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1.
Carcinogenesis ; 42(2): 169-179, 2021 02 25.
Artigo em Inglês | MEDLINE | ID: mdl-33152763

RESUMO

Although some previous studies have examined epigenomic alterations in lung adenocarcinomas, correlations between epigenomic events and genomic driver mutations have not been fully elucidated. Single-CpG resolution genome-wide DNA methylation analysis with the Infinium HumanMethylation27 BeadChip was performed using 162 paired samples of adjacent normal lung tissue (N) and the corresponding tumorous tissue (T) from patients with lung adenocarcinomas. Correlations between DNA methylation data on the one hand and clinicopathological parameters and genomic driver mutations, i.e. mutations of EGFR, KRAS, BRAF and HER2 and fusions involving ALK, RET and ROS1, were examined. DNA methylation levels in 12 629 probes from N samples were significantly correlated with recurrence-free survival. Principal component analysis revealed that distinct DNA methylation profiles at the precancerous N stage tended not to induce specific genomic driver aberrations. Most of the genes showing significant DNA methylation alterations during transition from N to T were shared by two or more driver aberration groups. After small interfering RNA knockdown of ZNF132, which showed DNA hypermethylation only in the pan-negative group and was correlated with vascular invasion, the proliferation, apoptosis and migration of cancer cell lines were examined. ZNF132 knockdown led to increased cell migration ability, rather than increased cell growth or reduced apoptosis. We concluded that DNA hypermethylation of the ZNF132 gene participates in the clinicopathological aggressiveness of 'pan-negative' lung adenocarcinomas. In addition, DNA methylation alterations at the precancerous stage may determine tumor aggressiveness, and such alterations that accumulate after driver mutation may additionally modify clinicopathological features through alterations of gene expression.


Assuntos
Adenocarcinoma de Pulmão/genética , Proteínas de Ligação a DNA/genética , Neoplasias Pulmonares/genética , Recidiva Local de Neoplasia/epidemiologia , Lesões Pré-Cancerosas/genética , Fatores de Transcrição/genética , Adenocarcinoma de Pulmão/diagnóstico , Adenocarcinoma de Pulmão/mortalidade , Adenocarcinoma de Pulmão/cirurgia , Adulto , Idoso , Apoptose/genética , Carcinogênese/genética , Linhagem Celular Tumoral , Movimento Celular/genética , Proliferação de Células/genética , Metilação de DNA , Epigênese Genética , Feminino , Seguimentos , Regulação Neoplásica da Expressão Gênica , Técnicas de Silenciamento de Genes , Humanos , Pulmão/patologia , Pulmão/cirurgia , Neoplasias Pulmonares/diagnóstico , Neoplasias Pulmonares/mortalidade , Neoplasias Pulmonares/cirurgia , Masculino , Pessoa de Meia-Idade , Mutação , Recidiva Local de Neoplasia/genética , Estadiamento de Neoplasias , Pneumonectomia , Lesões Pré-Cancerosas/diagnóstico , Lesões Pré-Cancerosas/patologia
2.
Sensors (Basel) ; 17(12)2017 Dec 06.
Artigo em Inglês | MEDLINE | ID: mdl-29210985

RESUMO

Carbon fiber-reinforced plastic (CFRP) is widely used for structural members of transportation vehicles such as automobile, aircraft, or spacecraft, utilizing its excellent specific strength and specific rigidity in contrast with the metal. Short carbon fiber composite materials are receiving a lot of attentions because of their excellent moldability and productivity, however they show complicated behaviors in fatigue fracture due to the random fibers orientation. In this study, thermoelastic stress analysis (TSA) using an infrared thermography was applied to evaluate fatigue damage in short carbon fiber composites. The distribution of the thermoelastic temperature change was measured during the fatigue test, as well as the phase difference between the thermoelastic temperature change and applied loading signal. Evolution of fatigue damage was detected from the distribution of thermoelastic temperature change according to the thermoelastic damage analysis (TDA) procedure. It was also found that fatigue damage evolution was more clearly detected than before by the newly developed thermoelastic phase damage analysis (TPDA) in which damaged area was emphasized in the differential phase delay images utilizing the property that carbon fiber shows opposite phase thermoelastic temperature change.

3.
J Biomed Mater Res B Appl Biomater ; 112(1): e35335, 2024 01.
Artigo em Inglês | MEDLINE | ID: mdl-37772460

RESUMO

Calcium phosphate cement (CPC) is generally used for bone repair and augmentation. Poloxamers are tri-block copolymers that are used as surfactants but have applications in drug and antibiotic delivery. However, their biological effects on bone regeneration systems remain unelucidated. Here, we aimed to understand how supplementing the prototype CPC with poloxamer would impact cellular activity and its function as a bone-grafting material. A novel CPC, modified beta-tricalcium phosphate (mß-TCP) powder, was developed through a planetary ball-milling process using a beta-tricalcium phosphate (ß-TCP). The mß-TCP dissolves rapidly and accelerates hydroxyapatite precipitation; successfully shortening the cement setting time and enhancing the strength. Furthermore, the addition of poloxamer 407 to mß-TCP could reduce the risk of leakage from bone defects and improve fracture toughness while maintaining mechanical properties. In this study, the poloxamer addition effects (0.05 and 0.1 g/mL) on the cellular activities of MC3T3-E1 cells cultured in vitro were investigated. The cell viability of mß-TCP containing poloxamer 407 was similar to that of mß-TCP. All specimens showed effective cell attachment and healthy polygonal extension of the cytoplasm firmly attached to hydroxyapatite (HA) crystals. Therefore, even with the addition of poloxamer to mß-TCP, it does not have a negative effect to osteoblast growth. These data demonstrated that the addition of poloxamer 407 to mß-TCP might be considered a potential therapeutic application for the repair and regeneration of bone defects.


Assuntos
Fosfatos de Cálcio , Poloxâmero , Poloxâmero/farmacologia , Fosfatos de Cálcio/farmacologia , Fosfatos de Cálcio/química , Cimentos Ósseos/farmacologia , Cimentos Ósseos/química , Hidroxiapatitas
4.
J Biomed Mater Res B Appl Biomater ; 111(1): 184-193, 2023 01.
Artigo em Inglês | MEDLINE | ID: mdl-36053744

RESUMO

Decellularized extracellular matrix (dECM) hydrogels have cytocompatibility, and are currently being investigated for application in soft tissues as a material that promotes native cell infiltration and tissue reconstruction. A dECM hydrogel has broad potential for application in organs with complex structures or various tissue injury models. In this study, we investigated the practical application of a dECM hydrogel by injecting a kidney-derived dECM hydrogel into a rat partial nephrectomy model. The prepared dECM hydrogel was adjustable in viscosity to allow holding at the excision site, and after gelation, had an elastic modulus similar to that of kidney tissue. In addition, the migration of renal epithelial cells and vascular endothelial cells embedded in dECM hydrogels was observed in vitro. Four weeks after injection of the dECM hydrogel to the partial excision site of the kidneys, infiltration of renal tubular constituent cells and native cells with high proliferative activity, as well as angiogenesis, were observed inside the injected areas. This study is the first to show that dECM hydrogels can be applied to the kidney, one of the most complex structural organs and that they can function as a scaffold to induce angiogenesis and infiltration of organ-specific renal tubular constituent cells, providing fundamental insights for further application of dECM hydrogels.


Assuntos
Células Endoteliais , Hidrogéis , Ratos , Animais , Hidrogéis/química , Matriz Extracelular/química , Injeções , Nefrectomia , Engenharia Tecidual , Alicerces Teciduais/química
5.
J Prosthodont Res ; 67(3): 384-391, 2023 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-36288959

RESUMO

PURPOSE: We aimed to evaluate the effectiveness of photoreactive 2-methacryloyloxyethyl phosphorylcholine (MPC) in inhibiting Candida albicans biofilm formation on polymethyl methacrylate (PMMA) and assess its mechanism and need for re-application by evaluating its interaction with salivary mucin and durability during temperature changes. METHODS: PMMA discs were used as specimens. The MPC coating was applied using the spray and cure technique for the treatment groups, whereas no coating was applied to the control. The MPC treatment (MT) groups were further differentiated based on the number of thermal cycles involved (0, 1000, 2500, and 5000). The optical density was measured to assess mucin adsorption (MA). Contact angle (CA) was calculated to evaluate surface hydrophilicity. The presence of MPC components on the PMMA surface was assessed using X-ray photoelectron spectroscopy (XPS). C. albicans biofilms were evaluated qualitatively (scanning electron microscope images) and quantitatively (colony-forming units (CFUs)). Statistical analysis was conducted using two-way analysis of variance and Tukey's multiple comparison test. RESULTS: MA rate and CA increased significantly in the MT groups, which exhibited significantly fewer CFUs and thinner biofilms than those of the control group. Based on the XPS, MA, and CFU evaluations, the durability and efficacy of the MPC coating were considered stable up to 2500 thermal cycles. Additionally, a significant interaction was observed between mucin concentration and MPC efficacy. CONCLUSIONS: The photoreactive MPC coating, which was resistant to temperature changes for approximately 3 months, effectively prevented C. albicans biofilm formation by modifying surface hydrophilicity and increasing mucin adsorption.


Assuntos
Resinas Acrílicas , Candida albicans , Resinas Acrílicas/química , Polímeros , Polimetil Metacrilato/farmacologia , Polimetil Metacrilato/química , Propriedades de Superfície , Biofilmes , Mucinas
6.
J Mech Behav Biomed Mater ; 130: 105182, 2022 06.
Artigo em Inglês | MEDLINE | ID: mdl-35305410

RESUMO

A new CPC was developed in this study using a ß-TCP powder mechano-chemically modified by ball-milling. The prototype CPC exhibits excellent fluidity for easy injection into bone defects; however, there is a risk of leakage from the defects immediately after implantation due to its high fluidity. The addition of poloxamer, an inverse thermoresponsive gelling agent, into CPC optimizes the fluidity. At lower temperatures, it forms a sol and maintains good injectability, whereas at the human body temperature, it transforms to a gel, reducing the fluidity and risk of leakage. In this study, the effects of poloxamer addition of 3, 5, and 10 mass% on the injectability, shape stability, and strength of the prototype CPC were evaluated. The calculated injectability of the prototype CPC pastes containing three different poloxamer contents was higher than that of the CPC paste without poloxamer for 15 min at 37 °C. Furthermore, the shape stability immediately after injection of the three CPC pastes with poloxamer was higher than that of the CPC paste without poloxamer. After 1 week of storage at 37 °C, the compressive strength and diametral tensile strength of the CPC compacts containing 10 mass% poloxamer were similar to those of the CPC compact without poloxamer. Additionally, the CPC compacts containing 10 mass% poloxamer exhibited clear plastic deformation after fracture. These results indicate that the addition of poloxamer to the prototype CPC could reduce the risk of leakage from bone defects and improve the fracture toughness with maintaining the injectability and strength.


Assuntos
Fosfatos de Cálcio , Poloxâmero , Cimentos Ósseos/química , Fosfatos de Cálcio/química , Força Compressiva , Materiais Dentários , Cimentos de Ionômeros de Vidro , Humanos
7.
Dent Mater J ; 41(3): 487-494, 2022 May 31.
Artigo em Inglês | MEDLINE | ID: mdl-35264547

RESUMO

Advancements in dental cements have considerably improved their bond strengths. However, high bond strength often makes the removal of restorations difficult. Thus, smart dental cements that show controllable bond strength are required. A conventional resin-modified glass-ionomer-cement demonstrated a significant reduction in the bond strength after current application. However, for this system, the ions in the cement are released into the oral cavity, resulting in a reduction of the electrical conductivity and in losses of the expected on-demand debonding property. Herein, the effects of immersion in 0.9 and 15% NaCl solutions on the electrical conductivity and debonding properties were investigated. The cement immersed in 0.9% NaCl solution from 1 to 28 days maintained similar bond strength reductions after current application, whereas that in 15% NaCl solution initially showed no bond strength reduction after 1 day but exhibited an increase in the bond strength reduction after immersion for 28 days.


Assuntos
Colagem Dentária , Cimentos de Ionômeros de Vidro , Resinas Compostas/química , Materiais Dentários/química , Análise do Estresse Dentário , Condutividade Elétrica , Cimentos de Ionômeros de Vidro/química , Imersão , Teste de Materiais , Cimentos de Resina/química , Resistência ao Cisalhamento , Cloreto de Sódio , Propriedades de Superfície
8.
Dent Mater J ; 40(5): 1270-1276, 2021 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-34193725

RESUMO

We aimed to elucidate stress distribution in miniscrews and the surrounding bone when miniscrews inserted at different depths were implanted vertically or obliquely. The distributions of the equivalent stress on the screw surface and the minimum principal stress in the surrounding bone were calculated using finite element models. When the miniscrews were inserted vertically and obliquely, screw head displacement, greatest equivalent stress on the miniscrew surface, and absolute value of minimum principal stresses in the surrounding bone decreased with increasing insertion depth. Stresses in the obliquely inserted miniscrew with upward traction were smaller than in other insertion conditions, irrespective of insertion depth. With the application of orthodontic force, stress distribution around the miniscrew and surrounding bone is closely related to the insertion depth and insertion angle, which mutually affect each other. In particular, the obliquely inserted miniscrew with upward traction might be the most secure against screw failure and fracture.


Assuntos
Procedimentos de Ancoragem Ortodôntica , Parafusos Ósseos , Análise do Estresse Dentário , Análise de Elementos Finitos , Estresse Mecânico
9.
Materials (Basel) ; 14(17)2021 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-34501030

RESUMO

Short fiber reinforced plastics (SFRPs) have excellent moldability and productivity compared to continuous fiber composites. In this study, thermoelastic stress analysis (TSA) was applied to detect delamination defects in short carbon fiber reinforced plastics (SCFRPs). The thermoelastic temperature change ΔTE, phase of thermal signal θE, and second harmonic temperature component ΔTD were measured. In the fatigue test of SCFRP, it was confirmed that changes in ΔTE, θE, and ΔTD appeared in the damaged regions. A staircase-like stress level test for a SCFRP specimen was conducted to investigate the generation mechanism of the ΔTD. The distortion of the temperature change appeared at the maximum tension stress of the sinusoidal load-and when the stress level decreased, the temperature change returned to the original sinusoidal waveform. ΔTD changed according to the change in the maximum stress during the staircase-like stress level test, and a large value of ΔTD was observed in the final ruptured region. A distortion of the temperature change and ΔTD was considered to be caused by the change in stress sharing condition between the fiber and resin due to delamination damage. Therefore, ΔTD can be applied to the detection of delamination defects and the evaluation of damage propagation.

10.
J Cardiol Cases ; 24(4): 149-152, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-35059046

RESUMO

Primary malignant pericardial mesothelioma is an extremely rare disease. Malignant disease of the pericardium is an infrequent cause of cardiac tamponade. Hence, cardiac tamponade in the context of primary malignant mesothelioma of the pericardium is an uncommon clinical scenario. A 67-year-old male patient, an ex-smoker, complaining of progressive lethargy was referred to a hospital for investigation of persistent pericardial effusion. The pericardial fluid cytology was categorized as class Ⅲ. Thereafter, he was referred to our hospital for further evaluation. Fluorodeoxyglucose (FDG) positron emission tomography (PET) revealed FDG accumulation in the pericardium and mediastinal lymph node. Surgical biopsy of the pericardium was performed through a subxiphoid approach for a definitive diagnosis. Histopathological examination revealed diffuse infiltration of the pericardium by a malignant tumor consisting of epithelioid cells with large round nuclei and prominent nucleoli, arranged in a tubular papillary pattern. Finally, the patient was diagnosed with primary malignant pericardial mesothelioma of epithelioid type. The patient died 6 weeks after admission. This diagnosis must be considered in patients having unexplained massive pericardial effusion. Furthermore, we should consider prompt cytological analysis and FDG PET to arrive rapidly at a definitive diagnosis to administer combination chemotherapy that may provide clinical benefit. .

11.
Ann Transl Med ; 9(4): 325, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33708952

RESUMO

BACKGROUND: Sarcopenia characterized by skeletal muscle loss may influence postoperative outcomes through physical decline and weakened immunity. We aimed to investigate clinical significance of sarcopenia in resected early-stage non-small cell lung cancer (NSCLC). METHODS: We retrospectively reviewed 315 consecutive patients with pathologic stage I NSCLC who had undergone lobectomy with systematic nodal dissection. Sarcopenia was defined as the lowest quartile of psoas muscle area on the 3rd vertebra on the high-resolution computed tomography (HRCT) image. Clinicopathological variables were used to investigate the correlation to postoperative complications as well as overall and recurrence-free survival. RESULTS: Upon multivariable analysis, male sex [odds ratio (OR) =5.780, 95% confidence interval (CI): 2.681-12.500, P<0.001], and sarcopenia (OR =21.00, 95% CI: 10.30-42.80, P<0.001) were independently associated with postoperative complications. The sarcopenia group showed significantly lower 5-over all survival (84.4% vs. 69.1%, P<0.001) and recurrence-free survival (77.2% vs. 62.0%, P<0.001) comparing with the non-sarcopenia group. In a multivariable analysis, sarcopenia was an independent prognostic factor [hazard ratio (HR) =1.978, 95% CI: 1.177-3.326, P=0.010] together with age ≥70 years (HR =1.956, 95% CI: 1.141-3.351, P=0.015) and non-adenocarcinoma histology (HR =1.958, 95% CI: 1.159-3.301, P=0.016). CONCLUSIONS: This is the first study which demonstrates that preoperative sarcopenia is significantly associated with unfavorable postoperative complications as well as long-term survival in pathologic stage I NSCLC. This readily available factor on HRCT may provide valuable information to consider possible choice of surgical procedure and perioperative management.

12.
Dent Mater J ; 40(1): 35-43, 2021 Jan 31.
Artigo em Inglês | MEDLINE | ID: mdl-32779608

RESUMO

The enhancement in the bonding strength of advanced dental cements has enabled long-lasting dental restorations. However, the high bonding strength can cause difficulty in removing these restorations. Therefore, "smart" dental cements with simultaneous strong bonding and easy on-demand debonding ability are required. A resin-modified glass-ionomer-cement (RMGIC) with an ionic liquid (IL) has demonstrated significant reduction in the bonding strength with current application (CA). This research investigates the effect of immersion in distilled water on the electric conductivity and bonding strength of RMGIC with and without an IL and CA. The RMGIC without the IL exhibited significant electric conductivity after immersion, and a significant decrease in bonding strength with CA. In comparison, the electric conductivity after immersion and the decrease in bonding strength with CA were greater for RMGIC with the IL. Thus, the feasibility of smart dental cements capable of electrically debonding-on-demand is indicated.


Assuntos
Colagem Dentária , Líquidos Iônicos , Resinas Compostas , Análise do Estresse Dentário , Cimentos de Ionômeros de Vidro , Imersão , Teste de Materiais , Cimentos de Resina , Resistência ao Cisalhamento , Água
13.
Nature ; 429(6987): 52-5, 2004 May 06.
Artigo em Inglês | MEDLINE | ID: mdl-15129276

RESUMO

Enzymes efficiently synthesize biopolymers by organizing monomer units within regularly structured molecular-scale spaces and exploiting weak non-covalent interactions, such as hydrogen bonds, to control the polymerization process. This 'template' approach is both attractive and challenging for synthetic polymer synthesis, where structurally regulated molecular-scale spaces could in principle provide solid-phase reaction sites for precision polymerization. Previously, free-radical polymerization of methyl methacrylate in solutions containing stereoregular isotactic (it) or syndiotactic (st) poly(methyl methacrylate) (PMMA) has been shown to result in template synthesis of the opposite PMMA based on stereocomplex formation with van der Waals interactions. However, using the structure of a solid to determine the stereochemical structure of a polymer has not been satisfactorily achieved. Here we show that macromolecularly porous ultrathin films, fabricated by a single assembly step, can be used for the highly efficient stereoregular template polymerization of methacrylates through stereocomplex formation. This reaction mould accurately transfers its structural properties of stereoregularity, molecular weight and organization within the template to the new polymer.

14.
Dent Mater J ; 29(2): 193-8, 2010 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-20379030

RESUMO

The purpose of this study was to examine the antibacterial activity of composite resin with glass-ionomer filler particles versus that of contemporary commercial composite resins. Three composite resins were used: Beautifil II (containing S-PRG filler), Clearfil AP-X, and Filtek Z250. Resin blocks were bonded to maxillary first molars, and plaque accumulation on the resin block surface was examined after 8 hours. For the antibacterial test, the number of Streptococcus mutans in contact with the composite resin blocks after incubation for 12 hours was determined, and adherence of radiolabeled bacteria was evaluated. Less dental plaque was formed on Beautifil II resin block as compared to the other two materials. Antibacterial test revealed that there were no significant differences in the number of Streptococcus mutans among the three composite resins. However, the adherence of radiolabeled bacteria to the saliva-treated resin surface was significantly (p<0.01) lower in Beautifil II than in the other two materials. These results suggested that Beautifil II could reduce dental plaque formation and bacterial adherence, leading to prevention of secondary caries.


Assuntos
Antibacterianos/farmacologia , Resinas Compostas/farmacologia , Materiais Dentários/farmacologia , Cimentos de Ionômeros de Vidro/farmacologia , Adulto , Aderência Bacteriana , Compostos de Bário/química , Compostos de Bário/farmacologia , Bis-Fenol A-Glicidil Metacrilato/química , Bis-Fenol A-Glicidil Metacrilato/farmacologia , Contagem de Colônia Microbiana , Resinas Compostas/química , Materiais Dentários/química , Placa Dentária/microbiologia , Feminino , Vidro/química , Cimentos de Ionômeros de Vidro/química , Humanos , Masculino , Teste de Materiais , Metacrilatos/química , Metacrilatos/farmacologia , Cimentos de Resina/química , Cimentos de Resina/farmacologia , Saliva/fisiologia , Dióxido de Silício/química , Dióxido de Silício/farmacologia , Método Simples-Cego , Espectrometria por Raios X , Streptococcus mutans/crescimento & desenvolvimento , Propriedades de Superfície , Fatores de Tempo , Zircônio/química , Zircônio/farmacologia
15.
Biomed Mater Eng ; 19(2-3): 193-204, 2009.
Artigo em Inglês | MEDLINE | ID: mdl-19581714

RESUMO

The purpose of this study was to determine the effects of heat treatment on the bioactivity of hydrothermal-modified titanium in CaO solution for improved bioactivity by immersion in simulated body fluid (SBF). The hydrothermal treatment of titanium in CaO solution was performed at 121 degrees C at 0.2 MPa for 1 h in an autoclave followed by 1 h heat treatments at 200, 400, 600 and 800 degrees C simultaneously. The bioactivity of titanium was evaluated by hydroxyapatite precipitation during immersion in SBF. Surface microstructure changes after the heat treatments and immersion in SBF were determined by X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). Heat treatments at high temperatures (600 and 800 degrees C) promoted the synthesis of anatase, increased the thickness of the titanium oxide layer on the modified titanium surface and promoted the synthesis of calcium titanate, which possibly promoted the precipitation of apatite in SBF. The extent of precipitations increased with the time of immersion in SBF and the temperature of the heat treatment. Island-like deposits of needle-like crystals were observed only on the surface of the 600 and 800 degrees C heat-treated specimens after two or four week immersions in SBF. The results suggested that treatments of the surface of hydrothermal-treated titanium specimens at high temperatures (600 and 800 degrees C) could be effective for the surface modification of titanium as an implant material offering better osseointegration.


Assuntos
Materiais Biocompatíveis/química , Líquidos Corporais/química , Cálcio/química , Titânio/química , Absorção , Cristalização/métodos , Temperatura Alta , Teste de Materiais , Tamanho da Partícula , Porosidade , Soluções , Propriedades de Superfície
16.
Dent Mater J ; 28(4): 419-25, 2009 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-19721278

RESUMO

This study aimed to evaluate the effectiveness of self-etching and phosphoric acid-etching orthodontic adhesives for enamel bonding in simulated clinical conditions. By using two self-etching (Transbond Plus, TP; Beauty Ortho Bond, BB) and two acid-etching (Transbond XT, TX; Superbond Orthomite, SB) adhesives, orthodontic brackets were bonded on human premolars (n=10 for each adhesive). Ten teeth without bracket bonding, i.e., intact enamel surfaces, were used as control for SEM observation. After 7-day storage in lactic acid solution, bracket debonding force by means of debonding pliers, adhesive remnant index (ARI), and enamel surface morphology were examined. All the tested adhesives exhibited sufficient bond strength for clinical use. The ARI scores were almost the same among the four adhesives. In terms of SEM observation, the enamel surfaces in the control and TP groups showed a slight change after immersion in lactic acid solution, while the BB group showed less change on the enamel surface compared with the TP group. Meanwhile, the two acid-etching adhesives caused considerable demineralization. Taken together, these findings indicated that the action of self-etching systems was evidently more conservative.


Assuntos
Colagem Dentária , Corrosão Dentária/métodos , Braquetes Ortodônticos , Cimentos de Resina , Dente Pré-Molar , Descolagem Dentária , Esmalte Dentário , Análise do Estresse Dentário , Humanos , Teste de Materiais , Propriedades de Superfície
17.
Dent Mater J ; 37(5): 768-774, 2018 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-29848856

RESUMO

With improvement of bonding strength of recent dental cement, it is difficult nowadays to remove restorations without excessive force or vibration to tooth, occasionally resulting in damage of dentin, enamel, and dental root. Therefore, "smart" dental cement indicating strong bonding and easy debonding-on-demand simultaneously is required. In this research, resin-modified glass-ionomer-cement containing an ionic-liquid, tris(2-hydroxyethyl)methylammonium methylsulfate was produced, and the shear bonding strength before and after direct current application were evaluated. The prototype cement containing 15 to 20 mass% ionic-liquid indicated simultaneously no significant reduction of shear bonding strength from that of the original cement not containing ionic-liquid, and significant reduction of bonding strength to approximately 20% of that of the original cement after direct current application of more than 2 mmC/mm2. The prototype cement in this research demonstrated that the concept of smart dental cement electrically debonding-on-demand is feasible.


Assuntos
Descolagem Dentária/métodos , Cimentos de Ionômeros de Vidro/química , Líquidos Iônicos/química , Cimentos de Resina/química , Resinas Compostas , Eletricidade , Teste de Materiais , Metilaminas/química , Resistência ao Cisalhamento , Ésteres do Ácido Sulfúrico/química , Propriedades de Superfície
18.
Dent Mater J ; 36(5): 590-599, 2017 Sep 26.
Artigo em Inglês | MEDLINE | ID: mdl-28450674

RESUMO

The authors have developed a ß-tricalcium-phosphate (ß-TCP) powder modified mechano-chemically through the application of a ball-milling process (mß-TCP). The resulting powder can be used in a calcium-phosphate-cement (CPC). In this study, the effects of the powder-to-liquid ratio (P/L ratio) on the properties of the CPCs were investigated, and an appropriate P/L ratio that would simultaneously improve injectability and strength was clarified. The mß-TCP cement mixed at a P/L ratio of 2.5 and set in air exhibited sufficient injectability until 20 min after mixing, and strength similar to or higher than that mixed at a P/L ratio of 2.0 and 2.78. Although the mß-TCP cements set in vivo and in SBF were found to exhibit a lower strength than those set in air, it did have an appropriate setting time and strength for clinical applications. In conclusion, P/L ratio optimization successfully improved the strength of injectable mß-TCP cement.


Assuntos
Cimentos Ósseos , Fosfatos de Cálcio , Força Compressiva , Cemento Dentário , Humanos , Teste de Materiais , Pós
19.
J Oral Maxillofac Res ; 7(4): e2, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-28154746

RESUMO

OBJECTIVES: The objective of this study is to develop a Ti fibre knit block without sintering, and to evaluate its deformability and new bone formation in vivo. MATERIAL AND METHODS: A Ti fibre with a diameter of 150 µm was knitted to fabricate a Ti mesh tube. The mesh tube was compressed in a metal mould to fabricate porous Ti fibre knit blocks with three different porosities of 88%, 69%, and 50%. The elastic modulus and deformability were evaluated using a compression test. The knit block was implanted into bone defects of a rabbit's hind limb, and new bone formation was evaluated using micro computed tomography (micro-CT) analysis and histological analysis. RESULTS: The knit blocks with 88% porosity showed excellent deformability, indicating potential appropriateness for bone defect filling. Although the porosities of the knit block were different, they indicated similar elastic modulus smaller than 1 GPa. The elastic modulus after deformation increased linearly as the applied compression stress increased. The micro-CT analysis indicated that in the block with 50% porosity new bone filled nearly all of the pore volume four weeks after implantation. In contrast, in the block with 88% porosity, new bone filled less than half of the pore volume even 12 weeks after implantation. The histological analysis also indicated new bone formation in the block. CONCLUSIONS: The titanium fibre knit block with high porosity is potentially appropriate for bone defect filling, indicating good bone ingrowth after porosity reduction with applied compression.

20.
J Mech Behav Biomed Mater ; 61: 581-589, 2016 08.
Artigo em Inglês | MEDLINE | ID: mdl-27148637

RESUMO

The prosthetic applications of titanium have been challenging because titanium does not possess suitable properties for the conventional casting method using the lost wax technique. We have developed a production method for biomedical application of porous titanium using a moldless process. This study aimed to evaluate the physical and mechanical properties of porous titanium using various particle sizes, shapes, and mixing ratio of titanium powder to wax binder for use in prosthesis production. CP Ti powders with different particle sizes, shapes, and mixing ratios were divided into five groups. A 90:10wt% mixture of titanium powder and wax binder was prepared manually at 70°C. After debinding at 380°C, the specimen was sintered in Ar at 1100°C without a mold for 1h. The linear shrinkage ratio of sintered specimens ranged from 2.5% to 14.2%. The linear shrinkage ratio increased with decreasing particle size. While the linear shrinkage ratio of Groups 3, 4, and 5 were approximately 2%, Group 1 showed the highest shrinkage of all. The bending strength ranged from 106 to 428MPa under the influence of porosity. Groups 1 and 2 presented low porosity followed by higher strength. The shear bond strength ranged from 32 to 100MPa. The shear bond strength was also particle-size dependent. The decrease in the porosity increased the linear shrinkage ratio and bending strength. Shrinkage and mechanical strength required for prostheses were dependent on the particle size and shape of titanium powders. These findings suggested that this production method can be applied to the prosthetic framework by selecting the material design.


Assuntos
Próteses e Implantes , Titânio/química , Teste de Materiais , Tamanho da Partícula , Porosidade
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