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1.
Dent Mater J ; 40(1): 26-34, 2021 Jan 31.
Artigo em Inglês | MEDLINE | ID: mdl-32779606

RESUMO

The poly (γ-glutamic acid)/tricalcium phosphate (γ-PGA/TCP) composite was fabricated as a novel biomineralization material function in preventing caries. Demineralized bovine dentin specimens were prepared and randomly divided into 5 groups (i. α-TCP, ⅱ. γ-PGA, ⅲ. γ-PGA/TCP, ⅳ. CPP-ACP, and ⅴ. deionized water) and subjected to 14 days of pH cycling. Remineralization ability was evaluated by lesion depth, mineral loss and microhardness. The morphology of dentin depositions was observed with scanning electron microscope (SEM), the crystal structure was determined by X-ray diffraction (XRD), and the wettability was tested by contact angle measurements. ANOVA revealed specimens treated by γ-PGA/TCP presented the statistically least lesion depth (p<0.01) and mineral loss (p<0.001), and the highest hardness (p<0.001). SEM revealed prominent intra- and inter-tubular precipitates in both γ-PGA and γ-PGA/TCP groups. The XRD patterns of the deposition structures in all groups were similar to those of sound dentin, and the contact angle of water decreased after γ-PGA/TCP treatment.


Assuntos
Fosfatos de Cálcio , Ácido Glutâmico , Animais , Fosfatos de Cálcio/farmacologia , Bovinos , Dentina , Ácido Poliglutâmico/análogos & derivados , Remineralização Dentária
2.
Odontology ; 108(3): 376-385, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31912370

RESUMO

For purpose of enhancing the antibacterial activity of a universal adhesive, the antimicrobial peptide nisin was incorporated into Single Bond Universal and its antibacterial effect on Streptococcus mutans monospecific biofilms and saliva-derived multispecies biofilms was studied. Nisin was incorporated into Single Bond Universal and the antibacterial activity was examined by confocal laser scanning microscopy (CLSM), reverse transcription-quantitative polymerase chain reaction (qRT-PCR), phenol-sulfuric acid method and lactate dehydrogenase enzymatic method. The bonding properties were tested by microtensile bond strength (µTBS) and degree of conversion (DC). Data were analyzed by one-way analysis of variance (ANOVA) and least significant difference multiple comparison tests (P < 0.05). The Single Bond Universal incorporated with 3% (w/v) nisin could significantly inhibit the growth of the S. mutans monospecific biofilms (P< 0.01) and decrease the expression of genes related to extracellular polysaccharide (EPS) synthesis (gtfB, gtfC, gtfD and spaP) and acidogenicity (ldh) (P < 0.05). 3% (w/v) nisin-incorporated Single Bond Universal could also inhibit the growth of saliva-derived multispecies biofilms and decrease the excretion of EPS and lactic acid ( P< 0.05). µTBS and DC of 3% (w/v) nisin-incorporated Single Bond Universal did not deteriorate obviously (P > 0.05). In conclusion, 3% (w/v) nisin-incorporated Single Bond Universal substantially inhibited the growth of both S. mutans monospecific and saliva-derived multispecies biofilms without compromising the bonding properties.


Assuntos
Nisina , Streptococcus mutans , Antibacterianos , Biofilmes , Cimentos Dentários , Saliva
3.
R Soc Open Sci ; 6(10): 182104, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31824679

RESUMO

The biomimetic remineralization of collagen fibrils has increased interest in restoring the demineralized dentine generated by dental caries. Carboxyl-terminated polyamidoamine dendrimers (PAMAM-COOH), hyperbranched polymeric macromolecules, can act as non-collagenous proteins to induce biomimetic remineralization on a dentine organic matrix. However, in vivo remineralization is an extremely time-consuming process; before complete remineralization, demineralized dentine collagen fibrils are susceptible to degradation by host-derived matrix metalloproteinases (MMPs). Therefore, we examined the effect of fourth-generation PAMAM-COOH (G4-PAMAM-COOH) on the collagenolytic activities of endogenous MMPs, the interaction between G4-PAMAM-COOH and demineralized dentine collagen and the influence of G4-PAMAM-COOH pre-treatment on resin-dentine bonding. G4-PAMAN-COOH not only inhibited exogenous soluble rhMMP9 but also hampered the proteolytic activities of dentine collagen-bound MMPs. Cooperated with the results of G4-PAMAM-COOH absorption and desorption, FTIR spectroscopy provided evidence for the exclusive electrostatic interaction rather than hydrogen or covalent bonding between G4-PAMAM-COOH and dentine collagen. Furthermore, G4-PAMAM-COOH pre-treatment showed no damage to resin-dentine bonding because it did not significantly decrease the elastic modulus of the demineralized dentine, degree of conversion, penetration of the adhesive into the dentinal tubules or ultimate tensile strength. Thus, G4-PAMAM-COOH can effectively inactivate MMPs, retard the enzymolysis of collagen by MMPs and scarcely influence the application of resin-dentine bonding.

4.
J Mech Behav Biomed Mater ; 89: 81-88, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30265869

RESUMO

This study investigated carboxymethyl chitosan (CMC)-induced biomimetic mineralization of collagen fibrils, with the aim of synthesizing experimental resins doped with CMC and calcium phosphate microfillers to remineralize artificial caries-affected dentin (ACAD) and enhance resin-dentin bonding durability. A size exclusion test provided evidence for the rejection of CMC (Mw 150 kDa) by collagen fibrils. Transmission electron microscopy and selected area electron diffraction conducted on reconstituted two-dimensional collagen showed typical deposition of needle-like hydroxyapatite crystals within collagen fibrils through CMC-induced biomimetic mineralization. The Vickers hardness test revealed significant improvement (P < 0.001) of the hardness of ACAD treated with CMC-containing experimental resins. Confocal laser scanning microscopy showed reduced dentin permeability and defect sites after biomimetic mineralization. On microtensile bond strength testing, the CMC-remineralized ACAD had better bonding with resin than ACAD and traditionally remineralized ACAD in both self-etch and etch-and-rinse bonding modes (P < 0.001). In conclusion, CMC is efficient in directing the biomimetic mineralization of collagen fibrils. The experimental resins containing CMC can induce dentin biomimetic remineralization and improve the bonding performance of ACAD.


Assuntos
Fosfatos de Cálcio/química , Quitosana/análogos & derivados , Cárie Dentária/metabolismo , Dentina/metabolismo , Minerais/metabolismo , Resinas Sintéticas/química , Resinas Sintéticas/farmacologia , Materiais Biocompatíveis/química , Materiais Biocompatíveis/farmacologia , Biomimética , Quitosana/química , Colágeno/metabolismo , Dentina/efeitos dos fármacos , Dureza
5.
ACS Biomater Sci Eng ; 5(2): 817-830, 2019 Feb 11.
Artigo em Inglês | MEDLINE | ID: mdl-33405842

RESUMO

Fluoride has essential effects on bone physiological activity and is widely used in bone biomaterials modification. However, this beneficial effect is highly related to the dose range and improper dosing can lead to pathological conditions such as fluorosis of bone. Therefore, this study first investigated the dose dependent effect of fluoride on bone regeneration. In the range of 0.24-240 µM, in vivo vascularized bone formation can be achieved via fine-tuning the fluoride concentration, and the peak osteogenic effect was found at 2.4-24 µM. The underlying mechanism is related to the modulation of the osteoimmune environment. Fluoride elicited significant osteoimmunomodulatory effect in modulation of the inflammatory cytokines and expression of osteogenic factors (BMP2, OSM, spermine/spermidine) and angiogenic factor (VEGF, IGF-1) during the early response. Fluorine with the doses of 2.4 and 24 µM could increase polyamines and IGF-1 production in macrophages, thus promoting osteogenesis of BMSCs and angiogenesis of HUVECs. These doses could also inhibit the inflammatory response of macrophages. In vitro osteogenesis and angiogenesis were both improved by the fluorine (2.4 and 24 µM)/macrophage conditioned medium, which is consistent with the in vivo results. These results collectively imply that fluoride is an effective osteoimmunomodulatory agent that can regulate both osteogenesis and angiogenesis. "Osteoimmune-smart" bone biomaterials can be developed via incorporating fluorine, and the release concentration should be controlled within the range of 2.4-24 µM for improved bone formation.

6.
Exp Cell Res ; 372(2): 178-187, 2018 11 15.
Artigo em Inglês | MEDLINE | ID: mdl-30287143

RESUMO

Oral diseases, such as periapical periodontitis and periodontitis, are characterized by inflammation-induced bone loss. LL-37, a human antimicrobial peptide (AMP), has multiple biological functions and the potential to promote osteogenesis. Therefore, this study aimed to investigate the regulatory effects of LL-37 within normal and inflammatory microenvironments. The roles of P2X7 receptor (P2X7R) and mitogen-activated protein kinase (MAPK) signaling pathway were also demonstrated. The results showed that LL-37 promoted bone marrow stromal cell (BMSC) proliferation, migration and osteogenic differentiation. LL-37 inhibited the expression of the inflammatory cytokines interleukin-1ß (IL-1ß), tumor necrosis factor-α (TNF-α) and receptor activator of nuclear factor kappa-B ligand (RANKL) at both protein and gene levels, and attenuated the lipopolysaccharide (LPS)-induced inhibition of osteogenesis. Immunofluorescence (IF) confirmed P2X7R expression in BMSCs. BBG, a P2X7R antagonist, significantly attenuated LL-37-promoted osteogenesis. The phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2) and c-Jun NH2-terminal kinase (JNK) increased after LL-37 stimulation, which did not affect p38 phosphorylation. The effects of LL-37 on osteogenesis-related gene expression were markedly attenuated by selective inhibitors of ERK1/2 and JNK. Furthermore, a mouse model of LPS-stimulated calvarial osteolysis was established, and results showed that LL-37 markedly inhibited osteoclastic bone resorption. In conclusion, we speculate that LL-37 inhibits inflammation and promotes BMSC osteogenesis via P2X7R and MAPK signaling pathway.


Assuntos
Peptídeos Catiônicos Antimicrobianos/administração & dosagem , Inflamação/tratamento farmacológico , Células-Tronco Mesenquimais/efeitos dos fármacos , Osteogênese/genética , Receptores Purinérgicos P2X7/efeitos dos fármacos , Perda do Osso Alveolar/tratamento farmacológico , Perda do Osso Alveolar/genética , Perda do Osso Alveolar/patologia , Animais , Diferenciação Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Microambiente Celular/efeitos dos fármacos , Regulação da Expressão Gênica no Desenvolvimento/efeitos dos fármacos , Humanos , Inflamação/induzido quimicamente , Inflamação/genética , Inflamação/patologia , Lipopolissacarídeos/toxicidade , Células-Tronco Mesenquimais/metabolismo , Camundongos , Quinases de Proteína Quinase Ativadas por Mitógeno/genética , NF-kappa B/genética , Osteogênese/efeitos dos fármacos , Fosforilação/efeitos dos fármacos , Transdução de Sinais/efeitos dos fármacos
7.
Peptides ; 99: 189-194, 2018 01.
Artigo em Inglês | MEDLINE | ID: mdl-29024714

RESUMO

This study attempted to incorporate the antibacterial peptide nisin into an etch-and-rinse dental adhesive to evaluate the antibacterial activity of the modified adhesive against Streptococcus mutans and the bond strength. Single Bond 2 was used as a negative control, and nisin was incorporated at 1%, 3%, and 5% (w/v). The antibacterial activity against S. mutans was evaluated using the film contact test, the agar diffusion test, XTT assays and confocal laser scanning microscopy (CLSM). The microtensile bond strength (µTBS) of the modified dental adhesive was also evaluated. The cured nisin-incorporated dental adhesive exhibited a significant inhibitory effect on the growth of S. mutans (P<0.05), and the inhibitory effect was strengthened as the nisin concentration increased (P<0.05). However, no significant differences in the agar diffusion test were found for the cured nisin-incorporated adhesives compared with the control group. Based on XTT results and CLSM images, the cured nisin-incorporated adhesive interfered with the adherence of S. mutans and the integrity of its biofilms (P<0.05). Compared with the control group, the 1% nisin group did not exhibit a significant difference in µTBS (P>0.05), whereas the 3% and 5% nisin groups displayed decreased bond strength (P<0.05).


Assuntos
Antibacterianos , Cimentos Dentários , Nisina , Streptococcus mutans/crescimento & desenvolvimento , Antibacterianos/química , Antibacterianos/farmacologia , Cimentos Dentários/síntese química , Cimentos Dentários/química , Cimentos Dentários/farmacologia , Nisina/química , Nisina/farmacologia
8.
Acta Biomater ; 57: 435-448, 2017 07 15.
Artigo em Inglês | MEDLINE | ID: mdl-28499631

RESUMO

Limitations associated with wet-bonding led to the recent development of a selective demineralization strategy in which dentin was etched with a reduced concentration of phosphoric acid to create exclusive extrafibrillar demineralization of the collagen matrix. However, the use of acidic conditioners removes calcium via diffusion of very small hydronium ions into the intrafibrillar collagen water compartments. This defeats the purpose of limiting the conditioner to the extrafibrillar space to create a collagen matrix containing only intrafibrillar minerals to prevent collapse of the collagen matrix. The present work examined the use of polymeric chelators (the sodium salt of polyacrylic acid) of different molecular weights to selectively demineralize extrafibrillar dentin. These polymeric chelators exhibit different affinities for calcium ions (isothermal titration calorimetry), penetrated intrafibrillar dentin collagen to different extents based on their molecular sizes (modified size-exclusion chromatography), and preserve the dynamic mechanical properties of mineralized dentin more favorably compared with completely demineralized phosphoric acid-etched dentin (nanoscopical dynamic mechanical analysis). Scanning and transmission electron microscopy provided evidence for retention of intrafibrillar minerals in dentin surfaces conditioned with polymeric chelators. Microtensile bond strengths to wet-bonded and dry-bonded dentin conditioned with these polymeric chelators showed that the use of sodium salts of polyacrylic acid for chelating dentin prior to bonding did not result in significant decline in resin-dentin bond strength. Taken together, the findings led to the conclusion that a chelate-and-rinse conditioning technique based on extrafibrillar collagen demineralization bridges the gap between wet and dry dentin bonding. STATEMENT OF SIGNIFICANCE: The chelate-and-rinse dental adhesive bonding concept differentiates from previous research in that it is based on the size-exclusion characteristics of fibrillar collagen; molecules larger than 40kDa are prevented from accessing the intrafibrillar water compartments of the collagen fibrils. Using this chelate-and-rinse extrafibrillar calcium chelation concept, collagen fibrils with retained intrafibrillar minerals will not collapse upon air-drying. This enables adhesive infiltration into the mineral-depleted extrafibrillar spaces without relying on wet-bonding. By bridging the gap between wet and dry dentine bonding, the chelate-and-rinse concept introduces additional insight to the field by preventing exposure of endogenous proteases via preservation of the intrafibrillar minerals within a collagen matrix. If successfully validated, this should help prevent degradation of resin-dentine bonds by collagenolytic enzymes.


Assuntos
Colágeno/química , Dentina/química , Dente Molar/química , Desmineralização do Dente , Humanos
9.
Acta Biomater ; 49: 16-35, 2017 02.
Artigo em Inglês | MEDLINE | ID: mdl-27845274

RESUMO

Antimicrobial peptides (AMPs) are short cationic host-defense molecules that provide the early stage of protection against invading microbes. They also have important modulatory roles and act as a bridge between innate and acquired immunity. The types and functions of oral AMPs were reviewed and experimental reports on the use of natural AMPs and their synthetic mimics in caries and pulpal infections were discussed. Natural AMPs in the oral cavity, predominantly defensins, cathelicidins and histatins, possess antimicrobial activities against oral pathogens and biofilms. Incomplete debridement of microorganisms in root canal space may precipitate an exacerbated immune response that results in periradicular bone resorption. Because of their immunomodulatory and wound healing potentials, AMPs stimulate pro-inflammatory cytokine production, recruit host defense cells and regulate immuno-inflammatory responses in the vicinity of the pulp and periapex. Recent rapid advances in the development of synthetic AMP mimics offer exciting opportunities for new therapeutic initiatives in root canal treatment and regenerative endodontics. STATEMENT OF SIGNIFICANCE: Identification of new therapeutic strategies to combat antibiotic-resistant pathogens and biofilm-associated infections continues to be one of the major challenges in modern medicine. Despite the presence of commercialization hurdles and scientific challenges, interests in using antimicrobial peptides as therapeutic alternatives and adjuvants to combat pathogenic biofilms have never been foreshortened. Not only do these cationic peptides possess rapid killing ability, their multi-modal mechanisms of action render them advantageous in targeting different biofilm sub-populations. These factors, together with adjunctive bioactive functions such as immunomodulation and wound healing enhancement, render AMPs or their synthetic mimics exciting candidates to be considered as adjuncts in the treatment of caries, infected pulps and root canals.


Assuntos
Peptídeos Catiônicos Antimicrobianos/uso terapêutico , Materiais Biomiméticos/uso terapêutico , Cárie Dentária/tratamento farmacológico , Polpa Dentária/microbiologia , Animais , Peptídeos Catiônicos Antimicrobianos/farmacologia , Materiais Biomiméticos/farmacologia , Cárie Dentária/microbiologia , Polpa Dentária/efeitos dos fármacos , Endodontia , Humanos , Imunomodulação/efeitos dos fármacos
10.
Eur J Oral Sci ; 125(1): 72-80, 2017 02.
Artigo em Inglês | MEDLINE | ID: mdl-27996182

RESUMO

The biomimetic remineralization of apatite-depleted dentin is a potential method for enhancing the durability of resin-dentin bonding. To advance this strategy from its initial proof-of-concept design, we sought to investigate the characteristics of polyacrylic acid (PAA) adsorption to desorption from type I collagen and to test the mineralization ability of PAA-bound collagen. Portland cement and ß-tricalcium phosphate (ß-TCP) were homogenized with a hydrophilic resin blend to produce experimental resins. The collagen fibrils reconstituted on nickel (Ni) grids were mineralized using different methods: (i) group I consisted of collagen treated with Portland cement-based resin in simulated body fluid (SBF); (ii) group II consisted of PAA-bound collagen treated with Portland cement-based resin in SBF; and (iii) group III consisted of PAA-bound collagen treated with ß-TCP-doped Portland cement-based resin in deionized water. Intrafibrillar mineralization was evaluated using transmission electron microscopy. We found that a carbonyl-associated peak at pH 3.0 increased as adsorption time increased, whereas a hydrogen bond-associated peak increased as desorption time increased. The experimental resins maintained an alkaline pH and the continuous release of calcium ions. Apatite was detected within PAA-bound collagen in groups II and III. Our results suggest that PAA-bound type I collagen fibrils can be mineralized using Portland cement-based resins.


Assuntos
Resinas Acrílicas/química , Colágeno Tipo I/química , Cimentos Dentários/química , Cimentos de Resina/química , Adsorção , Biomimética , Fosfatos de Cálcio/química , Colagem Dentária , Teste de Materiais , Microscopia Eletrônica de Transmissão , Níquel/química , Espectroscopia de Infravermelho com Transformada de Fourier
11.
Zhonghua Kou Qiang Yi Xue Za Zhi ; 51(3): 148-53, 2016 Mar.
Artigo em Chinês | MEDLINE | ID: mdl-26980652

RESUMO

OBJECTIVE: To investigate the effect of epigallocatechin-3-gallate (EGCG) on biomodification of demineralized dentine substrate, in its permeability, hydrophobicity, and inhibition ability to collagen enzymatic degradation. METHODS: The dentine substrates were treated with simulated pulpal pressure created by mixtures of 0.02%, 0.1% EGCG/bovine serum albumin (BSA) in acidic environment (pH4.4) for 48 h. A fluid-transport model was used to measure the fluid permeability through demineralized dentine substrate. Positive replicas of dentine substrate were fabricated before and after being subjected to acidic environment for scanning electron microscope (SEM) examination. The blank group contained no EGCG and the positive group were treated with Gluma desensitizer. Static contact angle measurements on demineralized dentin and 0.1% EGCG primed dentin were performed by contact angle analyzer. The priming time were 60 s, 120 s, 0.5 h, 1 h. Dentine specimens bonded with Adper single bond 2 were subjected to 100 mg/L collagenase and observed under SEM. Resin-bonded specimens (with 0.02%, 0.1%, 0.5% EGCG priming, or without EGCG priming) were created for micro-tensile bond strength evaluation (MTBS). Resin-bonded specimens after thermol cycling were created for MTBS evaluation. RESULTS: The fluid permeability in the blank control group increased ([151.3±22.3]%), the fluid permeability in 0.1% EGCG/BSA group decreased ([23.7±6.3]%). Compared to the blank control group, the contact angle of 120 s, 0.5 h, 1 h groups increased by 31.0%, 53.5%, 57.8% in deep dentin and 37.4%, 59.3%, 62.4% in shallow dentin. The SEM examination showed that 0.1% and 0.5% EGCG priming for 120 s significantly increased dentin collagen's resistance to collagenase. The immediate MTBS of 0.1% and 0.5% EGCG groups were (29.4±4.8) and (19.8± 4.9) MPa. After thermol cycling, the MTBS of 0.1% and 0.5% EGCG groups were (19.9±5.1) and (15.3± 6.3) MPa. CONCLUSIONS: Under acidic environment (pH4.4), the 0.1% EGCG can reduce dentine permeability under acidic environment. The 0.1% EGCG can increase hydrophobicity of dentin substrate, and strengthen dentin substrate's resistance to collagenase hydrolysis, thus increased the resin-dentin bonding durability.


Assuntos
Catequina/análogos & derivados , Permeabilidade da Dentina/efeitos dos fármacos , Dentina/efeitos dos fármacos , Condicionamento Ácido do Dente , Catequina/farmacologia , Colágeno/química , Colágeno/efeitos dos fármacos , Colagenases/farmacologia , Resinas Compostas , Colagem Dentária , Cimentos Dentários , Polpa Dentária , Dentina/química , Adesivos Dentinários , Glutaral/farmacologia , Concentração de Íons de Hidrogênio , Hidrólise , Metacrilatos/farmacologia , Microscopia Eletrônica de Varredura , Pressão , Cimentos de Resina , Soroalbumina Bovina/farmacologia , Resistência à Tração , Fatores de Tempo
12.
Sci Technol Adv Mater ; 16(3): 035006, 2015 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-27877807

RESUMO

Biological hydroxyapatite, derived from animal bones, is the most widely used bone substitute in orthopedic and dental treatments. Fluorine is the trace element involved in bone remodeling and has been confirmed to promote osteogenesis when administered at the appropriate dose. To take advantage of this knowledge, fluorinated porcine hydroxyapatite (FPHA) incorporating increasing levels of fluoride was derived from cancellous porcine bone through straightforward chemical and thermal treatments. Physiochemical characteristics, including crystalline phases, functional groups and dissolution behavior, were investigated on this novel FPHA. Human osteoblast-like MG63 cells were cultured on the FPHA to examine cell attachment, cytoskeleton, proliferation and osteoblastic differentiation for in vitro cellular evaluation. Results suggest that fluoride ions released from the FPHA play a significant role in stimulating osteoblastic activity in vitro, and appropriate level of fluoridation (1.5 to 3.1 atomic percents of fluorine) for the FPHA could be selected with high potential for use as a bone substitute.

13.
Clin Chim Acta ; 438: 231-5, 2015 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-25181611

RESUMO

BACKGROUND: The majority of studies examining anionic composition in human saliva have focused on inorganic anions only, and accompanying organic anion concentration has often been overlooked in the development of artificial salivas. The purpose of this study was to examine the major organic anionic species profile of human saliva, with a view to gaining further insight into human salivary chemistry. METHODS: Unstimulated whole saliva was collected from 11 healthy volunteers over a period of 18months. Samples were subjected to ion chromatography for detection and quantification of organic and inorganic anions. RESULTS: Among organic anions, acetate was predominant (0.24±0.38mmol/l), with lactate (0.01±0.04mmol/l), propionate (0.03±0.07mmol/l), and formate (0.02±0.03mmol/l) detected at lower levels. Acetate, propionate, and formate were detected in at least 80% of the saliva samples. Positive partial correlations were found between phosphate and sulfate (r=0.510, p-value=1.545×10(-4)), and between propionate and acetate (r=0.836, p-value=7.510×10(-14)). CONCLUSION: Organic anionic species were consistently detected at low levels in saliva samples collected longitudinally over a period of 18months. These salivary components must be considered in order to understand saliva chemistry, and should not be neglected during the continuing development of artificial salivas.


Assuntos
Ânions/análise , Saliva/química , Acetatos , Cromatografia por Troca Iônica , Feminino , Formiatos , Humanos , Ácido Láctico , Masculino , Fosfatos , Propionatos , Sulfatos , Adulto Jovem
14.
Huan Jing Ke Xue ; 35(6): 2249-55, 2014 Jun.
Artigo em Chinês | MEDLINE | ID: mdl-25158503

RESUMO

Based on the comparison of phosphorous removal in sludge water and its supernatant by polyaluminum chloride (PAC), separate and combined effects of Al/P mole ratio, pH and mixing speed (MS) on phosphorus removal by PAC for the supernatant of thickening and dewatering sludge water were analyzed by the response surface methodology (RSM), and kinetics of phosphorous removal by PAC was also investigated. The results showed that direct addition of PAC into sludge water deteriorated its settling characteristics, and suspended solids in the sludge water could decrease the phosphorus removal efficiency. The RSM analysis results demonstrated that the effect of individual operation parameter on phosphorus removal was followed as the order of Al/P > pH > MS, and the optimal process parameters with phosphorus removal efficiency of 97.8% were Al/P = 2.49, pH = 8.3 and MS 398 r x min(-1), respectively. The verification experiment showed that the RSM model was valid and effective. Kinetic analysis illustrated that phosphorus removal by PAC was divided into two stages, a chemical precipitation and rapid adsorption stage, followed by a chemical precipitation stage that conformed to the second-order kinetics.


Assuntos
Hidróxido de Alumínio/química , Fósforo/análise , Esgotos/química , Eliminação de Resíduos Líquidos/métodos , Adsorção , Precipitação Química , Cinética , Água/química
15.
Zhonghua Kou Qiang Yi Xue Za Zhi ; 49(4): 224-8, 2014 Apr.
Artigo em Chinês | MEDLINE | ID: mdl-24969597

RESUMO

OBJECTIVE: To investigate the functions of sodium tripolyphosphate (STTP) and polyacrylic acid (PAA) in the process of collagen biomimetic mineralization. This would allow future applications to other collagen matrices such as bone collagen or 3-D collagen scaffolds. METHODS: Glass cover slips and transmission electron microscopy (TEM) grids were coated with reconstituted typeIcollagen fibrils. Mineralization of the reconstituted collagens was demonstrated with scanning electron microscopy (SEM) and TEM using a Portland cement-containing resin composite and a phosphate-containing fluid in the presence of PAA and STTP. The rest were immersed in a biomimetic remineralization medium without PAA and/or STTP (control). RESULTS: In the presence of PAA and STTP in the mineralization medium, intrafibrillar mineralization based on the non-classical crystallisation pathway could be identified. Mineral phases were evident within the collagen fibrils as early as 12 h after the initially-formed amorphous calcium phosphate nanoprecursors were transformed into apatite nanocrystals. Collagens at 72 h were heavily mineralized with periodically arranged intrafibrillar apatite platelets. Conversely, only large mineral spheres with no preferred association with collagen fibrils were observed in the absence of biomimetic analogues in the medium (control). CONCLUSIONS: Intrafibrillar apatite deposition can be achieved via biomimetic mineralization system containing PAA and STTP when amorphous calcium phosphate precursor is stabilized.


Assuntos
Resinas Acrílicas/química , Biomimética , Colágeno Tipo I/química , Polifosfatos/química , Apatitas , Osso e Ossos , Fosfatos de Cálcio , Colágeno , Resinas Compostas , Humanos , Microscopia Eletrônica de Transmissão , Minerais , Fosfatos , Tecidos Suporte
16.
Zhonghua Kou Qiang Yi Xue Za Zhi ; 49(11): 672-6, 2014 Nov.
Artigo em Chinês | MEDLINE | ID: mdl-25622502

RESUMO

OBJECTIVE: To evaluate the sealing properties of three resin- based sealers, EndoREZ, RealSEAL and RealSEAL SE. METHODS: Forthy-eight extracted human anterior teeth with single root and canal were prepared using ProTaper files with crown-down technique to F3. The teeth were filled with three sealer respectively with hot gutta- percha vertical condensation technique simulating the clinical situation. Leakage quantity was detected using computerized fluid filtration meter with 10 samples in each group. The cross section morphology of apical parts of roots of 5 mm was observed with scanning electron microscope and transmission electron microscope in 3 samples of each group, respectively. RESULTS: The leakage quantity of EndoREZ, RealSEAL and RealSEAL SE were (2.61±0.60), (1.43±0.11) and (1.76±0.18) µl/min, respectively. The gaps between the the sealer and the canal wall were increased in in order of RealSEAL, RealSEAL SE and EndoREZ. No obvious demineralized dentin under EndoREZ and the smear layer was not completed removed. The partly demineralized dentin was observed under RealSEAL and the smear layer was totally removed. The partly demineralized dentin was seen under RealSEAL SE and the majority of smear layer was removed. CONCLUSIONS: Among the three resin- based sealers, RealSEAL has the best sealing properties, followed by RealSEAL SE and EndoREZ.


Assuntos
Resinas Compostas , Selantes de Fossas e Fissuras , Materiais Restauradores do Canal Radicular , Infiltração Dentária , Dentina , Resinas Epóxi , Guta-Percha , Humanos , Dente , Raiz Dentária
17.
J Formos Med Assoc ; 111(6): 340-6, 2012 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-22748625

RESUMO

BACKGROUND/PURPOSE: The aim of this study was to evaluate a new low-shrinkage, methacrylate resin-based root canal sealer (LSRCS) to determine its bond strength in radicular dentin and sealing ability. METHODS: Extracted single-root teeth were randomly divided into three experimental groups (n=20) for obturation with Gutta-percha (GP)/AH Plus, Resilon/Epiphany, or Resilon/LSRCS. One-half of each experimental group was analyzed by the push-out test, using sections perpendicular to the long axis divided into 1mm serial slices and a universal testing machine to detect the loading force. The other half was analyzed by the dye penetration test using 2% methylene blue solution (pH=7) and measuring dye leakage under a stereomicroscope. RESULTS: The push-out test revealed significant differences (p<0.05) in bond strength produced by the three sealers; the GP/AH Plus group showed the highest bond strength, followed by Resilon/LSRCS and Resilon/Epiphany. According to the microleakage data, GP/AH Plus showed the least dye penetration, which was significantly less than Resilon/Epiphany and Resilon/LSRCS. There was no difference in apical leakage between Resilon/Epiphany and Resilon/LSRCS. CONCLUSION: The newly developed LSRCS, although not superior to AH Plus in bond strength or sealing ability, possesses monoblock potential and application prospects.


Assuntos
Metacrilatos , Resinas Sintéticas , Materiais Restauradores do Canal Radicular , Corantes , Resinas Epóxi , Humanos , Técnicas In Vitro , Fenômenos Mecânicos , Azul de Metileno , Microscopia Eletrônica de Varredura , Materiais Restauradores do Canal Radicular/química , Suporte de Carga
18.
Hua Xi Kou Qiang Yi Xue Za Zhi ; 29(1): 1-4, 2011 Feb.
Artigo em Chinês | MEDLINE | ID: mdl-21427889

RESUMO

The application of adhesive root canal filling materials is the tendency in root canal obturation. The orientation is to develop the adhesive core material and sealer making a whole structure. In this review, we summarized the researches on the resin-dentin adhesion in the root canal obturation.


Assuntos
Adesivos Dentinários , Dentina , Humanos , Materiais Restauradores do Canal Radicular , Obturação do Canal Radicular
19.
Acta Biomater ; 7(4): 1742-51, 2011 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-21111071

RESUMO

Biominerals exhibit complex hierarchical structures derived from bottom-up self-assembly mechanisms. Type I collagen serves as the building block for mineralized tissues such as bone and dentin. In the present study, 250-300 µm thick, partially demineralized collagen scaffolds exhibiting a gradient of demineralization from the base to surface were mineralized using a classical top-down approach and a non-classical bottom-up approach. The top-down approach involved epitaxial growth over seed crystallites. The bottom-up approach utilized biomimetic analogs of matrix proteins to stabilize amorphous calcium phosphate nanoprecursors and template apatite nucleation and growth within the collagen matrix. Micro-computed tomography and transmission electron microscopy were employed to examine mineral uptake and apatite arrangement within the mineralized collagen matrix. The top-down approach could mineralize only the base of the partially demineralized scaffold, where remnant seed crystallites were abundant. Minimal mineralization was observed along the surface of the scaffold; extrafibrillar mineralization was predominantly observed. Conversely, the entire partially demineralized scaffold, including apatite-depleted collagen fibrils, was mineralized by the bottom-up approach, with evidence of both intrafibrillar and extrafibrillar mineralization. Understanding the different mechanisms involved in these two mineralization approaches is pivotal in adopting the optimum strategy for fabricating novel nanostructured materials in bioengineering research.


Assuntos
Colágeno/metabolismo , Minerais/metabolismo , Nanotecnologia/métodos , Tecidos Suporte/química , Colágeno/ultraestrutura , Humanos , Concentração de Íons de Hidrogênio , Fatores de Tempo
20.
Acta Biomater ; 6(9): 3729-39, 2010 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-20304110

RESUMO

Biomineralization is a dehydration process in which water from the intrafibrillar compartments of collagen fibrils are progressively replaced by apatites. As water is an important element that induces a lack of durability of resin-dentin bonds, this study has examined the use of a biomimetic remineralization strategy as a progressive dehydration mechanism to preserve joint integrity and maintain adhesive strength after ageing. Human dentin surfaces were bonded with dentin adhesives, restored with resin composites and sectioned into sticks containing the adhesive joint. Experimental specimens were aged in a biomimetic analog-containing remineralizing medium and control specimens in simulated body fluid for up to 12 months. Specimens retrieved after the designated periods were examined by transmission electron microscopy for the presence of water-rich regions using a silver tracer and for collagen degradation within the adhesive joints. Tensile testing was performed to determine the potential loss of bond integrity after ageing. Control specimens exhibited severe collagen degradation within the adhesive joint after ageing. Remineralized specimens exhibited progressive dehydration, as manifested by silver tracer reduction and partial remineralization of water-filled microchannels within the adhesive joint, as well as intrafibrillar remineralization of collagen fibrils that were demineralized initially as part of the bonding procedure. Biomimetic remineralization as a progressive dehydration mechanism of water-rich, resin-sparse collagen matrices enables these adhesive joints to resist degradation over a 12-month ageing period, as verified by the conservation of their tensile bond strength. The ability of the proof of concept biomimetic remineralization strategy to prevent bond degradation warrants further development of clinically relevant delivery systems.


Assuntos
Materiais Biomiméticos/farmacologia , Colágeno/metabolismo , Adesivos Dentinários/química , Dessecação/métodos , Resinas Sintéticas/química , Remineralização Dentária/métodos , Humanos , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Resistência à Tração , Fatores de Tempo
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