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1.
Braz. j. oral sci ; 20: e213859, jan.-dez. 2021. ilus
Artigo em Inglês | LILACS, BBO - Odontologia | ID: biblio-1253923

RESUMO

Aim: This study evaluated the effect of a desensitizer agent (DES) during bleaching with 10% carbamide peroxide (CP) on enamel microshear bond strength (µSBS). Methods: Sixty bovine incisors were obtained and randomly distributed into groups (n=15): (C) Control: no desensitizing or bleaching, (DES) desensitizing gel application, (CP) bleaching with 10% CP and (CP/DES) bleaching with 10% CP combined with DES. Bleaching was performed for 6 h/day for 14 consecutive days. DES was applied for 8 h only on the 7th and 14th days of therapy. Specimens were stored in artificial saliva among the CP or DES applications and submitted to µSBS testing at three postrestoration times (n=5): 24 h, 7 days, and 14 days after bleaching using a universal testing machine. Failure modes were observed under a stereomicroscope. Data were analyzed by two-way ANOVA and Tukey's test (α=5%). Results: Immediately after bleaching (24 h), CP promoted lower µSBS than the C and DES groups (p<0.05) but with no differences from the CP/DES. µSBS increased in the DES, CP, and CP/DES groups (p<0.05) when bonding was performed for 7 or 14 days elapsed from bleaching. CP/DES exhibited the highest µSBS among the groups 14 days after bleaching (p<0.05). Cohesive failure in enamel was predominant in the CP groups, while adhesive failure was mostly observed for the other groups. Conclusion: The use of a desensitizer during at-home bleaching maintained the enamel immediate bond strength, and its application favored bonding when the restoration was delayed for 14 days


Assuntos
Animais , Bovinos , Clareamento Dental , Esmalte Dentário , Resistência ao Cisalhamento
2.
J Contemp Dent Pract ; 22(4): 353-356, 2021 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-34267002

RESUMO

AIM AND OBJECTIVE: To compare between mineral trioxide aggregate (MTA) mixed with water and water-based gel regarding shear bond strength with resin-modified glass ionomer cement (RMGIC) and composite. METHODS AND MATERIALS: In this study, 40 blocks of cylindrical shape were prepared with acrylic. These blocks were divided into four groups with each group consisting of 10 blocks: group-1A: MTA + distilled water + composite, group-1B: MTA + distilled water + RMGIC, group-2A: MTA + polymer + composite, and group-2B: RMGIC + MTA + polymer. After that, a universal testing machine was used for the measurement of shear bond strength. The acrylic blocks were placed under this machine. A blade with a knife-edge was used to provide a crosshead speed of 1 mm/minute. This was continued till bond of MTA in both forms (distilled water/gel) and restorative material failed. RESULTS: It was observed that a statistically significant difference was found between MTAw + composite and MTAg + composite resin but no statistically significant difference between MTAw + RMGIC and MTAg + RMGIC with p ≥ 0.05. It was found that a statistically significant difference was present between the RMGIC and composite groups within the same MTA type with p ≤ 0.05. CONCLUSION: It was concluded from the present study that MTA with a water-based gel has a better shear bond strength than composite resin and RMGIC materials. CLINICAL SIGNIFICANCE: It has been found that MTA has different properties when it is mixed with polymer and water. Very few studies have been conducted in the past to compare MTA mixed with water and water-based gel regarding the shear bond strength with RMGIC and composite.


Assuntos
Colagem Dentária , Cimentos de Ionômeros de Vidro , Compostos de Alumínio , Compostos de Cálcio , Resinas Compostas , Combinação de Medicamentos , Teste de Materiais , Óxidos , Resistência ao Cisalhamento , Silicatos , Água
3.
Indian J Dent Res ; 32(1): 98-103, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34269245

RESUMO

Objective: This study aimed to evaluate the effects of Coca-Cola®, Sprite®, and Maaza® on Microleakage, shear bond strength (SBS) and adhesive remnants underneath orthodontic brackets. Materials and Methods: A total of 192 human premolar teeth were used in this study. The sample was divided into four groups: Artificial saliva (control) [Group 1], Coca-Cola [Group 2], Sprite [Group 3] and Maaza [Group 4]. All the samples were stored in artificial saliva and immersed in their respective testing media (except the control group) for 15 minutes 3 times a day, separated by intervals of 8 hours. The immersion cycle was repeated for 15 days. After the immersion cycle, 24 teeth from each group were tested for SBS and adhesive remnant index subsequently. The remaining 24 teeth from each group underwent dyeing with methylene blue and were analyzed stereomicroscopically to evaluate microleakage underneath the brackets. Kolmogorov-Smirnov and Shapiro normality tests were performed and homogeneity of variance was tested with the Levene test. One-way ANOVA and Kruskal-Wallis tests were carried out separately for SBS, ARI and microleakage. Statistical analyses were performed using SPSS 20 for Windows (SPSS Inc., Chicago) software. Results: Coca-Cola showed a significant reduction in SBS and microleakage (p < 0.05) compared to the other groups. ARI did not show any significant differences between any groups (p > 0.05). The mean microleakage scores were higher for the gingival side of the brackets compared to the incisal side. Both Sprite and Maaza showed significant differences compared to artificial saliva, despite the SBS not being statistically significant (p > 0.05). Conclusions: A significant reduction of SBS was observed in Coca-Cola while increased microleakage was seen in all three drinks compared to artificial saliva.


Assuntos
Colagem Dentária , Braquetes Ortodônticos , Bebidas Gaseificadas , Cimentos Dentários , Análise do Estresse Dentário , Humanos , Teste de Materiais , Braquetes Ortodônticos/efeitos adversos , Resistência ao Cisalhamento , Propriedades de Superfície
4.
J Adhes Dent ; 23(4): 287-296, 2021 Jul 23.
Artigo em Inglês | MEDLINE | ID: mdl-34269539

RESUMO

PURPOSE: To systematically review the literature to evaluate whether the bond strength of resin-based materials to enamel is affected by deproteinizing agents. MATERIALS AND METHODS: This systematic review and meta-analysis was conducted according to the PRISMA statement. PubMed, ISI Web of Science, Cochrane Library, SciELO, Scopus, LILACS, IBECS, and BVS databases were screened up to December 2020. Eligibility criteria included in vitro studies that reported the effect of a deproteinizing agent applied before or after acid etching on the immediate or long-term bond strength of resin-based materials to enamel. The meta-analysis was carried out using Review Manager (version 5.3.5). A global comparison was performed with the standardized mean difference based on random-effect models at a significance level of α = 0.05. RESULTS: A total of 23 studies were included in the meta-analysis. In all the studies, only the immediate bond strength was evaluated. The bond strength of the materials was improved by the application of NaOCl or papain prior to enamel etching with phosphoric acid (p ≤ 0.006). None of the deproteinizing agents had a significant effect when applied after etching with phosphoric acid (p ≥ 0.27). CONCLUSIONS: Based on in vitro studies, deproteinization with sodium hypochlorite or papain-based agents increases the immediate bond strength of resin-based materials to enamel only when used prior to phosphoric-acid etching.


Assuntos
Condicionamento Ácido do Dente , Colagem Dentária , Esmalte Dentário , Teste de Materiais , Ácidos Fosfóricos , Cimentos de Resina , Resistência ao Cisalhamento , Hipoclorito de Sódio , Propriedades de Superfície
5.
Int J Mol Sci ; 22(11)2021 May 26.
Artigo em Inglês | MEDLINE | ID: mdl-34073212

RESUMO

In the 1900s, researchers established animal models experimentally to induce atherosclerosis by feeding them with a cholesterol-rich diet. It is now accepted that high circulating cholesterol is one of the main causes of atherosclerosis; however, plaque localization cannot be explained solely by hyperlipidemia. A tremendous amount of studies has demonstrated that hemodynamic forces modify endothelial athero-susceptibility phenotypes. Endothelial cells possess mechanosensors on the apical surface to detect a blood stream-induced force on the vessel wall, known as "wall shear stress (WSS)", and induce cellular and molecular responses. Investigations to elucidate the mechanisms of this process are on-going: on the one hand, hemodynamics in complex vessel systems have been described in detail, owing to the recent progress in imaging and computational techniques. On the other hand, investigations using unique in vitro chamber systems with various flow applications have enhanced the understanding of WSS-induced changes in endothelial cell function and the involvement of the glycocalyx, the apical surface layer of endothelial cells, in this process. In the clinical setting, attempts have been made to measure WSS and/or glycocalyx degradation non-invasively, for the purpose of their diagnostic utilization. An increasing body of evidence shows that WSS, as well as serum glycocalyx components, can serve as a predicting factor for atherosclerosis development and, most importantly, for the rupture of plaques in patients with high risk of coronary heart disease.


Assuntos
Doença da Artéria Coronariana , Circulação Coronária , Células Endoteliais , Placa Aterosclerótica , Resistência ao Cisalhamento , Estresse Mecânico , Doença da Artéria Coronariana/metabolismo , Doença da Artéria Coronariana/patologia , Doença da Artéria Coronariana/fisiopatologia , Células Endoteliais/metabolismo , Células Endoteliais/patologia , Humanos , Placa Aterosclerótica/metabolismo , Placa Aterosclerótica/patologia , Placa Aterosclerótica/fisiopatologia , Placa Aterosclerótica/terapia
6.
Dental Press J Orthod ; 26(3): e2119177, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34190770

RESUMO

OBJECTIVE: This study aims to determine shear debonding strength of metal and ceramic brackets, and the degree of enamel crack healing. MATERIAL AND METHODS: Extracted human maxillary premolars were flattened on the buccal surface, and randomly separated into five groups (n = 15). In control groups (groups 1 and 2), metal and ceramic brackets were bonded on flat polished enamel, while in experimental groups (groups 3 and 4), metal and ceramic brackets were bonded on the surface with boundary where corner cracks were created. Additionally, fifteen specimens (group 5) were also prepared for an indentation procedure with no bracket installation. The degree of crack healing was measured. All brackets were detached with a universal testing machine, and the adhesive remnant index (ARI) was also identified. Healing degree and apparent fracture toughness were then calculated. RESULTS: Between groups with similar bracket types, there was no statistically significant difference in debonding strength. Regarding bracket types, ceramic brackets provided significantly higher debonding strength than metal brackets. There was a significant difference in ARI scores between metal and ceramic brackets. The corner cracks showed signs of healing in both horizontal and vertical directions. No statistically significant difference in the healing rates among the groups was found and the apparent fracture toughness increased from the initial to the final measurement. CONCLUSIONS: Within the limitations of this study, even though ceramic brackets required significantly higher debonding force compared to metal brackets, debonding stress was limited to the bonding site and did not affect the surrounding cracks on enamel.


Assuntos
Colagem Dentária , Braquetes Ortodônticos , Cerâmica , Cimentos Dentários , Descolagem Dentária , Esmalte Dentário , Análise do Estresse Dentário , Humanos , Teste de Materiais , Resistência ao Cisalhamento , Propriedades de Superfície
7.
Medicine (Baltimore) ; 100(26): e26518, 2021 Jul 02.
Artigo em Inglês | MEDLINE | ID: mdl-34190185

RESUMO

ABSTRACT: Bicuspid aortic valve (BAV) disease has significant gaps in its clinical management practices. To highlight the potential utility of advanced hemodynamic biomarkers in strengthening BAV assessment, we used 4-dimentional flow magnetic resonance imaging to investigate altered hemodynamics in the ascending aorta (AAo).A total of 32 healthy controls and 53 age-matched BAV patients underwent cardiac magnetic resonance imaging at 3T, with cine imaging and 4D-flow. Analysis planes were placed along 3D-segmented aortas at the left ventricular outflow tract (LVOT), sinuses of Valsalva, mid-ascending aorta (MAA), and proximal to the first aortic branch. Locations were analyzed for aortic diameter (normalized to body surface area), pressure drop (PD), viscous energy loss (EL), and wall shear stress (WSS) sub-vectors (axial wall shear stress, circumferential wall shear stress [WSSC], magnitude wall shear stress). Student's t tests, or non-parametric equivalents, compared parameters between cohorts. Univariable and multivariable analyses explored the associations of AAo diameter with hemodynamics within the BAV cohort.Compared to control cohort, BAV patients showed significantly greater PD (MAA: 9.5 ±â€Š8.0 vs 2.8 ±â€Š2.4 mm Hg; P < .01), EL (from LVOT-AA1: 7.39 ±â€Š4.57 mW vs 2.90 ±â€Š1.07 mW; P < .01), and WSSC (MAA: 0.3 ±â€Š0.1 vs 0.2 ±â€Š0.06 Pa; P ≤ .01) throughout the AAo. Correlational analyses revealed an inverse association between AAo diameter and both magnitude wall shear stress and axial wall shear stress.BAV patients exhibited increased PD, EL, and WSSC in the AAo, and an inverse association between AAo diameter and WSS sub-vectors. This demonstrated the impact of PD, EL, and WSS in BAV disease and the importance of altered hemodynamics in aortic remodelling.


Assuntos
Aorta , Valva Aórtica , Doença da Válvula Aórtica Bicúspide , Remodelação Vascular , Adulto , Aorta/diagnóstico por imagem , Aorta/patologia , Aorta/fisiopatologia , Valva Aórtica/diagnóstico por imagem , Valva Aórtica/fisiopatologia , Pressão Arterial , Doença da Válvula Aórtica Bicúspide/diagnóstico , Doença da Válvula Aórtica Bicúspide/fisiopatologia , Velocidade do Fluxo Sanguíneo , Correlação de Dados , Feminino , Hemodinâmica , Humanos , Imagem Cinética por Ressonância Magnética/métodos , Masculino , Tamanho do Órgão , Resistência ao Cisalhamento
8.
BMC Oral Health ; 21(1): 306, 2021 06 14.
Artigo em Inglês | MEDLINE | ID: mdl-34126965

RESUMO

BACKGROUND: Increased risk of enamel demineralization during and after orthodontic treatment raises the demand for better preventive measures including combinations of laser, CPP-ACP, and fluoride. The combination of Er,Cr:YSGG laser with CPP-ACP was proved to have a synergetic effect compared to each of them alone. Shear bond strength (SBS) of orthodontic brackets bonded to the enamel surface after being treated with preventive measures is critical. The aim of this study was to compare the SBS and failure mode of metallic brackets bonded to teeth with no pretreatment and pretreated enamel surface, either with Er,Cr:YSGG laser alone or combined with CPP-ACP. METHODS: Sixty sound extracted human premolar teeth were allocated randomly to 3 groups: In Group 1 (control), teeth were etched and bonded directly; in Group 2, laser pretreatment of the enamel surface was done followed by etching and bonding as in the control group; in Group 3, the enamel surface was lased then CPP-ACP was applied according to the manufacturer instructions, etched and bonded. SBS and Adhesive remnant index (ARI) were evaluated. RESULTS: No significant differences were found between the 3 groups neither in the SBS nor in the ARI scores. CONCLUSIONS: The use of combined Er,Cr:YSGG laser with CPP-ACP as a preventive measure before bonding orthodontic brackets does not endanger the bracket's bonding strength.


Assuntos
Colagem Dentária , Lasers de Estado Sólido , Braquetes Ortodônticos , Caseínas , Esmalte Dentário , Humanos , Lasers de Estado Sólido/uso terapêutico , Resistência ao Cisalhamento , Propriedades de Superfície
9.
J Oral Sci ; 63(3): 275-279, 2021 Jun 29.
Artigo em Inglês | MEDLINE | ID: mdl-34148925

RESUMO

PURPOSE: To evaluate the influence of polymerization methods and a metal priming agent on the bond strength between gold alloy for metal ceramic restorations and dual-cure-type resin luting agents, and on the strength and hardness of the luting agents. METHODS: A total of 154 disks cast by a gold alloy were treated with or without a metal priming agent. One of the three luting agents was applied on the disk. The luting agent was either chemically or dual-polymerized. The shear bond strength was measured both before and after thermocycling. In addition, scanning electron microscope (SEM) observation, flexural strength test, and Knoop hardness test were performed. RESULTS: Significant differences among the luting agents were observed in terms of bond strength and flexural strength. Significant differences between chemically and dual-polymerized luting agents were observed regarding shear bond strength, flexural strength, and Knoop hardness before thermocycling. The application of the priming agent was effective only for a luting agent. CONCLUSION: Both bond strength and flexural strength differed among three luting agents. The effect of the priming agent on bond strength differed among the luting agents. Both the bond and flexural strength of a chemically polymerized luting agent differed before or after thermocycling.


Assuntos
Colagem Dentária , Ligas de Ouro , Cimentos Dentários , Teste de Materiais , Polimerização , Cimentos de Resina , Resistência ao Cisalhamento , Propriedades de Superfície
10.
J Clin Pediatr Dent ; 45(3): 186-192, 2021 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-34192754

RESUMO

OBJECTIVE: To compare the shear bond strength (SBS) after thermocycling of four universal adhesives applied in self-etch mode on dentin and etch-and-rinse mode on enamel. STUDY DESIGN: Flat 144 buccal or lingual dentin and enamel surfaces from 72 non-carious primary molars were prepared. Samples were segregated into 12 groups (n=12): Adper Single Bond 2 etch-and-rinse (SB_T) and Clearfil SE Bond self-etch (SE_S) applied to enamel and dentin served as controls. Scotch Bond Universal Adhesive (SBU), Clearfil S3 Bond Universal Adhesive (SEU), Tetric N-Bond Universal Adhesive (TEN), and All Bond Universal (BIS) were applied in etch-and-rinse mode to enamel and in self-etch mode to dentin. They were thermocycled for 5000 cycles. SBS testing and the evaluation of fracture mode were performed. RESULTS: SB_T showed statistically higher SBS than other adhesive groups using etch-and-rinse mode on enamel. SE_S and BIS had statistically higher SBS than other adhesive groups using self-etch mode on dentin. Mixed failure was the most common failure mode in each group. CONCLUSION: The universal adhesives did not show higher SBS than SB_T when using etch-and-rinse on enamel. All universal adhesives showed higher SBS than SB_T and had SBS similar to SE_S, except SBU when using self-etch mode on dentin.


Assuntos
Colagem Dentária , Adesivos Dentinários , Esmalte Dentário , Dentina , Humanos , Teste de Materiais , Cimentos de Resina , Resistência ao Cisalhamento , Dente Decíduo
11.
J Clin Pediatr Dent ; 45(3): 177-185, 2021 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-34192755

RESUMO

OBJECTIVES: To investigate the effect of Co-curing versus Staged-curing and No-bonding on retention of different resin-based sealants (RBS). STUDY DESIGN: For shear bond strength (SBS) and microleakage tests, 90 extracted premolars were divided equally into 3 groups (I, II, III). Each group was further subdivided equally into 3 subgroups (a, b, c). No-bonding subgroups did not receive a bonding agent, Staged-curing subgroups received a bonding agent that was cured before sealant application, while Co-curing subgroups received a bonding agent that was cured after sealant application. Seal-it was applied for group I, Helioseal-F for group II and Clinpro for group III. SBS buttons were tested using Instron machine, while microleakage specimens were examined using micro-CT. RESULTS: Clinpro showed the highest SBS values in Staged-curing and No-bonding groups (8.72±2.39, 12.51±3.16) respectively. Staged-curing was significantly greater in SBS values than those for other groups (P<0.05). There was a significant difference in microleakage values of Staged-curing among different RBS (P = 0.003), while there was no significant difference in values of No-bonding and Co-curing among different RBS (P = 0.541, P = 0.521). CONCLUSIONS: The use of a bonding agent as Staged-curing was more effective in improving sealant retention than No-bonding and Co-curing.


Assuntos
Colagem Dentária , Selantes de Fossas e Fissuras , Esmalte Dentário , Humanos , Teste de Materiais , Cimentos de Resina , Resistência ao Cisalhamento
12.
FASEB J ; 35(6): e21643, 2021 06.
Artigo em Inglês | MEDLINE | ID: mdl-33977574

RESUMO

The endothelial glycocalyx is a dynamic structure integral to blood vessel hemodynamics and capable of tightly regulating a range of biological processes (ie, innate immunity, inflammation, and coagulation) through dynamic changes in its composition of the brush structure. Evaluating the specific roles of the endothelial glycocalyx under a range of pathophysiologic conditions has been a challenge in vitro as it is difficult to generate functional glycocalyces using commonly employed 2D cell culture models. We present a new multi-height microfluidic platform that promotes the growth of functional glycocalyces by eliciting unique shear stress forces over a continuous human umbilical vein endothelial cell monolayer at magnitudes that recapitulate the physical environment in arterial, capillary and venous regions of the vasculature. Following 72 hours of shear stress, unique glycocalyx structures formed within each region that were distinct from that observed in short (3 days) and long-term (21 days) static cell culture. The model demonstrated glycocalyx-specific properties that match the characteristics of the endothelium in arteries, capillaries and veins, with respect to surface protein expression, platelet adhesion, lymphocyte binding and nanoparticle uptake. With artery-to-capillary-to-vein transition on a continuous endothelial monolayer, this in vitro platform is an improved system over static cell culture for more effectively studying the role of the glycocalyx in endothelial biology and disease.


Assuntos
Artérias/fisiologia , Capilares/fisiologia , Glicocálix/química , Glicocálix/metabolismo , Células Endoteliais da Veia Umbilical Humana/fisiologia , Estresse Mecânico , Veias/fisiologia , Hemodinâmica , Células Endoteliais da Veia Umbilical Humana/citologia , Humanos , Microfluídica , Resistência ao Cisalhamento
13.
Int J Mol Sci ; 22(9)2021 Apr 29.
Artigo em Inglês | MEDLINE | ID: mdl-33946824

RESUMO

Red blood cells (RBCs) serve a variety of functions beyond mere oxygen transport both in health and pathology. Notably, RRx-001, a minimally toxic pleiotropic anticancer agent with macrophage activating and vascular normalization properties currently in Phase III trials, induces modification to RBCs which could promote vascular adhesion similar to sickle cells. This study assessed whether RBCs exposed to RRx-001 adhere to the tumor microvasculature and whether this adhesion alters tumor viability. We next investigated the biomechanics of RBC adhesion in the context of local inflammatory cytokines after treatment with RRx-001 as a potential mechanism for preferential tumor aggregation. Human HEP-G2 and HT-29 tumor cells were subcutaneously implanted into nu/nu mice and were infused with RRx-001-treated and Technetium-99m (99mTc)-labeled blood. RBC adhesion was quantified in an in vitro human umbilical vein endothelial cell (HUVEC) assay under both normoxic and hypoxic conditions with administration of either lipopolysaccharide (LPS) or Tumor necrosis alpha (TNFα) to mimic the known inflammation in the tumor microenvironment. One hour following administration of 99mTc labeled RBCs treated with 10 mg/kg RRx-001, we observed an approximate 2.0-fold and 1.5-fold increase in 99mTc-labeled RBCs compared to vehicle control in HEPG2 and HT-29 tumor models, respectively. Furthermore, we observed an approximate 40% and 36% decrease in HEP-G2 and HT-29 tumor weight, respectively, following treatment with RRx-001. To quantify RBC adhesive potential, we determined τ50, or the shear stress required for 50% disassociation of RBCs from HUVECs. After administration of TNF-α under normoxia, τ50 was determined to be 4.5 dynes/cm2 (95% CI: 4.3-4.7 dynes/cm2) for RBCs treated with 10 µM RRx-001, which was significantly different (p < 0.05) from τ50 in the absence of treatment. Under hypoxic conditions, the difference of τ50 with (4.8 dynes/cm2; 95% CI: 4.6-5.1 dynes/cm2) and without (2.6 dynes/cm2; 95% CI: 2.4-2.8 dynes/cm2) 10 µM RRx-001 treatment was exacerbated (p = 0.05). In conclusion, we demonstrated that RBCs treated with RRx-001 preferentially aggregate in HEP-G2 and HT-29 tumors, likely due to interactions between RRx-001 and cysteine residues within RBCs. Furthermore, RRx-001 treated RBCs demonstrated increased adhesive potential to endothelial cells upon introduction of TNF-α and hypoxia suggesting that RRx-001 may induce preferential adhesion in the tumor but not in other tissues with endothelial dysfunction due to conditions prevalent in older cancer patients such as heart disease or diabetic vasculopathy.


Assuntos
Antineoplásicos/farmacologia , Azetidinas/farmacologia , Células Endoteliais/citologia , Membrana Eritrocítica/efeitos dos fármacos , Nitrocompostos/farmacologia , Animais , Antineoplásicos/uso terapêutico , Azetidinas/uso terapêutico , Adesão Celular/efeitos dos fármacos , Hipóxia Celular , Cisteína/química , Citocinas/metabolismo , Células Endoteliais/química , Agregação Eritrocítica/efeitos dos fármacos , Membrana Eritrocítica/química , Células HT29/transplante , Células Hep G2/transplante , Células Endoteliais da Veia Umbilical Humana , Humanos , Lipopolissacarídeos/farmacologia , Lipídeos de Membrana/biossíntese , Camundongos , Camundongos Nus , Neoplasias/irrigação sanguínea , Neoplasias Experimentais/irrigação sanguínea , Neoplasias Experimentais/tratamento farmacológico , Nitrocompostos/uso terapêutico , Fosfatidilserinas/biossíntese , Receptores de Superfície Celular/biossíntese , Resistência ao Cisalhamento , Microambiente Tumoral , Fator de Necrose Tumoral alfa/farmacologia
14.
J Mech Behav Biomed Mater ; 120: 104547, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-33940486

RESUMO

This study aimed to analyze different methodologies (tensile, microtensile, shear, microshear, and interfacial toughness) for evaluation of the bond strength between zirconia (Y-TZP) and resin cement. Zirconia ceramic blocks (VITA in-Ceram® YZ, VITA Zahnfabrik, Germany) were obtained, substrate surfaces were air-abraded with aluminum oxide (50 µm) for 10 s (2 bar pressure, distance: 10 mm, angle: 90°). Then, the specimens were washed with distilled water, dried, and coated with Clearfil Ceramic Primer that was actively applied with a microbrush for 20 s. The specimens were then cemented with resin cement under a load of 750 g, followed by photo-polymerization (40 s on each surface). After cementation, the specimens were aged in thermocycling (8000 cycles, 5-55 °C, 30 s for each bath) and subjected to tensile, microtensile, shear, microshear or interfacial toughness tests. All specimens were inspected for failure modes. The microtensile test showed the highest bond value (18.29 N/mm2). The microshear tests showed the highest coefficient of variation (0.59) and highest number of pre-test failures. The interfacial energy to fracture test showed that as the shear stress increased its interaction in the adhesive interface, the coefficient of variation also increased. The bond strength of Y-TZP showed different results according to the methodology, as well as its interfacial energy to fracture varied according to the angulation/type of stress specimen was submitted. The lower the shear stress at the adhesive interface of the mixed tests (interfacial energy to fracture), the lower was the variability of the test.


Assuntos
Colagem Dentária , Cimentos de Resina , Óxido de Alumínio , Cerâmica , Análise do Estresse Dentário , Teste de Materiais , Resistência ao Cisalhamento , Propriedades de Superfície , Zircônio
15.
Gen Dent ; 69(3): 24-29, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33908874

RESUMO

This study evaluated the failure load and the shear bond strength of 4 block materials indicated for computer-aided design/computer-aided manufacturing (CAD/CAM) of dental veneers: lithium disilicate, feldspathic ceramic, polymer-infiltrated ceramic, and nanohybrid composite. The tested hypothesis was that the material that combined an elastic modulus similar to that of enamel with the highest bond strength values would present the highest failure load. From prefabricated CAD/CAM blocks, disc-shaped specimens (6.0 × 0.7 mm; n = 10) and cylinders (2.4 × 2.5 mm; n = 10) were fabricated for load-to-failure and shear bond strength tests, respectively. Materials were adhesively bonded to flattened bovine enamel surfaces, stored in distilled water at 37°C for 90 days, and subjected to thermocycling (2000 cycles of 5°C to 55°C). Discs of restorative material were bonded to enamel and subjected to an increasing load that was applied perpendicular to the bonding interface until catastrophic failure occurred. A chisel was used to apply an increasing load parallel to the adhesive interface between the enamel and a cylinder of restorative material to measure shear bond strength. Data were subjected to a Weibull analysis and 1-way analysis of variance followed by a Tukey post hoc test (α = 0.05). The type of restorative material significantly affected the (mean [SD]) failure load when bonded to enamel (P = 0.006): polymer-infiltrated ceramic (1167.9 [310.2] N) = feldspathic ceramic (1115.0 [382.0] N) = nanohybrid composite (1067.3 [251.0] N) > lithium disilicate (786.2 [304.5] N). The type of restorative material also significantly affected the (mean [SD]) bond strength to enamel (P < 0.001): lithium disilicate (32.81 [11.19] MPa) = polymer-infiltrated ceramic (27.04 [7.65] MPa) > feldspathic ceramic (21.11 [9.16] MPa) > nanohybrid composite (9.08 [3.66] MPa). The polymer-infiltrated ceramic presented the best performance when bonded to enamel.


Assuntos
Colagem Dentária , Cimentos de Resina , Animais , Bovinos , Cerâmica , Esmalte Dentário , Porcelana Dentária , Análise do Estresse Dentário , Humanos , Teste de Materiais , Resistência ao Cisalhamento , Propriedades de Superfície
16.
Dent Med Probl ; 58(1): 107-113, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33847469

RESUMO

BACKGROUND: Considering the use of silane-containing universal adhesives to enhance the repair bond strength of porcelain restorations, a question arises whether the application of these adhesives eliminates the need for a separate application of silane or not. OBJECTIVES: This study aimed to assess the effect of various kinds of surface treatment, including hydrofluoric acid (HF) etching, the application of bis-silane and the use of universal adhesives, on the repair bond strength of feldspathic porcelain. MATERIAL AND METHODS: In this experimental in vitro study, 70 porcelain disks were fabricated and divided into 7 groups (n = 10) for the following types of surface treatment: C (control group) ­ HF etching + silane + Porcelain Bond; HSB ­ HF etching + Single Bond; HSSB ­ HF etching + silane + Single Bond; HAB ­ HF etching + All Bond; HSAB ­ HF etching + silane + All Bond; HFB ­ HF etching + FuturaBond®; and HSFB ­ HF etching + silane + FuturaBond. After applying different kinds of surface treatment, the specimens were light-cured and the Filtek® Z250 composite was bonded to the treated surfaces. The specimens were incubated in distilled water at 37°C for 24 h, and then underwent 5,000 thermal cycles. The repair bond strength of porcelain was measured and the mode of failure was determined under a stereomicroscope. Data was analyzed using the one-way analysis of variance (ANOVA) and Tukey's test. RESULTS: Differences between the groups in the porcelain repair bond strength were significant (p < 0.0001). Bond strength for Single Bond (p < 0.001) and All Bond (p < 0.001) along with silane was significantly higher than for the application of these adhesives without a separate silane application step. This difference was not significant for FuturaBond. Mixed failure was the dominant mode of failure in all groups. CONCLUSIONS: The application of silane, irrespective of the use of universal adhesives with or without silane, increased the porcelain repair bond strength. Thus, a separate silane application step following HF etching and the use of universal adhesives with or without silane can enhance the repair bond strength of feldspathic porcelain.


Assuntos
Colagem Dentária , Porcelana Dentária , Condicionamento Ácido do Dente , Humanos , Teste de Materiais , Cimentos de Resina , Resistência ao Cisalhamento , Propriedades de Superfície
17.
Magn Reson Med ; 86(3): 1531-1543, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-33914962

RESUMO

PURPOSE: First, to investigate the agreement between velocity, velocity gradient, and Reynolds stress obtained from four-dimensional flow magnetic resonance (4D flow MRI) measurements and direct numerical simulation (DNS). Second, to propose and optimize based on DNS, 2 alternative methods for the accurate estimation of wall shear stress (WSS) when the resolution of the flow measurements is limited. Thirdly, to validate the 2 methods based on 4D flow MRI data. METHODS: In vitro 4D MRI has been conducted in a realistic rigid stenosed aorta model under a constant flow rate of 12 L/min. A DNS of transitional stenotic flow has been performed using the same geometry and boundary conditions. RESULTS: Time-averaged velocity and Reynolds stresses are in good agreement between in vitro 4D MRI data and DNS (errors between 2% and 8% of the reference downsampled data). WSS estimation based on the 2 proposed methods applied to MRI data provide good agreement with DNS for slice-averaged values (maximum error is less than 15% of the mean reference WSS for the first method and 25% for the second method). The performance of both models is not strongly sensitive to spatial resolution up to 1.5 mm voxel size. While the performance of model 1 deteriorates appreciably at low signal-to-noise ratios, model 2 remains robust. CONCLUSIONS: The 2 methods for WSS magnitude give an overall better agreement than the standard approach used in the literature based on direct calculation of the velocity gradient close to the wall (relative error of 84%).


Assuntos
Imageamento Tridimensional , Imageamento por Ressonância Magnética , Velocidade do Fluxo Sanguíneo , Constrição Patológica , Humanos , Espectroscopia de Ressonância Magnética , Resistência ao Cisalhamento , Estresse Mecânico
18.
Dent Mater J ; 40(3): 781-791, 2021 May 29.
Artigo em Inglês | MEDLINE | ID: mdl-33814532

RESUMO

To evaluate the bonding reliability of a universal adhesive compared to a commercial ceramic repair system for metal-ceramic cracks. In vitro part: sixty specimens with porcelain, metal and porcelain-metal substrate were fabricated. Half specimens were bonded by Singlebond Universal adhesive and Filtek Z350 resin composite. The other were processed by Ceramic Repair N. Shear bond strength was tested. In vivo part: forty patients with sixty ceramic fractured porcelain-fused-metal restorations were involved. Half were repaired by Singlebond Universal and Filtek Z350. The other were restored by Ceramic Repair N. The mean observation period was 65 weeks. Results showed the bond strength ranged from 13.97 MPa to 15.85 MPa using two different repair system on different substrate with no statistical difference. There was no statistical difference between the two adhesive system in survival rate according to Kaplan-Meier analysis. The universal adhesive had a similar repair performance compared to commercial ceramic repair system.


Assuntos
Colagem Dentária , Cerâmica , Resinas Compostas , Cimentos Dentários , Porcelana Dentária , Análise do Estresse Dentário , Humanos , Teste de Materiais , Reprodutibilidade dos Testes , Cimentos de Resina , Resistência ao Cisalhamento , Propriedades de Superfície
19.
Biomed Res Int ; 2021: 6634595, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33816623

RESUMO

Background: Orthodontic patients are at high risk to develop caries. This study is introducing a clinical method detecting interfacial defects between ceramic brackets and enamel utilizing optical coherent tomography in addition to using the nanoleakage expression in vitro test. Methods: Transbond XT primer and moisture insensitive primer (MIP) were bonded to 75 human premolar enamel surfaces and divided into (XTD), (MIPD), and (MIPW) groups. The (XTD) and (MIPD) groups had ceramic brackets bonded to dry enamel surfaces using TransBond and moisture insensitive primers, respectively, while the (MIPW) samples were bonded to moist enamel using moisture insensitive primer. All specimens were examined under crosspolarization optical coherence tomography. Debonding forces of the brackets to 45 teeth (15 teeth/group). 30 bonded specimens (15 specimens/group) were cross-sectioned to detect the nanoleakage expression using scanning electron microscope equipped with energy-dispersive spectroscopy (SEM/EDS). The degree of conversion of the specimens in the experimental groups was tested using attenuated total reflectance Fourier transform infrared spectroscopy (FTIR/ATR). Results: Optical coherence tomography detected the interfacial defects between the ceramic brackets and tooth structure. One way ANOVA showed that (XTD) and (MIPD) groups recorded significantly higher bond strength values and less nanoleakage expression when compared to MIPW (p > 0.05). Conclusions: Optical coherence tomography can be utilized to detect interfacial adhesive-tooth defects. Dry enamel surfaces improve the quality of the enamel/primer interface (200 words).


Assuntos
Dente Pré-Molar , Esmalte Dentário , Braquetes Ortodônticos , Cimentos de Resina/química , Humanos , Resistência ao Cisalhamento , Espectrometria por Raios X
20.
Biomed Res Int ; 2021: 5534294, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33869625

RESUMO

Aim: Root canal filling materials have the tendency to inhibit adhesion of resin-based composites. This study was aimed at evaluating the effect of root canal filling materials and their solvents on the shear bond strength (SBS) of resin composite with the primary tooth dentin. Methods and Materials: Seventy-two intact anterior primary teeth were selected. Smooth dentinal surfaces were prepared to a minimum diameter of 3 mm and thickness of 1.5-2.0 mm. The samples were equally divided into six groups (n = 12). In group 1: control group, no root filling material; in group 2: Metapex, no solvent; in group 3: Metapex+ethanol solvent; in group 4: ZOE, no solvent; in group 5: ZOE+ethanol solvent; and in group 6: ZOE+orange oil solvent were applied. Then, dentin surfaces were etched, and composite restorations were placed and cured. The specimens were stored in distilled water at 37°C for 24 hours. SBS values were determined using a universal testing machine. Results: The SBS values of composite to dentin in groups 2 and 4 were significantly lower than those in the control group (P < 0.001). Cleansing of the specimens with 96% ethanol after removal of Metapex significantly increased the composite-dentin bond (P < 0.001). Applying ZOE, only orange oil solvent significantly increased the SBS of the composite to the primary tooth dentin (P = 0.01). Conclusion: To reduce the negative effects of endodontic root filling materials on the SBS of composite and primary tooth dentin, ethanol is a suitable solvent when Metapex is used, while orange oil might be a better choice than ethanol when applying ZOE.


Assuntos
Resinas Compostas/química , Colagem Dentária , Dentina/efeitos dos fármacos , Materiais Restauradores do Canal Radicular/farmacologia , Resistência ao Cisalhamento/efeitos dos fármacos , Solventes/química , Dente Decíduo/química , Dentina/ultraestrutura , Humanos , Propriedades de Superfície
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