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1.
Food Chem ; 335: 127629, 2021 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-32736156

RESUMO

Folate deficiencies are prevalent in countries with insufficient food diversity. Rice fortification is seen as a viable way to improve the daily intake of folates. This work reports an efficient process of rice fortification involving ultrasonic treatment and absorption of the folic acid fortificant. Increased porosity due to sonication allowed the efficient absorption of folic acid into the brown rice kernel up to 5.195 × 104 µg/100 g, a 1,982-fold increase from its inherent content. The absorbed folic acid in brown rice has 93.53% retention after washing and cooking. Fortification of ultrasound-treated milled rice with folic acid was also efficient affording 6.559 × 104 µg/100 g, a 4,054-fold increase from its basal content. The effect of fortification caused a decrease in the thermal and pasting temperatures. The fortification also caused yellow coloration, decrease in hardness, and increase in the adhesiveness of the rice. The resulting fortified brown rice showed improved textural properties favorable for consumers.


Assuntos
Absorção Fisico-Química , Ácido Fólico/química , Alimentos Fortificados/análise , Oryza/química , Ondas Ultrassônicas , Adesividade , Cor , Dureza
2.
Food Chem ; 336: 127709, 2021 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-32763738

RESUMO

The microbiological, microstructural, and physicochemical impact of aqueous ozone mixing (AOM) on semi-dried buckwheat noodles (SBWN) was elucidated in this study. Microbiological measurements declared that AOM reduced the initial total plate count (TPC) of SBWN significantly (P < 0.05) with a prolonged shelf-life of 2 ~ 5 days. Meanwhile, AOM reduced the cooking loss and water absorption along with the enhancement of hardness and tension force. Scanning electron microscopy (SEM) showed that the protein network of surface and cross section became continuous and compact, and wrapped starch granules more effectively. Moreover, an obvious increase in the intensity of the high molecular protein bands was observed in the sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) patterns. Furthermore, the sodium dodecyl sulfate extractable protein (SDSEP) under non-reducing condition obviously decreased, and then the SDSEP under reducing condition changed insignificantly (P > 0.05). These results indicated that AOM mainly promoted the protein cross-linking of SBWN by disulfide bond (SS) cross-links.


Assuntos
Fagopyrum/química , Indústria de Processamento de Alimentos/métodos , Ozônio/química , Culinária , Dissulfetos/química , Eletroforese em Gel de Poliacrilamida , Farinha/análise , Qualidade dos Alimentos , Armazenamento de Alimentos , Dureza , Microscopia Eletrônica de Varredura , Proteínas de Plantas/química , Água/química
3.
Food Chem ; 337: 127682, 2021 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-32795852

RESUMO

Consumers are increasingly interested in low-fat meat products. Therefore, there is demand for new fat replacers that improve the quality of low-fat meat products. Whey protein isolate (WPI; 10% (w/v)) and sodium dodecyl sulfate (SDS; 0-0.09% (w/v)) were used to produce WPI-SDS gel as a fat replacer of low-fat meat products. Characteristics of WPI-SDS gel were evaluated using SDS-PAGE, FT-IR, viscometer, and texture analyzer. Addition of SDS to WPI increased gelation while reducing aggregation. Addition of 0.06% SDS to WPI-SDS gel has the highest viscosity and hardness, while 0.09% SDS decreased the heat stability of WPI. Quality characteristics including cooking loss, emulsion stability, hardness, and chewiness were significantly improved in WPI-SDS gel-supplemented low-fat sausages. Particularly, the highest hardness and chewiness were obtained in the low-fat sausage added with WPI-SDS gel containing 0.06% SDS. Our results suggest that WPI-SDS gel can be used as a fat replacer in low-fat meat products.


Assuntos
Culinária , Produtos da Carne/análise , Dodecilsulfato de Sódio/química , Proteínas do Soro do Leite/química , Géis , Dureza , Viscosidade
4.
J Contemp Dent Pract ; 21(6): 673-677, 2020 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-33025937

RESUMO

AIM: Simulated pulpal pressure (PP) has been shown to affect the bond strength and nanoleakage of different adhesives at dentin interfaces but the effect of simulated PP on polymerization of adhesives has not been studied yet. Furthermore, it has been proposed that strong and mild self-etch adhesives have different polymerization behaviors. This study aimed to evaluate the effect of simulated PP on polymerization of two self-etch adhesives, Adper Prompt L-Pop (APLP) and Adper Easy Bond (AEB), by means of the Knoop hardness test. MATERIALS AND METHODS: Sixty caries-free human molars were used to prepare deep dentin specimens with a mean remaining dentin thickness of 0.9 mm. The specimens were bonded in the absence or presence of PP. The specimens were assigned to four equal groups (n = 15) as follows: AEB/-PP, APLP/-PP, AEB/+PP, and APLP/+PP. Bonding procedures were completed; then the specimens' hardness was measured with the Knoop test. Data were analyzed with two-way ANOVA and the t test. RESULTS: In the absence of PP, the hardness of AEB was significantly higher than that of APLP (p < 0.001). In contrast, when PP was simulated, the hardness of APLP was higher than that of AEB (p = 0.002). The hardness of AEB was not influenced by the presence of PP (p = 0.153). Simulation of PP resulted in a significant improvement in the hardness of APLP (p < 0.001). CONCLUSION: The polymerization degree of strong self-etch adhesive was lower compared to mild self-etch adhesive. In the presence of hydrostatic PP, the polymerization degree of strong self-etch adhesive was higher than mild self-etch adhesive. CLINICAL SIGNIFICANCE: Dentin moisture caused by positive PP might improve polymerization of strong self-etch adhesives.


Assuntos
Cimentos Dentários , Polpa Dentária , Dureza , Humanos , Dente Molar , Polimerização
5.
J Contemp Dent Pract ; 21(6): 678-682, 2020 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-33025938

RESUMO

AIMS: The purpose of this study was to assess the influence of hot and dry weather on the hardness and surface roughness of four different maxillofacial silicone elastomeric materials (MFSEM) including two room-temperature vulcanized (RTV) and two high-temperature vulcanized (HTV) materials. MATERIALS AND METHODS: Eighty test specimens were fabricated according to the manufacturer's instructions into rectangular test specimens. The hardness and surface roughness were tested, after 6 months of exposure to natural hot and dry weather. The hardness was measured through the International Rubber Hardness Degree (IRHD) scale using an automated hardness tester. The surface roughness was measured using a novel 3D optical noncontact technique using a combination of a light sectioning microscope and a computer vision system. Statistical Package for Social Sciences software SPSS/version 24 was used for analysis and a comparison between two independent variables was done using an independent t test, while more than two variables were analyzed, F test (ANOVA) to be used followed by a post hoc test to determine the level of significance between every two groups. RESULTS: The hot and dry weather statistically influenced the hardness and surface roughness of MFSEM. Cosmesil M-511 showed the least hardness in test groups while A-2000 showed the hardest material (p < 0.05). A-2000 showed significant changes from rough in case of nonweathered to become smoother in weather followed by A-2186 (p < 0.05). Cosmesil M-511 showed the roughest material. CONCLUSION: Cosmesil M-511 showed the least hard MFSEM after outdoor weathering while A-2000, the highest and least material showed hardness and surface roughness, respectively. CLINICAL IMPLICATION: A-2000 had a high IRHD scale hardness. This makes this material more suitable for the replacement of ear and nose defects. Cosmesil M-511 is soft and easily adaptable material that makes the material more appropriate for the replacement of small facial defect with undercut area to be easily inserted and removed. Whilst A-2000 is smoother and finer in test specimens after weathering, Cosmesil M-511 became rougher after weathering.


Assuntos
Prótese Maxilofacial , Dureza , Teste de Materiais , Propriedades de Superfície , Tempo (Meteorologia)
6.
Braz Dent J ; 31(4): 431-439, 2020 Sep 04.
Artigo em Inglês | MEDLINE | ID: mdl-32901721

RESUMO

The aim of this study was to evaluate the Streptococcus mutans biofilm influence on the roughness (Ra), gloss (GU), surface hardness (KHN) and flexural strength (FS) of high viscosity bulk fill composites. Filtek Bulk Fill (FBF), Tetric N Ceram Bulk Fill (TNC), X-tra fil Bulk Fill (XF) and Filtek Z350 (FZ) were used. Ten discs of each composite were prepared for Ra, KHN and GU and 20 bars for the FS. After 24 h, specimens were polished and initial analyzes performed. Samples were sterilized and subjected to biodegradation for 7 days and final analyzes performed. Representative samples of each group were evaluated in Scanning Electron Microscope. Data were submitted to ANOVA two factors and Tukey test. XF presented the highest values (p<0.05) of Ra before and after biodegradation (0.1251; 0.3100), and FZ (0.1443) the lowest after biodegradation (p<0.05). The highest GU values (p<0.05) were observed for FZ (71.7; 62) and FBF (69.0; 64.6), and the lowest (p<0.05) for TNC (61.4; 53.3) and XF (58.5; 53.5), both before and after biodegradation. For KHN the highest values were obtained by XF (151.7; 106), and the (p< 0.05) lowest values for TNC (62.2; 51.8), both before and after biodegradation. The highest values (p<0.05) of FS were observed for FZ (127.6) and the lowest (p<0.05) for TNC (86.9); after biodegradation, XF (117.7) presented the highest (p<0.05) values compared to TNC and FZ." In conclusion, biodegradation increased Ra and decreased GU and KHN for all. Concerning FS, degradation provided a significant decreased value only for FZ.


Assuntos
Resistência à Flexão , Streptococcus mutans , Dureza , Teste de Materiais , Propriedades de Superfície
7.
J Int Acad Periodontol ; 22(4): 231-235, 2020 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-32980835

RESUMO

AIMS: This study evaluated the mechanical properties of mandibular bone tissue retrieved from postmenopausal women under alendronate treatment. METHODS: Twenty postmenopausal women were divided into two groups: healthy postmenopausal subjects (control group) and osteoporotic subjects treated with alendronate (alendronate group). Mandibular bone samples were retrieved with a trephine bur at the time of dental implant placement and fixed in 4% formalin. Samples were processed for hard tissue histology, and the bone surface was analyzed for nanohardness measurement. Nanohardness and elastic modulus were evaluated by using a Berkovich tip with elastic modulus of 1.016x106 MPa, Poisson coefficient of 0.3, and a load of 100 mN. Each cycle was configured with a load time of 18 seconds (speed of 1 mN/second), the discharge time of 18 seconds, and a rest time of 5 seconds during indentation at a depth of 10 µm. RESULTS: The control group presented the highest values for nanohardness and elastic modulus (p less than 0.05) in relation to the osteoporotic subjects. CONCLUSIONS: Within the limitations of the study, it can be concluded that treatment with alendronate negatively influenced the mechanical properties of mandibular bone in postmenopausal women by reducing bone nanohardness and elastic modulus.


Assuntos
Alendronato , Pós-Menopausa , Módulo de Elasticidade , Feminino , Dureza , Humanos , Mandíbula
8.
PLoS One ; 15(9): e0225293, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32991576

RESUMO

Grain hardness is an important quality trait of cereal crops. In wheat, it is mainly determined by the Hardness locus that harbors genes encoding puroindoline A (PINA) and puroindoline B (PINB). Any deletion or mutation of these genes leading to the absence of PINA or to single amino acid changes in PINB leads to hard endosperms. Although it is generally acknowledged that hardness is controlled by adhesion strength between the protein matrix and starch granules, the physicochemical mechanisms connecting puroindolines and the starch-protein interactions are unknown as of this time. To explore these mechanisms, we focused on PINA. The overexpression in a hard wheat cultivar (cv. Courtot with the Pina-D1a and Pinb-D1d alleles) decreased grain hardness in a dose-related effect, suggesting an interactive process. When PINA was added to gliadins in solution, large aggregates of up to 13 µm in diameter were formed. Turbidimetry measurements showed that the PINA-gliadin interaction displayed a high cooperativity that increased with a decrease in pH from neutral to acid (pH 4) media, mimicking the pH change during endosperm development. No turbidity was observed in the presence of isolated α- and γ-gliadins, but non-cooperative interactions of PINA with these proteins could be confirmed by surface plasmon resonance. A significant higher interaction of PINA with γ-gliadins than with α-gliadins was observed. Similar binding behavior was observed with a recombinant repeated polypeptide that mimics the repeat domain of gliadins, i.e., (Pro-Gln-Gln-Pro-Tyr)8. Taken together, these results suggest that the interaction of PINA with a monomeric gliadin creates a nucleation point leading to the aggregation of other gliadins, a phenomenon that could prevent further interaction of the storage prolamins with starch granules. Consequently, the role of puroindoline-prolamin interactions on grain hardness should be addressed on the basis of previous observations that highlight the similar subcellular routing of storage prolamins and puroindolines.


Assuntos
Grão Comestível/metabolismo , Gliadina/metabolismo , Dureza/fisiologia , Proteínas de Plantas/metabolismo , Triticum/metabolismo , Produção Agrícola , Difusão Dinâmica da Luz , Grão Comestível/química , Gliadina/química , Concentração de Íons de Hidrogênio , Nefelometria e Turbidimetria , Tamanho da Partícula , Proteínas de Plantas/química , Agregados Proteicos/fisiologia , Ligação Proteica/fisiologia , Domínios Proteicos/fisiologia , Sequências Repetitivas de Aminoácidos/fisiologia , Amido/química , Amido/metabolismo , Ressonância de Plasmônio de Superfície , Triticum/química
9.
Proc Natl Acad Sci U S A ; 117(38): 23450-23459, 2020 09 22.
Artigo em Inglês | MEDLINE | ID: mdl-32913055

RESUMO

Cuttlefish, a unique group of marine mollusks, produces an internal biomineralized shell, known as cuttlebone, which is an ultra-lightweight cellular structure (porosity, ∼93 vol%) used as the animal's hard buoyancy tank. Although cuttlebone is primarily composed of a brittle mineral, aragonite, the structure is highly damage tolerant and can withstand water pressure of about 20 atmospheres (atm) for the species Sepia officinalis Currently, our knowledge on the structural origins for cuttlebone's remarkable mechanical performance is limited. Combining quantitative three-dimensional (3D) structural characterization, four-dimensional (4D) mechanical analysis, digital image correlation, and parametric simulations, here we reveal that the characteristic chambered "wall-septa" microstructure of cuttlebone, drastically distinct from other natural or engineering cellular solids, allows for simultaneous high specific stiffness (8.4 MN⋅m/kg) and energy absorption (4.4 kJ/kg) upon loading. We demonstrate that the vertical walls in the chambered cuttlebone microstructure have evolved an optimal waviness gradient, which leads to compression-dominant deformation and asymmetric wall fracture, accomplishing both high stiffness and high energy absorption. Moreover, the distribution of walls is found to reduce stress concentrations within the horizontal septa, facilitating a larger chamber crushing stress and a more significant densification. The design strategies revealed here can provide important lessons for the development of low-density, stiff, and damage-tolerant cellular ceramics.


Assuntos
Materiais Biomiméticos/química , Osso e Ossos/química , Sepia/química , Animais , Fenômenos Biomecânicos , Cerâmica/química , Desenho de Equipamento , Dureza , Porosidade
10.
Am J Dent ; 33(4): 191-195, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32794393

RESUMO

PURPOSE: To evaluate the surface roughness and hardness of thermopolymerized acrylic resin incorporated with nanostructured silver vanadate (AgVO3) subjected to saliva and beverages. METHODS: The 128 specimens (5×5×2 mm) were prepared in thermopolymerized acrylic resin, according to the AgVO3 concentrations (n=32): 0%, 2.5%, 5% and 10%. The roughness and hardness were analyzed before and after immersion in saliva, Coca-Cola, orange juice and red wine, for 12 and 24 days. 2-way ANOVA and Bonferroni test (α= 0.05) were performed. RESULTS: After 12 days, Coca-Cola caused the highest roughness increase in the 2.5% group. The 10% group with saliva presented a higher roughness increase (P= 0.009). The control presented a decrease in roughness when in beverages (P< 0.05). After 24 days, orange juice and Coca-Cola produced a higher decrease in roughness in the control group (P< 0.05). After 12 days, saliva and wine produced a higher decrease in hardness of the 2.5% group (P< 0.05). Coca-Cola produced a decrease in hardness and wine an increase in hardness in the group with 10% AgVO3 concentration (P< 0.05). After 24 days, the group with 2.5% presented the highest decrease in hardness (P< 0.05). The immersions produced decreased hardness in the acrylic resin. Initially, there was an increase in roughness, however, over time, it decreased. CLINICAL SIGNIFICANCE: The control of oral biofilm is fundamental for the maintenance of the patient's oral health; however the incorporation of antimicrobial nanomaterial into prosthetic materials frequently exposed to saliva and beverages in the oral cavity interfered with the physical-mechanical properties of the products tested.


Assuntos
Nanoestruturas , Saliva , Resinas Acrílicas , Bebidas , Dureza , Humanos , Teste de Materiais , Propriedades de Superfície
11.
Yakugaku Zasshi ; 140(8): 1071-1080, 2020.
Artigo em Japonês | MEDLINE | ID: mdl-32741865

RESUMO

The purpose of the present study was to establish a novel method to evaluate water penetration rates by combining the local dynamic contact angle and thermographic approach to characterize water conduction properties in orally disintegrating (OD) tablets. The OD tablet tester OD-mate was used to measure the disintegration times of OD tablets. Other formulation characteristics, such as tablet hardness and friability, were evaluated. By examining three formulation characteristics, such as the disintegration time, tablet hardness, and friability, of 33 OD tablets for generic drugs, four characteristic OD tablets containing aripiprazole were selected. To quantitatively evaluate water penetration rates into the tablet interior, we measured the dynamic contact angle after dropping water locally on the tablet surface. Linearity with a high correlation coefficient was observed for each of the initial time-dependent changes in the dynamic contact angle. Water penetration rates into tablets were approximately twice as fast for Pharmaceuticals A and B than for Pharmaceuticals C and D. These rates were consistent with changes observed in tablet thermographic imaging. The relationship between the rapid disintegration of the tablet and its physical strength was discussed based on the internal structure of the tablet by X-ray CT and the additives of each OD tablet. The present results demonstrated that the water penetration rates of OD tablets, as measured by dynamic contact angle, may accurately detect differences in disintegration times in the human oral cavity.


Assuntos
Química Farmacêutica/métodos , Comprimidos , Termografia , Administração Oral , Fenômenos Químicos , Dureza , Solubilidade , Água
12.
Braz Oral Res ; 34: e086, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32785480

RESUMO

This study evaluates how atenolol affects dental mineralization in offspring of female spontaneously hypertensive rats (fSHR) and normotensive Wistar rats (fW). fSHR and fW were treated with atenolol (100 mg/Kg/day, orally) during pregnancy and lactation. Non-treated fSHR and fW were the control groups. Enamel and dentin hardness were analyzed (Knoop, 15 g load, 10s) in mandibular incisor teeth (IT) and molar teeth (MT) obtained from the male offspring of atenolol-treated and non-treated fWistar and fSHR. Data were analyzed by ANOVA, followed by Tukey post hoc test (p < 0.05). Atenolol reduced the arterial blood pressure (SBP) in fSHR, but it did not change the SBP in fW. The offspring of non-treated fSHR had lower enamel (IT and MT) and dentin (IT) hardness than the offspring of non-treated fW (p < 0.05). Atenolol increased enamel and dentin hardness in the IT obtained from the offspring of fSHR and fW (p<0.05), but the offspring of fSHR presented higher values (p < 0.05). Atenolol did not alter enamel width in the IT obtained from any of the groups, but it increased enamel and dentin hardness in the IT obtained from the offspring of fSHR and fW. Atenolol affected the IT obtained from the offspring of fSHR. Atenolol increased only enamel hardness in the MT obtained from the offspring of fW. In conclusion, maternal hypertension reduces tooth hard tissues, and treatment with atenolol increases tooth hardness in male offspring of hypertensive and normotensive female rats.


Assuntos
Hipertensão , Animais , Atenolol , Esmalte Dentário , Dentina , Feminino , Dureza , Masculino , Gravidez , Ratos , Ratos Wistar
13.
Niger J Clin Pract ; 23(8): 1068-1072, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32788483

RESUMO

Aims: The aim of this study was to compare the influence of operators on the microhardness and compressive strength of mineral trioxide aggregate (MTA). Materials and Methods: Forty dental specialists were asked to prepare a series of MTA samples. The tested material was ProRoot MTA (DentsplyMaillefer, Switzerland). Each participant prepared one sample to a consistency they considered acceptable for use in practice (improvised group) and another one according to the manufacturer's recommended water-to-powder (WP) ratio (pre-weighed group). The samples were incubated at 37°C and 95% humidity for 4 days. Parameters evaluated in this study were microhardness and compressive strength. Results: Operators mixed MTA samples with varying WP ratios. However, there was no significant difference between the microhardness and compressive strength values of MTA samples between the improvised, the pre-weighed and the control groups. MTA was mixed in a thicker consistency than the manufacturers recommended ratio (0.33) by 62.5% of the operators. Conclusion: According to the results of this study, even though the WP ratios that were utilized in the clinical setting vary, microhardness and compressive strength values of MTA was not significantly affected.


Assuntos
Compostos de Alumínio/química , Compostos de Cálcio/química , Força Compressiva , Teste de Materiais/métodos , Óxidos/química , Materiais Restauradores do Canal Radicular , Silicatos/química , Estudos de Casos e Controles , Combinação de Medicamentos , Dureza , Humanos , Água
14.
AAPS PharmSciTech ; 21(6): 232, 2020 Aug 13.
Artigo em Inglês | MEDLINE | ID: mdl-32794080

RESUMO

The aims of the current study were to develop and evaluate clindamycin palmitate hydrochloride (CPH) 3D-printed tablets (printlets) manufactured by selective laser sintering (SLS). Optimization of the formulation was performed by studying the effect of formulation and process factors on critical quality attributes of the printlets. The independent factors studied were laser scanning speed, microcrystalline cellulose (MCC), and lactose monohydrate (LMH) concentration. The responses measured were printlets weight, hardness, disintegration time (DT), and dissolution in 30 min. The printlets were characterized for content uniformity, chemical interactions, crystallinity, drug distribution, morphology, and porosity. The laser scanning speed showed statistically significant effects on all the studied dependent responses (p < 0.05). MCC showed statistically significant effects on hardness, DT, and dissolution (p < 0.05), while LMH showed statistically significant effect on hardness and dissolution (p < 0.05). The model was validated by an independent formulation, and empirical values were in close agreement with model-predicted values. X-ray powder diffraction and differential scanning calorimetry data suggested a decrease in crystallinity of the LMH in the printlets. X-ray micro-CT scanning showed porous microstructure of the printlets with a porosity 24.4% and 31.1% for the printlets printed at 200 and 300 mm/s laser speed, respectively. In summary, the SLS method provides an opportunity to fabricate customized dosage forms as per patients' need.


Assuntos
Clindamicina/análogos & derivados , Lasers , Impressão Tridimensional , Antibacterianos/análise , Antibacterianos/síntese química , Varredura Diferencial de Calorimetria/métodos , Clindamicina/análise , Clindamicina/síntese química , Dureza , Humanos , Porosidade , Propriedades de Superfície , Comprimidos/química , Difração de Raios X/métodos
15.
Braz Dent J ; 31(3): 264-271, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32667515

RESUMO

The objective of this work was to evaluate the effects of in vitro and in situ biodegradation on the surface characteristics of two resin cements and a hybrid ceramic system. One hundred and eighty specimens (4X1.5mm) of each material (Maxcem Elite, NX3 Nexus and Vita Enamic) were made and randomly distributed in twelve groups (n=15) according to the material and biodegradation method. The specimens were then submitted to the following challenges: storage in distilled water 37 ºC for 24 h or 7 days, storage for 7 days, at 37 ºC, in stimulated saliva or in situ. The in situ stage corresponded to the preparation of 15 intraoral palatal devices, used for 7 days. Each device presented 3 niches, where a sample of each materials was accommodated. Specimens from both saliva and in situ groups suffered a cariogenic challenge, corresponding to the application of a solution of 20% of sucrose, 10 times throughout each day. After each biodegradation method, the surface roughness (Ra), Vickers hardness (VHN) and scanning electron microscopy (SEM) analyzes were performed. The data collected were evaluated by Levene test, two-way ANOVA and Tukey`s test (α=5%). The in situ challenge promoted the greater biodegradation, regardless of the material. Regarding the materials, the Vita Enamic VHN was negatively affected by all biodegradation methods and the Nexus NX3 presented better performance than the self-adhesive cement tested. Therefore, within the conditions of this work, it was concluded that in situ biodegradation can affect negatively the surface characteristics of indirect restorative materials.


Assuntos
Materiais Dentários , Cimentos de Resina , Cerâmica , Dureza , Teste de Materiais , Propriedades de Superfície
16.
J Adhes Dent ; 22(4): 373-382, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32666063

RESUMO

PURPOSE: To determine and compare the effects of tribochemical silica coating and alumina-particle air abrasion on 3 mol% and 5 mol% yttria-stabilized tetragonal zirconia polycrystals (Y-TZP). MATERIALS AND METHODS: Two different 3Y-TZP samples (Lava Plus, 3M Oral Care; Ceramill Zolid, Amann Girrbach) and one 5Y-TZP sample (Katana Zirconia UTML, Kuraray Noritake) were prepared and treated with alumina-particle air abrasion and a 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP)-containing self-adhesive composite cement or with tribochemical silica coating followed by silanization (n = 30). Resin columns were cemented onto the treated ceramic surfaces to form specimens. After 24-h water storage or aging with 10,000 thermocycles plus 60-day water storage, shear bond strength (SBS) testing was conducted. Surface roughness, surface Vickers hardness, and crystallographic phase analyses were also performed. RESULTS: The SBS of tribochemically silica-coated 5Y-TZP before and after aging were 13.8 ± 1.4 and 13.2 ± 1.5 MPa, resp., for Lava Plus (3Y-TZP) 14.4 ± 1.4 and 13.9 ± 1.6 MPa, respectively, and for Ceramill Zolid (3Y-TZP) 14.8 ± 1.1 and 13.9 ± 1.5 MPa, respectively. There was no statistical difference between tribochemical silica coating and alumina air abrasion treatments (p = 0.21) on the bonding performance (SBS) of the 3Y-TZPs and 5Y-TZP (p = 0.25) before and after aging (p = 0.50). After alumina air abrasion, 5Y-TZP showed higher surface roughness (Ra = 1.7 ± 0.1) than did the 3Y-TZPs (Ra = 1.2 ± 0.1 for Lava Plus; Ra = 1.2 ± 0.1 for Ceramill Zolid), while the Vickers hardness was similar among the three materials (p = 0.70). Monoclinic zirconia was not detected in 5Y-TZP irrespective of treatment, with the zirconia being mainly cubic phase. However, the 3Y-TZPs were mainly tetragonal phase with some monoclinic zirconia; the latter increased after being alumina-particle air abraded. CONCLUSION: The bond strength to 5Y-TZP is similar to those of the 3Y-TZPs under the same bonding strategies. Durable bonding can be achieved both by alumina air abrasion combined with a 10-MDP-containing self-adhesive composite cement and by tribochemical silica coating followed by silanization for both the 3Y-TZPs and 5Y-TZP.


Assuntos
Óxido de Alumínio , Colagem Dentária , Abrasão Dental por Ar , Dureza , Teste de Materiais , Cimentos de Resina , Dióxido de Silício , Propriedades de Superfície , Ítrio , Zircônio
17.
PLoS One ; 15(7): e0236324, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32706841

RESUMO

As the main actuator of high-speed running, the ostrich feet are highly capable of cushioning and shock absorption. In this study, based on the elastic modulus scales and assembly order of the 3rd toe soft tissues and the functions of the metatarsophalangeal (MTP) joint, we designed fourteen bio-inspired feet. The impact process on loose sand was simulated on the finite element software Abaqus. Also the stress distributions and deformations of each component of the bio-inspired feet were clarified. With the peak acceleration as the index, the cushioning performances of the bio-inspired feet were compared on both loose sand and solid ground through height-variable impact tests. The 15-15-15 HA (hardness unit) bio-inspired foot showed lower peak acceleration and thereby better cushioning performance, but larger deformation, less-uniform stress distribution and thereby lower stability than the 15-35-55 HA bio-inspired foot. In fact, the silicon rubbers with different hardness degrees (which simulate the elasticity modulus scales of the digital cushions, fascia and skin) and the spring mechanism (which simulates the functions of the MTP joint) work as an "integrated system" of cushioning and shock absorption.


Assuntos
Aceleração , Membros Artificiais , Modelos Anatômicos , Corrida , Struthioniformes/anatomia & histologia , Animais , Módulo de Elasticidade , Pé/anatomia & histologia , Dureza , Humanos , Articulação Metatarsofalângica/anatomia & histologia , Dedos do Pé/anatomia & histologia
18.
Chemosphere ; 259: 127473, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32622247

RESUMO

Cationic polymers (CPs) are widely used chemicals for wastewater treatment applications and in various "down-the-drain" household products. The aquatic toxicity of CPs results from an electrostatic interaction with negatively charged cell surfaces. These effects are greatly mitigated by the binding affinity of CPs to total organic carbon (TOC) in surface water. Consequently, baseline aquatic toxicity tests of CPs using clean lab water (TOC < 2 mg/L) typically overestimate toxicity and risk which is greatly mitigated at higher environmentally relevant OC levels. However, the point at which mitigation begins is not well defined and low-level TOC in lab water may influence the baseline toxicity outcome. Similarly, divalent cations, quantified as water hardness, may modulate the electrostatic binding between OC and CP. Although standard guidelines define limits for lab water hardness and TOC, the consequences of variability within those limits on test outcome is unknown. We investigated the impact of part-per-billion (ppb) additions of TOC to lab water at different hardness levels on CP acute toxicity to Daphnia magna and Raphidocelis subcapitata. In both species, the acute toxicities of CPs with different molecular weight and charge density varied by > 10-fold in response to slight changes in TOC and water hardness, although parameters were maintained within guideline limits. When determining the baseline aquatic toxicity of CPs, the lab water should be standardized at the lowest biologically tolerable hardness and TOC at a reliably measurable level (>1 - < 2 mg/L) to reduce variability and increase the reliability of the toxicity estimate.


Assuntos
Monitoramento Ambiental/métodos , Poluentes Químicos da Água/análise , Animais , Cátions , Daphnia/efeitos dos fármacos , Monitoramento Ambiental/normas , Água Doce/química , Dureza , Polímeros/toxicidade , Reprodutibilidade dos Testes , Testes de Toxicidade
19.
Braz Oral Res ; 34: e061, 2020 Jun 24.
Artigo em Inglês | MEDLINE | ID: mdl-32609230

RESUMO

The purpose of this double-blind, randomized, crossover in situ study is to compare remineralization of preformed enamel lesions by casein phosphopeptide-stabilized amorphous calcium phosphate (CPP-ACP) and fluoride dentifrice products. During each of four 10-day experimental legs, 10 participants wore intraoral removable palatal acrylic appliances with four human enamel slabs with preformed lesions. A 0.03-mL treatment paste was dripped extraorally onto the enamel blocks once a day for 3 min. The four randomly allocated treatments were as follows: CO- Control: silica dentifrice without fluoride; MP: MI Paste; MPP: MI Paste Plus and FD: Fluoride dentifrice - 1100 ppm F as NaF). Knoop surface hardness (SH) test was performed in three stages (T0 - sound enamel, T1 - after preformed lesion, and T2 - after treatment) and the cross-sectional hardness (CSH) test was performed after treatment using a 50-gram Knoop load for 15 s. Knoop hardness number (KHN) was similar between treatments. %SHr was significantly higher in the MP, FD, and MPP when compared to CO group (Kruskal-Wallis and Mann-Whitney tests, p < 0.05). Harder enamel was found in MP (75 µm) and FD groups at 75 to 175 µm. Treatment with DF, MP, and MPP promoted an increase of 20.27%, 19.24%, and 14.71%, respectively, in Integral Hardness Change (ΔIHC) when compared to CO (p<0.05). Remineralizing agents (MP, MPP, and DF) were able to inhibit demineralization of human enamel subjected to high cariogenic challenge in situ. DF had the greatest preventive potential against the progression of carious lesions.


Assuntos
Remineralização Dentária , Cariostáticos , Caseínas , Estudos Transversais , Método Duplo-Cego , Fluoretos , Dureza , Humanos
20.
J Contemp Dent Pract ; 21(5): 543-548, 2020 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-32690837

RESUMO

AIM: To assess the influence of three probiotic mouthrinses on the microhardness of three esthetic materials used for teeth restorations. MATERIALS AND METHODS: Thirty specimens of each material: conventional glass ionomer cement (GIC), resin-modified glass ionomer, and resin composite were randomly assigned to three groups. Surface microhardness was measured at baseline. The specimens were immersed in probiotic mouthrinses, group I: (P2 probiotic power), group II: (Probioclean), and group III (BoKU natural). Microhardness was measured after 21 and 63 minutes of immersion which is comparable with 3 and 9 weeks of mouthrinse use every day, respectively. Measurements of microhardness were completed using Micro Vickers testing machine with a 200 g load applied for a duration of 15 seconds. RESULTS: The microhardness change of the three restorative materials reveled statistically significant differences in all mouthrinse groups (p = 0.001). BoKU natural mouthrinse decreased microhardness significantly in all restorative materials (p < 0.05). However, Probioclean mouthrinse was associated with an increase in microhardness in all restorative materials. The effect of P2 probiotic power mouthrinse varied depending on time cycles and the restorative material. The mean difference in mouthrinse groups of resin composite was highest in BoKU natural at immersion time of 63 minutes. While no mean difference was seen in P2 probiotic power group at immersion time of 21 minutes which had no effect on the microhardness of resin composite. CONCLUSION: Surface microhardness was affected by immersion in probiotic mouthrinses. The BoKU natural mouthrinse had the highest reduction, while resin composite showed the least change in surface microhardness. CLINICAL SIGNIFICANCE: There is lack of studies that investigated the effect of probiotics mouthrinses on the surface properties of restorative materials. This study showed evidence that some of the tested probiotic mouthrinses in this study decreased the microhardness of the tested tooth-colored restorative materials after immersion for 21 and 63 minutes which is equivalent to 3 and 9 weeks of everyday use.


Assuntos
Probióticos , Resinas Compostas , Restauração Dentária Permanente , Estética Dentária , Cimentos de Ionômeros de Vidro , Dureza , Teste de Materiais , Propriedades de Superfície
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