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1.
Acta Odontol Latinoam ; 33(2): 98, 2020 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-32920611

RESUMO

The aim of the current study was to compare the effect of two lithium disilicate ceramic processing techniques (pressing and CAD/CAM) on the degree of conversion of resin cement when it is photoactivated and the microshear bond strength of resin cement to ceramics. Two ceramic discs were manufactured: one by the Press technique and another by CAD/CAM technique. Five Variolink Veneer resin cement samples were photoactivated through each ceramic disc and subjected to attenuated total reflectance Fourier transform infrared spectroscopy to evaluate their degree of conversion. To evaluate microshear bond strength, 20 ceramic bars were prepared: 10 using the Press technique and 10 using the CAD/CAM technique. The bars were air abraded with 50-µm Al2O3 particles, treated with 10% hydrofluoric acid for 20 s and subjected to RelyX Ceramic Primer application. Adper Scotchbond Multi-Purpose Adhesive was applied to the bars and cured for 10 s. Two 1-mm-height plastic tubes were placed on each bar and filled with Variolink Veneer resin cement. Each cylinder was cured for 20 s. Then the plastic tubes were removed and the microshear bond strength of each cylinder was tested. Data for degree of conversion (%) and microshear bond strength (MPa) were subjected to Student's t-test (α = 0.05). Both degree of conversion of resin cement photoactivated through ceramic and microshear bond strength of resin cement to ceramic were statistically higher in the group in which ceramic was prepared by CAD/CAM technique (44.74% and 22.18 MPa) than in the group in which the ceramic was prepared by the Press technique (25.71% and 19.83 MPa). The lithium disilicate ceramic processing techniques affected the degree of conversion of resin cement when it is photoactivated through the ceramics and the microshear bond strength of resin cement to ceramics.


Assuntos
Cerâmica/química , Colagem Dentária , Porcelana Dentária/química , Cimentos de Resina/química , Humanos , Teste de Materiais , Propriedades de Superfície
2.
Niger J Clin Pract ; 23(8): 1148-1154, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32788494

RESUMO

Aims: The effect of mechanical loading on the microtensile bond strength (µTBS) of universal adhesives to dentin was evaluated in this study. Methods and Materials: Human molar teeth had the occlusal dentin surfaces exposed and were allocated into ten groups (five experimental groups and five control groups) that used the following universal adhesive systems in self-etch mode: All-Bond Universal (ABU), Single Bond Universal (SBU), Gluma Bond Universal (GBU), Tetric N-Bond Universal (TBU), and Clearfil Universal Bond (CUB). Following the bonding procedures and build-ups, the specimens were either stored in water at 37°C for 24 h or were mechanically loaded (50 N for 60,000 cycles) prior to the µTBS test. Data were analyzed using the one-way analysis of variance (ANOVA) and Tukey's posthoc test (P = 0.05). Results: Both the adhesive type and mechanical loading had significant effects on the µTBS (P < 0.05). The µTBS values of SBU and ABU were significantly higher than the values of the other adhesives (P < 0.05). However, the µTBS values of ABU decreased significantly after mechanical loading (P < 0.05). Conclusions: With the exception of ABU, mechanical loading had no deleterious effects on the µTBS of the universal adhesive systems examined in this study.


Assuntos
Adesivos/química , Colagem Dentária/métodos , Adesivos Dentinários/química , Bis-Fenol A-Glicidil Metacrilato , Resinas Compostas , Glutaral , Humanos , Teste de Materiais/métodos , Dente Molar , Ácidos Polimetacrílicos , Cimentos de Resina/química , Resistência à Tração
3.
PLoS One ; 15(7): e0236489, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32726365

RESUMO

Ground-nesting birds face many challenges to reproduce successfully, with nest predation being the main cause of reproductive failure. Visual predators such as corvids and egg-eating raptors, are among the most common causes of nest failure; thus, parental strategies that reduce the risk of visual nest predation should be favored by selection. To date, most research has focused on egg crypsis without considering adult crypsis, although in natural circumstances the eggs are covered by an incubating parent most of the time. Here we use a ground-nesting shorebird, the Kentish plover (Charadrius alexandrinus) as model species to experimentally test whether decoy parents influence nest predation. Using artificial nests with a male decoy, a female decoy or no decoy, we found that the presence of a decoy increased nest predation (N = 107 nests, p < 0.001). However, no difference was found in predation rates between nests with a male versus female decoy (p > 0.05). Additionally, we found that nests in densely vegetated habitats experienced higher survival compared to nests placed in sparsely vegetated habitats. Nest camera images, predator tracks and marks left on eggs identified the brown-necked raven (Corvus ruficollis) as the main visual nest predator. Our study suggests that the presence of incubating parents may enhance nest detectability to visual predators. However, parents may reduce the predation risk by placing a nest in sites where they are covered by vegetation. Our findings highlight the importance of nest site selection not only regarding egg crypsis but also considering incubating adult camouflage.


Assuntos
Aves/fisiologia , Comportamento de Nidação/fisiologia , Reprodução/fisiologia , Animais , Ecossistema , Feminino , Óvulo/fisiologia , Densidade Demográfica , Comportamento Predatório/fisiologia , Cimentos de Resina/química
4.
Niger J Clin Pract ; 23(7): 950-956, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32620724

RESUMO

Background: During post restoration, different root structures require several types of posts to increase duration of their clinical use. Several materials have been investigated to enhance their quality and optimize their length according to the available root canal. Aims: The aim of this study was to determine the effect of zirconia, fiber, and ceromer posts with 3- and 6-mm post sizes on the bonding strength of them to root canal dentinal wall with the means of pull-out bond strength test. Methods: Forty-eight single-rooted mandibular human premolar teeth were collected and prepared for this in vitro study. With resin cement, 3- and 6-mm study posts including zirconia, fiber, and ceromer were luted to prepare teeth. For the retention testing, the pull-out force was applied to each specimen parallel to longitudinal axis of both the post and tooth. Results: Both type of materials and size of posts changed the value of bonding strength. In all the post types, 6-mm ones performed better. Overall, the best bonding strength was obtained with fiber posts and the better bonding strength was obtained with zirconia; however, ceromer provided the least bonding strength. Conclusion: Current experiments supported that 6-mm post size can increase the bonding between root canal dentin and studied posts. When considering post materials, fiber provided the best bonding strength in current laboratory setup. Second, zirconia had meaningfully acceptable bonding strength; however, the bonding strength of ceromer posts was not favorable. Further studies optimizing post fabrication techniques of root materials may increase the bonding strength of posts to human dentin to an acceptable clinical degree.


Assuntos
Colagem Dentária , Cavidade Pulpar , Dentina , Técnica para Retentor Intrarradicular , Cimentos de Resina/química , Tratamento do Canal Radicular/métodos , Raiz Dentária/cirurgia , Cerâmica , Resinas Compostas , Vidro/química , Humanos , Teste de Materiais , Zircônio
5.
Niger J Clin Pract ; 23(6): 792-797, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32525113

RESUMO

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.


Assuntos
Cerâmica/química , Colagem Dentária , Dentina , Cimentos de Resina/química , Resistência ao Cisalhamento , Dente Decíduo , Zircônio/química , Resinas Acrílicas , Adesivos , Cimentos de Ionômeros de Vidro , Humanos , Teste de Materiais , Dióxido de Silício , Propriedades de Superfície
6.
Braz Oral Res ; 34: e045, 2020 May 08.
Artigo em Inglês | MEDLINE | ID: mdl-32401935

RESUMO

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.


Assuntos
Resinas Compostas/química , Cimentos Dentários/química , Cimentos de Resina/química , Silanos/química , Análise de Variância , Colagem Dentária/métodos , Teste de Materiais , Valores de Referência , Reprodutibilidade dos Testes , Propriedades de Superfície , Resistência à Tração , Fatores de Tempo
7.
Braz Oral Res ; 34: e020, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32236317

RESUMO

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.


Assuntos
Adesivos Dentinários/farmacologia , Etanol/farmacologia , Técnica para Retentor Intrarradicular , Cimentos de Resina/química , Raiz Dentária/efeitos dos fármacos , Animais , Bovinos , Colagem Dentária , Materiais Dentários/química , Cavidade Pulpar , Vidro , Teste de Materiais , Porosidade , Irrigantes do Canal Radicular/química , Microtomografia por Raio-X
8.
Braz Oral Res ; 34: e018, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32187304

RESUMO

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.


Assuntos
Silicatos de Alumínio/química , Colagem Dentária/métodos , Ácido Fluorídrico/química , Ácidos Fosfóricos/química , Compostos de Potássio/química , Análise de Variância , Porcelana Dentária/química , Teste de Materiais , Metacrilatos/química , Microscopia Eletrônica de Varredura , Valores de Referência , Reprodutibilidade dos Testes , Cimentos de Resina/química , Resistência ao Cisalhamento/efeitos dos fármacos , Silanos/química , Propriedades de Superfície , Fatores de Tempo
9.
Lasers Med Sci ; 35(6): 1385-1392, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32056078

RESUMO

In clinical dentistry, the strength of bonding zirconia posts to root canal dentinal walls currently needs enhancement, and laser application can be an important contribution owing to its features that accommodate adjustable modifications on dental materials. Herein, the effect of different laser treatments applied to dentin surfaces on the strength of bonding zirconia posts to root canal dentinal walls is evaluated by using the pull-out bond strength test in a laboratory setting. A total of 40 single-rooted permanent mandibular premolar teeth that were freshly extracted were used here. The root canal preparation steps were performed using the crown-down technique. Custom-made zirconia posts were produced using CAD/CAM technology. Prior to the application of resin cement, the internal surfaces of the root canals were irradiated using Nd:YAG, Er:YAG, and KTP lasers. Pull-out tests were performed on each specimen by using a universal testing machine. One-way analysis of variance and Tukey post hoc tests were used to compare the pull-out bond strength data. The bond strengths of the laser-treated specimens were greater than those of the untreated controls (p < 0.05). While the value of the pull-out bond strength after Nd:YAG laser treatment was significantly higher than the values obtained after the applications of the Er:YAG and KTP lasers (p < 0.05), the pull-out bond strength after Er:YAG laser treatment was considerably greater than that after KTP laser treatment (p < 0.05). The bond strength between the root canal dentin and the CAD/CAM custom-made zirconia post was improved upon using all the laser modalities in current laboratory settings, among which, application of the Nd:YAG laser was the most successful.


Assuntos
Desenho Assistido por Computador , Cavidade Pulpar/efeitos dos fármacos , Cavidade Pulpar/efeitos da radiação , Dentina/efeitos dos fármacos , Dentina/efeitos da radiação , Lasers de Estado Sólido/uso terapêutico , Zircônio/farmacologia , Cavidade Pulpar/ultraestrutura , Humanos , Cimentos de Resina/química
10.
J Appl Oral Sci ; 28: e20190371, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32049135

RESUMO

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.


Assuntos
Abrasão Dental por Ar/métodos , Óxido de Alumínio/química , Colagem Dentária/métodos , Cimentos de Resina/química , Zircônio/química , Análise de Variância , Resistência à Flexão , Temperatura Alta , Teste de Materiais , Microscopia Confocal/métodos , Valores de Referência , Reprodutibilidade dos Testes , Propriedades de Superfície , Resistência à Tração , Difração de Raios X/métodos
11.
Braz Oral Res ; 34: e001, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32022221

RESUMO

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.


Assuntos
Colagem Dentária/métodos , Adesivos Dentinários/química , Dentina/efeitos dos fármacos , Fabaceae/química , Óleos Vegetais/química , Análise de Variância , Clorexidina/química , Resinas Compostas/química , Cimentos Dentários/química , Infiltração Dentária , Dentina/química , Emulsões/química , Humanos , Teste de Materiais , Reprodutibilidade dos Testes , Cimentos de Resina/química , Estatísticas não Paramétricas , Propriedades de Superfície , Resistência à Tração
12.
Braz Oral Res ; 34: e004, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32022223

RESUMO

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.


Assuntos
Cerâmica/química , Desenho Assistido por Computador , Porcelana Dentária/química , Vidro/química , Análise de Variância , Colagem Dentária/métodos , Resistência à Flexão , Teste de Materiais , Microscopia Eletrônica de Varredura , Porosidade , Valores de Referência , Reprodutibilidade dos Testes , Cimentos de Resina/química , Resistência ao Cisalhamento , Propriedades de Superfície , Difração de Raios X
13.
Gen Dent ; 68(1): 22-28, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31859658

RESUMO

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.


Assuntos
Colagem Dentária , Cimentos Dentários , Teste de Materiais , Cimentos de Resina , Resistência ao Cisalhamento , Condicionamento Ácido do Dente , Cimentos Dentários/química , Análise do Estresse Dentário , Dentina , Adesivos Dentinários , Humanos , Cimentos de Resina/química , Propriedades de Superfície
14.
J. appl. oral sci ; 28: e20190371, 2020. tab, graf
Artigo em Inglês | LILACS, BBO - Odontologia | ID: biblio-1056595

RESUMO

Abstract 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.


Assuntos
Zircônio/química , Colagem Dentária/métodos , Cimentos de Resina/química , Abrasão Dental por Ar/métodos , Óxido de Alumínio/química , Valores de Referência , Propriedades de Superfície , Resistência à Tração , Difração de Raios X/métodos , Teste de Materiais , Reprodutibilidade dos Testes , Análise de Variância , Microscopia Confocal/métodos , Resistência à Flexão , Temperatura Alta
15.
J. appl. oral sci ; 28: e20190371, 2020. tab, graf
Artigo em Inglês | LILACS, BBO - Odontologia | ID: biblio-1090787

RESUMO

Abstract 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.


Assuntos
Zircônio/química , Colagem Dentária/métodos , Cimentos de Resina/química , Abrasão Dental por Ar/métodos , Óxido de Alumínio/química , Valores de Referência , Propriedades de Superfície , Resistência à Tração , Difração de Raios X/métodos , Teste de Materiais , Reprodutibilidade dos Testes , Análise de Variância , Microscopia Confocal/métodos , Resistência à Flexão , Temperatura Alta
16.
Niger J Clin Pract ; 22(12): 1675-1679, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31793473

RESUMO

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.


Assuntos
Resinas Compostas/química , Colagem Dentária/métodos , Esmalte Dentário/química , Adesivos Dentinários , Dentina/química , Cimentos de Resina/química , Adesivos , Análise do Estresse Dentário , Humanos , Teste de Materiais/métodos , Propriedades de Superfície , Resistência à Tração
17.
Biomed Res Int ; 2019: 2041348, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31828093

RESUMO

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.


Assuntos
Cimentos Dentários/química , Resinas Acrílicas/química , Austrália , Resinas Compostas/química , Colagem Dentária/métodos , Análise do Estresse Dentário/métodos , Humanos , Teste de Materiais/métodos , Poliuretanos/química , Cimentos de Resina/química , Resistência à Tração
18.
Niger J Clin Pract ; 22(11): 1475-1482, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31719267

RESUMO

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.


Assuntos
Cerâmica/química , Resinas Compostas/química , Teste de Materiais/métodos , Cimentos de Resina/química , Resistência ao Cisalhamento , Zircônio , Desenho Assistido por Computador , Colagem Dentária , Humanos , Microscopia Eletrônica de Varredura , Propriedades de Superfície , Ítrio
19.
Molecules ; 24(21)2019 Nov 05.
Artigo em Inglês | MEDLINE | ID: mdl-31694145

RESUMO

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.


Assuntos
Fibra de Carbono/química , Resinas Compostas/química , Cumarínicos/química , Cimentos de Resina/química , Silanos/química , Resinas Epóxi/química , Teste de Materiais/métodos , Resistência ao Cisalhamento , Estresse Mecânico , Propriedades de Superfície , Telas Cirúrgicas
20.
ACS Comb Sci ; 21(12): 794-804, 2019 12 09.
Artigo em Inglês | MEDLINE | ID: mdl-31710806

RESUMO

Cement and concrete have been important construction materials throughout human history. There is an urgent need to explore novel and untraditional cementitious materials to enhance the durability of building materials and structures in response to increased infrastructure demand worldwide. We report an exploratory study on a biocomposite cement based on a large-scale computational study using density functional theory. An explicitly solvated mixture of a mineral calcium silicate hydrate (C-S-H) crystal suolunite (Ca2Si2O5(OH)2·H2O) and a silicon binding peptide with amino acid sequence PRO-PRO-PRO-TRP-LEU-PRO-TYR-MET-PRO-PRO-TRP-SER is constructed using ab initio molecular dynamics (AIMD). Detailed analysis on the interface structure, interatomic bonding, mechanical properties, and solvent effect of this model reveals a complex interplay of different types of covalent and ionic bonding, including ubiquitous hydrogen bonding which plays a crucial role in their properties. The use of the total bond order density (TBOD), a single quantum mechanical metric, for assessing the interfacial cohesion for this composite biocement is proposed. We find that the solvated model has a slightly larger TBOD than the dried one. These results could lead to a systematic search and rational design for different types of bioinspired and hybrid functional materials with other inorganic minerals and organic peptides.


Assuntos
Compostos de Cálcio/química , Peptídeos/química , Cimentos de Resina/síntese química , Dióxido de Silício/química , Sítios de Ligação , Técnicas de Química Combinatória , Teoria da Densidade Funcional , Simulação de Dinâmica Molecular , Cimentos de Resina/química
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