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1.
Molecules ; 26(5)2021 Feb 26.
Artículo en Inglés | MEDLINE | ID: mdl-33652674

RESUMEN

The high intermittency of solar energy is still a challenge yet to be overcome. The use of thermal storage has proven to be a good option, with phase change materials (PCM) as very promising candidates. Nevertheless, PCM compounds have typically poor thermal conductivity, reducing their attractiveness for commercial uses. This paper demonstrates the viability of increasing the PCM effective thermal conductivity to industrial required values (around 4 W/m·K) by using metal wool infiltrated into the resin under vacuum conditions. To achieve this result, the authors used an inert resin, decoupling the specific PCM material selection from the enhancement effect of the metal wools. To ensure proper behavior of the metal wool under standard industrial environments at a broad range of temperatures, a set of analyses were performed at high temperatures and an inert atmosphere, presenting a thorough analysis of the obtained results.


Asunto(s)
Suministros de Energía Eléctrica , Metales/química , Transición de Fase , Energía Solar , Resinas Compuestas/química , Calor , Humanos , Conductividad Térmica , Vacio
2.
Molecules ; 26(5)2021 Feb 25.
Artículo en Inglés | MEDLINE | ID: mdl-33668952

RESUMEN

In this study, we investigated the influence of epoxy resin treatment on the mechanical and tribological properties of hemp fiber (HF)-reinforced plant-derived polyamide 1010 (PA1010) biomass composites. HFs were surface-treated using four types of surface treatment methods: (a) alkaline treatment using sodium chlorite (NaClO2) solution, (b) surface treatment using epoxy resin (EP) solution after NaClO2 alkaline treatment, (c) surface treatment using an ureidosilane coupling agent after NaClO2 alkaline treatment (NaClO2 + A-1160), and (d) surface treatment using epoxy resin solution after the (c) surface treatment (NaClO2 + A-1160 + EP). The HF/PA1010 biomass composites were extruded using a twin-screw extruder and injection-molded. Their mechanical properties, such as tensile, bending, and dynamic mechanical properties, and tribological properties were evaluated by the ring-on-plate-type sliding wear test. The strength, modulus, specific wear rate, and limiting pv value of HF/PA1010 biomass composites improved with surface treatment using epoxy resin (NaClO2 + A-1160 + EP). In particular, the bending modulus of NaClO2 + A-1160 + EP improved by 48% more than that of NaClO2, and the specific wear rate of NaClO2 + A-1160 + EP was one-third that of NaClO2. This may be attributed to the change in the internal microstructure of the composites, such as the interfacial interaction between HF and PA1010 and fiber dispersion. As a result, the mode of friction and wear mechanism of these biomass composites also changed.


Asunto(s)
Resinas Compuestas/química , Resinas Epoxi/química , Nylons/química , Biomasa , Ensayo de Materiales , Tamaño de la Partícula , Estrés Mecánico , Propiedades de Superficie
3.
Molecules ; 26(4)2021 Feb 21.
Artículo en Inglés | MEDLINE | ID: mdl-33670043

RESUMEN

The aim of this study was to investigate and understand bacterial adhesion to different dental material surfaces like amalgam, Chromasit, an Co-Cr alloy, an IPS InLine ceramic, yttrium stabilized tetragonal polycrystalline zirconia (TPZ), a resin-based composite, an Au-Pt alloy, and a tooth. For all materials, the surface roughness was assessed by profilometry, the surface hydrophobicity was determined by tensiometry, and the zeta potential was measured by electrokinetic phenomena. The arithmetic average roughness was the lowest for the TPZ ceramic (Ra = 0.23 µm ± 0.02 µm), while the highest value was observed for the Au-Pt alloy (Ra = 0.356 µm ± 0.075 µm). The hydrophobicity was the lowest on the TPZ ceramic and the highest on the Co-Cr alloy. All measured streaming potentials were negative. The most important cause of tooth caries is the bacterium Streptococcus mutans, which was chosen for this study. The bacterial adhesion to all material surfaces was determined by scanning electron microscopy. We showed that the lowest bacterial extent was on the amalgam, whereas the greatest extent was on tooth surfaces. In general, measurements showed that surface properties like roughness, hydrophobicity and charge have a significant influence on bacterial adhesion extent. Therefore, dental material development should focus on improving surface characteristics to reduce the risk of secondary caries.


Asunto(s)
Aleaciones/química , Cerámica/química , Resinas Compuestas/química , Amalgama Dental/química , Metacrilatos/química , Streptococcus mutans/crecimiento & desarrollo , Uretano/química , Adhesión Bacteriana , Humanos , Interacciones Hidrofóbicas e Hidrofílicas , Ensayo de Materiales , Microscopía Electrónica de Rastreo , Tamaño de la Partícula , Propiedades de Superficie
4.
Molecules ; 26(3)2021 Jan 28.
Artículo en Inglés | MEDLINE | ID: mdl-33525731

RESUMEN

In the current context of green mobility and sustainability, the use of new generation natural fillers, namely, α-cellulose, has gained significant recognition. The presence of hydroxyl groups on α-cellulose has generated immense eagerness to map its potency as filler in an elastomeric composite. In the present work, α-cellulose-emulsion-grade styrene butadiene rubber (E-SBR) composite is prepared by conventional rubber processing method by using variable proportions of α-cellulose (1 to 40 phr) to assess its reinforce ability. Rheological, physical, visco-elastic and dynamic-mechanical behavior have clearly established that 10 phr loading of α-cellulose can be considered as an optimized dosage in terms of performance parameters. Morphological characterization with the aid of scanning electron microscope (SEM) and transmission electron microscopy (TEM) also substantiated that composite with 10 phr loading of α-cellulose has achieved the morphological threshold. With this background, synthetic filler (silica) is substituted by green filler (α-cellulose) in an E-SBR-based composite. Characterization of the compound has clearly established the reinforcement ability of α-cellulose.


Asunto(s)
Butadienos/química , Celulosa/química , Elastómeros/química , Estirenos/química , Resinas Compuestas/química , Emulsiones/química , Dióxido de Silicio/química
5.
Int J Mol Sci ; 22(1)2021 Jan 03.
Artículo en Inglés | MEDLINE | ID: mdl-33401545

RESUMEN

Poly(methyl methacralyate) (PMMA) has long been used in dentistry as a base polymer for dentures, and it is recently being used for the 3D printing of dental materials. Despite its many advantages, its susceptibility to microbial colonization remains to be overcome. In this study, the interface between 3D-printed PMMA specimens and oral salivary biofilm was studied following the addition of zwitterionic materials, 2-methacryloyloxyethyl phosphorylcholine (MPC) or sulfobetaine methacrylate (SB). A significant reduction in bacterial and biofilm adhesions was observed following the addition of MPC or SB, owing to their protein-repellent properties, and there were no significant differences between the two test materials. Although the mechanical properties of the tested materials were degraded, the statistical value of the reduction was minimal and all the properties fulfilled the requirements set by the International Standard, ISO 20795-2. Additionally, both the test materials maintained their resistance to biofilm when subjected to hydrothermal fatigue, with no further deterioration of the mechanical properties. Thus, novel 3D-printable PMMA incorporated with MPC or SB shows durable oral salivary biofilm resistance with maintenance of the physical and mechanical properties.


Asunto(s)
Materiales Biocompatibles/farmacología , Biopelículas/efectos de los fármacos , Resinas Compuestas/química , Materiales Dentales/farmacología , Boca/efectos de los fármacos , Polímeros/química , Impresión Tridimensional/instrumentación , Adhesión Bacteriana , Biopelículas/crecimiento & desarrollo , Humanos , Ensayo de Materiales , Metacrilatos/química , Boca/microbiología , Fosforilcolina/análogos & derivados , Fosforilcolina/química , Streptococcus mutans/efectos de los fármacos , Streptococcus mutans/metabolismo
6.
Int J Nanomedicine ; 15: 9891-9907, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-33328732

RESUMEN

Purpose: The aim of this study was to investigate the effect of various mass fractions of 10-methacry-loyloxydecyl dihydrogen phosphate (MDP)-conditioned or unconditioned zirconia nano- or micro-particles with different initiator systems on the mechanical properties of nanohybrid resin composites. Methods: Both light-cured (L) and dual-cured (D) resin composites were prepared. When the mass fraction of the nano- or micro-zirconia fillers reached 55 wt%, resin composites were equipped with dual-cured initiator systems. We measured the three-point bending-strength, elastic modulus, Weibull modulus and translucency parameter of the nanohybrid resin composites containing various mass fractions of MDP-conditioned or unconditioned zirconia nano- or micro-particles (0%, 5 wt%, 10 wt%, 20 wt%, 30 wt% and 55 wt%). A Cell Counting Kit (CCK)-8 was used to test the cell cytotoxicity of the experimental resin composites. The zirconia nano- or micro-particles with MDP-conditioning or not were characterized by transmission electron microscopy (TEM), Fourier infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). Results: Resin composites containing 5-20 wt% MDP-conditioned or unconditioned nano-zirconia fillers exhibited better three-point bending-strength than the control group without zirconia fillers. Nano- or micro-zirconia fillers decreased the translucence of the nanohybrid resin composites. According to the cytotoxicity classification, all of the nano- or micro-zirconia fillers containing experimental resin composites were considered to have no significant cell cytotoxicity. The FTIR spectra of the conditioned nano- or micro-fillers showed new absorption bands at 1719 cm-1 and 1637 cm-1, indicating the successful combination of MDP and zirconia particles. The XPS analysis measured Zr-O-P peak area on MDP-conditioned nano- and micro-zirconia fillers at 39.91% and 34.89%, respectively. Conclusion: Nano-zirconia filler improved the mechanical properties of nanohybrid resin composites, but cannot be the main filler to replace silica filler. The experimental dual-cured composites can be resin cements with better opacity effects and a low viscosity.


Asunto(s)
Fenómenos Mecánicos , Nanopartículas/química , Circonio/química , Resinas Compuestas/química , Módulo de Elasticidad , Ensayo de Materiales , Metacrilatos/química , Fosfatos/química , Dióxido de Silicio/química , Propiedades de Superficie
7.
Acta Odontol Latinoam ; 33(2): 59-68, 2020 Sep 01.
Artículo en Inglés | MEDLINE | ID: mdl-32920607

RESUMEN

The aim of this in vitro study was to evaluate the effect of bleaching protocols on the surface roughness (Ra), color change and surface micromorphology of a low-viscosity bulk-fill composite (Filtek Bulk Fill Flow, 3M ESPE), a highviscosity bulk-fill composite (Filtek Bulk Fill, 3M ESPE) and a conventional nanoparticulate composite resin (control) (Filtek Z350 XT, 3M ESPE). Forty samples of each composite (disks 5 mm in diameter and 2 mm thick) were randomly divided into four groups (n=10), according to bleaching protocol: a) 10% carbamide peroxide gel (Opalescence, Ultradent Products) (2 h/ day, for 14 days); b) 40% hydrogen peroxide gel (Opalescence Boost, Ultradent Products) (three bleaching sessions, once a week, 45 min/session); c) whitening rinse (Listerine Whitening Extreme, Johnson & Johnson) (2 min/day, for 14 days); and d) distilled water (control). The samples were submitted to triplicate readings (Ra and color [CIELAB parameters]) before and after contact with bleaching protocols. Micromorphology was analyzed in a scanning electron microscope (SEM). Ra and color parameters (ΔL, Δa, Δb and ΔE) were analyzed by generalized linear models (α=0.05). The Ra of the high-viscosity bulk-fill was significantly higher than that of the other composites (p<0.05). Ra increased significantly (p<0.05) and surface became more irregular (SEM analysis) in all the composite resins, regardless of the bleaching protocol (p<0.05). The high-viscosity bulk-fill composite resin group had significantly lower ΔE (p<0.05) than the nanoparticulate composite resin group immersed in distilled water. It was concluded that the characteristics of each resin significantly influenced the Ra more than the bleaching protocol. The high-viscosity bulk-fill resin presented minor color change.


Asunto(s)
Resinas Compuestas/química , Peróxido de Hidrógeno/química , Blanqueadores Dentales/química , Blanqueamiento de Dientes/métodos , Decoloración de Dientes/tratamiento farmacológico , Viscosidad/efectos de los fármacos , Color , Humanos , Ensayo de Materiales
8.
Niger J Clin Pract ; 23(8): 1103-1109, 2020 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-32788488

RESUMEN

Background: Contamination is a common problem in pediatric restorative dentistry and there are a few studies that investigate blood contamination, hemostatic agents, and tooth dentin. Aim: The purpose of this study was to evaluate the effects of blood contamination and hemostatic agents on the bond strength of two different bonding systems with the dentin of primary teeth. Materials and Methods: Buccal and lingual dentin surfaces of 40 primary second molar teeth were used for this study. Specimens were divided into 4 groups according to the contamination and hemostatic agents (Blood-B, Ankaferd Blood Stopper-A, ViscoStat-V, Control-C) and then every group was further divided into two subgroups according to the bonding systems (Clearfil SE Bond-I, All Bond Universal-II, n = 10 per group). A bulk-fill composite resin was built-up on the surfaces. The specimens were tested in the micro shear mode at a crosshead speed of 1 mm/min on a universal test machine. Statistical analysis was performed with ANOVA and Tukey's tests at P < 0.05. Results: Significant differences have been detected in the micro shear bond strengths only between the Ankaferd Blood Stopper (ABS) (AI = 13.72 ± 4.47 and AII = 9.12 ± 4.4) and control groups (CI = 22.78 ± 10.86 and CII = 16.49 ± 6.55) without regards to the bonding systems. The highest scores were obtained in the control groups. Clearfil SE Bond showed better performance than All Bond Universal in all groups. Conclusion: It was determined that only the ABS contamination groups showed statistically significant decreases in the bond strengths when compared with control groups.


Asunto(s)
Sangre , Resinas Compuestas/química , Recubrimiento Dental Adhesivo , Recubrimientos Dentinarios/química , Hemostáticos/efectos adversos , Análisis del Estrés Dental , Dentina , Humanos , Ensayo de Materiales , Diente Molar , Cementos de Resina , Resistencia al Corte , Diente Primario
9.
Niger J Clin Pract ; 23(7): 957-964, 2020 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-32620725

RESUMEN

Aim: The aims of this study were to evaluate the surface morphology and surface roughness of restorative materials containing glass ionomer, analyze Streptococcus mutans biofilm formation on the surface of materials, and determine the correlation between surface roughness and biofilm. Materials and Methods: Four restorative materials: resin-modified glass ionomer; giomer; amalgomer; and glass carbomer were used and for each material, 6 mm in diameter and 2 mm in thickness disc-shaped specimens were prepared to evaluate the surface morphology (n = 3), surface roughness (n = 16), and biofilm (n = 20). Surface morphology was analyzed with a scanning electron microscope. Surface roughness was evaluated via an atomic force microscope. The biofilm was evaluated by counting the colony-forming units. Surface roughness measurements were evaluated using a one-way analysis of variance and Tukey HSD test. Biofilm parameters were analyzed using the Kruskal-Wallis H and Mann-Whitney U test. Pearson's correlation test was used to determine the correlation between surface roughness and biofilm. Results: While the highest roughness values were obtained for amalgomer and glass carbomer, the lowest roughness values belonged to giomer and resin-modified glass ionomer. Statistically significant differences in the number of adherent bacteria were observed between the materials only on day 1. No statistically significant correlation was determined between surface roughness and biofilm. Conclusions: The resin content and small filler particle size of material positively affect surface roughness. However, there is no direct relationship between surface roughness and biofilm.


Asunto(s)
Apatitas/química , Biopelículas/crecimiento & desarrollo , Resinas Compuestas/farmacología , Placa Dental/prevención & control , Cementos de Ionómero Vitreo/química , Streptococcus mutans/crecimiento & desarrollo , Resinas Acrílicas , Resinas Compuestas/química , Placa Dental/microbiología , Restauración Dental Permanente , Humanos , Ensayo de Materiales , Microscopía Electrónica de Rastreo , Dióxido de Silicio , Streptococcus mutans/efectos de los fármacos , Propiedades de Superficie
10.
Niger J Clin Pract ; 23(6): 798-804, 2020 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-32525114

RESUMEN

Aims: The aim of this study was to evaluation the treatment success of the short post technique (mushroom restoration) using a composite resin in severely decayed primary anterior teeth after 6, 12, and 18 months after treatment. Methods: Eighteen children aged 3-5 years with severely decayed primary maxillary anterior teeth (60 anterior maxillary primary teeth in total) were included. Patients were treated under general anesthesia (GA). After pulpectomy, a "mushroom shape" was formed in the root canals for the purpose of retention, and the root canals were filled with zinc oxide-eugenol (ZOE), and the teeth were restored with composite resin. The status of treatment was evaluated clinically and radiographically for periapical radiolucency, pathological root resorption, marginal fracture, and loss of restoration for each treated tooth. All findings were recorded. Results: As a result of the evaluation criteria, the success rates at 6, 12 and 18 months were 86%, 80%, and 71%, respectively. None of the teeth showed apical radiolucency or pathological root resorption at the end of the 18th month period. Conclusion: The short-post (mushroom restorations) technique is a clinically acceptable alternative method for restoration of severely decayed primary teeth. This study supports the feasibility of treatment with this technique for pediatric patients treated under GA.


Asunto(s)
Restauración Dental Permanente/métodos , Técnica de Perno Muñón , Pulpectomía/métodos , Materiales de Obturación del Conducto Radicular/uso terapéutico , Diente Primario/cirugía , Cemento de Óxido de Zinc-Eugenol/uso terapéutico , Anestesia General , Preescolar , Resinas Compuestas/química , Caries Dental/complicaciones , Preparación de la Cavidad Dental , Extravasación de Materiales Terapéuticos y Diagnósticos/complicaciones , Femenino , Humanos , Masculino , Maxilar , Pulpectomía/efectos adversos , Resorción Radicular , Traumatismos de los Dientes/complicaciones , Resultado del Tratamiento
11.
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
12.
Niger J Clin Pract ; 23(5): 660-667, 2020 May.
Artículo en Inglés | MEDLINE | ID: mdl-32367873

RESUMEN

Aims: The aim of this study is to investigate the color changes of three different traditional composites, one ceramic and two resin-based composites CAD/CAM blocks in different solutions. Methods: The materials used in the study were CAD/CAM block containing lithium disilicate glass ceramic (Ivoclar), Vita Enamic containing resin (VITA), Lava Ultimate Block containing resin (3M ESPE), G-aenial anterior composite (GC,), Filtek™ Ultimate Universal composite (3M ESPE) and Clearfil Majesty Esthetic composite (Kuaray). As colouring solutions, red wine (Buzbaǧ), black tea (Lipton), coffee (Nescafe) and distilled water (EAU distillee) were used. For the preparation of the traditional composite samples to be used in the study, 7 × 7 mm square-shaped plexiglass moulds, 1.2 mm in thickness, were used. The CAD/CAM blocks with ceramic and resin content were cut at the same thickness using a Struers sensitive cutting device. The samples were then randomly separated into grups of 10 and of the 240 samples, groups were separated into 6 different materials and 4 different solutions. The colour measurements of the 240 samples were taken at baseline, 30 days and 120 days with a Lovibond spectrophotometer (Tintometer). Results: A statistically significant difference was determined between the materials in respect of the ΔE values in the 30-day solution groups (P < 0.05). No statistically significant difference was determined in the ΔE values of the different materials in the 30-day and 120-day distilled water groups (P > 0.05). A statistically significant difference was determined between the materials in respect of the ΔE values in the 120-day solution groups (P < 0.05). Conclusion: In respect of discolouration, ceramic blocks are more successful. Resin-based blocks and traditional aesthetic composites showed more discolouration. The dietary habits of the patient should be taken into consideration in the selection of the restorative material.


Asunto(s)
Cerámica/química , Materiales Dentales/química , Ensayo de Materiales/métodos , Color , Resinas Compuestas/química , Diseño Asistido por Computadora
13.
Braz Oral Res ; 34: e035, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32321053

RESUMEN

Although fiber-reinforced composites are commonly used in dental practice, whether fiber-reinforced crowns and fixed partial dentures can be used as definitive prostheses remains to be determined. This study used scanning electron microscopy to evaluate the load-bearing capacity of non-reinforced and fiber-reinforced composite (FRC) molar crowns prepared by computer-aided design/computer-aided manufacturing (CAD/CAM). The crowns were fabricated from three empirical FRC blocks, one empirical composite block, and one commercial ceramic block. The FRC resin was prepared by mixing BaO silicate particles, E-glass fiber, and dimethacrylate resin. Specimens were divided into five groups (n = 10), differing in the amounts of filler, resin, and fiber. Crowns were statically loaded until fracture. One-way analysis of variance and Tukey's post hoc multiple comparison tests were used for statistical analyses. The groups showed significant differences in load-bearing capacity; empirical bidirectional FRC resin blocks had the highest capacity, while commercial ceramic blocks had the lowest capacity. Molar crowns formed from FRC resin blocks had higher load-bearing capacity compared to non-reinforced composite resin and ceramic blocks. These results show that fiber reinforcement increased the load-bearing capacity of molar crowns.


Asunto(s)
Resinas Compuestas/química , Diseño Asistido por Computadora , Coronas , Soporte de Peso , Análisis de Varianza , Cerámica/química , Diseño de Prótesis Dental , Humanos , Ensayo de Materiales , Microscopía Electrónica de Rastreo , Diente Molar , Valores de Referencia , Reproducibilidad de los Resultados , Propiedades de Superficie
14.
J Appl Oral Sci ; 28: e20190544, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32348440

RESUMEN

Objective To evaluate the influence of three levels of dental structure loss on stress distribution and bite load in root canal-treated young molar teeth that were filled with bulk-fill resin composite, using finite element analysis (FEA) to predict clinical failure. Methodology Three first mandibular molars with extensive caries lesions were selected in teenager patients. The habitual occlusion bite force was measured using gnathodynamometer before and after endodontic/restoration procedures. The recorded bite forces were used as input for patient-specific FEA models, generated from cone-beam computed tomographic (CT) scans of the teeth before and after treatment. Loads were simulated using the contact loading of the antagonist molars selected based on the CT scans and clinical evaluation. Pre and post treatment bite forces (N) in the 3 patients were 30.1/136.6, 34.3/133.4, and 47.9/124.1. Results Bite force increased 260% (from 36.7±11.6 to 131.9±17.8 N) after endodontic and direct restoration. Before endodontic intervention, the stress concentration was located in coronal tooth structure; after rehabilitation, the stresses were located in root dentin, regardless of the level of tooth structure loss. The bite force used on molar teeth after pulp removal during endodontic treatment resulted in high stress concentrations in weakened tooth areas and at the furcation. Conclusion Extensive caries negatively affected the bite force. After pulp removal and endodontic treatment, stress and strain concentrations were higher in the weakened dental structure. Root canal treatment associated with direct resin composite restorative procedure could restore the stress-strain conditions in permanent young molar teeth.


Asunto(s)
Fuerza de la Mordida , Resinas Compuestas/química , Resinas Compuestas/uso terapéutico , Restauración Dental Permanente/métodos , Diente Molar , Diente no Vital/terapia , Niño , Fuerza Compresiva , Tomografía Computarizada de Haz Cónico , Análisis del Estrés Dental , Módulo de Elasticidad , Análisis de Elementos Finitos , Humanos , Modelación Específica para el Paciente , Valores de Referencia , Reproducibilidad de los Resultados , Resistencia a la Tracción , Diente no Vital/diagnóstico por imagen , Resultado del Tratamiento
15.
Int. j interdiscip. dent. (Print) ; 13(1): 17-20, abr. 2020. tab, graf
Artículo en Inglés | LILACS | ID: biblio-1114887

RESUMEN

STATEMENT OF THE PROBLEM: The literature still lacks evidence regarding which polishing techniques have the ideal clinical outcomes for bulk-fill resin composites. PURPOSE: This study evaluated the surface gloss of two commercially available bulk-fill resin composites after different polishing procedures and characterized their micromorphology via scanning electron microscopy. MATERIAL AND METHODS: 80 bulk-fill compactable composite resin discs were created. The control group was left untreated, and remaining samples were subjected to different polishing techniques. Gloss units were measured and surface morphology of disc samples was assessed. The Tukey post-hoc test was used to identify any differences. RESULTS: Statistically significant differences were found between the different polishing systems applied to Filtek BulkFill Posterior and Tetric N Bulk-Fill. No differences were found when the same polishing system was applied for both resins. The highest gloss values were obtained in the control group and the ENA Shiny system; the lowest were obtained with SofLex XT and Soflex Spiral Wheels for the bulk-fill composite resins studied. CONCLUSIONS. Diamond pastes have the highest gloss behavior, followed by diamond rubber points. The systems with aluminum oxide discs present the lower gloss behavior. SEM images provided useful evidence, and future studies should include an evaluation over time.


Asunto(s)
Resinas Compuestas/química , Pulido Dental/métodos , Propiedades de Superficie , Ensayo de Materiales
16.
Niger J Clin Pract ; 23(3): 322-328, 2020 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-32134030

RESUMEN

Objective: The aim of this in-vitro study was to investigate the effects of frequently consumed beverages on the color stability and microhardness of various restorative materials. Materials and Methods: Twenty-four samples were prepared in each group to examine the effect of different beverages on coloration and surface hardness of two direct composite resins (Filtek Z250, Filtek Z550); one indirect composite resin (Solidex); and one high viscosity glass ionomer cement (Equia Forte Fil). Samples were stored in four solutions (distilled water, black tea, coffee, and cola) at room temperature for 1 week (n = 6). The color values are taken at the beginning and the color and microhardness values taken at the end of 1 week were evaluated by the Kruskal-Wallis and Mann-Whitney U tests. Results: The highest color change was observed in the Equia Fil, while the least color change was observed in the Z550 group. The highest degree of color change was observed in coffee and cola groups. While the lowest values of hardness were observed in the Solidex group, the highest values of hardness were observed in the Z550 group. The highest levels of hardness change were detected in the coffee and cola groups. Conclusion: The color and hardness of restorative materials can be negatively affected by consumed beverages. Nanohybrid composite resins are resistant to external coloration and hardness change.


Asunto(s)
Bebidas Gaseosas/efectos adversos , Café/efectos adversos , Color , Resinas Compuestas/química , Dureza , Té/efectos adversos , Decoloración de Dientes , Materiales Dentales , Restauración Dental Provisional , Cementos de Ionómero Vitreo , Pruebas de Dureza , Humanos , Ensayo de Materiales , Propiedades de Superficie
17.
Niger J Clin Pract ; 23(3): 355-361, 2020 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-32134035

RESUMEN

Objectives: This study evaluated the effect of Er, Cr: YSGG laser irradiation at different powers on repair bond strength (RBS) between ceramic restoration and composite resin (CR). Materials and Methods: Sixty ceramic samples were prepared and thermocycled for 2,500 cycles between 5°C and 55°C. Samples randomly divided into six groups (n = 10) according to the different surface treatment: control group (no surface treatment), 9.6% hydrofluoric acid etching, 37% phosphoric acid etching, and irradiations with Er, Cr: YSGG lasers (1 to 3W). The Cimara System was applied to all samples surface according to the manufacturer's instructions. CR resin was built-up on each ceramic surface using a tygon tube. The RBS test was performed at a crosshead speed of 1 mm/min, and one sample of each group was also observed under SEM and EDS was used to measure the elemental profiles of each specimen. Data was analyzed with one-way ANOVA and Tukey HSD test. Results: The lowest RBS was recorded in Group OF, and the highest RBS was recorded in Group HF, followed by Group 3W. There was no statistical difference between Group Control, 1W and 2W. Furthermore, differences in RBSs between Group 3W and the other groups except Group 2W were significant (P < 0.05). In EDS analysis, there are evident differences between surface treated samples and controls. Conclusions: 3W laser irradiation may be an alternative method to acid etching for enhancing the RBS of CR to ceramic.


Asunto(s)
Cerámica/química , Resinas Compuestas/química , Láseres de Estado Sólido , Ensayo de Materiales , Propiedades de Superficie
18.
Molecules ; 25(4)2020 Feb 14.
Artículo en Inglés | MEDLINE | ID: mdl-32075084

RESUMEN

Coating technology can be applied to decorate building constructions. Alkali-activated materials (AAM) are promising green and durable inorganic binders which show potential for development as innovative coating. In the paper, the possibility of using AAM composited with starch (CMS) as a novel plastic formable inorganic coating for decorating in building was investigated. The rheological properties, including plastic viscosity, yield stress, and thixotropy were considered to be critical properties to obtain the working requirements. Four different mixtures were systematically investigated to obtain the optimum formulation, and then were used to study their hardened properties, such as mechanical strengths (compressive, flexural, and adhesive strength), drying shrinkage, cracking behavior, and microstructure. Study results found that CMS could quickly and efficiently be hydrolyzed in an alkaline solution to produce organic plastic gel which filled in AAM paste, leading to the significant improvement of coating consistency, plastic viscosity, and thixotropy. The optimum coating composited with 15.40 wt% CMS shows a relatively stable rheological development, the setting time sufficient at higher than 4 h. Furthermore, CMS shows a significant positive effect on the cracking and shrinkage control due to padding effect and water retention of CMS, which results in no visible cracks on the coating surface. Although the mechanical strength development is relatively lower than that of plain AAM, its value, adhesive strength 2.11 MPa, compressive strength 55.09 MPa, and flexural strength 8.06 MPa highly meet the requirements of a relevant standard.


Asunto(s)
Materiales Biocompatibles Revestidos/química , Resinas Compuestas/química , Plásticos/química , Almidón/química , Álcalis/química , Compuestos Inorgánicos/química , Estrés Mecánico , Propiedades de Superficie , Resistencia a la Tracción
19.
BMC Oral Health ; 20(1): 30, 2020 01 30.
Artículo en Inglés | MEDLINE | ID: mdl-32000753

RESUMEN

BACKGROUND: Increased composite roughness enhances bacterial adhesion and discoloration, thus increasing the risk of gingival inflammation and secondary caries. Concerns about detrimental effects of sodium bicarbonate on surface roughness influenced the development of less abrasive powders: a glycine-based powder and an erythritol-based powder, additionally - sodium bicarbonate-based powder of reduced grain size. However, there is limited evidence on effects of these materials on the surface of dental fillings. The aim of the present study was to compare the effects of three air-polishing powders (of a reduced abrasiveness) on surface roughness of microhybrid restorative composite material. MATERIAL AND METHODS: Microhybrid light-cure resin composite samples were placed on 64 plaster cubes and light-cured through polyester strips. Surface roughness was measured using laser confocal microscope (magnification 2160x). The specimens were randomly divided into three groups (n = 20, 20 and 24) and air-polished with: sodium bicarbonate (40 µm), glycine (25 µm) and erythritol (14 µm), respectively. Then surface roughness was remeasured, keeping the same field of observation. Specialized 3D analysis software was used for data processing. Parameters according to ISO 25178: Sa, Sq, Sku, Sp, Sv, Sz, Ssk were used to describe surface roughness. RESULTS: Sa, Sq, Sp, Sv, Sz increased significantly following air polishing. Ssk was significantly higher, whereas Sku was significantly lower in sodium bicarbonate and erythritol groups than before air polishing. Comparison between the three powders revealed that Sa was significantly higher in sodium bicarbonate group than in glycine group. Sku was significantly higher in glycine and erythritol groups than in sodium bicarbonate group. CONCLUSIONS: Sodium bicarbonate has a stronger detrimental effect on composite surface than glycine or erythritol. No advantage of erythritol comparing to glycine could be found.


Asunto(s)
Resinas Compuestas , Materiales Dentales/química , Pulido Dental/métodos , Bicarbonato de Sodio/química , Presión del Aire , Resinas Compuestas/química , Humanos , Ensayo de Materiales , Polvos , Propiedades de Superficie
20.
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
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