RESUMEN
Purpose: Thiamazole (MMI) is frequently used for the treatment of Graves' disease, but it occasionally induces agranulocytosis at the beginning of the treatment. To date, the predictive factors of recovery from MMI-induced agranulocytosis remain unclear. The primary aim of this study was to evaluate the predictive factor of the recovery time from MMI-induced agranulocytosis. Method: This was a retrospective cohort study performed in a university hospital and a thyroid hospital. We included 27 Japanese patients with Graves' disease with MMI-induced agranulocytosis diagnosed during follow-up. All patients were administrated recombinant human granulocyte colony-stimulating factor daily until they had a neutrophil count>1 000/µL, which was defined as recovery. The predictive factors associated with recovery time were estimated using multivariable regression analysis. Results: At the onset of agranulocytosis, the median administration period of MMI was 33 days, the average white blood cell count was 1 896/µL, and the median neutrophil count was 22/µL. The median recovery time was 4 days. Stepwise multivariate regression analysis identified the monocyte and basophil counts to be significant predictors of MMI-induced agranulocytosis. Conclusion: Patients with agranulocytosis and decreased monocyte and basophil counts at onset may recover late and require careful treatment.
Asunto(s)
Agranulocitosis , Basófilos , Enfermedad de Graves , Metimazol , Monocitos , Neutrófilos , Recuperación de la Función/efectos de los fármacos , Adulto , Agranulocitosis/sangre , Agranulocitosis/inducido químicamente , Femenino , Enfermedad de Graves/sangre , Enfermedad de Graves/tratamiento farmacológico , Humanos , Recuento de Leucocitos , Masculino , Metimazol/administración & dosificación , Metimazol/efectos adversos , Persona de Mediana Edad , Valor Predictivo de las Pruebas , Estudios RetrospectivosRESUMEN
OBJECTIVES: The quality of the hybrid layer is believed to be more important than the thickness of this layer. The purpose of this study was to investigate a method to analyze the percentage of adhesive resin residual double bonds in the dentin-resin interface using laser Raman spectroscopy. METHODS: Bovine dentin was treated with dentin adhesives and resin composite was bonded according to the manufacturers' instructions. The specimens were sectioned parallel to dentinal tubules and the surfaces were then polished to 1 microm diamond pastes. Raman spectra were recorded along a line perpendicular to the dentin-resin interface in steps of 0.2 microm. The measurement of residual C=C bond was made on a relative basis by comparing the C=C unpolymerized methacrylate stretching vibration (1638 cm(-1)) against the C=O stretching mode of the ester group (1719 cm(-1)). The percentage of residual double bonds including pendant and monomeric double bonds was calculated by comparing the obtained ratio with that of uncured adhesive resin. RESULTS: The amount of residual double bonds in the hybrid layer varied from 10 to 25% compared to the uncured adhesives, a relatively higher percentage was detected for Fluoro Bond (12.3-23.6%) and Single Bond (9.5-21.8%), and lower for Mac Bond II (10.6-18.0%) and Mega Bond (10.7-16.3%). No relationship was seen between the percentage of remaining double bonds and the location within the resin-dentin interface. SIGNIFICANCE: Laser Raman microscopy used was a useful tool for measuring the residual double bonds in the dentin-resin interface.
Asunto(s)
Resinas Compuestas/química , Recubrimiento Dental Adhesivo , Recubrimientos Dentinarios/química , Dentina/ultraestructura , Análisis de Varianza , Animales , Bisfenol A Glicidil Metacrilato/química , Carbono/química , Bovinos , Ensayo de Materiales , Metacrilatos/química , Oxígeno/química , Cementos de Resina/química , Espectrometría Raman , Propiedades de SuperficieRESUMEN
OBJECTIVES: Adhesion of resin-bonding agents to dentin is currently believed to result from impregnation of adhesive resin into superficially demineralized dentin. The purpose of this study was to investigate the chemical composition of the resin-impregnated dentin (hybrid) layer using a micro-Raman spectroscopy. METHODS: Resin composites were bonded to bovine dentin with the two-step bonding systems, and specimens were sectioned parallel to dentinal tubules. These surfaces were then polished down to 1 microm diamond pastes. Raman spectra were successively recorded along a line perpendicular to the dentin-adhesive interface by steps of 0.2 microm on a computer controlled X-Y stage. The relative amounts of hydroxyapatite (960 cm(-1), P-O), adhesive resin (640 cm(-1), aromatic ring), and organic substrate (1450 cm(-1), C-H) in the dentin-adhesive bonding area were calculated. RESULTS: From the Raman spectroscopy results, the hybrid layer represents a gradual transition in the relative amount of adhesive from the resin side to dentin side. Evidence of poor saturation of the adhesive resin in the demineralized dentin with the one-bottle adhesive system was detected. SIGNIFICANCE: From the results of this study, inhomogeneity of the hybrid layer composition was detected, and the degree of resin impregnation was found to be different between the bonding systems tested.
Asunto(s)
Recubrimiento Dental Adhesivo , Permeabilidad de la Dentina , Recubrimientos Dentinarios , Cementos de Resina , Animales , Bisfenol A Glicidil Metacrilato , Bovinos , Resinas Compuestas , Dentina/química , Dióxido de Silicio , Espectrometría Raman , CirconioRESUMEN
Single application bonding systems have recently been developed in an effort to simplify and shorten bonding procedures. This study compared their bonding ability to enamel and dentin. Four commercial single application systems, Reactmer Bond (Shofu Inc), One-Up Bond F (Tokuyama Co), AQ Bond (Sun Medical Co, Japan) and Prompt L-Pop (ESPE, Germany) were used. F2000 compomer (3M Dental Products, St Paul, MN 55144, USA) was used as a control material. Bovine mandibular incisors were mounted in self-curing resin and the facial surfaces were ground to expose either enamel or dentin. Restoratives were bonded after adhesive application to tooth surface according to the manufacturer's instructions. Fifteen samples per test group were stored in 37degrees C water for 24 hours, then shear tested at a crosshead speed of 1.0 mm/minute. Statistical analysis was accomplished with a one-way ANOVA followed by the Duncan test (p<0.05) were done. The enamel bond strengths of the newly developed one step bonding systems were not significantly different from the compomer except for Prompt L-Pop, which showed the highest value. The dentin bond strengths of single application bonding systems did not differ from the compomer. The results of this study suggest that the adhesive properties of the newly developed single application bonding systems were comparable to a compomer restorative.
Asunto(s)
Recubrimiento Dental Adhesivo , Recubrimientos Dentinarios , Adhesividad , Análisis de Varianza , Animales , Bovinos , Compómeros , Esmalte Dental , Dentina , Cementos de Ionómero Vítreo , Ensayo de Materiales , Metacrilatos , Microscopía Electrónica de Rastreo , Cementos de Resina , Estadísticas no Paramétricas , Resistencia a la TracciónRESUMEN
A study was conducted to investigate the influence of temperature and relative humidity (RH) on the bond strengths of several recently developed dentin bonding systems. Six environmental conditions, (A) 25+/-0.5 degrees C, 50+/-5% RH, (B) 25+/-0.5 degrees C, 80+/-5% RH, (C) 25+/-0.5 degrees C, 95+/-5 % RH, (D) 37+/-0.5 degrees C, 50 +/-5 % RH, (E) 37+/-0.5 degrees C, 80+/-5% RH, (F) 37+/-0.5 degrees C, 95+/-5 % RH were used. Bovine mandibular incisors were mounted in self-curing resin and the facial surfaces were ground on wet #600 SiC paper to expose the dentin. After the tooth surface had been treated according to each manufacturer's instructions, adhesives were applied, followed by condensation of resin composites into a mold placed on the dentin surface. Fifteen specimens per group were stored in distilled water at 37 degrees C for 24 h, and then shear-tested at a cross-head speed of 1.0 mm/min. Statistical analysis was carried out with two-way ANOVA followed by Tukey's test (P<0.05). Dentin bond strengths decreased with increasing relative humidity but were not influenced by environmental temperature. Even though one-bottle adhesive systems require a wet dentin surface, their bond strengths are affected by an increase in environmental humidity.
Asunto(s)
Recubrimiento Dental Adhesivo , Recubrimientos Dentinarios/química , Dióxido de Silicio , Circonio , Alcanos/química , Análisis de Varianza , Animales , Bisfenol A Glicidil Metacrilato/química , Bovinos , Frío , Resinas Compuestas/química , Cementos Dentales/química , Dentina/ultraestructura , Calor , Humedad , Maleatos/química , Ensayo de Materiales , Metacrilatos/química , Ácidos Polimetacrílicos/química , Cementos de Resina/química , Estadística como Asunto , Estrés Mecánico , Propiedades de Superficie , Temperatura , Agua/químicaRESUMEN
PURPOSE: To investigate the bonding ability to enamel and dentin of new single application bonding systems (Reactmer and One-Up Bond) and compare these with a commercial compomer (Clicker/F2000), and 2-step resin-based composite bonding systems (Fluoro Bond/Lite-Fil II A and Single Bond/Z100). MATERIALS AND METHODS: Labial surfaces of extracted bovine teeth were ground on wet 600-grit SiC paper to expose a flattened area of enamel or dentin and then washed and dried with oil-free compressed air. These surfaces were treated according to each adhesive system's instructions and the restorative materials were condensed into a Teflon mold (2 mm height, 4 mm internal diameter) and then irradiated. The finished specimens were stored in 37 degrees C distilled water for 24 hours from the start of light exposure to the material. Then these specimens were tested in a shear mode at a crosshead speed of 1.0 mm/minute. The mean and standard deviation were subjected to an ANOVA followed by the Duncan test (P< 0.05). RESULTS: The bond strengths of the single application bonding systems were 12.3 to approximately 14.5 MPa for enamel, and 13.7 to approximately 13.8 MPa for dentin. These values were comparable to those of the compomer (12.6 MPa for enamel, and 13.1 MPa for dentin), but lower than those of the two-step resin composite bonding systems (16.8 to approximately 21.7 MPa for enamel and 18.1 to approximately 18.4 MPa for dentin).
Asunto(s)
Recubrimiento Dental Adhesivo/métodos , Cementos Dentales , Análisis de Varianza , Animales , Bisfenol A Glicidil Metacrilato , Bovinos , Compómeros , Resinas Compuestas , Esmalte Dental , Dentina , Recubrimientos Dentinarios , Fluoruros Tópicos , Cementos de Ionómero Vítreo , Ensayo de Materiales , Metacrilatos , Microscopía Electrónica de Rastreo , Cementos de Resina , Estadísticas no Paramétricas , Estrés Mecánico , Resistencia a la TracciónRESUMEN
We hypothesized that a change in composition of proteoglycans can regulate the bioactivity of fibroblast growth factor (FGF)-2 in the thyroid. In order to test this hypothesis, we established a simple and sensitive method for detecting FGF-2-binding heparan sulfates and characterized them in papillary thyroid carcinomas and normal thyroids. The thyroid extracts were applied to a Q-Sepharose anion exchange column. After the column was washed with 10 mM of phosphate buffer, 1 microgram of human recombinant FGF-2 was added onto the column. The column was eluted with a gradient of NaCl (0.3-1.5 M). Each fraction was blotted onto nitrocellulose membrane. Immunoreactivity of heparan sulfate and FGF-2 was revealed by the incubation of membranes with the specific antibodies, and quantitatively estimated by measuring the density of the color product. In normal thyroids, immunoreactivity of heparan sulfate was detected as two peaks at 0.7 and 0.9 M of NaCl. Heparan sulfate-containing fractions also showed FGF-2 immunoreactivity, indicating the complex formation of FGF-2 and heparan sulfate. In papillary thyroid carcinomas, immunoreactivity of heparan sulfate showed various elution profiles on Q-Sepharose chromatography, including single peak at 0.7 M of NaCl and the one similar to that of the normal thyroids. However, FGF-2 immunoreactivity was detected only in the fractions eluting at 0.7 M of NaCl. This loss of a subpopulation of FGF-2-binding heparan sulfate in human papillary thyroid carcinomas may lead to the increase of free FGF-2 bioavailable in extracellular matrix.
Asunto(s)
Carcinoma Papilar/metabolismo , Factor 2 de Crecimiento de Fibroblastos/metabolismo , Proteoglicanos de Heparán Sulfato/metabolismo , Neoplasias de la Tiroides/metabolismo , Resinas de Intercambio Aniónico , Proteoglicanos de Heparán Sulfato/análisis , Humanos , Immunoblotting , Unión Proteica , SefarosaRESUMEN
PURPOSE: To examine the influence of operator variability on adhesion to dentin of recently developed two-step bonding systems. MATERIALS AND METHODS: A self-etching primer system, Fluoro Bond/Lite-Fil II A (FB) and a one-bottle adhesive system, Single Bond/Z100 (SB) were employed. Three groups, each consisting of 15 operators, were selected from the dentists at the university (Group 1), undergraduate students (Group 2), and general practitioners (Group 3). Labial surfaces of extracted bovine teeth were ground on wet 600-grit SiC paper and then washed and dried with oil-free compressed air. These surfaces were treated according to each adhesive system's instructions and the restorative resins were condensed into a Teflon mold (2 mm height, 4 mm internal diameter) and then light-cured. The finished specimens were stored in 37 degrees C distilled water for 1 hr. These specimens were tested in a shear mode at a cross-head speed of 1.0 mm/min. The mean and standard deviation were subjected to two-way ANOVA (P < 0.05). RESULTS: Significant differences in bond strength of the two adhesives were found within each operator group. A wider variation in bond strength was seen for SB compared to FB for the three different groups. Mean bond strengths for the faculty group were statistically greater than those of the other two groups, which did not differ significantly. Even though the specimen preparation was done under in vitro conditions, the large coefficients of variation indicate it may be difficult to create suitable surface conditions for optimal bonding.
Asunto(s)
Recubrimiento Dental Adhesivo , Recubrimientos Dentinarios/química , Dióxido de Silicio , Circonio , Adhesividad , Análisis de Varianza , Animales , Bisfenol A Glicidil Metacrilato/química , Bovinos , Resinas Compuestas/química , Recubrimiento Dental Adhesivo/métodos , Cementos Dentales/química , Restauración Dental Permanente , Dentina/ultraestructura , Odontólogos , Docentes de Odontología , Fluoruros Tópicos/química , Odontología General , Humanos , Variaciones Dependientes del Observador , Estadística como Asunto , Estrés Mecánico , Estudiantes de Odontología , Temperatura , Agua/químicaRESUMEN
The purpose of this study was to investigate the influence of thermal cycling on enamel bond strength of 2-step bonding systems. The systems used were self-etching primer systems; Imperva Fluoro Bond, Clearfil Liner Bond II, and Mac Bond II; and self-priming adhesive systems; One Step, OptiBond Solo, Prime & Bond 2.0, and Single Bond. Bovine mandibular incisors were mounted in self-curing resin and the facial surfaces were wet ground with #600 SiC paper. Enamel surfaces were treated following each manufacturer's instructions. Adhesives were applied and composites were condensed into a Teflon mold (phi 4 x 2 mm) and light cured. Bonded specimens were divided into four groups; stored in 37 degrees C water for 24 hours, followed by thermal cycling between 5 degrees C and 60 degrees C for 3,000, 10,000, and 30,000 cycles. Ten samples per test group were tested in shear mode at a crosshead speed of 1.0 mm/min. One-way ANOVAs followed by Duncan's multiple range test (p < 0.05) were done. For self-etching primer systems, a significant decrease in bond strength was observed for the thermal cycling groups. For the self-priming adhesive systems, a small decrease in bond strength was observed but no significant differences were found for thermal cycling groups. The changes in bond strength after thermal cycling were different between the bonding systems.
Asunto(s)
Recubrimiento Dental Adhesivo , Esmalte Dental/ultraestructura , Recubrimientos Dentinarios/química , Grabado Ácido Dental , Alcanos/química , Análisis de Varianza , Animales , Bisfenol A Glicidil Metacrilato/química , Compuestos Inorgánicos de Carbono , Bovinos , Resinas Compuestas/química , Cementos Dentales/química , Fluoruros Tópicos/química , Luz , Maleatos/química , Ensayo de Materiales , Metacrilatos/química , Microscopía Electrónica de Rastreo , Ácidos Polimetacrílicos/química , Cementos de Resina/química , Compuestos de Silicona , Estadística como Asunto , Estrés Mecánico , Propiedades de Superficie , Termodinámica , AguaRESUMEN
The purpose of this study was to investigate the rate of development of dentin bond strengths of resin-modified glass-ionomer cements (RMGIC) with use of dentin primers. The prepared dentin surface was treated according to each manufacturer's instruction or the dentin primer. Cements were condensed into a vinyl mold and light activated. The shear bond strengths were measured at a crosshead speed of 1.0 mm/min after 1, 5, 10, 30, 60 min, 2, 5, and 24 h storage in water at 37 degrees C. Presence of a significant difference between the mean bond strength at 1 min and each of the other test times was analyzed. The first time at which there was a significant increase in bond strength was defined as the "initial increasing time". As compared with the manufacturer's suggested dentin treatments, the bond strengths increased significantly when the dentin primers were used. The initial increasing times when the specimens were made following each manufacturer's instructions were 10 approximately 60 min. When dentin primer was used, the initial increasing time shortened to 5 approximately 10 min. It was concluded that the use of dentin primers for RMGIC restorations resulted in reduction of the initial increasing time.
Asunto(s)
Recubrimiento Dental Adhesivo , Recubrimientos Dentinarios/química , Cementos de Ionómero Vítreo/química , Cementos de Resina/química , Resinas Acrílicas/química , Animales , Bovinos , Resinas Compuestas/química , Cementos Dentales/química , Dentina/ultraestructura , Fluoruros Tópicos/química , Ensayo de Materiales , Metacrilatos/química , Metilmetacrilatos/química , Ácidos Ftálicos/química , Resinas Sintéticas/química , Estrés Mecánico , Factores de Tiempo , Ácidos Tricarboxílicos/química , AguaRESUMEN
OBJECTIVE AND IMPORTANCE: Adrenocorticotropin (ACTH)-secreting pituitary adenomas causing Cushing's disease are often difficult to identify because of their variable locations and their small size. This report presents histological evidence of an ectopic ACTH-secreting adenoma located entirely within the cavernous sinus. CLINICAL PRESENTATION: A 62-year-old woman presented with central obesity, hypertension, and osteoporosis. Endocrinological evaluation suggested the presence of an ACTH-secreting pituitary adenoma; however, imaging studies, including dynamic magnetic resonance imaging, did not reveal any visible lesions in the pituitary gland. Bilateral cavernous sinus sampling demonstrated a large central/peripheral ACTH gradient, with a right/left ACTH gradient. The patient was treated as having pituitary-dependent Cushing's disease, until she died suddenly as a result of acute respiratory failure. INTERVENTION: In a postmortem histological examination, an ACTH-secreting adenoma was found in the right cavernous sinus, which was completely surrounded by dura mater and had no direct connection with the pituitary gland. CONCLUSION: Although they are rare, such adenomas located in the cavernous sinus should be recognized as one of the reasons for inaccurate cavernous sinus sampling and the failure of transsphenoidal surgery for patients with ACTH-dependent Cushing's syndrome.
Asunto(s)
Síndrome de ACTH Ectópico/diagnóstico , Seno Cavernoso , Neoplasias Vasculares/diagnóstico , Síndrome de ACTH Ectópico/tratamiento farmacológico , Síndrome de ACTH Ectópico/patología , Seno Cavernoso/patología , Muerte Súbita/patología , Duramadre/patología , Femenino , Humanos , Imagen por Resonancia Magnética , Metirapona/uso terapéutico , Persona de Mediana Edad , Flebografía , Hipófisis/patología , Neoplasias Vasculares/tratamiento farmacológico , Neoplasias Vasculares/patologíaRESUMEN
OBJECTIVES: In clinical situations, a dentine primer is usually applied to enamel, in addition to dentine. This study was carried out to determine the influence of the air drying time of self-etching primers on their bond strength to enamel. METHODS: Three self-etching primer systems, Fluoro Bond (FB, Shofu Inc.), Liner Bond II (LB, Kuraray Co.) and Mac Bond 2 (MB, Tokuyama Co.) were employed. Bovine mandibular incisors were mounted in self-curing resin and the enamel surfaces were wet ground with number 600 SiC paper. Following primer application, the enamel surface was dried with compressed air for 0, 2, 5, 10, 20, and 30 s from 10 cm above the enamel surface using a three-way syringe. Adhesives were applied and composites were condensed into a Teflon mold (4 x 2 mm) placed on the enamel and light activated. Ten samples per test group were stored in 37 degrees C water for 24 h, then shear tested at a crosshead speed of 1.0 mm min-1. One-way ANOVAs followed by Duncan tests (p < 0.05) were done. RESULTS: The enamel bond strengths varied with the different air drying times and ranged from 8.2 +/- 3.2-17.4 +/- 3.0 MPa for LB, 10.9 +/- 2.8-16.3 +/- 3.3 MPa for FB, and 17.5 +/- 2.5-19.4 +/- 2.2 MPa for MB. For LB and FB, there appeared to be a minimum drying time of 10 s. LB was the most affected by drying time, while MB did not change. CONCLUSIONS: The data suggests that the enamel bond strengths of these bonding systems can be influenced by the drying time of the primer applied prior to bond agent application and the tendency was different among the systems studied.
Asunto(s)
Grabado Ácido Dental/métodos , Resinas Compuestas/química , Recubrimiento Dental Adhesivo , Recubrimientos Dentinarios/química , Aire , Alcanos/química , Análisis de Varianza , Animales , Bovinos , Cementos Dentales/química , Esmalte Dental , Desecación , Fluoruros Tópicos/química , Maleatos/química , Ensayo de Materiales , Metacrilatos/química , Microscopía Electrónica de Rastreo , Estadísticas no Paramétricas , Propiedades de SuperficieRESUMEN
Recent reports indicate that a gain-of-function mutation in fibroblast growth factor receptor 3 (FGFR-3) inhibits cell growth in the cartilaginous growth plates. These results suggest that FGFR-3 may be the receptor transducing growth inhibitory signals. Using reverse transcription-PCR we examined seven papillary thyroid carcinomas to determine FGFR-3 expression. Six out of the seven papillary carcinomas expressed FGFR-3. To clarify the role of FGFR-3 in thyroid carcinoma, FGFR-3 was overexpressed in an established human papillary thyroid carcinoma cell line. High levels of FGFR-3 protein were identified in cells stably transfected with the vector containing FGFR-3 cDNA. The specific binding of 125I-FGF-2 of these cells was threefold higher than that of control cells. Growth rates of cells overexpressing FGFR-3 were similar to those of control cells. However, cells overexpressing FGFR-3 continued to grow beyond the density at which control cells stopped proliferating. These results suggest that FGFR-3 in thyroid carcinoma is not involved strongly in the cell proliferation mechanism but may contribute to the malignant extension of some of the carcinomas by modifying cell contact signaling.
Asunto(s)
Carcinoma Papilar/metabolismo , Proteínas Tirosina Quinasas , Receptores de Factores de Crecimiento de Fibroblastos/metabolismo , Neoplasias de la Tiroides/metabolismo , Carcinoma Papilar/patología , División Celular/fisiología , Humanos , Receptor Tipo 3 de Factor de Crecimiento de Fibroblastos , Receptores de Factores de Crecimiento de Fibroblastos/fisiología , Neoplasias de la Tiroides/patología , Transfección , Células Tumorales CultivadasRESUMEN
OBJECTIVES: Recently, a new restorative material called a 'compomer', which is classified as a polyacid-modified resin composite, has become available. The volumetric shrinkage of compomers may create marginal gaps that influence the bonding ability and longevity of a restoration. Since compomers have been introduced recently, their volumetric change during curing is not fully understood. The purpose of this study was to evaluate the volumetric change of compomers. METHODS: Three compomers, Compoglass (Vivadent), Dyract (Dentsply), and Ionosit Fil (DMG) were employed. The material was placed into a Teflon mould, 4 mm in diameter and 2 mm height, and extruded into the dilatometer. Then the specimens were light activated and the change in the height of the meniscus of water was recorded using a CCD camera and VRC. RESULTS: The average volumetric shrinkages of the compomers after 160 s were 2.4% for Compoglass, 2.7% for Dyract, and 2.1% for Ionosit-Fil. For all materials tested, there was a tendency of increasing volumetric shrinkage with increased irradiation time. CONCLUSIONS: The results of this study indicate that the volumetric change of compomer is influenced by the duration of light exposure, light intensity, and environmental conditions to which the materials are exposed.
Asunto(s)
Compómeros , Resinas Compuestas/efectos de la radiación , Cementos de Ionómero Vítreo/efectos de la radiación , Fenómenos Químicos , Química Física , Resinas Compuestas/química , Recubrimiento Dental Adhesivo , Restauración Dental Permanente , Estudios de Evaluación como Asunto , Cementos de Ionómero Vítreo/química , Humanos , Luz , Ensayo de Materiales , Metacrilatos/química , Metacrilatos/efectos de la radiación , Resinas Sintéticas/química , Resinas Sintéticas/efectos de la radiación , Silicatos/química , Silicatos/efectos de la radiación , Propiedades de Superficie , Factores de TiempoRESUMEN
PURPOSE: To investigate the influence of thermal cycling on bond strength to dentin of 2-step bonding systems. MATERIALS AND METHODS: The systems used were self-etching primer systems; Fluoro Bond (FB), Liner Bond II (LB), and Mac Bond II (MB); and self-priming adhesive systems; One-Step (OS), OptiBond Solo (OB), Prime & Bond 2.0 (PB), and Single Bond (SB). Bovine mandibular incisors were mounted in self-curing resin and the facial surfaces were wet ground with #600 SiC paper. Enamel and dentin surfaces were treated following each manufacturers' instructions. Adhesives were applied and composites were condensed into a Teflon mold (4x2 mm) placed on the dentin surface and light activated. Bonded specimens were divided into four groups; (a) stored in 37 degrees C water for 24 hours, (b) stored in 37 degrees C water for 24 hours followed by subjecting to thermal cycling between 5 degrees C and 60 degrees C for 3,000 times, (c) 10,000 times, and (d) 30,000 times. Twelve samples per test group were shear tested at a crosshead speed of 1.0 mm/minute. One-way ANOVAs followed by Duncan's multiple range test (P < 0.05) were performed. RESULTS: For FB, LB, and MB, a small decrease in bond strength was observed and no significant differences were observed among the thermal cycling groups. For OS, OB, PB, and SB, a significant decrease in bond strength was observed for the 30,000 thermal cycling groups. The changes in bond strength after TC were different between the bonding systems.
Asunto(s)
Recubrimiento Dental Adhesivo/métodos , Recubrimientos Dentinarios , Análisis de Varianza , Animales , Bisfenol A Glicidil Metacrilato , Bovinos , Cementos Dentales , Fluoruros Tópicos , Malonatos , Ensayo de Materiales , Metacrilatos , Ácidos Polimetacrílicos , Cementos de Resina , Estadísticas no ParamétricasRESUMEN
Most dentin bond strength tests of resin-modified glass-ionomer cements have been conducted after at least 24 hours' storage in water. In a clinical situation, debonding might occur soon after the restoration was placed if subjected to stress. The purpose of this study was to investigate the rate of development of shear bond strength of resin-modified glass-ionomer cements, two Type IIs of which, Fuji II LC and Vitremer, were used. A conventional glass-ionomer cement, Fuji II, and a resin composite, Herculite XRV/OptiBond system, were also employed as controls. Bovine incisors were mounted in self-curing resin, and the facial surfaces wet ground with 600-grit SiC paper to expose dentin. Materials were condensed into a vinyl mold and bonded following the manufacturers' instructions. The shear bond strengths of 10 specimens per group were measured at a crosshead speed of 1.0 mm/minute after 1, 5, 10, 30, and 60 minutes' and 2, 5, and 24 hours' storage in water at 37 degrees C. One-way ANOVAs followed by the Dunnet test (P < 0.05) were used to test for significant differences between the mean bond strength at 1 minute and each of the other test periods. The test period when there was a significant increase in bond strength was defined as the "initial increasing time." The dentin bond strengths of all the materials tested increased with prolonged storage time. The initial increasing times were 10 minutes for Fuji II LC and OptiBond, 20 minutes for Fuji II, and 60 minutes for Vitremer. The differences in the initial increasing time might have clinical implications if the restoration is subjected to significant stress immediately after placement.
Asunto(s)
Resinas Compuestas/química , Recubrimientos Dentinarios/química , Análisis de Varianza , Animales , Bovinos , Análisis del Estrés Dental , Almacenaje de Medicamentos , Cementos de Ionómero Vítreo , Ensayo de Materiales , Cementos de Resina , Factores de TiempoRESUMEN
Fibroblast growth factor (FGF)-2 is stored in the extracellular matrix (ECM). We hypothesized that FGF-2 is mobilized from the ECM and binds to receptors on the surface of FGF-2 responsive cells during thyroid enlargement. To test this hypothesis, we estimated levels of FGF-2 free from ECM in thyroids by comparing the efficiency of two methods for FGF-2 extraction (low salt and high salt). Because the high salt concentration (more than 1.5 M NaCl) is necessary to release FGF-2 from the normal ECM, FGF-2 extracted by low salt is indicative of ECM-free FGF-2. Human papillary thyroid carcinomas, normal part thyroid, and Graves' thyroid tissues were homogenized separately in an extraction buffer containing either 0 M NaCl (low salt) or 2.0 M NaCl (high salt), and the concentration of FGF-2 in the extracts was measured by enzyme-linked immunosorbent assay (ELISA). The yields of low and high salt extracts of immunoreactive (ir)FGF-2 from papillary carcinomas (low salt: 40.0 +/- 7.5, high salt: 233 +/- 53 ng/g tissue, mean +/- SE) were significantly higher than those of normal thyroid tissues extracted by the corresponding salt concentration (low salt: 14.6 +/- 1.8, high salt: 123 +/- 12 ng/g tissue). On the other hand, the extractable irFGF-2 from Graves' thyroid tissues (low salt: 25.2 +/- 2.5, high salt: 135 +/- 24 ng/g tissue) were not significantly different from that of normal thyroid tissues. However, the ratio of the extractable irFGF from carcinomas and Graves' thyroids by low salt to that by high salt (0 M/2 M ratio = 0.206 +/- 0.051, 0.209 +/- 0.025) were significantly higher than that of normal thyroids (0.120 +/- 0.014) (p < 0.05). These results suggest that intratissue ECM-free FGF-2 is increased in papillary thyroid carcinomas and Graves' thyroid tissues, and therefore a greater amount of FGF-2 may be available for stimulation of FGF-2 responsive cells.
Asunto(s)
Carcinoma Papilar/metabolismo , Matriz Extracelular/metabolismo , Factor 2 de Crecimiento de Fibroblastos/metabolismo , Enfermedad de Graves/metabolismo , Glándula Tiroides/metabolismo , Neoplasias de la Tiroides/metabolismo , Western Blotting , Ensayo de Inmunoadsorción Enzimática , Heparina/metabolismo , Humanos , Concentración Osmolar , Cloruro de Sodio/farmacologíaRESUMEN
Proliferation of vascular smooth muscle cells with the accumulation of proteoglycans in the extracellular matrix is one of the significant changes found in atherosclerotic lesions. In order to clarify the relationship between pericellular proteoglycan and cell growth, we established a simple method for quantitatively estimating the amount of pericellular proteoglycans and investigated the effects of various growth factors on the synthesis of pericellular proteoglycans by cultured A10 rat smooth muscle cells. Analysis of trypsin accessible [35SO4]-labeled material in the pericellular area of the A10 cell culture by Q-sepharose anion-exchange chromatography showed two peaks. One peak, eluted at 0.55 M NaCl, disappeared after treatment with 2 mU/ml of heparitinase, indicating that heparan sulfates (HS) were present. The other peak, which eluted at 0.65 M NaCl, disappeared with 20 mU/ml of chondroitinase ABC, indicating the presence of chondroitin sulfates and dermatan sulfates (CS/DS). We estimated the effects of several growth factors on the synthesis of the pericellular proteoglycans by measuring heparitinase- and chondroitinase-ABC-sensitive radioactivities. Although PDGF-AB significantly stimulated cell proliferation and the synthesis of pericellular CS/DS, its dose-dependent effect on the cell growth did not coincide with that on the proteoglycan synthesis. IGF-I (1 nM) increased pericellular CS/DS but not the cell number, while basic FGF (1 nM) and EGF (1 nM) increased the cell number but not pericellular CS/DS. All the growth factors we examined had no effect on the synthesis of pericellular HS. These results indicate that growth factors increase pericellular proteoglycans independently of their mitogenic effects.
Asunto(s)
Sustancias de Crecimiento/fisiología , Mitógenos/metabolismo , Músculo Liso Vascular/citología , Proteoglicanos/biosíntesis , Animales , División Celular/efectos de los fármacos , División Celular/fisiología , Células Cultivadas , Condroitina ABC Liasa/metabolismo , Condroitina ABC Liasa/farmacología , Sulfatos de Condroitina/metabolismo , Sulfatos de Condroitina/farmacología , Dermatán Sulfato/metabolismo , Dermatán Sulfato/farmacología , Relación Dosis-Respuesta a Droga , Factor de Crecimiento Epidérmico/farmacología , Factor de Crecimiento Epidérmico/fisiología , Factor 2 de Crecimiento de Fibroblastos/farmacología , Factor 2 de Crecimiento de Fibroblastos/fisiología , Sustancias de Crecimiento/farmacología , Heparitina Sulfato/metabolismo , Heparitina Sulfato/farmacología , Factor I del Crecimiento Similar a la Insulina/farmacología , Factor I del Crecimiento Similar a la Insulina/fisiología , Mitógenos/farmacología , Músculo Liso Vascular/efectos de los fármacos , Músculo Liso Vascular/metabolismo , Factor de Crecimiento Derivado de Plaquetas/farmacología , Factor de Crecimiento Derivado de Plaquetas/fisiología , Polisacárido Liasas/metabolismo , Proteoglicanos/análisis , Ratas , Proteínas Recombinantes/farmacologíaRESUMEN
It is well known that numerous factors influence the light output of curing units, but many dentists are unaware that the output of their curing lights are inadequate. This study was conducted to evaluate the light intensity of visible-light curing units in private dental offices and to assess their curing efficiency by measuring compressive strength of a light-cured resin. Also, in order to determine the maximum light intensity of the curing units, lamps, filters, and fiber optic bundles were replaced by new ones and curing efficiency remeasured. Light intensity was measured by employing a Quantum Radiometer LI-189 at a wavelength of 470 +/- 40 nm using a bandpass filter. Compressive strength of a light-cured resin using the light units was measured employing an Instron Testing Machine at a crosshead speed of 1.0 mm/min. From the evaluation of 105 light units, the light intensity ranged from 28 to 1368 W/m2 (0 approximately 500 W/m2; 41.9%, 500 approximately 1000 W/ m2; 45.7%, 1000 approximately 1500 W/m2; 12.4%). Light intensity of the light unit in private offices decreased 15.9 approximately 82.1% compared to brand-new units. Reduction of light intensity impaired compressive strength of the light-cured resin to varying degrees (148.3 approximately 279.9 MPa) compared with the highest value (317 MPa) obtained from brand-new light units. The replacement of the parts increased the light intensity, with maximum increases of 36.0% for lamps, 157.7% for filters, 46.2% for fiber optics, and 322.7% for all three parts. The results of this study indicated that the light intensities of the curing units used in private practice were lower than expected.
Asunto(s)
Equipo Dental , Resinas Compuestas/química , Resinas Compuestas/efectos de la radiación , Fuerza Compresiva , Equipo Dental/estadística & datos numéricos , Estudios de Evaluación como Asunto , Luz , Ensayo de Materiales/instrumentación , Ensayo de Materiales/estadística & datos numéricos , Radiometría/métodosRESUMEN
In Part I, it was found that (i) 2 vol.% admixture of reinforcing elements in PMMA (Jet) resin matrix had a significant beneficial effects on the mechanical properties, and (ii) among these, zirconia exhibited the greatest improvements in modulus of elasticity, transverse strength, toughness, and hardness number. Using the best combination (i.e., PMMA resin matrix and 2 vol.% ZrO2), exothermic temperature raise and polymerization shrinkage were further investigated. Deterioration in mechanical properties due to prolonged water sorption were also studied for 5 weeks. The following can be concluded: (1) By increasing liquid/powder ratio for PMMA control samples, the peak temperature occurrence was retarded by 3 min and raised by 8 degrees C. (2) The effect of admixed oxide particles to PMMA resin matrix or the heat generated during polymerization was not significant. (3) The polymerization volumetric shrinkage was influenced by the a mixture of particles, with increases as large as 0.9% (or 0.3% in linear shrinkage). (4) PMMA resin admixed with 2 vol.% of zirconia particles showed a continuous weight gain due to water sorption, mechanical properties appears to be increasing up to 1-week sorption, followed by rapid drop of all properties. (5) Autopolymerizing acrylic resins are a resin-resin composite material of pre-polymerized beads embedded in a newly formed acrylic matrix. The main fracture modality appears to occur through the matrix and at the interface, although some trans-beads fractures were identified. (6) It was suggested that incorporating certain type of oxide particles into the pre-polymerized beads would provide stronger resin matrix.