at the incisor and molar apexes, its expression was almost absent at the central area. Moreover for examining the specific expression of BMP7 at the apex, central superficial layer corresponding to the neck of the incisor and molar teeth was prepared. The result was that BMP7 was strongly expressed at the apex than in the central superficial layer and only a little expression was detected at central superficial layer of the incisor and molar tooth. In the current research, expressions of OP, DMP, BMP 2, 4, 5, 7 were seen in the tooth germ tissue. Thus the results suggested that expression of these genes played a central role in differentiation of the pulp. BMP7 was also suggested to have a specific role in apex formation (differentiation).

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Beta-tricalcium phosphate (β-TCP) has been used for bone regeneration in a variety of surgical procedures including dental implant therapy with satisfactory clinical results. However, very little is known about the molecular basis mechanisms enhancing the bone formation by β-TCP. To understand the molecular basis mechanism of β-TCP in bone formation, β-TCP was implanted into bone defects of mandible bones in beagle dogs. After 4, 7 and 14 days, bone tissues during the healing process were recovered and gene expression profiles were examined using an Affymetrix GeneChip system. A significantly higher high-temperature requirement protein A1 (HtrA1) mRNA level was found in the 4-day samples after β-TCP implantation compared with the controls. The elevated HtrA1 gene expressions in β-TCP-implanted bone tissues were confirmed by RT-PCR and real-time PCR. Because HtrA1 is known as a key regulator of physiological and pathological matrix mineralization, the enhancement of HtrA1 gene expression in β-TCP-implanted mandible bone might be one of the molecular mechanisms for stimulating bone formation.

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Metastases to distant organs are well known to be factors influencing prognosis in patients with oral cancer. Therefore, it is very important to detect the metastasis of cancer as early as possible and to investigate the factors associated with the mechanism of metastasis. This study evaluated the risk of distant metastasis by the degree of histological malignancy among 59 patients with oral squamous cell carcinoma (SCC) who were treated at our department during the past five years. The degree of histological malignancy of initial biopsy specimens was evaluated by Anneroth's classification and its relationship with metastasis was analyzed. Distant metastasis occurred in 7 of 59 patients (11.9%) and was located predominantly in the lung and bone. There was a significant correlation between the degree of histological malignancy and distant metastasis (P<0.05); however, there was no significant difference between T classification and metastasis in the distant organs. It is considered that histological malignancy is useful for predicting the prognosis and deciding additional treatments for oral SCC. When a total score on histological malignancy grading exceeds 14, metastasis in the distant organs should be carefully considered.

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Objectives: As an alternative to autograft harvesting, we develop a functionally graded hydroxyapatite (fg-HAp) to induce bone regeneration within extensive bone defects. The functionally graded crystallinity from the inside layer to the surface layer of the fg-HAp promotes bone remodeling and replacement. We evaluate the effects of fg-HAp alone and in combination with fibroblast growth factor (bFGF) on bone regeneration within a bone defect in a rabbit mandible.
Methods: The bone defect in the rabbit mandible was 12 x 9 x 3.5 mm in size. For the control group, no material was added to the defect. The experimental groups consisted of fg-HAp alone and fg-HAp combined with 5μg of bFGF. At 2, 4 and 8 weeks after implantation, we excised the mandibles and performed histomorphometrical analysis.
Results: The fg-HAp resorption and replacement with new bone occurred fastest at the lingual portion of the defect. The fg-HAp maintained the mandibular outline and was absorbed by multinucleated giant cells. Blood vessel infiltration into the framework of fg-HAp was also observed. Adding 5μg of bFGF did not accelerate bone regeneration. The fg-HAp fragment was observed at the buccal portion of the defect. Excavated bone healing was observed only in the control group.
Conclusions: The fg-HAp is an effective substrate for bone regeneration in critically sized bone defects.

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In the present study, we investigated the effects of a Kampo medicine hangeshashinto (TJ-14) on the production of prostaglandin E₂ (PGE₂), interleukin (IL)-6 and IL-8 by human gingival fibroblasts (HGFs) treated with lipopolysaccharide (LPS) from Porphyromonas gingivalis. HGFs proliferation was dose-dependently decreased with hangeshashinto at days 3 and 7. However, treatment with LPS (10 ng/ml), hangeshashinto (up to 1 mg/ml) and their combinations for 24 h did not affect the viability of HGFs. Hangeshashinto dose-dependently suppressed LPS-induced PGE₂ production but did not alter basal PGE₂ level. Hangeshashinto weakly decreased LPS-induced IL-6 and IL-8 productions. Hangeshashinto decreased cyclooxygenase (COX)-1 and COX-2 activities to approximately 60% at 1 mg/ml. Hangeshashinto decreased cytoplasmic phospholipase A₂ (cPLA₂) expression and LPS-induced COX-2 expression but not affected annexin1 expression. Hangeshashinto weakly suppressed LPS-induced extracellular signal-regulated kinase (ERK) phosphorylation, which is known to lead to ERK activation and cPLA₂ phosphorylation. These results suggest that hangeshashinto decreased PGE₂ production by (1) suppression of cPLA₂ and LPS-induced COX-2 expression, and to a lesser extent, (2) inhibition of COX-2 activity and (3) inhibition of cPLA₂ phosphorylation and its activation via inhibition of ERK phosphorylation. Moreover, it is also suggested that hangeshashinto may be useful to improve gingival inflammation in periodontal disease.

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It is very important to measure the enamel width of human teeth to decide the arch length discrepancy. The purpose of this research was to know the actual enamel width in extracted human teeth by a video microscope and to measure it in Soft-radiograph negative films to help our clinical consideration about relationship between actual enamel size and that in dental X-ray film. We used approximately 400 extracted teeth to measure the width by video microscope and Soft-radiograph negative films. Mean value of the teeth were of enamel from 0.78mm to 1.31mm according with the size of teeth. On the other hand, the Soft-radiograph films were 0.67mm to 1.32 mm. Moreover, we could get good correlation between the actual sizes and the Soft-radiograph films. In conclusion,we might clinically apply these data to supervise the enamel width from X-ray films, reducing orthodontic premolar extraction.

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Focal pigmented melanocytic lesions rarely occur in the oral cavity but should not be taken for granted for they may represent markers or risks for oral mucosal melanoma (OMM). The study investigated the clinical and pathological features of focal pigmented lesions of melanocytic origin focusing on oral melanotic macule (oral MM), oral pigmented nevus (OPN) and OMM. Immunohistochemistry was employed with S100, HMB-45, Melan A, c-kit and Ki-67. Oral MM mostly occurred on the gingiva and buccal mucosa while OPN mostly occurred on the buccal mucosa. OMM occurred on the palate and gingiva. A female gender predilection was observed in oral MM. Most of the benign lesions were less than 6 mm in diameter while OMM had greater than 10 mm in diameter. Benign lesions occurred in almost the same location as that of OMM. S100 and c-kit were detected in most benign cases while HMB-45 and Melan A were focally detected in some cases. S100, HMB-45 and Melan A expressions were detected in all cases of OMM. Ki-67 was only detected at the epithelial basal layer in oral MM and was completely negative in nevus cells. In OMM, Ki-67 was more than 80%. In conclusion, oral MM and OPN may not be markers of risk for OMM but excisional biopsy is highly recommended for clinically undefined lesions greater than 6 mm in diameter. The combination of S100, c-kit, HMB-45 and Melan A can be utilized to support the diagnosis of OMM.

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We previously demonstrated that parathyroid hormone (PTH) induced interleukin-6 (IL-6) expression in osteoblasts primarily via the cAMP-PKA signaling pathway. In this study, we explored the molecular mechanism(s) underlying this action. We used a fragment of the human IL-6 proximal promoter containing two previously identified, juxtaposed CRE and C/EBP sites at -165/-158 bp (CRE₁₆₅) and -157/-148 bp (C/EBP₁₅₇) to drive the expression of a luciferase reporter (IL6-Luc225). Osteoblastic MC3T3-E1 cells were stably and transiently transfected with IL6-Luc225 constructs carrying mutations or deletions of the CRE and C/EBP sites. We demonstrated that agonists that stimulated the cAMP-PKA pathway, also induced IL6-Luc225 activity. The proximal CRE sequence (CRE₁₆₅) was important in mediating cAMP induction of IL-6 promoter activity, whereas the C/EBP₁₅₇ did not play a role in this. We also identified a distal CRE-like site (CRE₂₀₉) that may involve in mediating cAMP-PKA induction of IL-6 promoter activity. Electrophoretic mobility shift assays showed the formation of DNA/protein complexes on the proximal CRE/C/EBP site. We used antibody supershift assays to show the presence of CREM/CREB, phosporylated CREB, C/EBPβ, and C/EBPδ” in the complexes. Our data suggest that PTH-mediated induction of IL-6 promoter activity is regulated primarily by the cAMP-PKA pathway and CRE₁₆₅ may play a key role in mediating this response.

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