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1.
Niger J Clin Pract ; 23(6): 792-797, 2020 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-32525113

RESUMEN

Background: There is no information about the shear bond strengths (SBS) of zirconia ceramic to primary tooth dentin. Aim: To investigate the effect of different surface treatments and cements on the shear bond strength (SBS) of zirconia ceramic to primary tooth dentin. Materials and Methods: Prepared zirconia bars were distributed into four groups according to surface treatment procedure: control, sandblasting, CoJet and hot etching. The zirconia specimens in each group were further divided into subgroups according to cement (n = 13): self-adhesive resin (Rely-X Unicem), resin-modified glass ionomer (Ketac-Cem Plus), and universal bioactive (BioCem). Zirconia specimens were bonded to the primary tooth dentin surface by cement. SBS was measured, and the data were subjected to two-way ANOVA and Tukey's tests. Results: Statistical differences were observed in the surface treatment procedures for Rely-X Unicem (P < 0.05), but no statistically significant differences were found in the sandblasting, CoJet and hot-etching groups for Ketac-Cem Plus (P > 0.05). For BioCem, the SBS value for the hot etching group was significantly lower than those for the CoJet and sandblasting groups (P < 0.05). The SBS values for the Rely-X Unicem subgroups (sandblasting, CoJet and hot etching) were significantly higher than those for the other cements (P < 0.05). Conclusion: The bond strength of zirconia ceramic to primary tooth dentin is affected by surface treatments and cements.


Asunto(s)
Cerámica/química , Recubrimiento Dental Adhesivo , Dentina , Cementos de Resina/química , Resistencia al Corte , Diente Primario , Circonio/química , Resinas Acrílicas , Adhesivos , Cementos de Ionómero Vitreo , Humanos , Ensayo de Materiales , Dióxido de Silicio , Propiedades de Superficie
2.
Braz Oral Res ; 34: e045, 2020 May 08.
Artículo en Inglés | MEDLINE | ID: mdl-32401935

RESUMEN

This in vitro study aimed to evaluate the effect of a silane-containing universal adhesive used with or without a silane agent on the repair bond strength between aged and new composites. Forty nanohybrid composite resin blocks were stored in distilled water for 14 d and thermo-cycled. Sandpaper ground, etched, and rinsed speciments were randomly assigned into four experimental groups: silane + two-step etch-and-rinse adhesive system, two-step etch-and-rinse adhesive system, silane + silane-containing universal adhesive system, and silane-containing universal adhesive system. Blocks were repaired using the same composite. After 24 h of water storage, the blocks were sectioned and bonded sticks were submitted to microtensile testing. Ten unaged, non-repaired composite blocks were used as a reference group to evaluate the cohesive strength of the composite. Two-way ANOVA and Tukey's tests were used to analyze average µTBS. One-way ANOVA and Dunnet post-hoc tests were used to compare the cohesive strength values and bond strength obtained in the repaired groups (α = 0.05). The µTBS values were higher for the silane-containing universal adhesive compared to the two-step etch-and-rinse adhesive system (p = 0.002). Silane application improved the repair bond strength (p = 0.03). The repair bond strength ranged from 39.3 to 65.8% of the cohesive strength of the reference group. Using universal silane-containing adhesive improved the repair bond strength of composite resin compared to two-step etch-and-rinse adhesive. However, it still required prior application of a silane agent for best direct composite resin repair outcomes.


Asunto(s)
Resinas Compuestas/química , Cementos Dentales/química , Cementos de Resina/química , Silanos/química , Análisis de Varianza , Recubrimiento Dental Adhesivo/métodos , Ensayo de Materiales , Valores de Referencia , Reproducibilidad de los Resultados , Propiedades de Superficie , Resistencia a la Tracción , Factores de Tiempo
3.
Braz Oral Res ; 34: e020, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32236317

RESUMEN

This in vitro study aimed to assess the effects of different pretreatments used to adapt glass-fiber posts cemented to root canals with different resin cements, regarding porosity percentage and bond strength. Twelve bovine incisor roots were prepared with Largo drills. After post space preparation, the specimens were randomized into two types of pretreatment groups (n = 3): water-wet bonding and ethanol-wet bonding. After the post were cemented, the roots were stored in 100% humidity at room temperature for 7 days. The samples were scanned by microcomputed tomography (micro-CT). Images were reconstructed by NRecon software, and CTAn software was used to analyze the porosity percentage (%) at the luting interface. Evaluation of the push-out bond strength was performed by serially cutting the roots, and submitting the slices to testing. Additionally, the resin cement post-gel shrinkage values (%) were measured using the strain-gauge method (n = 10). Data were analyzed by two-way ANOVA, Tukey's test and Student's t test (a = 0.05). The roots prepared with ethanol-wet bonding using RelyX™ U200 had significantly lower porosity in the coronal and apical thirds (p < 0.05). The group prepared with ethanol-wet bonding using RelyX™ ARC presented better bond strength results in the coronal and apical thirds (p < 0.05). RelyX™ ARC (0.97%) produced a higher post-gel shrinkage value than RelyX™ U200 (0.77%). Canals pretreated with ethanol-wet bonding presented better outcomes in regard to porosity percentage and push-out bond strength.


Asunto(s)
Recubrimientos Dentinarios/farmacología , Etanol/farmacología , Técnica de Perno Muñón , Cementos de Resina/química , Raíz del Diente/efectos de los fármacos , Animales , Bovinos , Recubrimiento Dental Adhesivo , Materiales Dentales/química , Cavidad Pulpar , Vidrio , Ensayo de Materiales , Porosidad , Irrigantes del Conducto Radicular/química , Microtomografía por Rayos X
4.
Braz Oral Res ; 34: e018, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32187304

RESUMEN

The objective of this study was to evaluate the influence of hydrofluoric acid (HF) concentration, etching time, and application of phosphoric acid (PA) followed by neutralization with sodium bicarbonate on the bond strength between a feldspar ceramic and resin cement. Thus, 80 blocks (10 x 12 x 2 mm) of glass ceramic (VM - Vita Mark II - Vita Zahnfabrik) were made and randomly assigned to eight groups (n = 10) according to the factors: HF concentration (5 and 10%), etching time (60 and 120 s), and use of phosphoric acid (PA) (with and without). According to the experimental group, 37% PA (Condac, FGM) was applied after HF etching for 60s. Afterwards, samples were immersed in sodium bicarbonate for 1 min then in an ultrasonic bath in distilled water (5 min) for cleaning. After surface bonding treatment, cylinders (Ø = 2 mm; h = 2 mm) of dual resin cement (AllCem / FGM) were made in the center of each block. The samples were then stored in water (37ºC) for 90 days and submitted to the shear bond test (50 KgF, 1 mm/min). Failure analysis was performed by stereomicroscope and scanning electron microscopy. Data (MPa) were analyzed with 3-way ANOVA and Tukey's test. Only the factor "HF concentration" was significant (p = 0.02). Most failures were of cohesive in ceramic (40%) and mixed types (42.5%). The 10% HF resulted in higher shear bond strength value than the 5% HF. Surface cleaning with phosphoric acid followed by sodium bicarbonate and HF time (60 or 120 seconds) did not influence the resin bond strength to feldspar ceramic.


Asunto(s)
Silicatos de Aluminio/química , Recubrimiento Dental Adhesivo/métodos , Ácido Fluorhídrico/química , Ácidos Fosfóricos/química , Compuestos de Potasio/química , Análisis de Varianza , Porcelana Dental/química , Ensayo de Materiales , Metacrilatos/química , Microscopía Electrónica de Rastreo , Valores de Referencia , Reproducibilidad de los Resultados , Cementos de Resina/química , Resistencia al Corte/efectos de los fármacos , Silanos/química , Propiedades de Superficie , Factores de Tiempo
5.
J Appl Oral Sci ; 28: e20190371, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32049135

RESUMEN

OBJECTIVE: This study aims to evaluate the influence of different air-abrasion pressures and subsequent heat treatment on the flexural strength, surface roughness, and crystallographic phases of highly translucent partially stabilized zirconia (Y-PSZ), and on the tensile bond strength of resin cement to Y-PSZ. METHODOLOGY: Fully sintered zirconia specimens were ground with SiC paper (control) and/or air-abraded with 50 µm particles of alumina at 0.1, 0.15, 0.2, or 0.3 MPa or left as-sintered. After air-abrasion at 0.2 MPa (0.2AB), additional specimens were then heated to 1500°C, and held for one hour at this temperature (0.2AB+HT1h). Flexural strength and surface roughness were evaluated. Crystalline phase identification was also carried out using X-ray diffraction. Bonded zirconia specimens with self-adhesive resin cement were stored in distilled water at 37°C for 24 h, either with or without aging (thermal cycling 4-60°C/20000). Results were analyzed statistically by ANOVA and Tukey-Kramer tests. RESULTS: The flexural strength decreased with the increase in air-abrasion pressure, while in contrast, the surface roughness increased. The lowest flexural strength and the highest roughness value were found for the 0.2AB and 0.3AB groups, respectively. All groups contained cubic-, tetragonal ( t )-, and rhombohedral ( r )-ZrO2 phases with the exception of the as-sintered group. Upon increasing the air-abrasion pressure, the relative amount of the r -ZrO2 phase increased, with a significant amount of r -ZrO2 phase being detected for the 0.2AB and 0.3AB groups. The 0.2AB+HT1h group exhibited a similar flexural strength and t -ZrO2 phase content as the as-sintered group. However, the 0.2AB group showed a significantly higher tensile bond strength (p<0.05) than the 0.2AB+HT1h group before and after aging. CONCLUSION: Micromechanical retention by alumina air-abrasion at 0.2 MPa, in combination with chemical bonding of a resin to highly translucent Y-PSZ using a MDP-containing resin cement may enable durable bonding.


Asunto(s)
Abrasión Dental por Aire/métodos , Óxido de Aluminio/química , Recubrimiento Dental Adhesivo/métodos , Cementos de Resina/química , Circonio/química , Análisis de Varianza , Resistencia Flexional , Calor , Ensayo de Materiales , Microscopía Confocal/métodos , Valores de Referencia , Reproducibilidad de los Resultados , Propiedades de Superficie , Resistencia a la Tracción , Difracción de Rayos X/métodos
6.
Braz Oral Res ; 34: e001, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32022221

RESUMEN

This study analyzed the effect of prior application of copaiba oil (CO) emulsions as a dentin cleaning substance on microleakage and microtensile adhesive strength. Twenty-five premolars and sixty-four molars were used for microleakage and microtensile assays. For the microleakage assays, specimens with standard class V cavities were divided (n = 5), according to the tested CO emulsions: CO10%X, CO10%Y, and CO10%Z, as well as chlorhexidine 2% (CHX) and distilled water (DW), as positive and negative controls, respectively. Restorations were performed using the Adper Single Bond® and/or Clearfil SE Bond® systems. Cervical, occlusal, distal and mesial sections were assessed for tracer penetration degree at the composite/tooth interface. For the microtensile assay, healthy molars were divided into sixteen groups, in which artificial caries were induced in half of the groups. Dentin surfaces were treated with CO10%X and CO10%Y, CHX and DW. Microtensile bond strength was measured by fixing each sample to the plate of a universal testing machine operated at a speed of 0.5 mm/minute until failure. Dentin treated with CO10%X showed a lower infiltration rate than dentin treated with the other CO emulsions, CHX2% and DW. According to the microtensile assay, both healthy and affected dentin treated with CO10%X and Adper Single Bond® adhesive system presented higher adhesive strength. CO emulsion, used as a dentin biomodifier, interfered positively in microleakage and improved adhesive strength after acid etching in the Adper Single Bond® adhesive system, or before applying the Clearfil SE Bond® self-etching system.


Asunto(s)
Recubrimiento Dental Adhesivo/métodos , Recubrimientos Dentinarios/química , Dentina/efectos de los fármacos , Fabaceae/química , Aceites Vegetales/química , Análisis de Varianza , Clorhexidina/química , Resinas Compuestas/química , Cementos Dentales/química , Filtración Dental , Dentina/química , Emulsiones/química , Humanos , Ensayo de Materiales , Reproducibilidad de los Resultados , Cementos de Resina/química , Estadísticas no Paramétricas , Propiedades de Superficie , Resistencia a la Tracción
7.
Braz Oral Res ; 34: e004, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32022223

RESUMEN

The aim of this study was to analyze the structural, morphological and mechanical properties of two different lithium disilicate glass-reinforced ceramics for CAD-CAM systems (IPS e.max CAD and Rosetta SM). Five methodologies were used for both ceramics: microstructure (n = 2) was analyzed using x-ray diffraction (XRD); morphological properties (n = 2) were analyzed by scanning electron microscopy (SEM), with and without hydrofluoric etching; porosity (n = 3) was assessed using 3D micro-computed tomography (micro-CT); flexural strength was measured (n =1 0) using the three-point bending test; and bond strength was determined with self-adhesive resin cement (n = 10), using a microshear bond test. After performing all the tests, the data were analyzed using t-Student test and two-way ANOVA. All the tests used a significance level of α = 0.05. High peak positions corresponding to standard lithium metasilicate and lithium disilicate with similar intensities were observed for both ceramics in the XRD analysis. Morphological analysis showed that the crystalline structure of the two ceramics studied showed no statistical difference after acid etching. Additionally, no significant differences were recorded in the number or size of the pores for the ceramics evaluated. Moreover, no differences in flexural strength were found for the ceramic materials tested, or in the bond strength to ceramic substrates for the resin cements. Based on the study results, no significant differences were found between the two CAD-CAM lithium disilicate glass-reinforced ceramics tested, since they presented similar crystalline structures with comparable intensities, and similar total porosity, flexural strength and bond strength.


Asunto(s)
Cerámica/química , Diseño Asistido por Computadora , Porcelana Dental/química , Vidrio/química , Análisis de Varianza , Recubrimiento Dental Adhesivo/métodos , Resistencia Flexional , Ensayo de Materiales , Microscopía Electrónica de Rastreo , Porosidad , Valores de Referencia , Reproducibilidad de los Resultados , Cementos de Resina/química , Resistencia al Corte , Propiedades de Superficie , Difracción de Rayos X
8.
Gen Dent ; 68(1): 22-28, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-31859658

RESUMEN

Self-adhesive resin cements that eliminate the primer step have been introduced to simplify the bonding protocol for indirect restorations. The aim of the present study was to compare the shear bond strengths (SBSs) of 2 self-adhesive resin cements used with or without a self-etching primer. The hypothesis was that adding a separate primer component to the self-adhesive systems would increase the SBS at the tooth-adhesive interface. One hundred twenty extracted human molars were hemisectioned and embedded in epoxy. Specimens were polished to expose enamel or dentin surfaces and randomly assigned to 12 test groups (n = 20). The tested variables were (1) the type of bonded tissue (enamel or dentin); (2) the cement used; (3) whether the cement was applied with or without a primer; (4) and whether the primer was air dried or photopolymerized. Bonding jigs were used to apply the self-adhesive resin cement to the tooth surfaces. A 2-minute self-cure was followed by 20 seconds of light curing. Specimens were stored in water for 24 hours and then subjected to SBS testing in a universal testing machine. Fractured specimens were examined under a microscope to determine the modes of failure. Mean SBS values were compared using a paired Student t test (with post hoc Tukey test) and an analysis of variance (α = 0.05). Compared to the control groups, the air-dried primer groups showed SBSs that were 4-6 times greater for the specimens bonded to dentin and 2-3 times greater for specimens bonded to enamel. The photopolymerized primer groups followed the same trend. The photopolymerized groups showed higher percentages of cohesive tooth failure than did air-dried primer groups. Placement of a self-etching primer prior to a self-adhesive resin cement significantly increased the SBS to tooth structure of the "all-in-1" resin cements that were tested. Photopolymerizing the primer did not significantly increase the bond strength.


Asunto(s)
Recubrimiento Dental Adhesivo , Cementos Dentales , Ensayo de Materiales , Cementos de Resina , Resistencia al Corte , Grabado Ácido Dental , Cementos Dentales/química , Análisis del Estrés Dental , Dentina , Recubrimientos Dentinarios , Humanos , Cementos de Resina/química , Propiedades de Superficie
9.
Biomed Res Int ; 2019: 2041348, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-31828093

RESUMEN

The introduction of resin-based cements and an adhesive-bonding system in daily dental practice has given the opportunity to increase the retention of previously conventional cemented restorations and the optimal results in esthetic. This experimental study employed the 3D Digital Image Correlation Method (3D-DIC) for detecting shrinkage strain in four dual cured composite cements. The aim was to visualize measure, analyze, and compare strain fields in four resin-based cements using the 3D-DIC method. A total of 72 samples were divided into 4 groups considering variations in sample types, diameter, and thickness. Four types of composite cements: RelyX U200 (3 M ESPE, St. Paul, MN, USA), MaxCem Elite (Kerr, Orange, CA, USA), Multilink Automix (Ivoclar Vivadent, Schaan, Liechtenstein), and SeT PP (SDI, Australia) were used. Each type had diameters of 3 mm, 4 mm, and 5 mm, respectively, combined with two different values of thickness: 1 mm and 2 mm. Thickness had an important role on strain detected in all tested materials showing higher strain in samples with 2 mm thickness compared to 1 mm samples. Shrinkage strain values were the highest in Set PP samples indicated the possibility of undesirable de-bonding.


Asunto(s)
Cementos Dentales/química , Resinas Acrílicas/química , Australia , Resinas Compuestas/química , Recubrimiento Dental Adhesivo/métodos , Análisis del Estrés Dental/métodos , Humanos , Ensayo de Materiales/métodos , Poliuretanos/química , Cementos de Resina/química , Resistencia a la Tracción
10.
Niger J Clin Pract ; 22(12): 1675-1679, 2019 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-31793473

RESUMEN

Aims: The aim of this in vitro investigation was to evaluate the efficiency of self-adhering flowable resin composite (Vertise Flow, Kerr, Orange, CA, USA) and different surface treatments in the repair microtensile bond strength (µTBS) of aged nanofill resin composites using a universal adhesive. Materials and Methods: Aged substrates (×5000 thermocycling) were prepared using a nanofill (Filtek Ultimate; 3M ESPE) resin composite and randomly assigned to different surface treatments: (1) no treatment (control), (2) acid etching with 37% phosphoric acid, (3) Al2O3sandblasting, and (4) sandblasting with CoJet (3M ESPE). After surface treatment, specimens were further divided into two groups: no universal adhesive application and universal adhesive application. Vertise Flow was added to the substrates at 2-mm layer increments to a height of 5 mm and light cured. Restored specimens were sectioned to obtain 1.0-mm2 beams for µTBS testing. Data were analyzed with two-way analysis of variance and Tukey's honest significant difference tests (P < 0.05). Results: The lowest µTBS values were recorded in the control and acid etching groups with no universal adhesive application (P < 0.05). Universal adhesive application significantly increased the repair µTBS values of all surface treatments (P < 0.05), except CoJet treatment. There were no significant differences between Al2O3sandblasting, CoJet application, and acid etching groups with the universal adhesive application (P > 0.05). Conclusion: Vertise Flow can be used effectively in the repair of old nanofill resin composites. The usage of universal adhesive with prior acid etching to obtain acceptable repair performance would be the practical choice under clinical conditions.


Asunto(s)
Resinas Compuestas/química , Recubrimiento Dental Adhesivo/métodos , Esmalte Dental/química , Recubrimientos Dentinarios , Dentina/química , Cementos de Resina/química , Adhesivos , Análisis del Estrés Dental , Humanos , Ensayo de Materiales/métodos , Propiedades de Superficie , Resistencia a la Tracción
11.
Niger J Clin Pract ; 22(11): 1475-1482, 2019 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-31719267

RESUMEN

Objective: To compare the shear bond strength of resin cement to zirconia-based monolithic CAD-CAM materials subjected to different surface treatments. Methods: 2 brands of monolithic zirconia blocks (Vita YZ HT, Sirona inCoris TZI), yttrium-stabilized tetragonal zirconia (IPS e.max ZirCAD) and zirconia-reinforced lithium silicate ceramic (Vita Suprinity) were divided into six groups according to the surface treatment received: no treatment (control), HF acid etching, sandblasting, sandblasting + Er:YAG laser irradiation, Er:YAG laser irradiation and CoJet. Composite resin cylinders were bonded to blocks with self-adhesive resin cement (Theracem). Shear bond strength was evaluated after thermocyling. Failure modes were examined using SEM. Data was analyzed statistically by using 2-way ANOVA and post-hoc Tukey's test (P < 0,05). Results: The bond strength was significantly affected by the surface treatment and the type of CAD-CAM blocks (P < 0,001). Surface treatment with CoJet revealed significantly higher bond strength compared to sandblasting in Y-TZP and monolithic zirconia specimens. Conclusions: Monolithic zirconia blocks showed higher bond strength values compared to Y-TZP zirconia block in sandblasting and CoJet groups. HF acid etching is more effective than sandblasting and CoJet for Vita Suprinity.


Asunto(s)
Cerámica/química , Resinas Compuestas/química , Ensayo de Materiales/métodos , Cementos de Resina/química , Resistencia al Corte , Circonio , Diseño Asistido por Computadora , Recubrimiento Dental Adhesivo , Humanos , Microscopía Electrónica de Rastreo , Propiedades de Superficie , Itrio
12.
Molecules ; 24(21)2019 Nov 05.
Artículo en Inglés | MEDLINE | ID: mdl-31694145

RESUMEN

Carbon fiber mesh reinforced cement-based composites (CMCCs) have received extensive attention in the field of engineering repair and structural reinforcement due to their outstanding properties such as two-way force, rust prevention, high specific strength, and low base surface requirements. However, the development of this material has been slowed down to some extent due to the poor interfacial bonding between the carbon fiber mesh and the cement matrix. In this paper, a novel fabrication strategy was proposed in which the carbon fiber mesh was modified with epoxy resin and silane coupling agent (SCA) to increase its surface chemical activity. Meanwhile, the hydroxymethyl cellulose (HMC) was also filled into the concrete matrix to improve the mechanical strength of the matrix as well as the load transfer behaviors between the mortar and carbon fiber (CF) mesh. The potential to employ SCA and HMC was evaluated for the making of CMCCs via the above methods. The results showed that the longitudinal shear strength of composites with SCA and SCA&HMC increased by 26.6% and 56.1% compared to those of CF with epoxy resin (EP) reinforced composites, respectively. The flexural strength of composite with SCA&HMC increases by 147.6% compared to I-(F) without CF. The novel II-HCM&CF/EP-SCA composites with excellent performance are promised to be applied in practical uses.


Asunto(s)
Fibra de Carbono/química , Resinas Compuestas/química , Cumarinas/química , Cementos de Resina/química , Silanos/química , Resinas Epoxi/química , Ensayo de Materiales/métodos , Resistencia al Corte , Estrés Mecánico , Propiedades de Superficie , Mallas Quirúrgicas
13.
Braz Oral Res ; 33: e120, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-31778475

RESUMEN

The objective of this study is to compare the resin-enamel bond strength (mµSBS), in-situ degree of conversion (DC), and the enamel-etching pattern (SEM/EDX) of universal adhesive systems when applied to sound and fluorotic enamel. Ninety-eight human molars were sectioned into 4 parts and divided into 24 groups according to 1) enamel surface (sound or fluorotic enamel), 2) adhesive system (Clearfil Universal Bond [CUB], Futurabond U [FBU], iBond Universal [IBU], and Scotchbond Universal [SBU]), and 3) application mode (etch-and-rinse [ER], active self-etch [Active-SE], and passive self-etch [Passive-SE]). Specimens were stored at 37 °C, for 24 hours and tested at 1.0 mm/min (µSBS). Enamel-resin interfaces were evaluated for in-situ DC. The enamel-etching pattern was evaluated under a SEM/EDX. Data from mµSBS and in-situ DC was analyzed using a three-way ANOVA and Tukey's test at 5 % level of significance. For all adhesives, the ER resulted in a statistically significant higher mean mµSBS than the passive-SE in both substrates (p < 0.001). For all adhesives, active-SE resulted in mean mµSBS (p > 0.31) and in-situ DC (p > 0.45) that were statistically similar to those obtained with the ERs in both substrates. A statistically significant, higher mean mµSBS and in-situ DC were obtained in sound enamel (p < 0.001) than in fluorotic enamel. In general, SBU showed higher mean values for mµSBS and in-situ DC compared to those of CUB and IBU (p < 0.001). ER and active-SE showed the deepest enamel-etching pattern in both substrates. A higher amount of fluor was observed in fluorotic enamel. The active application of universal adhesives in the SE-mode may be a viable alternative to increase the adhesive properties in sound and fluorotic enamel.


Asunto(s)
Recubrimiento Dental Adhesivo/métodos , Esmalte Dental/química , Esmalte Dental/efectos de los fármacos , Fluorosis Dental , Cementos de Resina/química , Análisis de Varianza , Humanos , Ensayo de Materiales , Microscopía Electrónica de Rastreo , Distribución Aleatoria , Valores de Referencia , Reproducibilidad de los Resultados , Resistencia al Corte/efectos de los fármacos , Espectrometría por Rayos X , Espectrometría Raman , Propiedades de Superficie/efectos de los fármacos
14.
Environ Sci Pollut Res Int ; 26(31): 32311-32321, 2019 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-31598927

RESUMEN

The climate change issue becomes more challenging with the increasing pace of urbanization in Africa. For this purpose, we attempt to examine the relationship urbanization and CO2 emissions by applying the panel smooth transition regression model for 47 African countries during the spanning time 1990-2014. Our results reveal that the nexus between urbanization and CO2 emissions is non-linear. Our highlights recorded a monotonic nexus confirming the existence of the EKC hypothesis for the urbanization. In addition, our empirical results determine the threshold of the transition which takes the value of 42.01. Moreover, the estimated slope parameter implies that the nexus between urbanization and CO2 emissions smoothly switches from one regime to another regime but relatively rapid. Hence, it is extremely important to understand this nexus to take seriously climate change vulnerabilities. Indeed, the African economies are invited to establish efficiently the low-carbon and reduce the spatial heterogeneity to generate the green development path and provide effective structures for a platform for sustainable cities.


Asunto(s)
Dióxido de Carbono/análisis , Cementos de Resina/química , África , Dióxido de Carbono/química , Cambio Climático , Desarrollo Económico , Urbanización
15.
Niger J Clin Pract ; 22(10): 1441-1447, 2019 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-31607737

RESUMEN

Background: There was no enough data about the appropriate surface cleaning of core composite material after temporary cementation. Aim: To evaluate the effects of surface cleaning techniques on initial shear bond strength (SBS) between core composite material and resin nanoceramic crown materials after temporary cementation. Material and Methods: Cubic specimens were prepared from prosthetic materials, including Lava Ultimate. Cylinder-shaped composites were cemented to glass slides with eugenol-free temporary cement, resulting in a total of 44 cylinders (n = 11). The surfaces of composite cylinders were then cleaned with an Er, Cr:YSGG laser, 37% orthophosphoric acid, yellow tape diamond bur, or dental explorer. Cleaned cylinders were bonded to cubic specimens with resin cement. Initial SBS tests were performed with a universal testing machine at 0.5 mm/min crosshead speed. One-way ANOVA and post hoc Tukey tests were used to analyze the obtained data (P =0.05). Results: Initial SBS values were significantly affected by the different surface cleaning methods (P <.05). The highest SBS value was obtained with the laser group (SBS = 17.14), while the lowest was obtained with dental explorer group (SBS = 5.95). There was no significant difference between the diamond bur group and the laser group (P =0.982). Conclusions: Laser irradiation or yellow tape diamond bur cleaning of the core composite surface could be recommended to strengthen bond strength between the resin luting cement and the core composite. Before adhesive or conventional cementation of prosthetic restoration, the core composite surface should be cleaned.


Asunto(s)
Recubrimiento Dental Adhesivo/métodos , Cementos Dentales/química , Grabado Dental/métodos , Recubrimientos Dentinarios/química , Vidrio/química , Láseres de Estado Sólido/uso terapéutico , Cementos de Resina/química , Cementación , Resinas Compuestas/química , Cementos de Ionómero Vitreo , Humanos , Ensayo de Materiales , Resistencia al Corte , Propiedades de Superficie
16.
Braz Oral Res ; 33: e095, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-31618283

RESUMEN

This study evaluates the shear bond strength (SBS) of various resin cements to different ceramics. Composite resin cylinders of Z100 were fabricated and cemented to disks of feldspathic ceramic (Creation), leucite-reinforced feldspathic ceramic (Empress I), and densely sintered aluminum oxide ceramic (Procera AllCeram) using five resin cements: Panavia F (PAN), RelyX ARC (ARC), RelyX Unicem (RXU), RelyX Veneer, and Variolink II. SBS was measured after three days of water storage (baseline) and after artificial aging (180 days of water storage along with 12,000 thermal cycles). Failure mode of fractured specimens also was evaluated. Data were analyzed with Kruskal-Wallis and Mann-Whitney tests (α=0.05). RXU showed 1) the lowest baseline median SBS to feldspathic ceramic, which was not statistically different from PAN; 2) the lowest median baseline SBS to leucite-reinforced feldspathic and densely sintered aluminum-oxide ceramics. All cements performed similarly after aging, except for ARC (median 0.0 MPa) and PAN (median 16.2 MPa) in the densely sintered aluminum-oxide ceramic group. Resin cements perform differently when bonded to different ceramic substrates. While all test resin cements worked similarly in the long-term to feldspathic and leucite-reinforced feldspathic ceramics, only the MDP-containing resin cement provided durable bonds to densely sintered aluminum-oxide ceramic.


Asunto(s)
Cerámica/química , Recubrimiento Dental Adhesivo/métodos , Cementos de Resina/química , Aluminio/química , Silicatos de Aluminio/química , Ensayo de Materiales , Compuestos de Potasio/química , Valores de Referencia , Reproducibilidad de los Resultados , Resistencia al Corte , Estadísticas no Paramétricas , Propiedades de Superficie
17.
Braz Oral Res ; 33: e053, 2019 Sep 09.
Artículo en Inglés | MEDLINE | ID: mdl-31531561

RESUMEN

Self-adhesive resin cements (RCs) activate matrix metalloproteinase (MMP) and cathepsin-related collagen degradation, and gallic acid (GA) inhibits the activity of both MMPs and cysteine cathepsins. The purpose of this study was to evaluate the setting time, biaxial flexural strength, and Vickers hardness of self-adhesive RCs after the addition of two different concentrations of GA. RelyX U200 (3M ESPE) and Panavia SA (Kuraray) were modified with 0.5 and 1 wt% GA. The setting time of five samples in each RC group was assessed using a thermocouple apparatus as described in the ISO 4049 test. Biaxial flexure strength was measured using a universal testing machine until failure. Vickers hardness was measured with three randomized indentations on the surface of each resin disc. RCs without GA were used as control. Data were analyzed using a one-way analysis of variance and Tukey's HSD test (α = 0.05). The setting times ranged from 2.4 to 4.6 min for RelyX and from 4.9 to 6.0 min for Panavia. The biaxial flexure strength ranged from 76.5 to 109.7 MPa for RelyX and from 73.3 to 108.2 MPa for Panavia. Vickers hardness values ranged from 41.6 to 58.6 for RelyX and 27.2 to 33.6 for Panavia. The addition of 0.5 and 1 wt% GA to improve durability of resin-dentin bonds had no adverse effects on setting time, whereas the biaxial flexure strength and Vickers hardness values for the tested materials were significantly reduced.


Asunto(s)
Ácido Gálico/química , Cementos de Resina/química , Análisis de Varianza , Resistencia Flexional , Pruebas de Dureza , Ensayo de Materiales , Metaloproteinasas de la Matriz/química , Valores de Referencia , Reproducibilidad de los Resultados , Estadísticas no Paramétricas , Propiedades de Superficie , Factores de Tiempo
18.
Braz Oral Res ; 33: e0088, 2019 Sep 09.
Artículo en Inglés | MEDLINE | ID: mdl-31531566

RESUMEN

The main of the study was quantify the effect of two ceramics with two underlying resin cements on apparent fluorescence levels. Buccal surfaces of two bovine incisors were ground flat producing one enamel and one dentin substrate. The veneers were fabricated (0.5 and 1.0 mm thickness) using two ceramics (IPSe.max Press and IPSe.max Zirpress, Ivoclar Vivadent). Veneers were cemented using either light-cured (Variolink II, Ivoclar Vivadent) or self-adhesive dual (Rely X U200, 3M ESPE) cement. The layered Control group materials had no cement application. Semi-quantitative fluorescence image analysis (Matlabs software, Matworks) involved processing the images as captured under each daylight (DL, Gretagmacbeth) and ultraviolet illuminants (UVA, Sylvania) within a neutral-gray lightbox (Macbeth Spectral Light). Statistical analysis of the quantitative fluorescence values was performed using two-way ANOVA and Tukey's test (p < 0.05). The e.max Zirpress on the dentin substrate produced greater fluorescence (p < 0.05) when subjected to UV illumination and more fluorescence (p < 0.05) than e.max Press in both cement groups. Light-cured cement produced higher (p < 0.05) fluorescence than the dual-cement with e.max Press on enamel under UV illumination. The fluorescence for e.max Press on the dentin substrate was greater (p < 0.05) than for e.max Zirpress using dual self-adhesive cement subjected to daylight illumination. Thus, it is possible to conclude that the combination of ceramic and cement produce definite, significant effects on the apparent fluorescence, vital quality for restorative dentistry.


Asunto(s)
Cerámica/química , Coronas con Frente Estético , Imagen Óptica/métodos , Cementos de Resina/química , Animales , Bovinos , Esmalte Dental/química , Esmalte Dental/efectos de los fármacos , Dentina/química , Dentina/efectos de los fármacos , Luz , Ensayo de Materiales , Valores de Referencia , Reproducibilidad de los Resultados , Propiedades de Superficie
19.
Braz Oral Res ; 33: e041, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-31508723

RESUMEN

The objective of this study was to evaluate the effect of the hydrofluoridric acid (HF) concentration and time of acid conditioning on bond strength of three glass ceramics to a resin cement. Thus, fifty blocks (10 mm x 5 mm x 2 mm) of each ceramic (LDCAD: IPS e.max CAD; LCAD: IPS Empress CAD and LDHP: IPS e.max Press) were made and embedded in acrylic resin. The surfaces were polished with sandpaper (#600, 800, 1000, and 1200 grits) and blocks were randomly divided into 15 groups (n = 10) according to the following factors: Concentration of HF (10% and 5%), conditioning time (20 s and 60 s) and ceramic (LDCAD, LDHP, and L). After conditioning, silane (Prosil / FGM) was applied and after 2 min, cylinders (Ø = 2 mm; h = 2 mm) of dual resin cement (AllCem / FGM) were made in the center of each block using a Teflon strip as matrix and light cured for 40 s (1,200 mW/cm2). Then, the samples were thermocycled (10,000 cycles, 5/55°C, 30s) and submitted to the shear bond test (50 KgF, 0.5 mm/min). The data (MPa) were analyzed with 3-way ANOVA and Tukey's test (5%). Failure analysis was performed using a stereomicroscope (20x) and a scanning electron microscope (SEM). ANOVA revealed that the "concentration" factor (p = 0.01) and the interaction "acid concentration X ceramic" (p = 0.009) had a significant effect, however, the "ceramic" (p = 0.897) and "conditioning time" (p = 0.260) factors did not influence the results. The LDHP10%60s (10.98 MPa)aA* group presented significantly higher bond strength than LDHP10%20s (6.57 MPa)bA, LCAD5%20s (6,90 ±3,5)aB and LDHP5%60s (5.66 ± 2,9MPa)aA* groups (Tukey). Failure analysis revealed that 100% of specimens had mixed failure. In conclusion, etching with 5% HF for 20 seconds is recommended for lithium disilicate and leucite-reinforced CAD/CAM ceramics. However, for pressed lithium disilicate ceramic, 10% HF for 60 s showed significantly higher bond strength to resin cement.


Asunto(s)
Grabado Ácido Dental , Cerámica/química , Recubrimiento Dental Adhesivo/métodos , Ácido Fluorhídrico/administración & dosificación , Porcelana Dental/química , Análisis del Estrés Dental , Ácido Fluorhídrico/química , Ensayo de Materiales , Microscopía Electrónica de Rastreo , Cementos de Resina/química , Resistencia al Corte , Propiedades de Superficie , Factores de Tiempo
20.
Braz Oral Res ; 33: e009, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-31508728

RESUMEN

This study investigates the color correspondence of resin cements and try-in pastes, and the color stability of bonded lithium disilicate ceramic disks. Resin composite disks were fabricated (n = 36) to serve as the background for lithium disilicate disks prepared in two thicknesses (0.5 and 1.0 mm, n = 18 each). Two brands were used for try-in and cement procedures: Variolink Veneer and AllCem Veneer. For baseline, water was applied between the ceramic disks and their respective backgrounds to achieve the control group. This set was subjected to color measurement using an intraoral measurement device (T0). The try-in was inserted between background and ceramic, and this set was subjected to color measurement (T1). After adhesive procedures, the ceramic disk was placed under cement, and color measurement was performed with uncured cement (T2) and 24 h after light-curing (T3). Each set was immersed in distilled water and thermal-cycled, with color measurement being performed after 10,000 (T4) and 20,000 (T5) cycles. Color differences were calculated by CIELab (rEab) and CIEDE2000 (rE00). Data were analyzed by two-way ANOVA for repeated measurements and Tukey's test (α=5%). There was color correspondence of try-in and resin cement for the Variolink system, regardless of the ceramic thickness (p > 0.05). For the AllCem system, the thickness significantly influenced the color measurement (p < 0.001). The Variolink system also demonstrated color stability after 20,000 thermal cycles with rEab < 3.46 and rE00 < 2.25. It was concluded that the color correspondence between a try-in and its respective cement may vary according to resin cement composition.


Asunto(s)
Color , Porcelana Dental/química , Cementos de Resina/química , Cerámica/química , Coronas con Frente Estético , Técnicas In Vitro , Ensayo de Materiales , Pomadas/química
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