The aim of this study was to compare oral health attitudes and behaviour between British and Chinese dental students. A cross-national survey using the Hiroshima University - Dental Behavioural Inventory (HU-DBI) was completed at the University of Leeds in Britain and West China University of Medical Sciences in China. In Britain and China, 192 of 266 and 180 of 303 dental students answered English and Chinese versions of the HU-DBI questionnaire, respectively. Data were statistically analyzed by logistic regression and the following results were obtained: 1) Self-reported gingival bleeding was more prevalent in Chinese students than in British students, although the number of students who had professional oral hygiene instruction was higher in China than in Britain; 2) 29% of Chinese students believed wearing dentures in old age was inevitable, whereas 7% of British students believed so; 3) Chinese students were substantially more concerned about the appearance of their teeth, gums and halitosis; and 4) 54% of Chinese students seek dental care only when symptoms arise, as compared to 13% of British students. In conclusion, bilateral comparison of countries using HU-DBI revealed interesting differences in oral health attitudes and behaviour, while the logistic regression model made it possible to differentiate British from Chinese students with a probability of nearly 95%. (J. Oral Sci. 47, 1-7, 2005)
The aim of the current study was to evaluate the influence of polycarboxylate temporary cement remaining on the dentin surface on the bond strength of a composite luting system. An acrylic resin plate was luted to bovine dentin with a polycarboxylate temporary cement (HY-Bond Temporary Cement Hard, HYB). The temporary cement was not used for the control groups. After removing the temporary cement with an excavator, dentin specimens were divided into five groups; 1) no subsequent treatment, 2) cleaning with a rotational brush (RTB), 3) cleaning with a rotational brush and non-fluoridated flour of pumice, 4) sweeping with an air scaler, and 5) treated with a sonic toothbrush. A silane-treated ceramic disk (IPS Empress) was bonded to each dentin specimen with a composite luting system (Panavia F). Shear testing results showed that the RTB groups exhibited the highest bond strength regardless of the use of temporary cement (P < 0.05). The use of a rotational brush with water coolant is recommended to achieve ideal bond strength between the Panavia F luting system and dentin to which HYB temporary cement was primarily applied. (J. Oral Sci. 47, 9-13, 2005)
Human polymeric immunoglobulin receptor (pIgR) protein was expressed in the adeno-carcinoma cell line HT-29 using a recombinant vaccinia virus transfection method. The pIgR protein was detected as 110- and 120-kDa bands by immuno-precipitation after metabolic labeling. PIgR was released as a free secretory component into the culture supernatant and was detected as a 110-kDa band. PIgR cleavage was investigated by adding the proteinase inhibitor leupeptin or protein kinase C activator PMA. Consistent with previous observations in the Madin Darby canine kidney cell system, cleavage of pIgR was inhibited by leupeptin and enhanced by PMA stimulation, thus indicating that it is regulated by common mechanisms. This experimental system should be very useful for pIgR investigation. (J. Oral Sci. 47, 15-20, 2005)
There is a need for effective polishing instruments for resin composite restorations with highly polished surfaces. The purpose of this study was to investigate the influence of polishing duration on surface roughness of light-cured resin composites. Four polishing systems, Compomaster (Shofu), Silicone Points C Type (Shofu), Super Snap (Shofu) and Enhance Finishing and Polishing System (Dentsply/Caulk), were used to polish two commercially available resin composites, Clearfil AP-X (Kuraray Medical) and Lite-Fil II A (Shofu). Resin pastes were condensed into molds (10 mm in diameter, 5 mm in depth) and light irradiated for 40 s. Composite surfaces were ground with # 600 SiC paper followed by polishing with an instrument for 30 s, and the surface roughness was measured every 10 s during polishing procedures. The average surface roughnesses (Ra) were determined using a profilometer. Data were analyzed by Tukey HSD test (P = 0.05). After 30 s of polishing, mean Ra values ranged from 0.07 to 0.50 for Clearfil AP-X, and from 0.11 to 0.57 for Lite-Fil II A. Although the time required for polishing was longer, the surface finish produced by multiple-step polishing systems was superior to that obtained with one-step polishing systems. (J. Oral Sci. 47, 21-25, 2005)
Ameloblastin and amelogenin are structural proteins present in the enamel matrix of developing teeth. Here we report the results of in situ hybridization analyses with DNA probes of ameloblastin and amelogenin expression in the mandibular first molars of ICR/Jcl mice from postnatal day 1 to day 15. Ameloblastin mRNA expression was observed in ameloblasts at day 2 while amelogenin mRNA was detected in secretory ameloblasts at day 3. Significant expression of both molecules was observed at days 4, 5 and 6, after which the levels decreased. Amelogenin expression ended on day 10, while ameloblastin mRNA was only weakly detected on day 12. Neither amelogenin nor ameloblastin expression was observed in day 15 mouse molars. Amelogenin and ameloblastin mRNAs were restricted to ameloblasts. We conclude that amelogenin and ameloblastin expression is enamel-specific, and suggest that these genes might be involved in the mineralization of enamel. It is possible that ameloblastin could participate in the attachment of ameloblasts to the enamel surface. In this case, the downregulation of expression may indicate the beginning of the maturation stage in which the ameloblasts tend to detach from the enamel layer. (J. Oral Sci. 47, 27-34, 2005)
This study evaluated the effect of sealants on enamel demineralization, focusing on physical protection of the sealed enamel and fluoride protection of the adjacent unsealed enamel. Occlusal fissures with areas measuring 12 mm2 were delimited in 48 extracted molars, randomly divided into 4 groups (n =12): 1) no sealing; 2) sealing with a resin-modified glass-ionomer (Vitremer™, 3M ESPE); 3) sealing with a fluoride-releasing composite sealant (Clinpro Sealant™, 3M ESPE); and 4) sealing with a non-fluoridated composite sealant (Concise™, 3M ESPE). A 4-mm2 window was outlined on the buccal enamel for analysis of fluoride uptake. Following treatment, groups 2, 3 and 4 were subjected to 5-days of pH-cycling, while group 1 was kept in a moist environment at 37°C. Fluoride uptake was assessed by dental biopsy, and the amount of fluoride released to the cycling solutions was determined by ion analysis. Enamel demineralization around the sealants was evaluated by cross-sectional micro-hardness analysis. Group 2 showed higher levels of fluoride release (P < 0.01) and uptake by enamel (P < 0.05), and lower levels of demineralization (P < 0.05) than groups 3 and 4. Group 3 exhibited reduced demineralization on unsealed enamel and provided fluoride uptake in a distant enamel area, while group 4 did not. (J. Oral Sci. 47, 35-41, 2005)
We previously demonstrated that tumor necrosis factor (TNF)-α stimulated the production of activation protein (AP)-1, a transcriptional factor, in mouse osteoblastic MC3T3-E1 cells. Recent studies have shown the importance of ceramide and its metabolites as signal molecules for TNF-α-induced gene expression in several cell types. Therefore, our interest was to investigate whether sphingosine metabolites are involved in TNF-α-induced signaling in MC3T3-E1 cells. DL-threo-1-phenyl-2-hexadecanoyl-amino-3-pyrrolidino-1-propanol (PPPP), which causes accumulation of intracellular ceramide, stimulated the TNF-α-induced expression of the c-fos and c-jun genes. Gel shift assay clearly showed that PPPP increased the cytokine-induced specific binding of nuclear proteins to the 12-tetra-decanoyl phorbol 13-acetate-responsive element (TRE), a consensus sequence for AP-1. In addition, cell-permeable ceramide (N-acetylsphingosine, N-hexanoylsphingosine or N-octanoylsphingosine) stimulated expression of the c-fos and c-jun genes and nuclear protein binding to TRE. Interestingly, DL-threo-dihydrosphingosine (DHS), an inhibitor of sphingosine kinase, clearly blocked the ceramide analogue-induced stimulation. Sphingosine 1-phosphate (SPP) actually induced expression of these oncogenes and activated AP-1. Although TNF-α stimulated the AP-1-mediated expression of the monocyte chemoattractant JE/MCP-1, this stimulation was inhibited by DHS. SPP also stimulated JE/MCP-1 gene expression. The present study thus suggests that SPP acts as a signal molecule in ceramide-dependent signal transduction in TNF-α-induced AP-1 in osteoblastic MC3T3-E1 cells. (J. Oral Sci. 47, 43-51, 2005)
The aim of this study was to determine the association between levels of a marker of oxidative stress, 8-hydroxydeoxyguanosine (8-OHdG), in saliva and the presence of teeth with a hopeless prognosis as a result of advanced periodontitis. Thirty-four periodontitis patients were divided into two groups based on the presence or absence of periodontally-involved teeth of hopeless prognosis. Salivary levels of 8-OHdG in those with were significantly higher than in subjects without periodontally-involved teeth of hopeless prognosis (4.78 ± 0.14 ng/ml and 2.35 ± 0.18 ng/ml, respectively). We also evaluated 8-OHdG levels in gingival crevicular fluid (GCF) of teeth with advanced periodontal destruction (mean probing depth = 7.2). In this case, 8-OHdG was detected only from those periodontally-involved teeth of hopeless prognosis, and only in some cases (8 out of 18 samples). These data suggest that periodontally-involved teeth of hopeless prognosis are a major source of salivary 8-OHdG. Measurement of salivary 8-OHdG levels may prove to be useful in identifying patients with teeth of hopeless prognosis. (J. Oral Sci. 47, 53-57, 2005)
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