Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 2.943
Filtrar
1.
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
2.
J Appl Oral Sci ; 28: e20190499, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32348441

RESUMEN

Enzymatic degradation of the hybrid layer can be accelerated by the activation of dentin metalloproteinases (MMP) during the bonding procedure. MMP inhibitors may be used to contain this process. Objective To evaluate the degree of conversion (DC%), dentin bond strength (µTBS) (immediate and after 1 year of storage in water), and nanoleakage of an experimental (EXP) and a commercial (SB) adhesive system, containing different concentrations of the MMP inhibitor GM1489: 0, 1 µM, 5 µM and 10 µM. Methodology DC% was evaluated by FT-IR spectroscopy. Dentin bond strength was evaluated by µTBS test. Half of beams were submitted to the µTBS test after 24 h and the other half, after storage for 1 year. From each tooth and storage time, 2 beams were reserved for nanoleakage testing. Data were analyzed using ANOVA and Tukey's test to compare means (α=0.05). Results All adhesive systems maintained the µTBS after 1 year of storage. Groups with higher concentrations of inhibitor (5 µM and 10 µM) showed higher µTBS values than groups without inhibitor or with 1 µM. The nanoleakage values of all groups showed no increase after 1 year of storage and values were similar for SB and EXP groups, in both storage periods. The inhibitor did not affect the DC% of the EXP groups, but the SB5 and SB10 groups showed higher DC% values than those of SB0 and SB1. Conclusions The incorporation of GM1489 in the adhesive systems had no detrimental effect on DC%. The concentrations of 5 µM GM1489 for SB and 5 µM or 10 µM for EXP provided higher µTBS than groups without GM1489, in the evaluation after 1 year of storage; whereas the concentration of inhibitor did not affect adhesive systems nanoleakage.


Asunto(s)
Cementos Dentales/química , Dentina/química , Inhibidores de la Metaloproteinasa de la Matriz/química , Metacrilatos/química , Polietilenglicoles/química , Ácidos Polimetacrílicos/química , Análisis de Varianza , Recubrimiento Dental Adhesivo/métodos , Grabado Dental/métodos , Filtración Dental , Dentina/efectos de los fármacos , Humanos , Ensayo de Materiales , Valores de Referencia , Reproducibilidad de los Resultados , Espectroscopía Infrarroja por Transformada de Fourier , Estadísticas no Paramétricas , Propiedades de Superficie , Resistencia a la Tracción , Factores de Tiempo
3.
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
4.
Niger J Clin Pract ; 23(1): 18-25, 2020 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-31929202

RESUMEN

Aim: This study evaluated the microtensile bond strength (MTBS) of an orthodontic adhesive to water-aged composite surfaces using different surface treatments. Subjects and Methods: Twelve composite blocks (10 mm × 10 mm × 5 mm) were fabricated and randomly divided into two groups. Half of the specimens were stored in distilled water for 1 day, and the other specimens were stored for 30 days. The specimens were randomly assigned to six groups according to surface treatments (n = 15): Group 1, control (no treatment); Group 2, phosphoric acid; Group 3, diamond bur; Group 4, diamond bur + phosphoric acid; Group 5, laser; and Group 6, laser + phosphoric acid. One coat of orthodontic adhesive was bonded to one surface of composite blocks, and a microhybrid composite resin was bonded to the surfaces via a Teflon mold. Bond strength was evaluated using an MTBS test. Surface topography was evaluated using scanning electron microscopy (SEM) analysis. The data were analyzed using one-way analysis of variance, Tamhane post-hoc test, and independent sample t-tests (P < 0.05). Results: Bond strength values tended to decrease in all groups (with the exception of Group 2) after storage in water for 30 days (P < 0.05). Laser and diamond bur application (with or without phosphoric acid) enhanced the bond strength. Conclusions: An Er,Cr:YSGG laser application may be a feasible alternative to diamond bur for enhancing the bond strength of orthodontic adhesive to composite resin.


Asunto(s)
Resinas Compuestas/química , Recubrimiento Dental Adhesivo , Cementos Dentales/química , Láseres de Estado Sólido/uso terapéutico , Resistencia a la Tracción , Agua/química , Resinas Compuestas/uso terapéutico , Análisis del Estrés Dental , Humanos , Ensayo de Materiales , Microscopía Electrónica de Rastreo , Ácidos Fosfóricos/química , Resistencia al Corte , Propiedades de Superficie
5.
J Appl Oral Sci ; 28: e20190105, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-31800873

RESUMEN

Calcium aluminate cement (CAC) has been highlighted as a promising alternative for endodontic use aiming at periapical tissue repair. However, its effects on dental pulp cells have been poorly explored. OBJECTIVE: This study assessed the impact of calcium chloride (CaCl2) and bismuth oxide (Bi2O3) or zinc oxide (ZnO) additives on odontoblast cell response to CAC. METHODOLOGY: MDPC-23 cells were exposed for up to 14 d: 1) CAC with 2.8% CaCl2 and 25% ZnO (CACz); 2) CAC with 2.8% CaCl2 and 25% Bi2O3 (CACb); 3) CAC with 10% CaCl2 and 25% Bi2O3 (CACb+); or 4) mineral trioxide aggregate (MTA), placed on inserts. Non-exposed cultures served as control. Cell morphology, cell viability, gene expression of alkaline phosphatase (ALP), bone sialoprotein (BSP), and dentin matrix protein 1 (DMP-1), ALP activity, and extracellular matrix mineralization were evaluated. Data were compared using ANOVA (α=5%). RESULTS: Lower cell density was detected only for MTA and CACb+ compared with Control, with areas showing reduced cell spreading. Cell viability was similar among groups at days one and three (p>0.05). CACb+ and MTA showed the lowest cell viability values at day seven (p>0.05). CACb and CACb+ promoted higher ALP and BSP expression compared with CACz (p<0.05); despite that, all cements supported ALP activity. Matrix mineralization were enhanced in CACb+ and MTA. CONCLUSION: In conclusion, CAC with Bi2O3, but not with ZnO, supported the expression of odontoblastic phenotype, but only the composition with 10% CaCl2 promoted mineralized matrix formation, rendering it suitable for dentin-pulp complex repair.


Asunto(s)
Compuestos de Aluminio/química , Compuestos de Aluminio/farmacología , Compuestos de Calcio/química , Compuestos de Calcio/farmacología , Cementos Dentales/química , Cementos Dentales/farmacología , Pulpa Dental/citología , Pulpa Dental/efectos de los fármacos , Fosfatasa Alcalina/análisis , Fosfatasa Alcalina/efectos de los fármacos , Animales , Bismuto/química , Bismuto/farmacología , Cloruro de Calcio/química , Cloruro de Calcio/farmacología , Supervivencia Celular/efectos de los fármacos , Células Cultivadas , Combinación de Medicamentos , Expresión Génica/efectos de los fármacos , Ensayo de Materiales , Ratones , Odontoblastos/efectos de los fármacos , Óxidos/química , Óxidos/farmacología , Reproducibilidad de los Resultados , Silicatos/química , Silicatos/farmacología , Factores de Tiempo , Óxido de Zinc/química , Óxido de Zinc/farmacología
6.
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
7.
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
8.
Molecules ; 25(1)2019 Dec 24.
Artículo en Inglés | MEDLINE | ID: mdl-31878187

RESUMEN

The translational molecular dynamics in porous materials are affected by the presence of the porous structure that presents an obstacle for diffusing molecules in longer time scales, but not as much in shorter time scales. The characteristic time scales have equivalent frequency ranges of molecular dynamics, where longer time scales correspond to lower frequencies while the shorter time scales correspond to higher frequencies of molecular dynamics. In this study, a novel method for direct measurement of diffusion at a given frequency of translational molecular dynamics is exploited to measure the diffusion spectra, i.e., distribution of diffusion in a wide range of frequencies. This method utilizes NMR modulated gradient spin-echo (MGSE) pulse sequence to measure the signal attenuation during the train of spin-echoes formed in the presence of a constant gradient. From attenuation, the diffusion coefficient at the frequency equal to the inverse double inter-echo time is calculated. The method was employed to study the white cement hydration process by the sequential acquisition of the diffusion spectra. The measured spectra were also analyzed by the diffusion spectra model to obtain the time-dependence of the best-fit model parameters. The presented method can also be applied to study other similar systems with the time evolution of porous structure.


Asunto(s)
Cementos Dentales/química , Simulación de Dinámica Molecular , Agua/química , Difusión , Espectroscopía de Resonancia Magnética , Modelos Teóricos , Marcadores de Spin , Factores de Tiempo
9.
Rev. Soc. Odontol. La Plata ; 29(57): 15-19, dic. 2019. ilus
Artículo en Español | LILACS | ID: biblio-1049929

RESUMEN

Se determinó la solubilidad en agua en ensayos in-vitro de un sellador para uso endodóntico a base de un conglomerado de trióxidos minerales (MTA), marca Endosealer® (Densell SA) de acuerdo a la norma UNE-EN ISO 6876:2012. En el ensayo de solubilidad en agua durante 24 hs se encontró pérdida de masa (3,3 %) y la presencia de sólidos en las aguas de lavado (6,4 %). Esto indica que durante el ensayo ocurre la solubilización de parte del material y la incorporación de agua, lo que no permite establecer un valor real de la solubilidad.(AU)


Solubility of a commercial endodontic sealer (Endosealer® (Densell SA)) was performed according to the UNE-EN ISO 6876:2012. The results show a mass loss of 3.3 % and 6.4 % of solid in the test solution. These indicate that during the solubility test part of the material solubilizes and an actual value of solubility cannot feasible be determined


Asunto(s)
Materiales de Obturación del Conducto Radicular , Cementos Dentales/análisis , Cementos Dentales/química , Solubilidad , Materiales Dentales
10.
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
11.
Infect Immun ; 87(12)2019 12.
Artículo en Inglés | MEDLINE | ID: mdl-31527130

RESUMEN

Candida-associated denture stomatitis (DS) is a persistent and chronic oral infection of the denture-bearing palatal mucosa. DS stems from the ability of the fungal opportunistic pathogen Candida albicans to adhere to denture material and invade palatal tissue. Although DS is the most prevalent form of oral candidiasis, there are currently no feasible therapeutic strategies for the prevention of this recurrent condition. We developed a peptide-based antimicrobial bioadhesive formulation specifically designed for oral topical formulation. In this study, we aimed to evaluate the applicability of the novel formulation for the prevention of C. albicans colonization on denture material and development of clinical disease. To that end, using the latest technological advances in dental digital design and three-dimensional (3D) printing, we fabricated an intraoral device for rats with universal fit. The device was successfully installed and used to develop clinical DS. Importantly, by taking a preventative therapeutic approach, we demonstrated the potential clinical utility of the novel formulation as a safe and feasible prophylactic agent against DS.


Asunto(s)
Antifúngicos/farmacología , Candida albicans/efectos de los fármacos , Candidiasis Bucal/prevención & control , Cementos Dentales/farmacología , Estomatitis Subprotética/prevención & control , Animales , Antifúngicos/química , Biopelículas/efectos de los fármacos , Biopelículas/crecimiento & desarrollo , Candida albicans/crecimiento & desarrollo , Candidiasis Bucal/tratamiento farmacológico , Candidiasis Bucal/microbiología , Cementos Dentales/química , Dentaduras/microbiología , Modelos Animales de Enfermedad , Masculino , Mucosa Bucal/microbiología , Ratas , Ratas Sprague-Dawley , Estomatitis Subprotética/tratamiento farmacológico , Estomatitis Subprotética/microbiología
12.
Mater Sci Eng C Mater Biol Appl ; 104: 109955, 2019 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-31500064

RESUMEN

Calcium phosphate cement (CPC), functionalized with iron oxide nanoparticles (IONP), is of great promise to promote osteoinduction and new bone formation. In this work, the IONP powder was added into the CPC powder to fabricate CPC + IONP scaffolds and the effects of the novel composite on bone matrix formation and osteogenesis of human dental pulp stem cells (hDPSCs) were explored. A series of CPC + IONP magnetic scaffolds with different IONP contents (1%, 3% and 6%) were fabricated using 5% chitosan solution as the cement liquid. Western blotting and RT-PCR were used to analyze the signaling pathway. The IONP incorporation substantially enhanced the performance of CPC + IONP, with increases in both mechanical strength and cellular activities. The IONP addition greatly promoted the osteogenesis of hDPSCs, elevating the ALP activity, the expression of osteogenic marker genes and bone matrix formation with 1.5-2-fold increases. The 3% IONP incorporation showed the most enhancement among all groups. Activation of the extracellular signal-related kinases WNT/ß-catenin in DPSCs was observed, and this activation was attenuated by the WNT inhibitor DKK1. The results indicated that the osteogenic behavior of hDPSCs was likely driven by CPC + IONP via the WNT signaling pathway. In conclusion, incorporate IONP into CPC scaffold remarkably enhanced the spreading, osteogenic differentiation and bone mineral synthesis of stem cell. Therefore, this method had great potential for bone tissue engineering. The novel CPC + IONP composite scaffolds with stem cells are promising to provide an innovative strategy to enhance bone regenerative therapies.


Asunto(s)
Cementos para Huesos/química , Cementos para Huesos/farmacología , Fosfatos de Calcio/química , Compuestos Férricos/química , Nanopartículas/química , Osteogénesis/efectos de los fármacos , Transducción de Señal/efectos de los fármacos , Células Madre/efectos de los fármacos , Regeneración Ósea/efectos de los fármacos , Huesos/efectos de los fármacos , Diferenciación Celular/efectos de los fármacos , Quitosano/química , Cementos Dentales/química , Pulpa Dental/efectos de los fármacos , Pulpa Dental/metabolismo , Humanos , Células Madre/metabolismo , Ingeniería de Tejidos/métodos , Andamios del Tejido/química , Proteínas Wnt/metabolismo , beta Catenina/metabolismo
13.
Gen Dent ; 67(5): e1-e6, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-31454330

RESUMEN

This study evaluated the influence of operator skill on the shear bond strength of a self-adhesive resin cement to dentin after different adhesive treatments. Flat dentin surfaces were prepared on 160 extracted molars. The teeth were distributed evenly (n = 80) to 2 groups based on the operator's skill (undergraduate dental student vs operative dentistry specialist). The teeth in each operator group were distributed into 5 groups based on pretreatments used before they were cemented to indirect composite resin cylinders with Panavia SA Luting Plus resin cement. The operators prepared the dentin surfaces for bonding according to the following pretreatment groups: 1, no treatment; 2, phosphoric acid etching; 3, Clearfil Universal Bond in etch-and-rinse mode; 4, Clearfil Universal Bond in self-etching mode; and 5, Clearfil SE Bond 2-step adhesive. After cementation was performed by the 2 operator groups, shear bond strength testing was performed, and data were analyzed with 2-way analysis of variance. The effects of operator skill and surface pretreatment and their cumulative effect were statistically significant (P < 0.05). The shear bond strength of the control group in the student group was significantly greater than that of the specialist group (P = 0.02). In group 5 (2-step adhesive), the shear bond strength of the specialist group was significantly greater than that of the student group (P < 0.001). The use of acid etching and the 3 adhesive treatments improved the bonding ability of resin cement for the expert group. This positive effect was observed only in the etch-and-rinse and self-etching modes for the student group. Extensive clinical experience did not have a positive effect on the bonding effectiveness of resin cement with no pretreatment, while the expert group showed better results in applying this cement with a 2-step adhesive pretreatment.


Asunto(s)
Recubrimiento Dental Adhesivo , Cementos Dentales/química , Recubrimientos Dentinarios/química , Cementos de Resina , Análisis del Estrés Dental , Humanos , Ensayo de Materiales , Estrés Mecánico , Propiedades de Superficie
14.
Int J Mol Sci ; 20(14)2019 Jul 16.
Artículo en Inglés | MEDLINE | ID: mdl-31315225

RESUMEN

Cariogenic oral biofilms are strongly linked to dental caries around dental sealants. Quaternary ammonium monomers copolymerized with dental resin systems have been increasingly explored for modulation of biofilm growth. Here, we investigated the effect of dimethylaminohexadecyl methacrylate (DMAHDM) on the cariogenic pathogenicity of Streptococcus mutans (S. mutans) biofilms. DMAHDM at 5 mass% was incorporated into a parental formulation containing 20 mass% nanoparticles of amorphous calcium phosphate (NACP). S. mutans biofilms were grown on the formulations, and biofilm inhibition and virulence properties were assessed. The tolerances to acid stress and hydrogen peroxide stress were also evaluated. Our findings suggest that incorporating 5% DMAHDM into 20% NACP-containing sealants (1) imparts a detrimental biological effect on S. mutans by reducing colony-forming unit counts, metabolic activity and exopolysaccharide synthesis; and (2) reduces overall acid production and tolerance to oxygen stress, two major virulence factors of this microorganism. These results provide a perspective on the value of integrating bioactive restorative materials with traditional caries management approaches in clinical practice. Contact-killing strategies via dental materials aiming to prevent or at least reduce high numbers of cariogenic bacteria may be a promising approach to decrease caries in patients at high risk.


Asunto(s)
Antibacterianos/farmacología , Biopelículas , Cementos Dentales/química , Metacrilatos/farmacología , Streptococcus mutans/efectos de los fármacos , Ácidos/farmacología , Antibacterianos/química , Fosfatos de Calcio/química , Fosfatos de Calcio/farmacología , Peróxido de Hidrógeno/farmacología , Metacrilatos/química , Streptococcus mutans/patogenicidad , Streptococcus mutans/fisiología
15.
Microsc Res Tech ; 82(10): 1720-1727, 2019 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-31290589

RESUMEN

This study evaluated the effects of an antioxidant application on the compromised bond strength of an adhesive to dentin bleached with 35% hydrogen peroxide. The dentin surfaces of the pulp chambers of 70 human third molars were ground, and the specimens were assigned randomly into seven groups, as follows: (a) control (unbleached); (b) bleached for 45 min, bonded immediately; (c) bleached for 45 min, treated with sodium ascorbate (SA) for 2 min, and bonded; (d) bleached for 45 min, bonded after 2 weeks; (e) bleached for 12 days, bonded immediately; (f) bleached for 12 days, treated with SA for 10 min, and bonded; and (g) bleached for 12 days, bonded after 2 weeks. In each group, the multimode adhesive was applied in etch-and-rinse and self-etch modes. The dentin surfaces were covered with a resin-based composite, and the bonded specimens were sectioned to produce composite-dentin sticks. The sticks were attached to a testing machine and subjected to a tensile force, and the representative specimens were examined via scanning electron microscopy. The bond strength was not affected by the application period of the bleaching agent. Both bleaching treatments significantly reduced the bond strength to the dentin in the self-etch or etch-and-rinse mode when compared with the control group. The bond strengths returned to normal levels with the SA applications or by waiting 2 weeks, regardless of the application period of the bleaching gel. The adhesive revealed a higher bond strength in the etch-and-rinse mode than in the self-etch mode.


Asunto(s)
Antioxidantes/metabolismo , Blanqueadores/metabolismo , Recubrimiento Dental Adhesivo , Cementos Dentales/química , Dentina/efectos de los fármacos , Humanos , Diente Molar/efectos de los fármacos , Factores de Tiempo
16.
Rom J Morphol Embryol ; 60(1): 133-138, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-31263837

RESUMEN

Polymerization stresses in adhesive structure could determine an adhesive or cohesive failure and interfacial gaps forming. Some clinical procedures - as light curing composite resin layering in 2-3 mm increments (especially for dental fills) or using dental reconfiguring clear acetate crowns - are sat up to combat (in some way) the polymerization shrinkage. This study approaches the manner how clinical dental adhesive application could influence the hard dental tissues-composite materials interface. The sample studied consisted of 12 upper bicuspids, extracted for orthodontic reasons. In our study, we chose the adhesion technique in "two steps". We prepared enamel and dentine areas, and then filled them with light-polymerization composite. After that, the teeth were subject of microscopic investigations, at 100× and 200× magnification. As conclusion of our study, we sustain that light curing composite resin applying clinical technique (by layering or with acetate crown) might influence a good dental restoration clinical performance.


Asunto(s)
Resinas Compuestas/química , Cementos Dentales/química , Restauración Dental Permanente/métodos , Ensayo de Materiales/métodos , Humanos
17.
Am J Orthod Dentofacial Orthop ; 155(6): 767-778, 2019 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-31153497

RESUMEN

INTRODUCTION: The aim of this laboratory and randomized clinical trial was to investigate particulate production at debonding and enamel clean-up following the use of flash-free ceramic brackets and to compare them with non-flash-free metal and ceramic brackets. METHODS: In the laboratory study, brackets were bonded to bovine teeth. After 24 hours of immersion in water, the brackets were debonded, the adhesive remnant scores noted, and the enamel cleaned with the use of rotary instruments. Four bracket-adhesive combinations and 2 different enamel pretreatment regimens were tested, including metal and ceramic brackets (conventional, adhesive precoat [APC], and APC flash-free) and conventional acid etch and self-etching primer. Quantitative (mg/m3) and qualitative analysis of particulate production was made in each case. In the clinical trial, 18 patients treated with the use of fixed appliances were recruited into this 3-arm parallel-design randomized controlled trial. They were randomly allocated to 1 of 3 groups: experimental flash-free ceramic bracket or non-flash-free ceramic or metal bracket group. Eligibility criteria included patients undergoing nonextraction maxillary and mandibular fixed appliance therapy. At completion of treatment, the brackets were debonded, and the primary outcome measure was particulate concentration (mg/m3). Randomization was by means of sealed envelopes. Data were analyzed with the use of quantile plots and linear mixed models. The effect of etch, bracket, and stage of debonding of clean-up on particle composition was analyzed with the use of mixed-effects regression. RESULTS: In the laboratory study, the APC brackets produced the highest particulate concentration. Although statistically significantly higher than the metal and conventional ceramic brackets, it was not significantly higher than the ceramic flash-free brackets. In the clinical study, there was no statistically significant effect of bracket type on particulate concentration (P = 0.29). This was despite 3 patients with APC flash-free and 1 patient with conventional Clarity (with 1 bracket) having 1 or more ceramic bracket fracture at debonding requiring removal. No adverse events reported. CONCLUSIONS: Particulates in the inhalable, thoracic, and respirable fractions were produced at enamel clean-up with all bracket types. Although APC and APC flash-free brackets produced the highest concentrations in the laboratory study, there was no difference between any of the brackets in the clinical trial. REGISTRATION: The trial was not registered. FUNDING: This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.


Asunto(s)
Cerámica/química , Cementos Dentales/química , Desconsolidación Dental/métodos , Aparatos Ortodóncicos Fijos , Soportes Ortodóncicos , Material Particulado/química , Animales , Bovinos , Humanos , Ensayo de Materiales , Microscopía Electrónica de Rastreo , Espectrometría por Rayos X , Propiedades de Superficie
18.
Photodiagnosis Photodyn Ther ; 27: 184-192, 2019 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-31163283

RESUMEN

BACKGROUND: The bonding of fiber posts (FPs) to composite resin core buildups is a challenge due to limited penetration of resin to the polymeric matrix of FPs. This review article tries to answer this question: "What are the effects of laser surface treatment of FPs, compared to other surface roughening methods, on push-out bond strength (PBS) of FPs bonded to composite resin core buildups?" METHODS: Searches were run in seven electronic databases with a focus on proper key words. Related titles and abstracts, up to February 2019, were screened, selected, read and subjected to quality assessments. RESULTS: After the initial search, a total of 2635 articles were included in the study. Finally, 6 studies were reliable enough in methodology to be included. All the studies were in vitro with a total of 359 samples. Er:YAG (-0.05, 95% CI: -2.96 to 2.86; P = 0.97) and Er,Cr:YSGG (0.84, 95% CI: -0.12 to 1.81; P = 0.08) treated samples showed no significant overall mean differences in final PBS compared to the control groups. Moreover, pretreatment with Er,Cr:YSGG laser and sandblasting with 50 µm alumina showed an overall mean difference of -0.42 for PBS (95% CI: -1.23 to 0.39) with no significant differences. CONCLUSIONS: Laser irradiation of FPs seems to provide no significant increase in PBS values of FPs bonded to composite resin core buildups. Effects of surface treatment of FPs with laser irradiation and sandblasting with 50 µm alumina might be similar in increasing the final PBS, either.


Asunto(s)
Resinas Compuestas/química , Cementos Dentales/química , Implantes Dentales , Láseres de Estado Sólido , Propiedades de Superficie , Humanos
19.
ACS Sens ; 4(6): 1515-1523, 2019 06 28.
Artículo en Inglés | MEDLINE | ID: mdl-31140789

RESUMEN

Lipopolysaccharides (LPS) are the major component of the outer membrane of all Gram-negative bacteria and some cyanobacteria and are released during growth and cell death. LPS pose a potential health risk in water, causing acute respiratory illnesses, inhalation fever, and gastrointestinal disorders. The need for rapid and accurate detection of LPS has become a major priority to facilitate more timely and efficacious intervention and, hence, avoid unsafe water distribution. In this context, a porous silicon membrane (pSiM)-based electrochemical biosensor was developed for direct and sensitive detection of LPS. pSiM, featuring arrays of nanochannels, was modified with polymyxin B (PmB), an antimicrobial peptide with strong affinity to LPS. Detection of LPS was based on measuring the changes in the diffusion through the nanochannels of an electroactive species added in solution, caused by the nanochannel blockage upon LPS binding to PmB. Results showed a limit of detection of 1.8 ng/mL, and a linear response up to 10,000 ng/mL spiked in buffer. Selectivity of the sensor toward potential interfering species in water supplies was also assessed. Sensor performance was then evaluated in water samples from a water treatment plant (WTP), and detection of LPS well below the levels encountered in episodes of water contamination and in humidifiers was demonstrated. The same platform was also tested for bacterial detection including Pseudomonas aeruginosa and Escherichia coli spiked in water samples from a WTP. Considering its performance characteristics, this platform represents a promising screening tool to identify the presence of LPS in water supplies and provide early warning of contamination events.


Asunto(s)
Técnicas Biosensibles/métodos , Técnicas Electroquímicas/métodos , Lipopolisacáridos/análisis , Microbiología del Agua , Cementos Dentales/química , Técnicas Electroquímicas/instrumentación , Electrodos , Escherichia coli/química , Lipopolisacáridos/metabolismo , Membranas Artificiales , Polimixina B/química , Polimixina B/metabolismo , Pseudomonas aeruginosa/química , Salmonella typhimurium/química
20.
Med Sci Monit ; 25: 3397-3405, 2019 May 08.
Artículo en Inglés | MEDLINE | ID: mdl-31066356

RESUMEN

BACKGROUND While several tests can be used in the laboratory evaluation of composite resin-based cement materials, the push-out test remains the most prevalent. Due to difficulties in sample preparation, as well as a highly complex procedure, we attempted to develop an alternative method for testing the bond strength of dental resin cement materials. MATERIAL AND METHODS Ninety-six experimental samples of 2 dual-cure resin cements and 1 fiber post system were prepared for the 2 testing procedures: the push-out test and the modified Microbond test. The degree of monomer conversion was measured by Fourier-transform infrared spectroscopy. RESULTS The push-out test results indicated that the bond strength of dual-cure resin cement differs depending on the tooth root region to which it is applied (p<0.05), In addition, our findings show that Variolink II exhibits a much lower bond strength relative to RelyX ARC. These findings were confirmed by the modified Microbond test results. The monomer conversion rate results indicate average conversion rates of 85.81% and 61.35% for RelyX ARC and Variolnik II, respectively. CONCLUSIONS Our study confirms the practical utility of the modified Microbond test in the assessment of bond strength of dental cement resin-based materials. The proposed test method is particularly useful given that, relative to the push-out test, it requires a much smaller number of preparation and execution steps, thus reducing the potential for introducing errors, while increasing the reliability of the obtained findings.


Asunto(s)
Recubrimiento Dental Adhesivo/métodos , Cementos Dentales/química , Cementos de Resina/química , Adhesivos , Bisfenol A Glicidil Metacrilato , Resinas Compuestas/química , Materiales Dentales/química , Porcelana Dental , Cavidad Pulpar , Análisis del Estrés Dental , Dentina , Humanos , Ensayo de Materiales , Polietilenglicoles , Ácidos Polimetacrílicos , Reproducibilidad de los Resultados , Resinas Sintéticas/química , Raíz del Diente
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA