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1.
Int J Mol Sci ; 25(8)2024 Apr 09.
Artículo en Inglés | MEDLINE | ID: mdl-38673728

RESUMEN

BTB and CNC homology 1 (BACH1) represses the expression of genes involved in the metabolism of iron, heme and reactive oxygen species. While BACH1 is rapidly degraded when it is bound to heme, it remains unclear how BACH1 degradation is regulated under other conditions. We found that FBXO22, a ubiquitin ligase previously reported to promote BACH1 degradation, polyubiquitinated BACH1 only in the presence of heme in a highly purified reconstitution assay. In parallel to this regulatory mechanism, TANK binding kinase 1 (TBK1), a protein kinase that activates innate immune response and regulates iron metabolism via ferritinophagy, was found to promote BACH1 degradation when overexpressed in 293T cells. While TBK1 phosphorylated BACH1 at multiple serine and threonine residues, BACH1 degradation was observed with not only the wild-type TBK1 but also catalytically impaired TBK1. The BACH1 degradation in response to catalytically impaired TBK1 was not dependent on FBXO22 but involved both autophagy-lysosome and ubiquitin-proteasome pathways judging from its suppression by using inhibitors of lysosome and proteasome. Chemical inhibition of TBK1 in hepatoma Hepa1 cells showed that TBK1 was not required for the heme-induced BACH1 degradation. Its inhibition in Namalwa B lymphoma cells increased endogenous BACH1 protein. These results suggest that TBK1 promotes BACH1 degradation in parallel to the FBXO22- and heme-dependent pathway, placing BACH1 as a downstream effector of TBK1 in iron metabolism or innate immune response.


Asunto(s)
Factores de Transcripción con Cremalleras de Leucina de Carácter Básico , Proteínas F-Box , Hemo , Proteínas Serina-Treonina Quinasas , Proteolisis , Receptores Citoplasmáticos y Nucleares , Humanos , Hemo/metabolismo , Factores de Transcripción con Cremalleras de Leucina de Carácter Básico/metabolismo , Factores de Transcripción con Cremalleras de Leucina de Carácter Básico/genética , Fosforilación , Proteínas Serina-Treonina Quinasas/metabolismo , Proteínas Serina-Treonina Quinasas/genética , Proteínas F-Box/metabolismo , Proteínas F-Box/genética , Células HEK293 , Ubiquitinación , Línea Celular Tumoral , Lisosomas/metabolismo , Autofagia , Complejo de la Endopetidasa Proteasomal/metabolismo
2.
Cell Rep ; 38(12): 110541, 2022 03 22.
Artículo en Inglés | MEDLINE | ID: mdl-35320725

RESUMEN

The histone chaperone complex FACT comprises SPT16 and SSRP1 and contributes to DNA replication, transcription, and repair, but how it plays such various roles is unclear. Here, we show that human SPT16 is ubiquitylated at lysine-674 (K674) by the DCAF14-CRL4 ubiquitin ligase. K674 is located in the middle domain of SPT16, and the corresponding residue of the yeast ortholog is critical for binding to histone H3.1-H4. We show that the middle domain of human SPT16 binds to histone H3.1-H4 and that this binding is inhibited by K674 ubiquitylation. Cells with heterozygous knockin of a K674R mutant of SPT16 manifest reduction of both SPT16 ubiquitylation and H3.1 in chromatin, a reduced population in mid S phase, impaired proliferation, and increased susceptibility to S phase stress. Our data thus indicate that SPT16 ubiquitylation by DCAF14-CRL4 regulates FACT binding to histones and may thereby control DNA replication-coupled histone incorporation into chromatin.


Asunto(s)
Histonas , Proteínas de Saccharomyces cerevisiae , Cromatina , Proteínas de Unión al ADN , Proteínas del Grupo de Alta Movilidad , Chaperonas de Histonas , Humanos , Lisina , Receptores de Interleucina-17 , Saccharomyces cerevisiae , Factores de Elongación Transcripcional , Ubiquitina-Proteína Ligasas , Ubiquitinación
3.
Odontology ; 110(1): 70-80, 2022 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-34272634

RESUMEN

The aim of this study was to investigate the effect of two different priming agents and/or sandblasting on the shear bond strength of self-adhesive resin cement to the resin composite for core build-up to CAD/CAM blocks. A CAD/CAM ceramic block (GN I CERAMIC BLOCK, GC) and a CAD/CAM resin composite block (CERASMART 270, GC), a self-adhesive resin cement (G-CEM ONE, GC) and two different primers, i.e., a multipurpose primer (MP; G-Multi Primer, GC) and a ceramic primer (CP; Ceramic Primer II, GC), were examined. Five different surface treatments with priming and/or sandblasting and no surface treatment (control) were performed on the block. Disk specimens (6 mm in diameter and 4 mm in thickness) made from core composites were cemented to the blocks after the surface treatments. Then, the 24-h shear bond strength of the resin cement between the block and the resin composite core was determined (n = 15). Sandblasted specimens had greater bond strength than controls for both blocks (p < 0.05). Priming to both blocks significantly increased the bond strength of resin cement compared to that of controls (p < 0.05). Although Weibull moduli were not significantly changed among all surface treatments for both blocks, the strengths with 5% and 95% failure probability of sandblasted and/or primed blocks were estimated to be greater than those of controls. The combination of priming and sandblasting to the CAD/CAM composite and ceramic surface was effective in increasing the bond strength of the resin cement.


Asunto(s)
Recubrimiento Dental Adhesivo , Cementos de Resina , Cerámica , Cementos Dentales , Ensayo de Materiales , Resistencia al Corte , Propiedades de Superficie
4.
Int J Clin Oncol ; 27(1): 25-34, 2022 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-34779961

RESUMEN

Although the incidence of the various gynecological cancers has been increasing in recent years, long-term survival is now possible for many patients thanks to advances in multimodality treatment. When treating gynecological cancer in adolescent and young adult (AYA) patients who desire future pregnancy, it is necessary to preserve the reproductive organs and their function to prevent loss of fertility. However, because treatment targets these organs, in the large majority of cases, patients must have these organs removed. In the subfield of oncofertility, treatment of the underlying disease takes priority, and the main principle is preventing delay in treatment. Close cooperation between obstetricians and gynecologists involved in reproductive medicine and oncologists involved in cancer treatment is necessary. In addition, it is important that clinicians work closely not only with other specialists but also with such medical professionals as nurses and counselors so that cancer patients of the AYA generation can be provided the support they need to fight their cancer with hope. Herein, we describe the current status of fertility-sparing therapy for AYA patients with gynecological cancer (cervical cancer, endometrial cancer, or ovarian cancer). In addition, we explain points to keep in mind during a patient's pregnancy after fertility preservation, the latest findings on assisted reproductive technology, and the challenges and prospects of fertility preservation therapy for patients with gynecologic cancer.


Asunto(s)
Preservación de la Fertilidad , Neoplasias de los Genitales Femeninos , Oncólogos , Neoplasias Ováricas , Adolescente , Femenino , Fertilidad , Neoplasias de los Genitales Femeninos/terapia , Humanos , Embarazo , Adulto Joven
5.
Asian J Endosc Surg ; 14(3): 665-668, 2021 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-33393218

RESUMEN

INTRODUCTION: The Laparoscopic Approach to Cervical Cancer (LACC) trial, a prospective randomized phase III clinical trial reported in 2018, unexpectedly showed inferior oncologic outcomes in laparoscopic radical hysterectomy (LRH) for cervical cancer compared with those in open surgery. It was proposed that the spillage of tumor cells into the peritoneal cavity might cause the inferiority of LRH. It has been suggested, based on retrospective studies, that transvaginal closure of the vaginal cuff before the colpotomy part of the surgery may prevent this. MATERIALS AND SURGICAL TECHNIQUE: Before starting colpotomy, we closed the vaginal cuff transvaginally. After the assessment of the cutline of the vagina, the vaginal mucosa is pulled at the eight sites using the sutures. The four pairs of sutures on the diagonal line are ligated. A purse string suture is additionally placed on the vaginal mucosa to close the vaginal cuff completely. After that, we start the intracorporeal colpotomy using a vaginal pipe. DISCUSSION: Our technique is simple and quick. The blood loss during the transvaginal procedures is minimal. The use of the vaginal pipe helps keep the vaginal cuff closed during the colpotomy. Our technique may be an alternative to the conventional approach closing the vaginal cuff.


Asunto(s)
Histerectomía , Laparoscopía , Siembra Neoplásica , Neoplasias del Cuello Uterino , Vagina/cirugía , Femenino , Humanos , Histerectomía/métodos , Histerectomía Vaginal , Metástasis de la Neoplasia/prevención & control , Estudios Prospectivos , Ensayos Clínicos Controlados Aleatorios como Asunto , Estudios Retrospectivos , Neoplasias del Cuello Uterino/cirugía
6.
Dent Mater J ; 40(2): 364-378, 2021 Mar 31.
Artículo en Inglés | MEDLINE | ID: mdl-33100298

RESUMEN

This study examined the effects of sandblasting, hydrofluoric acid etching and priming on the shear bond strength of self-adhesive resin cement between seven different CAD/CAM resin composites and a resin composite core material at 24-h after cement mixing. Five surface treatments [control (C), sandblasting (S), priming (P), sandblasting with priming (SP), and 9% HF etching with priming (HFP)] were performed respectively for disc specimens of CAD/CAM blocks. There were no significant differences in bond strength among the C, S, and P, except for one block (p>0.05). SP showed a greater bond strength than S. Weibull moduli were not changed significantly among all treatments for all blocks, whereas the strengths with 5% and 95% failure probability of SP and HFP showed greater values than the others. The bond strengths of HFP were comparable to those of SP. Priming after sandblasting or HF etching could be effective to increase the bond strength of CAD/CAM blocks.


Asunto(s)
Recubrimiento Dental Adhesivo , Cementos de Resina , Cerámica , Resinas Compuestas , Cementos Dentales , Ensayo de Materiales , Resistencia al Corte , Propiedades de Superficie
7.
In Vivo ; 34(4): 1729-1738, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32606141

RESUMEN

BACKGROUND/AIM: Chitosan-coated iron oxide nanoparticles (Chi-NP) have gained attention because of their biocompatibility, biodegradability, low toxicity and targetability under magnetic field. In this study, we investigated various biological properties of Chi-NP. MATERIALS AND METHODS: Chi-NP was prepared by mixing magnetic NP with chitosan FL-80. Particle size was determined by scanning and transmission electron microscopes, cell viability by MTT assay, cell cycle distribution by cell sorter, synergism with anticancer drugs by combination index, PGE2 production in human gingival fibroblast was assayed by ELISA. RESULTS: The synthetic process of Chi-NP from FL-80 and magnetic NP increased the affinity to cells, up to the level attained by nanofibers. Upon contact with the culture medium, Chi-NP instantly formed aggregates and interfered with intracellular uptake. Aggregated Chi-NP did not show cytotoxicity, synergism with anticancer drugs, induce apoptosis (accumulation of subG1 cell population), protect the cells from X-ray-induced damage, nor affected both basal and IL-1ß-induced PGE2 production. CONCLUSION: Chi-NP is biologically inert and shows high affinity to cells, further confirming its superiority as a scaffold for drug delivery.


Asunto(s)
Quitosano , Nanopartículas de Magnetita , Nanopartículas , Portadores de Fármacos , Sistemas de Liberación de Medicamentos , Humanos , Tamaño de la Partícula
8.
Dent Mater J ; 39(5): 742-751, 2020 Sep 29.
Artículo en Inglés | MEDLINE | ID: mdl-32418950

RESUMEN

The objective of this study was to examine the effects of storage conditions on the flexural strengths of resin composite materials for CAD/CAM restorations. Seven commercially available resin composite CAD/CAM blanks were examined. Rectangular specimens (4.0×1.2×4.0 mm) of each material were trimmed from the blanks and subjected to thermal cycling between 5°C and 55°C in deionized water at 10,000 cycles or stored in 37°C deionized water for one week or air for one day (n=10 for each condition). The difference in storage condition between water immersion and thermal cycling did not affect the flexural strengths of resin composite materials for CAD/CAM examined in this study. The resin composite block CS300 made from Bis-MEPP and UDMA showed the greatest flexural strength under all storage conditions and less deterioration of strength by thermal cycling and water immersion among the resin composite blocks tested.


Asunto(s)
Resinas Compuestas , Coronas , Diseño Asistido por Computadora , Resistencia Flexional , Ensayo de Materiales , Propiedades de Superficie
9.
iScience ; 23(4): 101030, 2020 Apr 24.
Artículo en Inglés | MEDLINE | ID: mdl-32299058

RESUMEN

Haploinsufficiency of SETD5 is implicated in syndromic autism spectrum disorder (ASD), but the molecular mechanism underlying the pathological role of this protein has remained unclear. We have now shown that Setd5+/- mice manifest ASD-related behavioral phenotypes and that the expression of ribosomal protein genes and rDNA is disturbed in the brain of these mice. SETD5 recruited the HDAC3 complex to the rDNA promoter, resulting in removal of the histone mark H4K16ac and its reader protein TIP5, a repressor of rDNA expression. Depletion of SETD5 attenuated rDNA expression, translational activity, and neural cell proliferation, whereas ablation of TIP5 in SETD5-deficient cells rescued these effects. Translation of cyclin D1 mRNA was specifically down-regulated in SETD5-insufficient cells. Our results thus suggest that SETD5 positively regulates rDNA expression via an HDAC3-mediated epigenetic mechanism and that such regulation is essential for translation of cyclin D1 mRNA and neural cell proliferation.

10.
Dent Mater J ; 39(3): 355-366, 2020 Jun 05.
Artículo en Inglés | MEDLINE | ID: mdl-31852877

RESUMEN

This study evaluated the physical and mechanical properties of a dental stone mixed by shaking. A shake-mix dental stone (Shake! Mix STONE; SM) was characterized in comparison with three conventional dental stones. The fluidity at pouring time, setting time, density, powder particle distributions, linear setting expansion, compressive strength and surface reproduction of detail for dental stones were investigated. The marginal adaptations of cast crowns to dies made with each stone were also determined. SM had higher fluidity and faster setting time than the other stones (p<0.05). The setting expansion of SM at 2 h was lower than those of other two stones (p<0.05). The 15-min compressive strength of SM was higher than the others (p<0.05). There were no significant differences in the marginal adaptations of the cast crowns fabricated using all the stones (p>0.05). In spite of the different mixing method, the shake-mix type dental stone had comparable physical and mechanical properties to the conventional dental stones.


Asunto(s)
Sulfato de Calcio , Materiales Dentales , Fuerza Compresiva , Coronas , Ensayo de Materiales , Modelos Dentales , Propiedades de Superficie
11.
Int J Oral Maxillofac Implants ; 34(5): 1053-1058, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-31528861

RESUMEN

PURPOSE: To evaluate the bonding ability of self-adhesive and dual-cure resin cement systems applied to zirconia materials of different translucency in combination with each other and with titanium. MATERIALS AND METHODS: Computer-aided design/computer-assisted manufacture (CAD/CAM) disks of three different zirconia materials (Zenostar MO 0 [medium opacity], MT 0 [medium translucency], and T 1 [translucent], Wieland Dental) were milled and hard sintered in order to obtain cylindrical samples of either 12 mm high × 12 mm diameter (used as a substrate) or 12 mm high × 8 mm diameter (to be bonded to the substrate). CAD/CAM disks of titanium (Starbond Ti4 Disc, S&S Scheftner) were milled in order to obtain a cylinder shape (12 mm high × 8 mm diameter to be bonded to the zirconia substrate). The bonding surfaces were sandblasted with alumina particles (70 µm/2 ATM). Two resin cement systems were tested in this study: a self-adhesive resin cement (SpeedCEM Plus, Ivoclar Vivadent) and a dual-cure resin cement (Variolink Esthetic DC, Ivoclar Vivadent) in combination with a primer (Monobond Plus, Ivoclar Vivadent). The smaller cylinders were bonded to the substrate following the manufacturer's instructions. After 24 hours at 37°C storage, each specimen was subjected to shear bond strength testing in a universal testing machine. The substrate was fixed to the machine, and shear force was applied to the small cylinder close to the bonding interface. Shear bond strength data were statistically analyzed by a three-way analysis of variance (ANOVA) followed by the Tukey test for post hoc comparison (P < .05). RESULTS: No significant differences were found between substrates in the shear bond strength test (P = .078). Variolink Esthetic DC showed a statistically significantly higher bond strength compared with the SpeedCEM Plus (P = .001) with the exception of Zenostar MT substrate (P = .014). CONCLUSION: The resin cement systems showed high shear bond strength values when zirconia was resin bonded to either titanium or the corresponding zirconia substrate. Different zirconia translucencies did not affect the bond strength. The use of MDP primer and a dual-cure cement showed statistically significantly higher strength compared with the self-adhesive resin cement system with the only exception being the bonding of the translucent zirconia Zenostar MT.


Asunto(s)
Recubrimiento Dental Adhesivo , Titanio , Análisis del Estrés Dental , Estética Dental , Ensayo de Materiales , Cementos de Resina , Resistencia al Corte , Propiedades de Superficie , Circonio
12.
Dev Biol ; 445(2): 178-188, 2019 01 15.
Artículo en Inglés | MEDLINE | ID: mdl-30391586

RESUMEN

ß-TrCP is the substrate recognition subunit of an SCF-type ubiquitin ligase. We recently showed that deletion of the genes for both ß-TrCP1 and ß-TrCP2 paralogs in germ cells of male mice resulted in accumulation of the transcription factor DMRT1 and spermatogenic failure, whereas systemic ß-TrCP1 knockout combined with ß-TrCP2 knockdown had previously been shown to lead to disruption of testicular organization and accumulation of the transcription factor SNAIL. Here we investigated ß-TrCP function in Sertoli cells by generating mice with targeted deletion of the ß-TrCP2 gene in Sertoli cells on a background of whole-body ß-TrCP1 knockout. Loss of ß-TrCP in Sertoli cells caused infertility due to a reduction in the number of mature sperm. Whereas spermatogonia were not affected, male germ cells entered meiosis prematurely and the number of round spermatids was reduced in the mutant mice. Extracts of Sertoli cells and of the testis from the mutant mice manifested accumulation of SNAIL, and expression of the SNAIL target gene for E-cadherin was down-regulated in Sertoli cells from these animals. Our results indicate that ß-TrCP in Sertoli cells regulates Sertoli cell-germ cell interaction through degradation of SNAIL, with such regulation being critical for sperm development.


Asunto(s)
Células de Sertoli/metabolismo , Espermatogénesis/fisiología , Proteínas con Repetición de beta-Transducina/metabolismo , Animales , Infertilidad Masculina/genética , Infertilidad Masculina/metabolismo , Infertilidad Masculina/patología , Masculino , Meiosis/genética , Meiosis/fisiología , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , ARN/genética , ARN/metabolismo , Células de Sertoli/patología , Factores de Transcripción de la Familia Snail/metabolismo , Espermátides/metabolismo , Espermátides/patología , Espermatogénesis/genética , Espermatogonias/metabolismo , Espermatogonias/patología , Proteínas con Repetición de beta-Transducina/deficiencia , Proteínas con Repetición de beta-Transducina/genética
13.
Mol Cell Biol ; 37(4)2017 02 15.
Artículo en Inglés | MEDLINE | ID: mdl-27895153

RESUMEN

Repair of damaged DNA is critical for maintenance of genetic information. In eukaryotes, DNA double-strand breaks (DSBs) are recognized by the Ku70-Ku80 heterodimer, which then recruits proteins that mediate repair by nonhomologous end joining (NHEJ). Prolonged retention of Ku70/80 at DSBs prevents completion of repair, however, with ubiquitylation of Ku80 having been implicated in Ku70/80 dissociation from DNA. Here, we identify RNF126 as a ubiquitin ligase that is recruited to DSBs and ubiquitylates Ku80, with UBE2D3 serving as an E2 enzyme. Knockdown of RNF126 prevented Ku70/80 dissociation from DSBs and inhibited break repair. Attenuation of Ku80 ubiquitylation by replacement of ubiquitylation site lysines with arginine residues delayed Ku70/80 release from chromatin after DSB induction by genotoxic insults. Together, our data indicate that RNF126 is a novel regulator of NHEJ that promotes completion of DNA repair by ubiquitylating Ku80 and releasing Ku70/80 from damaged DNA.


Asunto(s)
Reparación del ADN por Unión de Extremidades , Autoantígeno Ku/metabolismo , Ubiquitina-Proteína Ligasas/metabolismo , Ubiquitinación , Animales , Cromatina/metabolismo , Roturas del ADN de Doble Cadena/efectos de la radiación , Células HEK293 , Células HeLa , Humanos , Ratones , Modelos Biológicos , Células 3T3 NIH , Multimerización de Proteína/efectos de la radiación , Proteolisis/efectos de la radiación , Radiación Ionizante , Ubiquitinación/efectos de la radiación
14.
Dent Mater J ; 34(1): 70-7, 2015.
Artículo en Inglés | MEDLINE | ID: mdl-25748461

RESUMEN

The influence of monomer content on the viscoelasticity, water sorption and solubility of experimental fluorinated soft lining materials was investigated. Changes in the viscoelastic properties of the materials were also examined after thermal cycling. Four fluorinated soft lining materials containing different amounts of methoxy diethylene glycol methacrylate (MDGMA) and tridecafluorooctyl methacrylate (13FMA) were prepared. The viscoelastic displacement for specimens containing 13FMA was found to be less than that without 13FMA (p<0.05), and the values tended to decrease with increasing 13FMA content. Reduction of the MDGMA content and addition of 13FMA caused a decrease of water sorption and solubility (p<0.05). Thermal cycling was found to affect the viscoelastic deformation of the specimens without 13FMA and those specimens with relatively large amounts of 13FMA.


Asunto(s)
Materiales Dentales/química , Alineadores Dentales , Flúor/química , Metacrilatos/química , Elasticidad , Ensayo de Materiales , Estructura Molecular , Solubilidad , Viscosidad , Agua
15.
Dent Mater J ; 33(6): 835-44, 2014.
Artículo en Inglés | MEDLINE | ID: mdl-25483383

RESUMEN

This study was to examine the retentive force of crowns to implant abutments with commercial temporary cements. Six different temporary cements were investigated. Cast crowns were cemented to the abutments using each cement and their retentive forces to abutments were determined 7 or 28 days after cementing (n=10). The retentive force of the cements to abutments varied widely among the products [27-109 N (7-day), 18-80 N (28-days)]. The retentive force of all the cements was not reduced as the time elapsed, except for two products tested. The polycarboxylate cements and paste-mixing type eugenol-free cements revealed comparable retentive force after 28 days of storage. The powder-liquid type cements showed a positive correlation (p<0.05) between the retentive force and the shear strength, while a negative correlation (p<0.05) was obtained for paste-mixing type cement between the retentive force and compressive strength. Mechanical strength of temporary cements could not be a prominent predicting factor for retention of the crowns on the abutments.


Asunto(s)
Coronas , Pilares Dentales , Cementos Dentales/química , Retención de Prótesis Dentales , Análisis del Estrés Dental , Eugenol/química , Ensayo de Materiales , Propiedades de Superficie , Óxido de Zinc/química , Cemento de Fosfato de Zinc/química
16.
Dent Mater J ; 33(5): 621-30, 2014.
Artículo en Inglés | MEDLINE | ID: mdl-25273041

RESUMEN

The purpose of the present study was to investigate the effect of the composition of experimental fluorinated soft lining materials on bond strength to denture base resin. Vinylidene fluoride/hexafluoro propylene copolymer (2-6F), tridecafluorooctyl methacrylate (13FMA), methoxy diethylene glycol methacrylate (MDGMA), and silica (as filler) were used for fabrication of the experimental soft lining materials. Nine experimental soft lining materials having various compositions of 2-6F, 13FMA, and MDGMA were prepared. Shear and tensile bond strength tests were performed before and after immersion in water. The water sorption for the materials was also measured. An increase in the content of acrylic monomer, MDGMA, in the experimental materials increased the bond strength before immersion in water but reduced the bond strength after immersion in water as compared to that before immersion in water. The inclusion of fluorinated monomer (13FMA) in the materials appeared to affect water sorption.


Asunto(s)
Recubrimiento Dental Adhesivo , Bases para Dentadura , Alineadores Dentales , Flúor/química , Ensayo de Materiales
17.
Dent Mater J ; 26(5): 708-12, 2007 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-18203472

RESUMEN

This study examined the effect of ambient water on the shear strength of glass ionomer cements for luting. Disk specimens were fabricated from four commercially available glass ionomer cements with different setting modes. At one hour after the start of mixing, the specimens were stored at 37 degrees C for 24 and 168 hours in dry condition or in deionized water. Shear strength was then determined using a punch tool. The shear strengths of both conventional cements were significantly greater for the specimens stored dry as compared to those kept in deionized water (p < 0.05). Conversely, resin-modified cement specimens stored dry had significantly lower strength compared to the specimens kept in deionized water (p < 0.05). This was because the ambient water surrounding the resin-modified glass ionomer cements helped increase the shear strength of the cements under the experimental conditions tested.


Asunto(s)
Recubrimiento Dental Adhesivo , Cementos de Ionómero Vítreo , Análisis de Varianza , Análisis del Estrés Dental , Almacenaje de Medicamentos , Ensayo de Materiales , Resistencia al Corte , Agua
18.
Dent Mater J ; 23(4): 656-60, 2004 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-15688735

RESUMEN

This study examined the possible correlation between the strength of glass ionomers and their adhesive strength to bovine teeth. The shear bond strengths of three different brands of glass ionomer mixed at four different P/L ratios to bovine teeth were measured 24 hours after the cement specimens were prepared. The correlation between shear bond strength and mechanical strength reported in our previous study was also examined. No significant (p > 0.05) increases in the bond strength to bovine teeth were found in any of the cements when the mixing ratio increased. The present study showed no significant (p > 0.05) correlation between mechanical strength of cement and its bond strength to bovine teeth. Rather than trying to increase the strength of the cement, it would be more effective to enhance the adhesive bond strength through procedures such as surface conditioning or cleaning of the tooth structure when glass ionomers are used as luting agents.


Asunto(s)
Recubrimiento Dental Adhesivo , Cementos de Ionómero Vítreo/química , Adhesividad , Análisis de Varianza , Animales , Bovinos , Fuerza Compresiva , Esmalte Dental , Análisis del Estrés Dental , Dentina , Ensayo de Materiales , Resistencia al Corte , Estadísticas no Paramétricas , Resistencia a la Tracción
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