There are several benefits in using adhesive technique in removable prosthodontics as well as fixed prosthodontics. Previous studies have examined denture-base surface treatments that improve bond strength between a denture base resin and autopolymerizing repair resin. Dichloromethane and ethyl acetate are organic solvents that swell the denture base surface, thereby permitting diffusion of the acrylic resin. The optimal treatment duration is 5-10 s for dichloromethane and 120 s for ethyl acetate. It was reported that the bond durability of dichloromethane was superiorto that of ethyl acetate. Bonding between metal components and the denture base resin has an important role in the longevity of removable prostheses. The combination of metal conditioners and alumina air-abrasion is effective in fabricating and repairing removable dentures. Acidic monomers (4-META and MDP) are appropriate for base metal alloys, including Co-Cr alloy and titanium alloy, while thione monomers (MTU-6 and VBATDT) are suitable for noble metal alloys such as gold alloy and silver-palladium-copper-gold (Ag-Pd-Cu-Au) alloy. As an alternative to conventional restorations, resin-bonded restorations can provide precisely parallel guide planes with well-made rest seats. Careful consideration should be paid to stabilizing loosened teeth by fixing them with resin-bonded splints or fixed partial dentures. (J Oral Sci 54, 205-211, 2012)
This study examines the cytotoxicity of Super-Bond C&B (SB-C&B), Super-Bond RC Sealer (SB-RC), MetaSEAL (Meta), and AH Plus Sealer (AH+). Freshly mixed and set materials (100 mg) were prepared in vitro and placed in cell culture medium (1 mL) for the working time and for 6 h, respectively. L929 cells seeded into 96-well plates at 5,000 cells/well were incubated with the eluted medium (200 µL) for 24 h. Cells cultured with medium alone served as the control. Cytotoxicity was evaluated by MTS assay and analyzed with ANOVA. In the freshly mixed group, the average ± SD (%) for cell viability were 66.0 ± 13.6, 55.5 ± 15.6, 10.6 ± 0.7, and 8.9 ± 2.2 for SB-C&B, SB-RC, Meta, and AH+, respectively. In the set group, the average ± SD (%) for cell viability were 100 ± 21.9, 81.8 ± 38.5, 24.9 ± 7.9, and 23.6 ± 10.0 for SB-C&B, SB-RC, Meta, and AH+, respectively. SB-C&B and SB-RC are less cytotoxic than are Meta and AH+. (J Oral Sci 54, 213-217, 2012)
The present study compared the efficacy of cone beam computed tomography using different voxel sizes in the diagnosis of simulated external root resorption. The presence or absence of simulated defects on buccal, mesial and distal root surfaces of 20 premolars was evaluated. The defects were small (0.26 mm in diameter and 0.08 mm deep), medium (0.62 mm in diameter and 0.19 mm deep) and large (1.05 mm in diameter and 0.24 mm deep), equally distributed on each root surface. Images were obtained using Classic i-CAT cone beam computed tomography with different voxel sizes: 0.12, 0.20, 0.25 and 0.30 mm. Five oral radiologists evaluated the images. Accuracy, sensitivity, specificity, positive and negative predictive values were determined. The sensitivity decreased and specificity increased as voxel size increased. Accuracy values were the highest for the smallest voxel size (0.12 mm). The results for voxel sizes 0.20 mm and 0.25 mm were similar. Positive and negative predictive values were similar in all protocols, except with 0.30 mm, in which they were the lowest. In conclusion, external root resorption was more easily diagnosed when a smaller voxel size was used. (J Oral Sci 54, 219-225, 2012)
Each of three cone beam computed tomography (CBCT) machines offer a small field of view (FOV); Promax, Accuitomo 3D, and Kodak 9000. The objectives were to determine, when using a small FOV, the difference in contrast-to-noise ratios (CNR) of images obtained from different machines and different scan settings within each machine. A phantom made of a dry mandible with an epoxy resin based substitute (ERBS) block was used. The ERBS block was fixed to the lingual cortex in the posterior left mandible. Water was used to simulate soft tissue. Twenty scans were acquired. CNR was calculated as the difference in density of the ERBS block and a control area divided by the standard deviation of the difference. The CNR obtained from images acquired with the Promax machine (voxel size of 0.2 mm) was higher than the other machines (voxel sizes 0.076, 0.08, or 0.125 mm) when using a small FOV. The Accuitomo 360° scan had higher CNR than the Accuitomo 180° scan due to the doubling of the number of basis images acquired. Smaller voxel size does not necessarily lead to enhanced CNR. Increasing the number of basis images did increase the CNR. (J Oral Sci 54, 227-232, 2012)
The aim of this study was to evaluate the sealing ability of mineral trioxide aggregate (MTA Bio) combined with different mixing agents (distilled water, chlorhexidine, doxycycline), used as an apical root-end filling material. Forty-two extracted human teeth were divided into three groups (n = 12); six teeth were used as controls. Root-ends were resected at 90 degrees, 3 mm from the apex. Root-end cavities were prepared using ultrasonic tips and filled with MTA Bio plus distilled water, 2% chlorhexidine solution, or 10% doxycycline solution. Apical sealing was assessed by microleakage of 50% silver nitrate solution. Roots were longitudinally sectioned in a buccolingual plane and analyzed using an operating microscope (20× magnification). Depth of dye leakage into the dentinal walls was measured in millimeters. Results were analyzed using ANOVA and Tukey's test (P = 0.05). MTA Bio plus distilled water showed significantly higher mean leakage results (1.06 mm) when compared with MTA Bio plus doxycycline (0.61 mm), and higher, although not significant, results when compared with MTA Bio plus chlorhexidine (0.79 mm). In conclusion, replacing distilled water with two biologically active mixing agents (doxycycline and chlorhexidine) did not alter the sealing properties of MTABio. The antimicrobial properties of these combinations should be further investigated. (J Oral Sci 54, 233-239, 2012)
Human podoplanin is a type-1 transmembrane sialomucin-like glycoprotein that is involved in cell migration, tumor cell invasion and metastasis. Our recent study of oral squamous cell carcinoma (OSCC) demonstrated that the degree of immunohistochemical expression of podoplanin was correlated with the severity of epithelial dysplasia and significantly associated with a poor pathologic grade of differentiation. Furthermore, it has been reported that Src directly associates with the epidermal growth factor receptor (EGFR) in OSCC cells upon stimulation with EGF and phosphorylates Crk-associated substrate (Cas), podoplanin acting downstream of Src and Cas to promote cell migration. However, the molecular function of podoplanin remains unclear. In this study we performed real-time RT-PCR, Western blotting and scratch assay using OSCC cell lines in order to clarify the molecular biological function of podoplanin expression associated with various growth factors including EGF and with the Src-Cas signaling pathway. Podoplanin was found to have a marked influence on cancer cell migration and the expression of matrix metalloprotease-9 (MMP-9) in the oral cavity upon stimulation with EGF. Podoplanin promotes oral cancer cell migration, and the EGF-Src-Cas pathway is one of the possible mechanisms responsible for progression of cancer in the oral cavity. (J Oral Sci 54, 241-250, 2012)
Fibroblast growth factor 2 (FGF2) and cyclic AMP (cAMP) play critical roles in controlling the differentiation of osteoblasts and mineralization of bone. We have previously reported that each of FGF2 and forskolin (FSK) alone increase transcription of the bone sialoprotein (BSP) gene, and that together (FGF/FSK) they upregulate BSP gene expression synergistically in rat osteoblast-like ROS 17/2.8 cells. However, other genes that are upregulated after stimulation by FGF2, FSK or FGF/FSK remain unclear. In the present study, we investigated candidate genes associated with mineralization after stimulation by FGF2, FSK and FGF/FSK in two kinds of osteoblast-like cells using microarray and real-time PCR. In ROS17/2.8 cells, FGF2 and FSK each increased the gene expression of c-FOS (7.2-fold and 10.7-fold, respectively). However, FGF/FSK did not induce c-FOS gene expression. FGF2 increased the expression of the dentin matrix protein 1 (DMP1, 129.8-fold) gene. In contrast, FGF/FSK increased the expression of the amphiregulin (AREG, 73-fold) gene maximally. In human osteoblast-like Saos2 cells, FGF2 increased the expression of the osteopontin (SPP1, 16.7-fold), interleukin-8 (IL8, 6.4-fold) and IL11 (4.8-fold) genes. FSK induced the expression of the IL6 (2.6-fold), IL11 (4.0-fold), chemokine ligand 13 (CXCL13, 2.8-fold) and bone morphogenetic protein 2 (BMP2, 2.5-fold) genes. These results suggest that FGF2 and FSK might be crucial regulators of mineralization and bone formation. (J Oral Sci 54, 251-259, 2012)
We evaluated the effect of activation mode (immediate or delayed light activation vs. no light activation) on diametral tensile strength (DTS), elastic modulus, ultimate tensile strength (UTS), and degree of conversion (DC) in dual-cured resin cements. Three resin cements were evaluated: Enforce, RelyX ARC, and Panavia F. The mixed cements were inserted into circular molds for the DTS test and into dumbbell-shaped molds for the UTS test. Inside the molds, the cements were light-activated either immediately or after 5 min (delayed light activation). If no light activation was performed, the materials were protected from light exposure (control). The DTS and UTS tests were performed until fracture. The elastic modulus was calculated using data from the DTS test, and DC was evaluated 24 h after manipulation using near-infrared spectroscopy. Data for each variable were individually analyzed by two-way ANOVA and the post-hoc Tukey test (α = 0.05). Regarding DTS, activation mode influenced only Panavia Fspecimens, which had the lowest DTS values in the absence of light activation. Activation mode did not influence the elastic modulus or UTS of any resin cement evaluated. Immediate light activation yielded higher DC values as compared with the absence of light activation. (J Oral Sci 54, 261-266, 2012)
Silver diamine fluoride (Ag(NH3)2F) arrests caries but stains teeth black. To overcome this drawback, we applied ammonium hexafluorosilicate (AHF; (NH4)2SiF6) and observed changes in the color and structure of demineralized enamel and dentin of extracted primary teeth. Enamel and dentin were demineralized in 10% EDTA solution for 90 s followed by 35% phosphoric acid gel for 60 s, then soaked in AHF solution for 60 s. Before analysis by scanning electron microscopy (SEM) and energy-dispersive X-ray spectrometry (EDS), enamel and dentin were demineralized in 10% EDTA for 90 s. Teeth were divided into 4 groups according to AHF application and artificial saliva immersion status and then examined. The data were statistically analyzed using one-way ANOVA and Fisher's PLSD test at a significance level of P < 0.05. AHF treatment did not cause visible discoloration. Enamel prisms and dental tubules appeared by demineralization were covered with precipitates by AHF application. A sphere-filled membranous structure was observed in the saliva immersion groups. EDS analysis showed that AHF application had no effect on enamel; however, F% and Ca/P ratio were significantly higher on dentin surfaces after AHF application without artificial saliva immersion. Further study on arresting caries treatment is required. (J Oral Sci 54, 267-272, 2012)
A study was performed to examine the correlation between maxillary central incisor tooth form and face form in males and females in an Indian population. The selection of prosthetic teeth for edentulous patients is a primary issue in denture esthetics, especially in the case of maxillary central incisors, which are the most prominent teeth in the arch. Two hundred dental students of Indian origin comprising 79 males and 121 females aged 18-28 years studying at Bapuji Dental College and Hospital were randomly selected as the study subjects. A standardized photographic procedure was used to obtain images of the face and the maxillary central incisors. The outline forms of the face and the maxillary right central incisor tooth were determined using a standardized method. The outline forms obtained were used to classify both face form and tooth form on the basis of visual and William's methods. The means were considered after evaluation by five prosthodontists, and the results were tabulated. Statistical analysis was performed using the chi-squared test for association and Z-test for equality of proportions. A correlation greater than 50% was observed between tooth form and face form by the visual method, compared with one of 31.5% by William's method. There was no highly defined correlation between maxillary central incisor tooth form and face form among the male and female Indian subjects studied. (J Oral Sci 54, 273-278, 2012)
Oral cancer is the leading cause of death worldwide and it is the eighth most common cause of cancer death. Cancer cells utilize more glucose and amino acids than their benign counterparts. Diagnosis of disease via the analysis of saliva is potentially valuable, as the collection of fluid is associated with fewer compliance problems than the collection of blood. Hence, the present study was undertaken to evaluate the comprehensive amino acid profiling of saliva by high performance liquid chromatography (HPLC). The study group comprised 16 subjects, of whom eight were classified as having well-differentiated oral squamous (OSCC) cell carcinoma (Group I) and eight were classified as having moderately differentiated oral squamous cell carcinoma (Group II). Eight healthy individuals comprised the control group (Group III). The results showed increased salivary levels of all the amino acids in both groups of OSCC patients (Groups I and II) when compared with healthy controls (Group III). Hence, our study showed higher levels of all amino acids in the saliva of OSCC patients than in the saliva of healthy controls. The increased levels may serve as a “diagnostic and prognostic marker” for oral squamous cell carcinoma and for further detection of metastatic spread. (J Oral Sci 54, 279-283, 2012)
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