This study investigated biomechanical aspects of the action of the biting force during mastication upon the mandibular bone in the lower first molar area. A three-dimensional (3D) finite element model (FEM) consisting of the tooth, periodontal ligament (PDL), alveolar bone, and cortical bone corresponding to the lower first molar area based on computed tomogram (CT) images was constructed. The model was then analyzed while applying a biting force during mastication, which was transmitted from the tooth to the cortical bone, through the PDL and cancellous bone. A compressive stress of 0.3-7.9 MPa acted on the cortical bone during mastication. In the model, the stress in the cortical bone was distributed from the linguo-superior margin to the basal area, and was also observed in the bucco-medial area. These areas completely agreed with the areas that were significantly thicker in the morphological study described by Masumoto et al. (10). It is suggested that there may be a relationship between masticatory force and cortical bone hypertrophy. Further study of the effects of various factors is required.
Ipriflavone (7-isopropoxyisoflavone, IP), a drug used in the treatment of osteoporosis, may promote bone formation during bone remodeling. IP has been shown to accelerate both the activity of, and formation of mineralized nodules by a human osteosarcoma cell line at an early stage. However, the direct effects of IP on bone augmentation have not been investigated. The purpose of this study was to determine whether IP induces bone augmentation within a titanium cap in rabbit calvaria at an early stage. Five adult male Japanese white rabbits were used. One cap (test site) was packed with IP in a collagen gel, and the other (control site) was packed with the collagen gel alone. After the one- and three- month healing periods, we measured the newly generated tissue and bone within the titanium caps. The amount of newly generated tissue within the titanium caps of the control sites was higher than the tests sites after one month and three months. However, the percentage of newly generated bone/bone marrow in the newly generated tissue at the test sites was higher than for the control sites after one month and three months. These results suggest that IP affects the quality of bone augmentation at an early stage.
It has been generally recognized that the radiological appearances of cysts and tumors related to an embedded tooth are similar. However, based on their clinical experience, Abrams et al. pointed out that there was a difference between the two lesions at the attachment point to the embedded tooth. To investigate this difference, we conducted a study employing the radiographs of patients who visited Nihon University Dental Hospital at Matsudo and were pathologically defined as having a cyst or tumor. Using radiographs of these patients, we investigated the attachment point to the embedded tooth, and expressed the results as the proportion of the attachment point to the embedded tooth root length. The study was carried out in 100 patients with cysts (87 dentigerous cysts and 13 odontogenic keratocysts), and 27 patients with benign tumors (24 ameloblastomas and three adenomatoid odontogenic tumors). Prior to treatment based on the numerical results, the distribution of the results was examined. Thus, we evaluated several methods of examining the distributions, and found the best method to be discriminant analysis. The results showed that the discriminated boundary value (from the cemento-enamel junction) was 0.38 for the embedded tooth root length. The cases showing a boundary value of less than 0.4 for the cemento-enameljunction were judged to be cysts, and those showing a value of 0.4 or more were judged to be benign tumors. The rate of misjudgement was 28 % in the cyst group and 33.3 % in the benign tumor group.
The mechanical properties of dentin substrate are one of the important factors in determining bond strength of dentin bonding systems. The purpose of this study was to determine the elastic modulus of dentin substrate with the use of an ultrasonic device. The dentin disks of about 1 mm thickness were obtaining from freshly extracted human third molars, and the dentin disk was shaped in a rectangular form with a fine diamond point. The size and weight of each specimen was measured to calculate the density of the specimen. The ultrasonic equipment employed in this study was composed of a Pulser-Receiver (Model 5900PR, Panametrics), transducers (V155, V156, Panametrics) and an oscilloscope. The measured twoway transit time through the dentin disk was divided by two to account for the down-and-back travel path, and then multiplied by the velocity of sound in the test material. Measuring the longitudinal and share wave sound velocity determine elastic modulus. The mean elastic modulus of horizontally sectioned specimens was 21.8 GPa and 18.5 GPa for the vertically sectioned specimens, and a significant difference was found between the two groups. The ultrasonic method used in this study shows considerable promise for determination of the elastic modulus of the tooth substrate.
Our previous studies demonstrated retinoic acid (RA) inhibition of activation protein-1 (AP-1) formation in TNF-α-treated osteoblastic MC3T3-E1 cells via fos suppression. In the present study, we observed that 1α25 (OH) 2D3 was able to interfere at the transcriptional level with RA inhibition of TNF-α-induced c-fos gene expression in cells when the cells were incubated with the vitamin for 24 hr before the RA treatment. 22-Oxa-1, 25 (OH) 2D3 (OCT), an analog derivative of 1α25 (OH) 2D3, having high affinity for the vitamin D3 receptor (VDR), also interfered with the RA-induced inhibition of c-fos gene expression in the TNF-α-treated cells. In contrast, this was not the case for 24, 25 (OH) 2D3. Moreover, we observed that the interfering effect was clearly blocked by pretreatment with VDR antisense oligonucleotide. 1α25 (OH) 2D3 interfered with RA inhibition of the TPA-response element binding activity of AP-1 in the cytokine-treated cells. Furthermore, 1oc25 (OH) 2D3 actually blocked the AP-1-mediated gene expression of monocyte chemoattractant JE/MCP-1 induced in the cytokine-treated cells. The present study suggests a regulatory interference by 1oc25 (OH) 2D3 for RA inhibition of TNF-α-induced AP-1 activity in osteoblasts
Hepatocyte growth factor (HGF) acts as a mitogen, motogen, morphogen and anti-apoptotic factor for various kinds of epithelial cells. We previously showed that periodontal fibroblasts secreted an HGFlike chemoattractant for a gingival epithelial cell line and found that HGF content in gingival crevicular fluid was well correlated with probing depth, gingival index, and interleukin-1Β concentration. To examine whether HGF in whole (mixed) saliva would be a useful marker for periodontal disease status, we investigated the relationship between salivary HGF levels and clinical parameters of 65 adults (50 men and 15 women). Unstimulated whole (mixed) saliva was collected from each subject and the HGF level was determined with an ELISA kit. After sample collection, probing depths and bleeding on probing were monitored. Significant correlations were found between salivary HGF levels and the number of probing depths exceeding 4 mm (r = 0.541), the number of probing depths exceeding 6 mm (r = 0.683), the deepest probing depth of each subject (r = 0.558) and the percentage of sites positive forbleeding on probing (r = 0.511). These results suggest that salivary HGF may be a novel marker for periodontal diagnosis in screening tests
The present study assessed the susceptibility of Candida albicans strains, collected from HIV-positive patients with oral candidiasis, to a commercial 20% ethanol propolis extract (EPE) and compare it to the inhibitory action of the standardized antifungal agents nystatin (NYS), clotrimazole (CL), econazole (EC), and fluconazole (FL). Twelve C. albicans strains collected from MV-positive patients with oral candidiasis were tested. The inhibition zones were measured with a pachimeter and the results are reported as means and standard deviation (M ± SD). Data were analyzed statistically by the non-parametric Kruskal-Wallis test. EPE inhibited all the C. albicans strained tested. No significant difference was observed between the results obtained with NYS and EPE, while significant differences were observed between EPE and other antifungals. The C. albicans strains tested showed resistance to the remaining antifungal agents. The propolis extract used in this study inhibited the in vitro growth of C. albicans collected from HIV-seropositive Brazilian patients, creating/forminginhibition zones like those ones formed by NYS. This fact suggests that commercial EPE could be an alternative medicine in the treatment of candidiasis from HIV-positive patients. However, in vivo studies of the effect of EPE are needed to determine its possible effects on the oral mucosa.
A rare case of primary intraosseous carcinoma (PIOC) arising from an odontogenic cyst in a 58-year-old man is reported. Clinical and radiological examinations revealed an odontogenic cyst of the maxilla. Histopathologically, the lesion was composed of a cyst with a parakeratotic epithelial lining and well-differentiated squamous cell carcinoma, showing continuity between them without a connection to the oral mucosa. Twenty-eight well-documented Japanese cases of Type-1 PIOC, including the present case, were reviewed. The mean age of the 28 patients was 56.1 years, and the male to female ratio was 1.8 : 1.0. Compared with currently reported Japanese reviews of Type-3, foreign Type-1 and Type-3, there were no significant differences in mean patient age and sexual predominance, and no racial difference. The pathogenesis of Type-1 PIOC is also discussed.
A case of primary tuberculosis of the tongue, an extremely rare entity is presented. The clinical manifestation, diagnosis and the response to antituberculous treatment are considered. The literature is also reviewed.
We report a distinct morphologic type of neurofibroma, lipomatous neurofibroma, arising in the oral mucosa, which has not been described previously in the literature. A 25-year-old female patient presented with a solitary mucosal mass on the palatal gingiva. Although the limited biopsy material was diagnosed as a spindle cell lipoma, characteristic light microscopic neurofibromatous areas, intricately admixed with mature fat, were found in the entire resection specimen. Immunohistochemically, many of the spindle cells were positive, either diffusely or focally, for common neural markers, with patchy staining for CD34 and epithelial membrane antigen. S-100 protein was also positive in adipocytes. Ultrastructural examination confirmed the diagnosis of neurofibroma and suggested an intimate relationship between neoplastic neural cells and adipocytes.
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