RESUMEN
STATEMENT OF PROBLEM: Microwave irradiation and immersion in solutions have been recommended for denture disinfection. However, the effect of dry conditions and impression materials has not been completely evaluated. PURPOSE: The purpose of this study was to evaluate the effectiveness of microwave irradiation and hydrogen peroxide for the disinfection of dental impression materials. MATERIAL AND METHODS: Specimens (diameter 10 mm, thickness 2 mm) were made with polyvinyl siloxane. Experimental groups were treated with hydrogen peroxide (group H), microwave irradiation (group M), and a combination of both hydrogen peroxide and microwave irradiation (group MH) for 1 minute, 2 minutes, and 3 minutes. The control group was untreated. The total sample size was 120. The specimens were divided into 2 groups, those exposed to Streptococcus mutans and those exposed to Escherichia coli. The disinfection effect and physical properties (contact angle, compatibility with gypsum, strain in compression, tear strength) were evaluated. RESULTS: All 3 groups (H, M, MH) were effective in reducing the number of colony forming units (CFU) per unit volume (mL) for both S mutans and E coli compared with the control. The most significant reduction in the CFU/mL of both bacteria was noted in the MH group and was used to compare either treatment alone (P<.05). No statistically significant difference was noted between the control and treatment groups in terms of all of the physical properties tested (P>.05). CONCLUSIONS: Microwave irradiation was identified as a useful disinfection method against S mutans and E coli, especially when combined with H2O2, without adversely affecting the physical properties of dental impression materials.
Asunto(s)
Desinfectantes Dentales/uso terapéutico , Materiales de Impresión Dental/química , Desinfección/métodos , Peróxido de Hidrógeno/uso terapéutico , Microondas/uso terapéutico , Carga Bacteriana/efectos de los fármacos , Carga Bacteriana/efectos de la radiación , Técnicas Bacteriológicas , Sulfato de Calcio/química , Materiales de Impresión Dental/efectos de la radiación , Análisis del Estrés Dental/instrumentación , Escherichia coli/efectos de los fármacos , Escherichia coli/efectos de la radiación , Humanos , Ensayo de Materiales , Polivinilos/química , Polivinilos/efectos de la radiación , Dosis de Radiación , Siloxanos/química , Siloxanos/efectos de la radiación , Streptococcus mutans/efectos de los fármacos , Streptococcus mutans/efectos de la radiación , Estrés Mecánico , Propiedades de Superficie , Temperatura , Resistencia a la Tracción , Factores de Tiempo , HumectabilidadRESUMEN
BACKGROUND: This study evaluated the effect of disinfection by immersion and microwave irradiation on the roughness of one denture base resin (Lucitone-L) and five relining materials, three hard (Tokuyama Rebase II-TR, New Truliner-NT, Ufigel Hard-UH) and two resilient (Trusoft-T, Sofreliner-S). METHODS: Fifty specimens were made and divided into groups: CL2 specimens were brushed with 4% chlorhexidine (1 min), immersed in the same solution (10 min) and immersed in water (3 min); MW2 specimens were immersed in water and microwave irradiated (650W; 6 min); CL2 and MW2 specimens were disinfected twice; CL7 and MW7 specimens were submitted to seven cycles using chlorhexidine or microwave irradiation, respectively; W specimens were not disinfected and remained in water (37°C; 7 days). RESULTS: Results were statistically analysed (p = 0.05) and revealed that, at baseline, the highest mean value was observed for T (p < 0.001). Material NT showed increase in roughness after the first (p = 0.003), second (p = 0.001), seventh (p = 0.000) cycles of microwave disinfection and after 7 days of immersion in water (p = 0.033). CONCLUSIONS: Resilient liner S presented significant increase in roughness after the second cycle of disinfection with chlorhexidine (p = 0.003). Material T exhibited significantly decreased roughness in group W (p = 0.010), while microwaving produced severe alterations on its surface.
Asunto(s)
Clorhexidina/química , Desinfectantes Dentales/química , Materiales Dentales/química , Bases para Dentadura , Alineadores Dentales , Rebasado de Dentaduras , Desinfección/métodos , Microondas/uso terapéutico , Resinas Acrílicas/química , Resinas Acrílicas/efectos de la radiación , Materiales Dentales/efectos de la radiación , Humanos , Inmersión , Ensayo de Materiales , Metacrilatos/química , Metacrilatos/efectos de la radiación , Metilmetacrilatos/química , Metilmetacrilatos/efectos de la radiación , Plastificantes/química , Plastificantes/efectos de la radiación , Dosis de Radiación , Elastómeros de Silicona/química , Elastómeros de Silicona/efectos de la radiación , Siliconas/química , Siliconas/efectos de la radiación , Siloxanos/química , Siloxanos/efectos de la radiación , Propiedades de Superficie , Temperatura , Factores de Tiempo , Agua/químicaRESUMEN
OBJECTIVE: The purpose of this study was to determine the depth of cure, degree of conversion (DC), hardness, and cervical sealing ability of silorane-based composite (Filtek Silorane [FS; 3M, Seefeld, Germany]) and to compare with methacrylate-based composites (MBCs = Filtek Supreme XT [FSXT] and Filtek P60 [FP60]). MATERIALS AND METHODS: The DC and hardness of every material were evaluated after 1, 7, and 30 days. The depth of cure was determined using the ISO 4049:2000 standard. Microleakage was evaluated by measuring dye penetration across the gingival wall in cross-sectioned specimens. RESULTS: FS showed lower depth of cure than FSXT and FP60. The DC of FS was significantly lower when compared to FP60 and FSXT. FS exhibited lower hardness than both FSXT and FP60 after 1 day of storage. The hardness of FS remained unchanged during the storage period. FS showed reduced microleakage scores compared to FSXT and showed similar microleakage scores compared to FP60. CONCLUSIONS: In conclusion, the DC and cure depth of FS are lower than those of MBCs. However, FS revealed stable hardness in water that is comparable to MBCs. The sealing ability of FS is similar or even better than that of MBCs.
Asunto(s)
Resinas Compuestas/química , Resinas Compuestas/efectos de la radiación , Metacrilatos , Siloxanos , Luces de Curación Dental , Preparación de la Cavidad Dental/clasificación , Filtración Dental , Dureza , Humanos , Curación por Luz de Adhesivos Dentales , Metacrilatos/química , Metacrilatos/efectos de la radiación , Polimerizacion , Resinas de Silorano , Siloxanos/química , Siloxanos/efectos de la radiación , Estadísticas no ParamétricasRESUMEN
PURPOSE: The aim of this study was to evaluate the effect of different accelerated aging times on permanent deformation and tensile bond strength of two soft chairside liners, acrylic resin (T) and silicone (MS) based. MATERIALS AND METHODS: Different specimens were made for each test of each reliner. The specimens (n = 10) were submitted to accelerated aging for 2, 4, 8, 16, 32, and 64 cycles. Tensile bond strength testing was performed at a crosshead speed of 5 mm/min and permanent deformation with a compressive load of 750 gf. Data were submitted to Mann-Whitney test to compare the materials at different times, and Kruskal-Wallis and Dunn tests were used for comparing aging intervals within a given reliner. RESULTS: MS presented a lower percentage of permanent deformation (p < 0.0001) and higher tensile bond strength (p < 0.0001) than T in all time intervals and was not affected by the accelerated aging process, which reduced the permanent deformation and increased tensile bond strength of T (p < 0.05). CONCLUSION: MS presented lower permanent deformation and higher tensile bond strength than T. Although T presented changes in those properties after accelerated aging, both materials might be suited for long-term use.
Asunto(s)
Resinas Acrílicas/química , Recubrimiento Dental Adhesivo , Materiales Dentales/química , Alineadores Dentales , Siliconas/química , Resinas Acrílicas/efectos de la radiación , Adhesividad , Materiales Dentales/efectos de la radiación , Análisis del Estrés Dental/instrumentación , Humanos , Ensayo de Materiales , Polimerizacion , Polivinilos/química , Polivinilos/efectos de la radiación , Siliconas/efectos de la radiación , Siloxanos/química , Siloxanos/efectos de la radiación , Estrés Mecánico , Propiedades de Superficie , Temperatura , Resistencia a la Tracción , Factores de Tiempo , Rayos Ultravioleta , Agua/químicaRESUMEN
AIM: This study investigated the influence of different composite resin organic matrix (methacrylate - Filtek Z350 XT and silorane - Filtek P90) on light energy transmission through the composite and bottom/top rate. MATERIALS AND METHODS: A light-emitting diode (New Blue Phase), light-curing unit was used with different photoactivation protocols (high-continuous mode - HCM, 1400 mW/cm2 for 20 seconds; low-continuous mode - LCM , 700 mW/cm2 for 40 seconds; and soft-start mode - SSM, 140 mW/cm2 for 5s followed by 39 seconds for 700 mW/cm2). Twenty specimens were prepared for each composite. The light energy transmission through the composite was calculated (n=10). The bottom/top rate of the same specimen was calculated (n=10). The data were compared by Tukey's test in different tests (light energy transmission through the composite and bottom/top rate). RESULTS: The light energy transmission through the Filtek Z350 XT composite (HCM - 576 mW/cm2, LCM - 238 mW/cm2, SSM - 232 mW/cm2) did not show statistical difference when compared with Filtek P90 composite (HCM - 572 mW/cm2, LCM - 233 mW/cm2, SSM - 230 mW/cm2). The bottom/top rate of the Filtek Z350 XT composite (HCM - 88.98%, LCM - 90.94%, SSM - 89.92%) was statistically higher than that of the Filtek P90 composite (HCM-77.29%, LCM-77.51%, SSM- 77.79%). CONCLUSION: Light energy transmission through the composite was not influenced by the use of different dental composite restoratives. However, the bottom/top rate of the composites was influenced by the use of different dental composite restoratives. CLINICAL SIGNIFICANCE: Insufficiently polymerized composite resin may present a large number of problems. For this reason, dental composite resins should have the similar deep surface polymerization as the top surface in dental restorations.
Asunto(s)
Resinas Compuestas/efectos de la radiación , Luz , Metacrilatos/efectos de la radiación , Siloxanos/efectos de la radiación , Bisfenol A Glicidil Metacrilato/química , Bisfenol A Glicidil Metacrilato/efectos de la radiación , Compuestos Inorgánicos de Carbono/química , Resinas Compuestas/química , Luces de Curación Dental , Dureza , Humanos , Ensayo de Materiales , Metacrilatos/química , Procesos Fotoquímicos , Polietilenglicoles/química , Polietilenglicoles/efectos de la radiación , Polimerizacion , Ácidos Polimetacrílicos/química , Ácidos Polimetacrílicos/efectos de la radiación , Poliuretanos/química , Poliuretanos/efectos de la radiación , Dosis de Radiación , Compuestos de Silicona/química , Resinas de Silorano , Siloxanos/química , Propiedades de Superficie , Temperatura , Factores de TiempoRESUMEN
The main objective of the current study was to investigate the dynamic mechanical properties of a room-temperature vulcanizing silicone incorporating different fractions of zinc oxide (ZnO) after indoor and outdoor photoaging. Forty-eight samples were produced by adding different amounts of ZnO into a commercial maxillofacial silicone (EPISIL-E). The samples were divided into 4 groups containing 0.0, 0.2, 0.5, and 1 wt% ZnO additive, respectively. Samples were exposed to sunlight (subgroup 2), ultraviolet (subgroup 3), and fluorescence (subgroup 4) aging, whereas nonaged samples comprised the control subgroup (subgroup 1). Dynamic mechanical analysis was used to determine the storage modulus (E'), loss modulus (Eâ³), and damping capacity (tanδ). General linear statistic model was conducted to evaluate the effects of aging, testing frequency, and composition on the dynamic mechanical properties of the silicone with the ZnO additive. Post hoc analysis was performed using Tukey test. Statistical analysis revealed a significant impact of composition on tanδ (P < 0.05). Aging influenced E' and Eâ³ (P < 0.01). The combination of aging and composition had a significant effect on all dynamic properties (P < 0.01).
Asunto(s)
Materiales Biocompatibles/química , Elastómeros de Silicona/química , Óxido de Zinc/química , Materiales Biocompatibles/efectos de la radiación , Módulo de Elasticidad , Elasticidad , Fluorescencia , Calor , Humanos , Ensayo de Materiales , Prótesis Maxilofacial , Polimerizacion , Polivinilos/química , Polivinilos/efectos de la radiación , Elastómeros de Silicona/efectos de la radiación , Siloxanos/química , Siloxanos/efectos de la radiación , Estrés Mecánico , Luz Solar , Propiedades de Superficie , Temperatura , Factores de Tiempo , Rayos Ultravioleta , Óxido de Zinc/efectos de la radiaciónRESUMEN
Manipulation makes light work: The morphology and rheological properties of a liquid-crystalline system can be dynamically manipulated with UV light by attaching photoresponsive liquid-crystalline moieties to a siloxane-based polymer. Stimulation with UV light induces a conformational change in the molecule, which disrupts the liquid-crystalline mesophase (see picture), and results in a dramatic change in its rheological properties.
Asunto(s)
Polímeros/química , Polímeros/efectos de la radiación , Siloxanos/química , Siloxanos/efectos de la radiación , Rayos UltravioletaRESUMEN
Comparing with normal cells, Lipid droplets (LDs) of cancer cells show lower polarity and less quantity, which can be utilized as a marker for cancer diagnosis. However, the investigation of LDs in living cancer cells is restricted by the lack of effective molecular tools. Herein, we first reported a novel polysiloxane-based polymer fluorescent polar probe TR-1 with AIE properties, which realized the possibilities for locating LDs. It can aggregate in the LDs of cancer cells and show a stronger fluorescent signal to conduct cancer diagnosis. Moreover, the excellent photostability of TR-1 enable stable fluorescence to exhibit in cancer cells during effective time.
Asunto(s)
Colorantes Fluorescentes/química , Gotas Lipídicas/metabolismo , Neoplasias/diagnóstico por imagen , Siloxanos/química , Animales , Línea Celular Tumoral , Fluorescencia , Colorantes Fluorescentes/síntesis química , Colorantes Fluorescentes/efectos de la radiación , Humanos , Luz , Ratones , Microscopía Confocal/métodos , Microscopía Fluorescente/métodos , Siloxanos/síntesis química , Siloxanos/efectos de la radiaciónRESUMEN
A bifunctional interfacial layer was introduced onto the surface of cotton fabric which not only enhanced the interfacial bonding between Ag@ZnO and organic substrates but also improved the photocatalytic performance simultaneously. In detail, a modified cotton fabric (denoted as Cot-g-Si/Ag@ZnO) was fabricated through radiation-induced graft polymerization of γ-methacryloxypropyl trimethoxysilane and followed the in-situ formation of ZnO and loading of Ag nanoparticles simultaneously. Owing to ZnOSi between the graft chains and Ag@ZnO photocatalyst, the charge carrier concentration increased and Ag was prevented from oxidizing through the partial separation from ZnO, leading to enhanced near-field amplitudes of the localized surface plasmon resonance. Cot-g-Si/Ag@ZnO also exhibited excellent photocorrosion resistance, photostability and laundering durability. Its photocatalytic activity was fully maintained after several photodegradation cycles; moreover, after laundering durability test, the photocatalytic activity was improved compared with the newly prepared one. Credible mechanism for the photocatalytic activity of Cot-g-Si/Ag@ZnO under sunlight irradiation is proposed.
Asunto(s)
Antibacterianos/farmacología , Fibra de Algodón , Nanopartículas del Metal/química , Siloxanos/farmacología , Plata/química , Óxido de Zinc/farmacología , Antibacterianos/química , Antibacterianos/efectos de la radiación , Catálisis , Escherichia coli/efectos de los fármacos , Gossypium/química , Luz , Nanopartículas del Metal/efectos de la radiación , Azul de Metileno/efectos de la radiación , Fotólisis , Rodaminas/efectos de la radiación , Siloxanos/química , Siloxanos/efectos de la radiación , Plata/efectos de la radiación , Staphylococcus aureus/efectos de los fármacos , Óxido de Zinc/química , Óxido de Zinc/efectos de la radiaciónRESUMEN
OBJECTIVES: The potential of a recently marketed resin-based composite (RBC), namely X-tra fil (shade A3), which claims to be amenable to curing to a depth of 4mm was investigated. METHODS: Disc-shaped specimens (11mm diameter, 2mm thickness) of Filtek Z250, Admira and X-tra fil were tested in bi-axial flexure to determine the strength. Water sorption, water solubility and Vickers hardness measurements were determined following short-term (0.1, 0.5, 1, 4, 24 and 48h) and medium-term (1, 4, 12 and 26 weeks) water immersion on disc-shaped specimens (11mm diameter, 1mm thickness). The top (t) 0-1mm depth and bottom (b) 3-4mm depth of X-tra fil were tested for water sorption, water solubility and Vickers hardness measurements. In addition an analysis of pulpal cell cytotoxicity at 1, 2, 3, 7 and 14 days was also performed on the RBCs. RESULTS: No significant differences in the bi-axial flexure strength or top to bottom hardness ratios were evident between the materials examined. However, the water sorption and water solubility values obtained for Filtek Z250 (12.3+/-1.8 and 2.7+/-1.6microg/mm3, respectively) and Admira (16.0+/-1.5 and 4.3+/-0.2microg/mm3, respectively) were increased compared with X-tra fil (t) (5.4+/-0.7 and 0.8+/-0.2microg/mm3, respectively) and X-tra fil (b) (6.8+/-0.6 and 2.4+/-1.1microg/mm3, respectively) but within the ISO specification standard of < or =40 and < or =7.5microg/mm(3), respectively. No statistically significant differences were identified on cell viability between the RBCs used in the current study. SIGNIFICANCE: The manufacturer claims that the recently marketed material X-tra fil could be cured to a depth of 4mm appear to be vindicated and the performance in terms of flexure strength, water uptake and biocompatibility are comparable with conventional RBCs.
Asunto(s)
Resinas Compuestas/efectos de la radiación , Metacrilatos/efectos de la radiación , Animales , Línea Celular , Resinas Compuestas/química , Resinas Compuestas/toxicidad , Pulpa Dental/citología , Pulpa Dental/efectos de los fármacos , Restauración Dental Permanente , Análisis del Estrés Dental , Elasticidad , Dureza , Ensayo de Materiales , Metacrilatos/química , Metacrilatos/toxicidad , Ratones , Transición de Fase , Docilidad , Siloxanos/química , Siloxanos/efectos de la radiación , Siloxanos/toxicidad , Solubilidad , HumectabilidadRESUMEN
OBJECTIVE: To investigate the color stability of resin-based restorative materials when polymerized with light-emitting diode (LED) curing light in the constant or exponential mode. MATERIAL AND METHODS: Eight specimens of Admira (AD), Compoglass F (CO), and Tetric EvoCeram (TE) constantly cured or exponentially cured with a high-powered LED curing light for 10, 20, or 60 s. The CIE-Lab values (L*, a*, b*) were measured prior to and after performing the water storage or color stability test according to EN ISO 7491 (Suntest). RESULTS: Statistical analysis showed significant changes in the color values after each of the aging processes, as well as between DeltaL, Deltaa, Deltab, and DeltaE of the materials, which were dependent on curing time, mode, and aging condition (p<0.05). CO performed very well during water storage, but AD and TE exceeded the clinically relevant limit DeltaE=1. After the Suntest and 180 d additional water storage, TE showed the highest mean (SD) DeltaE=4.4 (1.1) to 5.4 (1.9). Although AD and CO performed best in the constant mode, they exceeded DeltaE=1. All materials shifted to more red. CONCLUSIONS: The extent of discoloration depended on (a) the curing mode, (b) the curing time, and (c) the aging condition. Not all materials performed clinically acceptably in all tests; TE even showed unacceptable DeltaE>3.3. The optimal curing time was 20 s for both curing modes and all tested materials.
Asunto(s)
Color , Resinas Compuestas/química , Resinas Compuestas/efectos de la radiación , Análisis de Varianza , Colorimetría , Equipo Dental , Restauración Dental Permanente , Luz , Ensayo de Materiales , Metacrilatos/química , Metacrilatos/efectos de la radiación , Transición de Fase , Semiconductores , Siloxanos/química , Siloxanos/efectos de la radiación , Factores de TiempoRESUMEN
Polysiloxanes have shown exquisite properties for fabrication of microstructures for various biomedical and biotechnological applications. Nevertheless, their biocompatibility in terms of cell adhesion and survival ability is controversial. A simple polysiloxane modifying procedure that reproducibly enhances cell adhesion was proposed. Sonication of the hybrid organic-inorganic polymer of polysiloxane type, Ormocomp, in potassium hydroxide (KOH)/ethanol solution enhanced adhesion and subsequent survival of a panel of four cell lines. Characterization of surface properties of untreated and KOH-treated Ormocomp coatings has revealed considerable negative charge of Ormocomp substrates based on measurements of zeta potentials. KOH treatment did not modify surface morphology as visualized by scanning electron microscopy, but it resulted in alteration in both chemical composition according to SIMS analysis and hydrophilicity evaluated by static water contact angles. The results suggest that the failure of the adherent cells to survive on Ormocomp coatings is related to cell adhesion. The negative surface charge of Ormocomp substrates may be one of the influencing factors; however, the modification of surface chemistry mediated by KOH and the resulting increase in hydrophilicity accompanied by modification of protein adsorption are more likely responsible for enhanced cell adhesion and survival on Ormocomp coatings. KOH treatment thus may serve as a simple, cost-effective procedure modifying polysiloxane-type polymers that leads to reproducible enhancement of cell adhesion.
Asunto(s)
Materiales Biocompatibles/metabolismo , Adhesión Celular , Hidróxidos/metabolismo , Compuestos de Potasio/metabolismo , Siloxanos/metabolismo , Rayos Ultravioleta , Animales , Materiales Biocompatibles/química , Materiales Biocompatibles/efectos de la radiación , Línea Celular , Supervivencia Celular , Materiales Biocompatibles Revestidos , Humanos , Interacciones Hidrofóbicas e Hidrofílicas , Ensayo de Materiales , Microscopía Electrónica de Rastreo , Siloxanos/química , Siloxanos/efectos de la radiación , Sonicación , Espectrometría de Masa de Ion Secundario , Propiedades de SuperficieRESUMEN
The preparation of stationary phases with enhanced chemical stability in alkaline eluents has been the principal objective of many chromatographers. New and improved silica substrates and advanced chemical modification methods are among the possibilities being investigated to reach this objective. The present work has evaluated these two possibilities for new stationary phases. First, the silica surface was modified by reaction with zirconium tetrabutoxide to produce zirconized silica particles having about 21% (w/w) of zirconium. Then poly(methyltetradecylsiloxane) (PMTDS) was immobilized onto this surface using different doses (50-120 kGy) of gamma radiation. These new phases were characterized using elemental analysis and infrared and solid-state (29)Si-nuclear magnetic resonance (NMR) spectroscopies. These new stationary phases presented column efficiencies of about 68,000 plates m(-1), symmetric peaks for apolar compounds and retention factors that depend on the irradiation dose and show improved stability in high pH mobile phases. The separation of several pharmaceuticals at pH 11 is presented.
Asunto(s)
Cromatografía Líquida de Alta Presión/instrumentación , Dióxido de Silicio/efectos de la radiación , Siloxanos/efectos de la radiación , Acetaminofén/aislamiento & purificación , Alprazolam/aislamiento & purificación , Derivados del Benceno/aislamiento & purificación , Ibuprofeno/aislamiento & purificación , Lorazepam/aislamiento & purificación , Espectroscopía de Resonancia Magnética , Siloxanos/síntesis química , Siloxanos/química , Espectrofotometría Infrarroja , Uracilo/aislamiento & purificación , CirconioRESUMEN
OBJECTIVES: To investigate the polymerisation shrinkage strain, associated cuspal movement, degree of conversion (DC) and cervical gingival microleakage of mesio-occlusal-distal (MOD) cavities restored with four resin-based composite (RBC) filling materials placed incrementally using a light emitting diode (LED) light curing unit (LCU). METHODS: Standardised extensive MOD cavity preparations on extracted teeth were performed on 40 sound upper premolar teeth. Restoration of the teeth involved the placement of RBCs in eight increments with the appropriate bonding system before irradiation using an LED LCU. Buccal and palatal cusp deflections at each stage of polymerisation were recorded using a twin channel deflection measuring gauge. Following restoration, the teeth were thermocycled, immersed in a 0.2% basic fuchsin dye for 24 h, sagittally sectioned and examined for cervical microleakage. The DC was determined using a Fourier transform infra-red (FT-IR) spectrometer. RESULTS: No significantly difference (P=0.677) in cuspal movement was recorded for Z100 (13.1+/-3.2 microm) compared with Filtek Z250 (8.4+/-3.5 microm), P60 (7.3+/-3.8 microm) and Admira (6.7+/-2.7 microm). The LED LCU deflections were compared with a halogen LCU used in a conventional (Fleming GJP, Hall D, Shorthall ACC, Burke FJT. Cuspal movement and microleakage in premolar teeth restored with posterior filling materials of varying reported volumetric shrinkage values. Journal of Dentistry, 2005;33:139-146) and soft-start mode (Fleming GJP, Cara RR, Palin WM, Burke FJT. Cuspal movement and microleakage in premolar teeth restored with posterior filling materials cured using 'soft-start' polymerization. Dental Materials, 2006, , in press) and a significant reduction in cuspal movement was identified for curing type and material type (P<0.001 and P=0.002, respectively). No significant differences were noted between the four RBC materials investigated when the DC or microleakage scores were examined for the LED LCU. SIGNIFICANCE: It would appear that irradiation of RBCs using the LED LCU offered a significant reduction in associated cuspal movement in large MOD cavities. However, the microleakage scores following polymerisation were significantly increased with dye penetration into the pulp chamber from the axial wall evident in teeth restored with the LED LCU.
Asunto(s)
Resinas Compuestas/química , Filtración Dental/clasificación , Materiales Dentales/química , Restauración Dental Permanente/clasificación , Iluminación/instrumentación , Corona del Diente/patología , Diente Premolar , Colorantes , Resinas Compuestas/efectos de la radiación , Recubrimiento Dental Adhesivo , Preparación de la Cavidad Dental/clasificación , Materiales Dentales/efectos de la radiación , Restauración Dental Permanente/métodos , Diseño de Equipo , Humanos , Luz , Metacrilatos/química , Metacrilatos/efectos de la radiación , Polímeros/química , Colorantes de Rosanilina , Dióxido de Silicio/química , Dióxido de Silicio/efectos de la radiación , Siloxanos/química , Siloxanos/efectos de la radiación , Espectroscopía Infrarroja por Transformada de Fourier , Estrés Mecánico , Propiedades de Superficie , Circonio/química , Circonio/efectos de la radiaciónRESUMEN
In modern research, development of monomers that reduce shrinkage of composite materials remains an ongoing quest and perennial challenge. The purpose of this study, therefore, was to analyze the shrinkage behaviour of an innovative composite material for dental restorations based on a monomer with a new chemical formulation, known as silorane. To this end, shrinkage stress development during curing, gel point, and coefficient of near linear fit of contraction stress/time were evaluated after polymerizing the material with 10 different curing regimes. Shrinkage stress varied between 1.4 MPa after a 10-second curing in a pulsed regime to 4.4 MPa after curing for 40 seconds with a high energy curing unit, Bluephase. Pearson correlation analysis showed that with respect to the tested curing units, shrinkage stress correlated significantly with energy density (0.89), irradiance (0.70), curing time (0.51), coefficient of near linear fit of contraction (0.70), and gel point (-0.60). Silorane exhibited low shrinkage stress values in comparison to regular methacrylate composites. Nevertheless, stress due to thermal contraction when the light exposure ended was not negligible-but could be reduced by applying the appropriate curing strategy.
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Resinas Compuestas/química , Resinas Compuestas/efectos de la radiación , Adaptación Marginal Dental , Restauración Dental Permanente , Análisis del Estrés Dental , Compuestos Epoxi/química , Luz , Ensayo de Materiales , Transición de Fase , Siloxanos/química , Siloxanos/efectos de la radiaciónRESUMEN
The removal of polychlorinated biphenyls (PCBs) both from siloxane transformer oil and hydrocarbon engine oil was investigated through the application of microwave (MW) irradiation and a reaction system based on polyethyleneglycol (PEG) and potassium hydroxide. The influence of the main reaction parameters (MW irradiation time, molecular weight of PEG, amount of added reactants and temperature) on the dechlorination behavior was studied. Promising performances were reached, allowing about 50% of dechlorination under the best experimental conditions, together time and energy saving compared to conventional heating systems. Moreover, an interesting dechlorination degree (up to 32%) was achieved for siloxane transformer oil when MW irradiation was employed as the unique driving force. To the best of our knowledge, this is the first time in which MW irradiation is tested as the single driving force for the dechlorination of these two types of PCB-contaminated oils.
Asunto(s)
Microondas , Aceites/efectos de la radiación , Bifenilos Policlorados/efectos de la radiación , Siloxanos/efectos de la radiación , Halogenación , Hidrocarburos/química , Hidrocarburos/efectos de la radiación , Hidróxidos/química , Peso Molecular , Aceites/química , Bifenilos Policlorados/química , Polietilenglicoles/química , Compuestos de Potasio/química , Siloxanos/química , TemperaturaRESUMEN
OBJECTIVES: The polymerization shrinkage of light cured dental composites presents the major drawback for these aesthetically adaptable restorative materials. LED based light curing technology has recently become commercially available. Therefore, the aim of the present study was to investigate if there was a statistically significant difference in linear and volumetric composite shrinkage strain if a LED LCU is used for the light curing process rather than a conventional halogen LCU. METHODS: The volumetric shrinkage strain was determined using the Archimedes buoyancy principle after 5, 10, 20, 40 s of light curing and after 120 s following the 40 s light curing time period. The linear shrinkage strain was determined with a dynamic mechanical analyzer for the composites Z100, Spectrum, Solitaire2 and Definite polymerized with the LCUs Trilight (halogen), Freelight I (LED) and LED63 (LED LCU prototype). The changes in irradiance and spectra of the LCUs were measured after 0, 312 and 360 min of duty time. RESULTS: In general there was no considerable difference in shrinkage of the composites Z100, Spectrum or Solitaire2 when the LED63 was used instead of the Trilight. There was, however, a statistically significant difference in shrinkage strain when the composite Definite was polymerized with the LED63 instead of the Trilight. The spectrum of the Trilight changed during the experiment considerably whereas the LED63 showed an almost constant light output. The Freelight I dropped considerably in irradiance and had to be withdrawn from the study because of technical problems. SIGNIFICANCE: The composites containing only the photoinitiator camphorquinone showed similar shrinkage strain behaviour when a LED or halogen LCU is used for the polymerization. The irradiance of some LED LCUs can also decrease over time and should therefore be checked on a regular basis.
Asunto(s)
Resinas Compuestas/efectos de la radiación , Equipo Dental , Análisis de Varianza , Cerámica , Adaptación Marginal Dental , Análisis del Estrés Dental , Halógenos , Dureza , Luz , Ensayo de Materiales , Cerámicas Modificadas Orgánicamente , Transición de Fase , Semiconductores , Silanos , Dióxido de Silicio/efectos de la radiación , Siloxanos/efectos de la radiación , Terpenos/efectos de la radiación , Factores de Tiempo , Circonio/efectos de la radiaciónRESUMEN
The influence of the surface chemical structure and related physicochemical properties on the adhesion of P. aeruginosa has been studied for moderately hydrophobic polymers and for hydrophilic surfaces obtained by O2-plasma treatments and 50 keV Ar+ beam irradiation of poly(hydroxymethylsiloxane) and poly(ethyleneterephthalate). The surface chemical structure has been obtained by X-ray photoelectron spectroscopy, the roughness was measured by atomic force microscopy, and the surface free energy was evaluated from contact angle measurements for all the polymer substrates before and after the irradiation treatments. It is shown that a massive and unusually fast secretion of exopolysaccharides onto highly polar surfaces, corresponding to the formation of complex three-dimensional multilayers (i.e., biofilm-like structures), occurs already after 2 h of incubation. It is suggested that such highly polar surfaces can operate either by promoting, by means of a still unknown biomolecular mechanism, an early gene expression process or by mimicking the P. aeruginosa cellular walls.
Asunto(s)
Tereftalatos Polietilenos/química , Polímeros/química , Polisacáridos Bacterianos/química , Polisacáridos Bacterianos/fisiología , Pseudomonas aeruginosa/química , Siloxanos/química , Argón , Isótopos , Membranas Artificiales , Oxígeno/química , Tamaño de la Partícula , Tereftalatos Polietilenos/efectos de la radiación , Polímeros/efectos de la radiación , Pseudomonas aeruginosa/citología , Pseudomonas aeruginosa/fisiología , Siloxanos/efectos de la radiación , Propiedades de SuperficieRESUMEN
The adsorption behavior of H-Arg-Gly-Asp-OH (RGD) oligopeptide on ion-irradiated polymer surfaces has been studied. The RGD-incubated surfaces of poly(ethylene terephtalate) (PET) and poly(hydroxymethylsiloxane) (PHMS) thin films, before and after irradiation with 50 keV Ar+ to 1x10(15) ions/cm2, were investigated by X-Ray Photoelectron Spectroscopy and Atomic Force Microscopy. It was found that no significant adsorption occurs on PET, while a measurable amount of RGD is preferentially adsorbed onto irradiated PHMS surfaces. The evaluated surface coverage was found to range between 5 and 12%. In situ adsorption measurements performed by using the Quartz Crystal Microbalance with Dissipation monitoring technique showed that the irradiation induced remarkable changes of mass uptake with respect to the unirradiated surfaces, mostly attributed to the change in the water adsorption capability of the irradiated surfaces. The adsorption results are discussed in terms of the ion-induced changes on the morphology, chemical structure and composition, surface free energy and surface charge.
Asunto(s)
Moléculas de Adhesión Celular/química , Materiales Biocompatibles Revestidos/química , Materiales Biocompatibles Revestidos/efectos de la radiación , Oligopéptidos/química , Polietilenglicoles/química , Polietilenglicoles/efectos de la radiación , Siloxanos/química , Siloxanos/efectos de la radiación , Adsorción/efectos de la radiación , Moléculas de Adhesión Celular/análisis , Materiales Biocompatibles Revestidos/análisis , Iones Pesados , Oligopéptidos/análisis , Polietilenglicoles/análisis , Tereftalatos Polietilenos , Polímeros/análisis , Polímeros/química , Polímeros/efectos de la radiación , Unión Proteica/efectos de la radiación , Siloxanos/análisis , Propiedades de Superficie/efectos de la radiaciónRESUMEN
Novel photopolymerized network films based on a polysiloxane matrix containing varied amounts of polyoxyethylene (P3) or perfluorohexylethyl (F) dangling side chains were investigated. For films containing less than 10 wt % P3 and F, the wettability and elastic modulus were similar to those of the photopolymerized network matrix. However, angle-resolved X-ray photoelectron spectroscopy measurements proved that the surface of films with F dangling chains was highly enriched in fluorine depending on both the amount of P3 and F and their relative ratio in the films. The biological performance of the films was evaluated against a new widespread and invasive marine biofoulant, the serpulid Ficopomatus enigmaticus. The diatom Navicula salinicola was also assayed as a conventional model organism for comparison. Films richer in P3 better resisted the settlement and promoted the release of calcified tubeworms of F. enigmaticus.