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At least 343 records · Page 19Linked to original sources
PubMed2004

Inhibition of osteoclast formation by 3-methylcholanthrene, a ligand for arylhydrocarbon receptor: suppression of osteoclast differentiation factor in osteogenic cells.

We investigated the effects of 3-methylcholanthrene (3MC), a ligand for arylhydrocarbon receptor (AhR), on osteoclastogenesis. Osteoclast-like cells, in cocultures with mouse spleen cells and clonal osteogenic stromal ST2 cells, are formed from spleen cells by a combination of the receptor activator of nuclear factor-kappaB ligand (RANKL) and macrophage colony-stimulating factor (M-CSF) produced by ST2 cells in response to 1alpha,25(OH)(2) Vitamin D(3). 3MC dose-dependently inhibited the formation of mono- and multinuclear osteoclast-like cells. However, 3MC did not inhibit the formation of osteoclast-like cells from mouse spleen cells which was supported by the exogenous soluble RANKL and M-CSF. 3MC did not affect the formation of an actin ring and pits on slices of dentine by osteoclast-like cells, both of which are typical indices of osteoclast activity. These results suggest that 3MC affects osteoclast-supporting cells such as ST2 cells but not osteoclast precursor cells and mature osteoclastic cells. When we measured the expression levels of RANKL mRNA in ST2 cells, 3MC dose-dependently decreased the level of this mRNA. However, 3MC did not affect levels of mRNAs for osteoprotegerin (OPG), M-CSF, and the receptor of 1alpha,25(OH)(2) Vitamin D(3) in ST2 cells. Furthermore, soluble RANKL was able to counteract the inhibitory effect of 3MC on the formation of osteoclast-like cells. Our findings indicate that 3MC inhibits osteoclastogenesis via the inhibition of RANKL expression in osteoblastic cells.

Animals↗
PubMed1999

Human osteoclast-like cells are formed from peripheral blood mononuclear cells in a coculture with SaOS-2 cells transfected with the parathyroid hormone (PTH)/PTH-related protein receptor gene.

Subclones of the human osteosarcoma cell line SaOS-2 were established by transfecting with an expression vector containing the human PTH/PTH-related protein (PTHrP) receptor, and their abilities to support osteoclast-like multinucleated cell (OCL) formation were examined in coculture with mouse or human hemopoietic cells. Of four subclones examined, SaOS-2/4 and SaOS-4/3 bound high levels of [125I]-PTH and produced a significant amount of cAMP in response to PTH. OCLs were formed in response to PTH in the cocultures of mouse bone marrow cells with either SaOS-2/4 cells or SaOS-4/3 cells. Human OCLs were also formed in response to PTH in the coculture of SaOS-4/3 cells and human peripheral blood mononuclear cells. Adding dexamethasone together with PTH greatly enhanced PTH-induced human OCL formation. Like mouse OCLs, human OCLs formed in response to PTH were tartrate-resistant acid phosphatase positive, expressed abundant calcitonin receptors and vitronectin receptors, and formed resorption pits on dentine slices. Other osteotropic factors such as 1alpha,25-dihydroxyvitamin D3, prostaglandin E2, and interleukin 6 plus soluble interleukin 6 receptors failed to induce mouse and human OCLs in cocultures with SaOS-4/3 cells. Both mouse and human OCL formation supported by SaOS-4/3 cells were inhibited by either adding an antibody against macrophage-colony stimulating factor or adding granulocyte/macrophage-colony stimulating factor. Thus, it is likely that human and mouse OCL formation supported by SaOS-4/3 cells are similarly regulated. These results indicate that the target cells of PTH for inducing osteoclast formation are osteoblast/stromal cells but not osteoclast progenitor cells in the coculture. This coculture model will be useful for investigating the abnormalities ofosteoclast differentiation and function in human metabolic bone diseases.

Acid Phosphatase↗
PubMed2005

Protein profile of pepsin-digested carious and sound human dentine.

The purpose of this study was to describe the protein profile of pepsin-digested carious and sound dentine using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Carious and sound dentine powder was decalcified using 10% EDTA at pH 7.4 for 48 h. The decalcified pellet was digested using pepsin at pH 2 under sequenced conditions: at 4 degrees C for 24 h, a further 24 h at 23 degrees C, and finally for 24 h at 37 degrees C. After every step, the soluble fraction was separated by centrifugation and analyzed in 15% SDS-PAGE. Two bands at 56 and 62 kDa could be observed in carious dentine digests and were considered specific carious bands. Similar bands could be observed in sound dentine samples, but only after pepsin digestion at higher temperatures (23 degrees C and 37 degrees C). Pepsin digests non-helical collagen and the triple helix structure of collagen is lost when the temperature rises. The bands at 56 and 62 kDa in sound dentine specimens thus represent pepsin-cleaved collagen. There is a possibility that the specific carious bands in carious dentine represent collagen decomposed in a manner similar to the way pepsin digests native dentine collagen at 23 degrees C and 37 degrees C.

Collagen↗
PubMed1977

[A technic to prepare fixed ground sections for a quantitative microradiography study of the dentin].

The preparation of ground sections for the quantitative microradiographic study of dentine was carried out either by hand or by machine using a new technique of fixing the sections to the holder by a soluble adhesive. After setting up a method of control for the plano-parallelism of the sections, the times of preparation and the quality of the sections obtained with both methods were compared: engine grinding gave the best results in terms of both quantity and quality.

Dentin↗
PubMed2005

Cytotoxicity of substances leached or dissolved from pulp capping materials.

AIM: To evaluate the cytotoxic effects of substances leached or dissolved from pulp capping materials on human pulp fibroblasts. METHODOLOGY: The substances were applied to cell cultures in conditioned media. The experimental groups were: GI (control; n = 24)--cultures treated with fresh medium; GII (n = 24)--cultures treated with calcium hydroxide cement; GIII (n = 24)--cultures treated with adhesive resin and GIV (n = 24)--cultures treated with 37% orthophosphoric acid. The media were conditioned by placing the crude materials in contact with fresh culture medium for 1 h. The cytotoxicity analysis was performed using the Trypan blue dye exclusion assay at times of 0, 6, 12 and 24 h for cell viability assay, and at 1, 3, 5 and 7 days for survival assay. Data were treated by anova (P < 0.05) and Tukey's test (P < 0.05). RESULTS: GI and II presented similar cell viability and cell growth. GIII and IV exhibited statistically significant lower percentages of cell viability: GIV only at the 0 h experimental time, whereas in GIII this viability markedly diminished reaching values of 10% by 12 h. Cell growth was impaired only in cultures of GIII. CONCLUSIONS: Substances dissolved from the adhesive system tested were cytotoxic for human dental pulp fibroblasts in culture, whilst substances leached from calcium hydroxide were biocompatible.

Acid Etching, Dental↗
PubMed1997

Resin bonding to enamel and dentin with one-component UDMA/HEMA adhesives.

The aim of this study was to investigate the potential of UDMA/HEMA mixtures as priming and sealing components of dental adhesives. The monomers were mixed in weight ratios 100/0, 80/20, 60/40, 50/50, 40/60, 20/80, 10/90, and 0/100, light activated, and dissolved in acetone at equal parts. The 60/40 UDMA/HEMA mixture served as a reference which was modified with 5, 10, 20, and 30 parts 4-MET relative to the mass of the basic monomer mixture. Shear bond strengths (24 h) of resin composite cylinders, bonded with the adhesive monomers on human enamel and dentin, were determined following a total etch technique with phosphoric acid and application of the adhesives in 2 coats on moist tooth surfaces. Average bond strength to enamel was 32 MPa with no difference between the adhesives. On dentin, significantly different bond strengths were found between UDMA (12.9 MPA) and HEMA (19.4 MPa), whereas all binary mixtures' bond strengths were not significantly different (mean 16.2 MPa). Addition of 5 to 20 wt% 4-MET resulted in a significantly increased mean shear bond strength of 22.3 MPa on dentin. At 10%, a maximum mean strength of 25.4 MPa was recorded. It is concluded that mixtures of commonly used polymerizable monomers, characterized by hydrophilic moieties and dissolved in acetone, are promising candidates for effective resin bonding to enamel and dentin, provided application by the moist bonding technique.

Acetone↗
PubMed1998

Efficacy of self-etching primers containing carboxylic acid monomers on the adhesion between composite resin and dentin.

A study was conducted to examine the efficacy of carboxylic acid monomers as self-etching primers by measuring the tensile bond strengths between composite resin and dentin. Several kinds of carboxylic acid monomers, such as o-(N-methacryloyl amino)benzoic acid (o-MABA), m-(N-methacryloyl amino)benzoic acid (m-MABA), p-(N-methacryloyl amino)benzoic acid (p-MABA), 4-methacryloxy phthalic acid (4-MPA), 2-(N-methacryloyl amino) terephthalic acid (2-MATPA), and 5-(N-methacryloyl) amino)isophthalic acid (5-MAIPA), were prepared. 4-methacryloxyethyl trimellitic anhydride (4-META) was also used as a component of the self-etching primer. The DMSO solutions of these monomers were used as self-etching primers. The tensile bond strengths between composite resin and dentin were measured after 24 h immersion in water at 37 degrees C. When DMSO was used as a self-etching primer, the bond strengths were below 5 MPa. Among the monocarboxylic acid monomers, m-MABA gave the highest mean bond strength at 60 s application, and 5MAIPA gave the highest mean bond strength at 30 s application among the dicarboxylic acid monomers, although the differences among the values were not always significant. The smear layer was partially dissolved by treatment with the self-etching primer.

Acid Etching, Dental↗
PubMed1986

Identification of dentin phosphophoryn localization by histochemical stainings.

Phosphophoryn, the most abundant of the dentin non-collagenous proteins, has been considered to be related in function to the mineralization process. In the present study, identification of dentin phosphophoryn localization was attempted using newly developed, precautionary histological methods by which phosphophoryn was retained in the sections during the specimen preparation and stained selectively in situ. Phosphophoryn was found to be present widely in all of the calcified dentin except the mantle dentin, the external, first-formed portion of dentin, but was not found in the predentin, the inner, uncalcified layer of dentin. These results indicate that phosphophoryn is apparently related to the mineral phase of calcified dentin and that the mineralization process of mantle dentin, which is formed before the odontoblasts are fully differentiated, may be different from that of circumpulpal dentin.

Acetates↗
PubMed1996

The overwet phenomenon: a transmission electron microscopic study of surface moisture in the acid-conditioned, resin-dentin interface.

PURPOSE: To identify ultrastructural features resulting from possible primer-water interaction when a two-bottle, acetone- and alcohol-based dentin adhesive (All-Bond 2) was applied to acid-conditioned dentin in the presence of excess water. MATERIALS AND METHODS: Three groups (3-second dry, visibly moist, overwet), each comprising eight dentin discs prepared from human third molars, were established and bonded with All-Bond 2 under different degrees of surface moisture. Variations in the ultrastructural appearance of the resin-dentin interface from laboratory demineralized and epoxy resin embedded disc pairs were examined either with en bloc ruthenium red pre-staining alone or further stained with uranyl acetate and lead citrate. RESULTS: Displacement of water by the volatile primer solvents resulted in the formation of a layer of resin-impregnated dentin in the three groups. Interaction of the primer with water following the evaporation of the volatile primer solvents resulted in phase separation of the primer components. Ultrastructural features observed within the previously water-filled blister-like spaces on the dentin surface in the visibly moist and overwet groups recapitulated what was observed within partially water-filled dentin tubules in the 3-second dry group. The overwet phenomenon appeared to be a result of emulsion polymerization, involving irreversible interaction of water-soluble bifunctional primer components with those that are water-immiscible, through the formation of micelles, resulting in the absence of total interfacial integrity.

Acid Etching, Dental↗
PubMed1988

Solvent extraction clean-up for pre-treatment in amino acid analysis by gas chromatography. Application to age estimation from the D/L ratio of aspartic acid in human dentine.

Solvent extraction, a clean-up method for samples for the determination of amino acids by gas chromatography, was investigated and compared with a conventional ion-exchange purification. Amino acids were esterified with isopropanol and extracted with various organic solvents. The solubilities of the amino acid isopropyl esters increased with increasing solvent polarity and the size of the amino acids. The optimum pH was found to be 10.5. The method was applied to the estimation of ages by measurement of the D/L ratio of aspartic acid in human dentine. The D/L ratios so determined were slightly lower than from the ion-exchange method with respect to all dentines examined. However, there were little or no significant differences in the ages estimated by both methods, and the correlation coefficient of this method was 0.982. The method is suitable for the enantiomeric analysis of amino acids, and has several advantages in the technique and time.

Adult↗
PubMedDate not supplied

Estimation of the caries-related risk associated with infant formulas.

PURPOSE: Baby bottle tooth decay (BBTD) affects 6% of children under three years of age and is associated with inappropriate bottle use. The objective of this study was to estimate the caries-related risk associated with 26 infant formulas and whole milk. METHODS: First, the plaque pH of adult volunteers was monitored before and after an oral rinse with infant formula to determine the minimum pH obtained in response to each formula. Second, Streptococcus sobrinus 6715 was cultured in each infant formula, and the increase in the number of colony forming units was measured. Third, each infant formula was incubated with powdered enamel and the solubility of enamel mineral was calculated in the absence of bacteria. Fourth, each formula was mixed with standardized concentrations of acid to determine the buffering capabilities. Finally, enamel windows were created on extracted permanent molars and exfoliated primary incisor crowns that were then colonized with mutans streptococci and incubated with infant formula. Caries was assessed visually and radiographically for 18 weeks. The length of time required for the development of enamel caries, dentinal caries and pulpal involvement was recorded. RESULTS: One-way or two-way ANOVA of these five assays demonstrated that 1. Plaque pH varied in response to oral rinsing with infant formula and most formulas did have the ability to reduce the pH significantly below the pH obtained after rinsing with water 2. Some infant formulas supported significant bacterial growth 3. Enamel mineral was dissolved by incubation with certain infant formula 4. The buffer capacity varied among the infant formulas tested 5. The length of time required for caries to reach dentin or pulp differed for the formulas, with some formulas causing dentinal caries by 3.4 weeks and pulpal involvement by 7.2 weeks.

Acids↗
PubMed1991

Effects of phosphoprotein moieties on the remineralization of human root caries.

The noncollagenous proteins, especially phosphoprotein, have been shown to modulate biomineralization. The objective of this study was to investigate the remineralization potential of human tooth root organic matrices which did or did not contain soluble non-collagenous proteins including phosphoprotein. Human tooth roots were completely demineralized using conditions that either removed or did not remove soluble phosphoprotein and were then subjected to remineralization conditions. Removal of soluble phosphoprotein resulted in remineralization while no remineralization occurred in tooth roots that still contained soluble phosphoprotein. Transmission electron microscopy and microradiography demonstrated that demineralized cementum did not remineralize under any of the conditions used in this study. Collagenase digestion of demineralized and salt-reextracted tooth root organic matrices revealed that a nonsoluble phosphoprotein was present in the matrices. Amino acid analysis and SDS-PAGE showed that this nonsoluble phosphoprotein was similar in composition to the soluble phosphoprotein. This work suggests that the removal of soluble, noncollagenous proteins, especially phosphoprotein from root caries lesions, may enhance their remineralization potential.

Amino Acids↗
PubMed1979

Aspartic acid-rich proteins: major components of the soluble organic matrix of mollusk shells.

DEAE-cellulose ion-exchange chromatography separates soluble organic matrix components of three mollusk shells, each from a different taxonomic class, into analogous subfractions. The proteins of all subfractions are enriched in acidic and polar amino acids. In each chromatogram, however, the subfraction which contains the major portion of total protein also contains the highest concentration of aspartic acid. Thus the major components of the soluble organic matrix are aspartic acid-rich proteins. The identification of these proteins in mollusks, together with the known occurrence of aspartic acid and phosphoserine-rich proteins in vertebrate tooth dentin, emphasizes the fundamental importance of such acidic proteins in the processes of mineralization.

Amino Acids↗
PubMed1998

A study on the promotion and suppression of demineralization of human dental hard tissues and hydroxyapatite.

Demineralization of human dental enamel and dentine and their analogue compound, hydroxyapatite, was examined by using pH-metry to measure the time-courses of neutralization of acetate, formate, lactate or propionate buffer solution or of acidification of EDTA solution. The extent of neutralization by enamel, dentine and hydroxyapatite was different for each acid but increased in the same order: propionate, acetate, lactate and formate. This order was consistent with that of the K values of these acids. The pH-metry was used to determine the influences of sodium chloride and sucrose on demineralization of enamel, dentine and hydroxyapatite by acetate, formate, lactate and propionate and by EDTA. The demineralization by these bioorganic acids was suppressed by sucrose but promoted by sodium chloride, except that the demineralization of enamel by acetate and propionate was little affected. The demineralization of enamel, dentine and hydroxyapatite by EDTA was little affected by sucrose but promoted by sodium chloride. The promotive effect of sodium chloride on demineralization may be due to the increasing of solubility product by this salt and the suppressive effect of sucrose may be due to the formation of a calcium saccharate formed from the sucrose reacted with calcium on the surface of apatite crystal and/or the reduction of solubility product by the sucrose. In this study, it was also ascertained that the use of pH-metry made it possible to determine easily the demineralization.

Acetic Acid↗
PubMed2002

A new fluoride-releasing rubber cup for professional oral hygiene.

Rubber cups in combination with prophylaxis pastes are commonly used for supragingival professional tooth cleaning. This procedure requires frequent interruption in order to collect fresh paste. Moreover, the paste-saliva slurry blurs the visibility, which implies intermittent rinsing to look for residual discolorations. Hawe Neos Dental (Bioggio, Switzerland) has developed a new prophylaxis cup aimed at cleaning and smoothing the tooth surfaces, while simultaneously fluoridating the enamel without a prophylaxis paste. This new prophylaxis cup was tested with respect to cleaning efficiency, resulting surface roughness, abrasivity, and the promotion of fluoride uptake into enamel. After 15 seconds of use, the new cup showed a cleaning efficiency which was 20 to 30% higher than that of a conventional rubber cup (p < 0.01) used with the prophylaxis pastes Nupro coarse or Hawe cleanic (78% vs. 57 and 49%). The fluoride cup had a smoothing effect on the enamel surface comparable to that effected by the two prophylaxis pastes. The abrasivity on enamel was lowest with the new cup. On dentin, abrasivity was comparable to Nupro coarse, but higher than with Hawe cleanic. The fluoride cup also produced a higher amount of KOH-soluble fluoride on the enamel surface when compared to Hawe cleanic. With respect to the structurally bound fluoride, no difference was found. The newly developed fluoride releasing Hawe Neos cup represents an effective alternative to conventional procedures for supragingival professional tooth cleaning on enamel.

Acidulated Phosphate Fluoride↗
PubMed1994

Effect of food and oral simulating fluids on dentine bond and composite strength.

The effect of up to 30 days' immersion in 75% ethanol solution and in an artificial saliva (Moi-Stir) on the dentine shear bond strength (SBS) of three adhesive/composite systems (Tenure/Marathon One, Scotchbond Multi-Purpose/Z100 and Optibond/Herculite XRV) was evaluated. Two control series were stored either in 100% humidity or in air. Diametral tensile specimens (DTS) of the composites studied were stored in 75% ethanol for up to 30 days. The fracture mode and morphology of the failure interface were examined by scanning electron microscopy (SEM). Data were analysed using ANOVA and the Tukey LSD test. The SBS for all systems stored in Moi-Stir (24.8 +/- 3.0 MPa) and air (28.3 +/- 3.0 MPa) was not influenced by length of storage. Microscopic (SEM) examination of the debonded air, and Moi-Stir stored specimens showed that failure had primarily occurred through the dentine. Significant decreases (30-50%) in the SBS of all systems occurred after immersion in 75% ethanol. There was no significant difference among brands. The DTS of the composites showed significant decreases as a function of ethanol exposure. Marathon One and Herculite XRV showed significantly lower DTS after 14 days' storage while Z100 showed no reduction in DTS until after 30 days. The decrease in both SBS and DTS after storage in ethanol was a function of the square root of time (P < 0.001) and followed Fick's laws of diffusion. Ethanol diffusivity was approximated as 1.8 x 10(-6) cm2 s-1 for both SBS and DTS specimens, suggesting that alcohol attack in SBS specimens occurred primarily in the composite system.(ABSTRACT TRUNCATED AT 250 WORDS)

Composite Resins↗