RESUMEN
This study compared the relative fracture toughness of a Bis-GMA//TEGDMA (50:50 wt%)-based resin system modified by 5, 10, and 15 wt% of a methacrylate-terminated poly(butadiene-acrylonitrile-acrylic acid) terpolymer toughening agent. After storage in distilled water at 37 +/- 2 degrees C for 7 days, plane strain fracture toughness (KIC) was determined on an Instron testing machine at a 0.5-mm min-1 displacement rate. The glass transition temperature (Tg) in degrees C was determined after 7 days (dry and wet) storage by thermomechanical analysis. The results of this study showed significantly improved fracture toughness and lowered water sorption with the modified resin systems which was indicated by higher wet glass transition temperatures.
Asunto(s)
Bisfenol A Glicidil Metacrilato/química , Resinas Compuestas/química , Análisis de Varianza , Análisis del Estrés Dental , Vidrio , Humanos , Ensayo de Materiales , Temperatura , Resistencia a la TracciónRESUMEN
STATEMENT OF PROBLEM: The introduction of resin-modified glass ionomer cements has expanded the choices of luting cements available to the clinician; however, few independent studies are available on the fracture toughness of the currently available resin-modified glass ionomer luting agents compared with the composite cements. PURPOSE: This investigation evaluated the relative fracture toughness (K(IC)) of 3 composite luting cements (Panavia 21, Enforce, and C&B Metabond), 3 resin-modified glass ionomer luting cements (Advance, Vitremer Luting, and Fuji Duet), and a conventional glass ionomer luting cement (Ketac-Cem) at 24-hour and 7-day storage times. MATERIAL AND METHODS: K(IC) was determined by preparing minicompact test specimens (n = 8) with introduced precracks. Specimens were stored in distilled water at 37 degrees C + 2 degrees C until testing. Testing was performed on an Instron testing machine at a displacement rate of 0.5 mm/min. RESULTS: ANOVA (P <.001) and REGW Multiple Range Test (P <.05) demonstrated significant differences among several of the cements tested. The mean fracture toughness values of C&B Metabond at 24 hours and Enforce at both 24 hours and 7 days were significantly greater than use any of the other cements tested. CONCLUSION: The resin-modified glass ionomer cements exhibited improved fracture toughness when compared with the conventional glass ionomer; however, they were still inferior to Enforce and C&B Metabond composite cements.
Asunto(s)
Compómeros , Recubrimiento Dental Adhesivo , Cementos de Ionómero Vítreo , Cementos de Resina , Análisis de Varianza , Compuestos de Boro , Compómeros/química , Resinas Compuestas , Recubrimientos Dentinarios/química , Cementos de Ionómero Vítreo/química , Dureza , Óxido de Magnesio , Ensayo de Materiales/métodos , Metacrilatos , Metilmetacrilatos , Fosfatos , Cemento de Policarboxilato , Cementos de Resina/química , Estadísticas no Paramétricas , Resistencia a la Tracción , Factores de Tiempo , Torque , Óxido de ZincRESUMEN
This study compared the seven-day water sorption, water solubility and lactic acid solubility of three composite cements and three resin-modified glass-ionomer cements. Disc-shaped specimens measuring 15 mm x 0.5 mm were prepared according to each manufacturer's specifications and desiccated to a constant mass. Specimens were then placed in distilled water at 37 degrees C for seven days. Acid solubility was performed in 0.01 M lactic acid. The weight changes of the specimens after immersion in distilled water or 0.01 M lactic acid were measured using an electronic analytical balance. A one-way ANOVA followed by the Ryan-Einot-Gabriel-Welsch (REGW) multiple range test was performed on all data. Significant differences (p < 0.05) were found among several cements tested for each of the properties investigated. Due to their hydrophilic nature, all resin-modified glass-ionomer cements showed significantly higher water sorption compared to composite cements.
Asunto(s)
Resinas Compuestas/química , Cementos de Ionómero Vítreo/química , Cementos de Resina/química , Absorción , Adsorción , Análisis de Varianza , Desecación , Humanos , Ácido Láctico/química , Ensayo de Materiales , Fosfatos/química , Solubilidad , Propiedades de Superficie , Agua/químicaRESUMEN
PURPOSE: The purpose of this investigation was to evaluate the relative 2-body abrasive wear and degree of conversion of 4 laboratory-processed composites (Targis, Concept, belleGlass, and Artglass) and 2 direct placement composites (Herculite and Heliomolar) after 7 days of storage. MATERIALS AND METHODS: Human enamel was used as a positive control for 2-body abrasive wear, and 10 cylindric specimens (3.5-mm diameter, 8-mm height) of each material were prepared and stored in distilled water at 37 +/- 2 degrees C for wear testing. Relative 2-body abrasive wear rates were determined using a 30-micron diamond disk and a 2-body pin-on-disk apparatus. Subsequently, 3 polymerized specimens that had been stored in sealed polyethylene vials for 7 days were prepared for degree of conversion testing. The degree of conversion was determined on an infrared spectrometer using standard baseline techniques and various internal standards. RESULTS: Statistical analysis using analysis of variance and the Tukey-Kramer multiple range test indicated significant differences between several of the materials tested for both 2-body abrasive wear and degree of conversion. CONCLUSION: Concept exhibited significantly less 2-body abrasive wear compared to the direct and indirect composites (P < 0.01). Concept and belleGlass exhibited a mean degree of conversion that was significantly higher than any of the other composites tested (P < 0.01).
Asunto(s)
Resinas Compuestas/química , Alisadura de la Restauración Dental , Resinas Acrílicas/química , Fricción , Cementos de Ionómero Vítreo/química , Ensayo de Materiales , Metacrilatos/química , Poliuretanos/química , Cementos de Resina/química , Cemento de Silicato/químicaRESUMEN
A new generation of glass ionomers containing polymerizable methacrylate monomers and/or prepolymers are now available for use as direct esthetic restorative materials. Proper clinical application of these new resin-modified glass ionomers requires an understanding of their benefits and limitations. The purpose of this investigation was to compare the compressive and diametral tensile strength at 1 hour, 24 hours, and 7 days of three visible-light-cured glass-ionomer cements, a polyacid-modified composite resin, and a composite resin core build-up material under both light-cure and dark-cure conditions. Statistical analysis indicated significant differences between several of the cements tested for both compressive and diametral tensile strengths at all three testing times (P > 0.05). Prosthodent composite resin and Vitremer tricure visible-light-cured glass-ionomer cement are significantly greater in both compressive and diametral tensile strength than any of the other materials tested after 7 days.
Asunto(s)
Resinas Compuestas/química , Cementos de Ionómero Vítreo/química , Resinas Acrílicas/química , Análisis de Varianza , Fuerza Compresiva , Luz , Ensayo de Materiales , Polímeros/química , Cementos de Resina/química , Resinas Sintéticas/química , Resistencia a la TracciónRESUMEN
This investigation evaluated the shear rebond strength of Rexillium III to enamel using various resin composite luting systems (Panavia, Imperva Dual, ABC Enhanced, C&B Metabond, Optibond, and Comspan). Cast Rexillium III cylinders (3.9 x 6.0 mm) were bonded to human molar buccal enamel surfaces (n = 8) with each cement type after etching with 37% phosphoric acid for 30 seconds. Bonded specimens were stored in distilled water for 7 days at 37 degrees C +/- 2 degrees C and thermocycled (1,500 cycles) in 5 degrees C and 55 degrees C water baths (1 minute dwell time). Specimens were randomly tested in shear mode on an Instron Testing Machine at a crosshead speed of 0.5 mm per minute. Debonded specimens were then rebonded after appropriate metal conditioning and re-etching the enamel surface for 30 seconds. Analysis of variance (P < 0.001) and the Ryan-Einot-Gabriel-Welsh multiple range test showed significant differences between several of the resin cements (P < 0.05). Panavia exhibited significantly higher shear rebond strength than any of the other cements tested. Only Imperva Dual exhibited a significantly lower shear rebond strength compared to its initial shear bond strength.
Asunto(s)
Aleaciones de Cromo/química , Aleaciones Dentales/química , Recubrimiento Dental Adhesivo , Esmalte Dental/efectos de los fármacos , Cementos de Resina/química , Grabado Ácido Dental , Análisis de Varianza , Esmalte Dental/ultraestructura , Humanos , Técnicas In Vitro , Ensayo de Materiales/métodos , Ensayo de Materiales/estadística & datos numéricos , Microscopía Electrónica de Rastreo , Diente Molar , Distribución Aleatoria , Propiedades de Superficie , Resistencia a la TracciónRESUMEN
This study evaluated the shear bond strength of Rexillium III (Jeneric Pentron, Wallingford, CT) to enamel using various resin composite luting systems. Cast alloy cylinders (3.9 mm X 6.0 mm) were bonded with each cement to human molar buccal enamel surfaces (n = 8). The enamel was etched using a 35% phosphoric acid solution for 30 seconds. Bonded specimens were stored in distilled water for 7 days at 37 degrees C and thermocycled (1,500 cycles) in 5 degrees C and 55 degrees C water baths (1-minute dwell time). Specimens were randomly tested in shear using a crosshead speed of 0.5 mm per minute. Use of a one-way analysis of variance (P < .001) and Ryan-Einot-Gabriel-Welsh multiple range test showed significant differences between several of the resin cements. Panavia exhibited a significantly higher shear bond strength than any of the other cements tested.
Asunto(s)
Aleaciones de Cromo , Recubrimiento Dental Adhesivo , Cementos de Resina , Análisis de Varianza , Bisfenol A Glicidil Metacrilato , Compuestos de Boro , Esmalte Dental/ultraestructura , Combinación de Medicamentos , Humanos , Ensayo de Materiales , Metacrilatos , Metilmetacrilatos , Microscopía Electrónica de Rastreo , Fosfatos , Resistencia a la Tracción , ToluidinasRESUMEN
The thermal diffusivity has been measured for 10 glass ionomer and resin-based materials: three conventional (water-hardened) glass ionomer cements, two silver-reinforced glass ionomers, an experimental stainless steel-reinforced glass ionomer, three visible light-cured (VLC) glass ionomer-resin hybrid materials, and a VLC resin-based product developed for the same clinical uses as the hybrid materials. Cube-shaped specimens, c. 10 x 10 x 10 mm, initially at room temperature were immersed in mercury surrounded by an ice-water bath. From the experimental cooling curve a semi-log plot of relative temperature decrease vs. time yielded a straight line whose slope is proportional to the thermal diffusivity. The values ranged from 1.74-5.16 x 10(-3) cm2 s-1, and all of the materials tested would have adequate insulating properties provided normal clinical thickness levels for lining materials are maintained. It was found that the thermal diffusivities for the three metal-reinforced glass ionomers, where composition information is available, do not follow a rule of mixtures applied to the individual components.
Asunto(s)
Cementos de Ionómero Vítreo/química , Cementos Cermet/química , Ensayo de Materiales , Metacrilatos/química , Poliuretanos/química , Plata/química , Fluoruro de Sodio/química , Acero Inoxidable/química , Propiedades de Superficie , Temperatura , Conductividad Térmica , Factores de Tiempo , Uretano/análogos & derivados , Uretano/químicaRESUMEN
The purpose of this study was to compare the shear bond strength to composite resin of a light-curing glass-ionomer cement with that of various chemically curing glass-ionomer cements. Light-cured composite resin cylinders were bonded to cylindrical glass-ionomer substrates after etching for 30 seconds with 37% phosphoric acid. Specimens were maintained in distilled water for 7 days and then thermocycled in water baths. One group of light-cured glass-ionomer cement substrates was not etched. The interfacial bond strength of these specimens was measured in shear. Cement shear strength was also evaluated. Statistical analysis showed the light-curing cement to have a significantly higher bond strength to composite resin than any of the chemically curing cements tested.
Asunto(s)
Recubrimiento Dental Adhesivo , Cementos de Ionómero Vítreo/química , Análisis de Varianza , Luz , Maleatos/química , Ensayo de Materiales , Resistencia a la TracciónRESUMEN
The shear bond strength to human dentin and enamel was evaluated for four glass-ionomer cements: an experimental stainless steel-reinforced glass-ionomer cement, two commercially available silver-reinforced cements, and a conventional glass-ionomer cement. Bonded specimens were stored in distilled water for 7 days during which time they were subjected to thermocycling in water baths at 5 degrees C and 55 degrees C for a 1-minute dwell time per bath and 1500 cycles. Specimens were then shear tested. The experimental stainless steel-reinforced glass-ionomer cement had a significantly higher bond strength to enamel (P < .01) and dentin (P < .05) than did the commercially available cements.
Asunto(s)
Cementos Cermet/química , Recubrimiento Dental Adhesivo , Análisis de Varianza , Esmalte Dental , Análisis del Estrés Dental , Dentina , Cementos de Ionómero Vítreo/química , Humanos , Ensayo de Materiales , Plata , Acero Inoxidable , Resistencia a la TracciónRESUMEN
The purpose of this investigation was to compare the compressive and diametral tensile strengths of two silver-reinforced and three conventional glass-ionomer cements of different powder-to-liquid ratios at 1 and 24 hours. ANOVA (P < 0.001) and Tukey's Studentized Multiple Range Test indicated significant differences between the compressive strengths of several of the cements tested (P < 0.05). No significant differences were noted between any of the cements for the diametral tensile strength test (alpha = 0.05).
Asunto(s)
Cementos de Ionómero Vítreo/química , Análisis de Varianza , Cementos Cermet/química , Ensayo de Materiales , Resistencia a la TracciónRESUMEN
The dislodging force, the compressive strength at 24 hours, and the film thickness of four resin composite luting cements (UDA, UDA with fluoride, Panavia OP, and DenMat) and a conventional glass-ionomer cement (Shofu Type I) were compared. The axial force necessary to dislodge each cemented 0 degree abutment from an internally threaded Steri-Oss implant (n = 5) was then determined using a mechanical testing machine. UDA with fluoride appears to be a significantly stronger luting agent for abutment cementation than is either UDA or DenMat (P less than .05). DenMat resin composite cement exhibited the highest mean compressive strength whereas Panavia OP had the lowest value for film thickness.
Asunto(s)
Cementos Dentales/química , Resinas Acrílicas/química , Análisis de Varianza , Bisfenol A Glicidil Metacrilato , Resinas Compuestas/química , Pilares Dentales , Implantes Dentales , Fluoruros/química , Cementos de Ionómero Vítreo/química , Ensayo de Materiales , Metacrilatos/química , Resistencia a la TracciónRESUMEN
The purpose of this study was to compare specific physical properties of an experimental stainless-steel-reinforced glass-ionomer cement with those of two commercially available silver-reinforced cements. Properties evaluated were compressive and diametral tensile strengths (one and 24 h), percent solubility in 0.01 mol/L lactic acid over 23 h, and working and setting times. Cylindrical specimens 6 mm (diameter) x 12 mm were prepared and maintained in distilled water at 37 +/- 2 degrees C and then tested on an MTS mechanical testing machine with a cross-head displacement rate of 0.5 mm/min for the diametral tensile strength test and 1.0 mm/min for the compressive strength test. ANOVA and Tukey's Studentized Multiple Range Test indicated significant differences between the experimental and commercially available cements for both compressive and tensile strengths at one and 24 h (p less than 0.01). The experimental stainless-steel-reinforced cement appeared to be significantly stronger in both tensile and compressive strengths than either of the commercially available cements. Working and setting times--as well as acid solubility of the experimental cement--also compared favorably with those of the commercial cements. Results suggest that the stainless-steel-reinforced glass-ionomer cement possesses strength properties that should lead to a stronger, more fracture-resistant restorative filling material when compared with those presently available.