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1.
J Esthet Restor Dent ; 32(7): 726-733, 2020 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-32886852

RESUMEN

OBJECTIVE: To evaluate the microtensile bond strength of four dental computer-aided design/computer-aided manufactured (CAD/CAM) ceramics after application of four different surface treatments. MATERIALS AND METHODS: Four dental CAD/CAM ceramics were tested: feldspathic ceramic (VITABLOCKS-Mark II), polymer-infiltrated ceramic network (VITA ENAMIC), zirconia-reinforced lithium silicate (VITA SUPRINITY), and yttria-stabilized zirconia (VITA YZ T). Four surface treatments were applied: no treatment, 5% hydrofluoric acid-etching, airborne particle abrasion, and tribochemical silica coating. The ceramic blocks were repaired with nanohybrid composite (Tetric N-Collection). Sixteen test groups of 12 specimens were prepared. After thermocycling, microtensile bond testing was performed. The microtensile strengths values were statistically analyzed using two-way analysis of variance and Tukey's post-hoc test. RESULTS: Repaired feldspathic and resin polymer-infiltrated ceramic network ceramics demonstrated superior microtensile bond strengths compared to zirconia-reinforced lithium silicate and yttria-stabilized zirconia. Etched feldspathic and polymer-infiltrated ceramic network ceramics had higher bond strength than the untreated groups. Surface treatments did not affect the bond strength of zirconia-reinforced lithium silicate and yttria-stabilized zirconia with the exception of etching, which reduced the bond strength of yttria-stabilized zirconia. CONCLUSION: Feldspathic ceramic and polymer-infiltrated ceramic network were repaired with dental composite after surface etching with hydrofluoric acid. Repair of zirconia-reinforced lithium silicate and yttria-stabilized zirconia did not demonstrate promising results. CLINICAL SIGNIFICANCE: Repair of feldspathic ceramic and polymer-infiltrated ceramic network restorations may be a cost-effective means to promote the longevity of dental restorations. However, zirconia and zirconia-reinforced lithium disilicate restorations do not offer such an option.


Asunto(s)
Recubrimiento Dental Adhesivo , Cerámica , Diseño Asistido por Computadora , Porcelana Dental , Análisis del Estrés Dental , Ensayo de Materiales , Cementos de Resina , Propiedades de Superficie , Circonio
2.
Saudi J Kidney Dis Transpl ; 28(4): 737-742, 2017.
Artículo en Inglés | MEDLINE | ID: mdl-28748874

RESUMEN

Erythropoietin resistance index calculation has been used as a tool to evaluate anemia response to erythropoietin therapy. Very little has been reported in its use when using darbepoetin and factors influencing in Arab patients. Darbepoetin resistance index (DRI) was calculated in all our patients using darbepoetin. This was correlated to demographic, clinical, and laboratory parameters. Of the 250 patients, 40.4% were diabetic, 71.1% on hemodialysis, and 28.6% on hemodiafiltration), 23.9% with PermCaths (PC), and 76.1 % with arteriovenous fistula (AVF). The mean DRI was 10.96 ± 12.9 I. Females had 45% higher DRI than males (P = 0.005), and patients with PC had a 66% higher DRI than those with AVF (P = 0.029). Patients with Vitamin D level below the 50th percentile had 55.9% higher DRI than those above it (P = 0.05). DRI was negatively correlated with age (P = 0.018), dialysis vintage (P = 0.039), interdialytic weight gain P = 0.007), Vitamin D level, and serum albumin (P = 0.005) and positively correlate with parathyroid hormone (PTH) level (P = 0.000). No impact was seen by the mode of dialysis, being diabetic, using anti-hypertensive therapy, body mass index, Kt/V, serum iron, total iron binding capacity, transferrin saturation, ferritin, C-reactive protein, Ca, or P. DRI in our Arab patients was comparable to erythropoietin resistance indices reported in other communities. Higher DRI was observed in females, PC users, lower serum albumin, lower Vitamin D, and shorter dialysis vintage. A negative correlation existed between DRI and age, dialysis vintage, interdialytic weight, and serum albumin and a positive correlation with PTH level.


Asunto(s)
Anemia/tratamiento farmacológico , Darbepoetina alfa/administración & dosificación , Resistencia a Medicamentos , Hematínicos/administración & dosificación , Enfermedades Renales/terapia , Modelos Biológicos , Diálisis Renal , Adulto , Anciano , Anemia/sangre , Anemia/diagnóstico , Anemia/etiología , Biomarcadores/sangre , Darbepoetina alfa/efectos adversos , Femenino , Hematínicos/efectos adversos , Hemodiafiltración/efectos adversos , Hemoglobinas/metabolismo , Humanos , Enfermedades Renales/sangre , Enfermedades Renales/complicaciones , Enfermedades Renales/diagnóstico , Masculino , Persona de Mediana Edad , Diálisis Renal/efectos adversos , Factores de Riesgo , Arabia Saudita , Resultado del Tratamiento
3.
J Dent ; 37(5): 321-30, 2009 May.
Artículo en Inglés | MEDLINE | ID: mdl-19181429

RESUMEN

OBJECTIVE: The intent of the project was to evaluate the fatigue behavior of particle and fiber filled dental composites that are fabricated either directly or indirectly using a notched specimen with respect to the number of cycles until failure. METHODS: The materials were five dental composites, three normally cured in the oral cavity (Restolux, Renew and Filtek Supreme), direct processing, and two laboratory produced (BelleGlass, and Tescera), indirect processing. The specimens were 3mmx3mmx25mm bars with a 0.75 or 1.0mm notch in the mid-span of the bars, polished with 320 grit SiC paper and aged for 6 months in air, distilled water, artificial saliva, and a 50/50 mixture of ethanol and distilled water. Testing was performed with a stress mean range of 5-49MPa, the maximum number of cycles was 100,000, and the number of cycles to failure was recorded. RESULTS: For the specimens that failed, BelleGlass, Restolux, and Tescera were able to withstand a higher cyclic loaded stress than Renew and Filtek. The 50/50 by volume mixture of water and ethanol resulted in the lowest resistance to fatigue for all materials. CONCLUSIONS: Of the dental composite materials investigated, the indirect processed and those with large particle fillers (higher weight percent filler) had better cyclic fatigue resistance than micro- and nano-particle fillers (lower weight percent filler).


Asunto(s)
Resinas Compuestas , Análisis del Estrés Dental , Resinas Compuestas/química , Alisadura de la Restauración Dental , Restauración Dental Permanente/métodos , Incrustaciones , Modelos Lineales , Ensayo de Materiales , Microscopía Electrónica de Rastreo , Nanocompuestos/química , Tamaño de la Partícula
4.
Angle Orthod ; 78(3): 537-44, 2008 May.
Artículo en Inglés | MEDLINE | ID: mdl-18416615

RESUMEN

OBJECTIVE: The hypothesis of this two-part study is that adhesive systems for bonding orthodontic brackets (ie, two self-etch primers [Transbond and M-Bond] and a conventional phosphoric acid etch [Rely-a-Bond]) would show a difference with respect to rebonded enamel surface morphology and chemical composition. MATERIALS AND METHODS: This study examined the enamel surface before and after debonding with scanning electron microscopy and the enamel surface chemical composition for the elements Ca, P, O, F, Si, and C using x-ray photoelectron spectroscopy. RESULTS: The etching of the two self-etch groups is less aggressive and less uniform than that of phosphoric acid. The change in the concentration of C indicated that the separation of the bracket from the enamel surface is at the resin-enamel interface for the phosphoric acid-etched adhesive and a mixed mode involving the enamel-resin-bracket interfaces for the self-etching systems. F release appears to occur for Transbond but not for M-Bond. CONCLUSIONS: The results confirm the original hypothesis that differences in adhesive systems are manifested in less aggressive etches and less adhesive left on the enamel surface for the self-etching adhesive systems.


Asunto(s)
Recubrimiento Dental Adhesivo/métodos , Cementos Dentales/química , Esmalte Dental/ultraestructura , Soportes Ortodóncicos , Grabado Ácido Dental , Calcio/análisis , Carbono/análisis , Resinas Compuestas/química , Desconsolidación Dental , Esmalte Dental/química , Microanálisis por Sonda Electrónica , Flúor/análisis , Humanos , Ensayo de Materiales , Microscopía Electrónica de Rastreo , Oxígeno/análisis , Ácidos Fosfóricos/química , Fósforo/análisis , Cementos de Resina/química , Silicio/análisis , Propiedades de Superficie
5.
Dent Mater ; 23(5): 648-53, 2007 May.
Artículo en Inglés | MEDLINE | ID: mdl-16876859

RESUMEN

OBJECTIVE: The intent of this project was to examine the effect of two different modes of fatigue loading, contact and flexure, on the flexure strength of a dental composite. METHODS: The composite was Restolux (a fiber-filled composite) formed as bars 3 mm x 3 mm x 25 mm in size. The cyclic loading ranges were 30-50, 60-80, and 90-110 N for contact loading and 20-40 and 40-60 N for the flexure loading. Number of cycles completed was 1, 1000 or 100,000 in four different media: air, water, artificial saliva, and a 50/50 mixture of water and ethanol. Specimens were aged in sealed polyethylene containers in their respective media for 4 months at 37 degrees C. RESULTS: Statistical analysis indicated a significantly lower flexure strength for the specimens flexure loaded versus contact loaded. For the flexure loaded specimens, the number of cycles had no significant effect, but the aging, load, and the media were all significant. For the contact loaded specimens, a significant effect was observed for the media, aging, and cycles completed, but no effect for the different cycling loads. SIGNIFICANCE: In summary, the decrease in flexure strength from flexure loading was mainly affected by the aging media, whereas, the decrease from contact loading was attributed mainly to the number of cycles.


Asunto(s)
Resinas Compuestas/química , Materiales Dentales/química , Aire , Etanol/química , Análisis de Elementos Finitos , Humanos , Ensayo de Materiales , Docilidad , Saliva Artificial/química , Solventes/química , Estrés Mecánico , Propiedades de Superficie , Temperatura , Factores de Tiempo , Agua/química
6.
J Biomed Mater Res B Appl Biomater ; 71(1): 172-80, 2004 Oct 15.
Artículo en Inglés | MEDLINE | ID: mdl-15368242

RESUMEN

The objective of this study was to determine the leaching of Ba, Si, and Sr from four dental composites: Restolux (RX), Micronew (M), Renew (RW), and Choice (C) and to correlate the effects of such leaching with flexure strength and modulus of elasticity. The specimens were 3 x 3 x 25-mm bars, polished with 120- and 240-grit SiC paper, and were aged for 4, 6, and 8 months in artificial saliva, distilled water, and a 50/50 mixture of ethanol and distilled water. Inductively coupled plasma with mass spectroscopy (ICP/MS) was used to determine the ion concentrations after aging. The greatest release of Ba and Sr occurred after aging in 50/50 volume fraction mixture of ethanol/water and for Si in artificial saliva. The 50/50 solution caused a breakdown of the resin and glass matrix, resulting in an increase of Ba and Sr, whereas aging in artificial saliva resulted in an ion charge balance, which allowed an elevated and continuous release of Si. The flexure strength and the elastic modulus showed a gradual decrease over time, with the greatest decreases occurring following aging in the 50/50 water/ethanol solution, but little correlation with the leaching of the filler ions.


Asunto(s)
Materiales Dentales , Materiales Biocompatibles , Fenómenos Biomecánicos , Hidróxido de Calcio/química , Resinas Compuestas , Materiales Dentales/química , Técnica de Fractura por Congelación , Resistencia al Corte , Estrés Mecánico
7.
Int J Prosthodont ; 15(1): 38-42, 2002.
Artículo en Inglés | MEDLINE | ID: mdl-11887597

RESUMEN

PURPOSE: The effect of two levels of prosthesis misfit on prosthetic screw stability was evaluated. MATERIALS AND METHODS: Two levels of vertical discrepancies--100 and 175 microns--were introduced between an implant-supported complete denture and the terminal abutment. An implant-supported complete denture without vertical discrepancy served as a control. Cyclic load was delivered vertically on the cantilever portion of the prosthesis next to the terminal abutment for 48 hours for each trial. A total of seven sets of new screws were tested for each level of fit. RESULTS: The results revealed significant prosthetic screw instability at both the 100- and 175-micron levels of discrepancy. CONCLUSION: Vertical discrepancies of 100 and 175 microns introduced between an implant-supported fixed complete denture and the terminal abutment resulted in significant prosthetic screw instability.


Asunto(s)
Retención de Prótesis Dentales/instrumentación , Prótesis Dental de Soporte Implantado , Fracaso de la Restauración Dental , Análisis del Estrés Dental , Análisis de Varianza , Pilares Dentales , Humanos , Ajuste de Prótesis , Estadísticas no Paramétricas , Estrés Mecánico , Torque
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