Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 28
Filtrar
Más filtros

País/Región como asunto
Tipo del documento
Intervalo de año de publicación
1.
Nat Commun ; 15(1): 1941, 2024 Mar 02.
Artículo en Inglés | MEDLINE | ID: mdl-38431638

RESUMEN

Organismal aging is inherently connected to the aging of its constituent cells and systems. Reducing the biological age of the organism may be assisted by reducing the age of its cells - an approach exemplified by partial cell reprogramming through the expression of Yamanaka factors or exposure to chemical cocktails. It is crucial to protect cell type identity during partial reprogramming, as cells need to retain or rapidly regain their functions following the treatment. Another critical issue is the ability to quantify biological age as reprogrammed older cells acquire younger states. We discuss recent advances in reprogramming-induced rejuvenation and offer a critical review of this procedure and its relationship to the fundamental nature of aging. We further comparatively analyze partial reprogramming, full reprogramming and transdifferentiation approaches, assess safety concerns and emphasize the importance of distinguishing rejuvenation from dedifferentiation. Finally, we highlight translational opportunities that the reprogramming-induced rejuvenation approach offers.


Asunto(s)
Reprogramación Celular , Rejuvenecimiento , Reprogramación Celular/genética
2.
Iran J Public Health ; 52(12): 2572-2582, 2023 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-38435761

RESUMEN

Background: The decrease in the frequency and duration of participation in leisure activities has negative effects on the physical, cognitive and psychological health of individuals. In this context, identifying the obstacles, which prevent individuals from participating in leisure activities, may offer important clues to institutions and organizations in taking measures to increase participation. Methods: The bibliometric analysis method was used in this study. The research was carried out with 306 articles scanned from the Web of Science (WoS) core database between 1991 and 2019. Results: Studies conducted in leisure area increased systematically according to 5-year periods and mostly authors from USA, Australia and Canada produced them. The mainstream subjects, which attracted the attention of researchers during recent years, are detected to be self-efficacy, segmentation, mental health and fear related to intrapersonal constraint topics. Conclusion: In order to cope with physical and mental health problems resulting from aging of the world population, and technological developments, and negative effects generated by inactive modern life style, priority should be given to studies on leisure constraints to be conducted on a more comprehensive basis. Another suggestion is to encourage health policies and applications which can increase participation in leisure activities.

3.
Medicine (Baltimore) ; 102(39): e35316, 2023 Sep 29.
Artículo en Inglés | MEDLINE | ID: mdl-37773796

RESUMEN

BACKGROUND: Containment measures implemented during the COVID-19 pandemic have led to drastic changes in daily life and effects on health behaviors such as decrease in physical activity (PA) levels. This study aims to present a general framework to researchers on COVID-19 and PA research in relation with changes in studies within years, current trend topics, gaps in the research field and possible future trends. METHODS: A total of 1819 articles indexed in the WoS core collection database were analyzed according to publication year, citation, country and institution collaborations, coword, co-citation networks, concept-topic trends and topic clusters using bibliometric analysis. RESULTS: The most productive country was the USA(n = 335), and the most productive institution was University of London in UK (n = 38). The most cited publication was the study by Ammar et al, (2020) (n = 188). In 2020, the most popular topics were PA and health meanwhile in 2021 behavior, lifestyle, social media and in 2022 habits, long COVID, sleep quality topics were in the foreground. Studies in 2023 focus on how COVID-19 affects PA habits and the associations between COVID-19-based anxiety and sleep patterns. These studies focused especially on effects of sport participation on life quality, diet, depression, mental health on young athletes, children, adolescent persons, older adult groups. CONCLUSIONS: An important gap in the study area is research on effect of changing lifestyle due to pandemic on individuals and the society during the Post COVID-19 period. If benefits of PA will not be limited to only physical benefits and psychological emotional, cognitive and social benefits are also taken into consideration, it is important that researchers conduct long-term and widescale observations.


Asunto(s)
COVID-19 , Adolescente , Niño , Humanos , Anciano , COVID-19/epidemiología , Síndrome Post Agudo de COVID-19 , Pandemias , Ejercicio Físico , Bibliometría
4.
Environ Sci Pollut Res Int ; 28(37): 52082-52092, 2021 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-33997933

RESUMEN

Many studies in the literature confirm the validity of the technique effect, which improves the quality of the environment by investigating whether an inverted U-shaped relationship exists between environmental pollution and economic growth. Ignoring the role of the technological obsolescence effect, which may also exert influence on an economy, these studies reach an optimistic conclusion for growth policies. By controlling renewable energy, this study examines the existence of the obsolescence effect by constructing an N-shaped relationship between economic growth and environmental degradation for the most vulnerable countries in the Mediterranean region to climate change. We conducted a battery of cross-sectional dependence tests, second-generation panel unit root, and cointegration tests in 17 selected Mediterranean countries covering 1990-2017. The results provide evidence of an N-shaped relationship between economic growth and environmental degradation. The study provides important policy recommendations and discusses how renewable energy can be deployed to reduce CO2 emissions.


Asunto(s)
Dióxido de Carbono , Energía Renovable , Dióxido de Carbono/análisis , Estudios Transversales , Desarrollo Económico , Región Mediterránea
5.
Structure ; 29(12): 1382-1396.e6, 2021 12 02.
Artículo en Inglés | MEDLINE | ID: mdl-34403647

RESUMEN

The COVID-19 pandemic has resulted in 198 million reported infections and more than 4 million deaths as of July 2021 (covid19.who.int). Research to identify effective therapies for COVID-19 includes: (1) designing a vaccine as future protection; (2) de novo drug discovery; and (3) identifying existing drugs to repurpose them as effective and immediate treatments. To assist in drug repurposing and design, we determine two apo structures of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) main protease at ambient temperature by serial femtosecond X-ray crystallography. We employ detailed molecular simulations of selected known main protease inhibitors with the structures and compare binding modes and energies. The combined structural and molecular modeling studies not only reveal the dynamics of small molecules targeting the main protease but also provide invaluable opportunities for drug repurposing and structure-based drug design strategies against SARS-CoV-2.


Asunto(s)
Tratamiento Farmacológico de COVID-19 , Proteasas 3C de Coronavirus/química , Diseño de Fármacos , Reposicionamiento de Medicamentos , SARS-CoV-2 , Dominio Catalítico , Simulación por Computador , Cristalografía por Rayos X , Dimerización , Conformación Molecular , Simulación del Acoplamiento Molecular , Análisis de Componente Principal , Conformación Proteica , Proteínas Recombinantes/química , Temperatura
6.
Oper Dent ; 34(3): 299-305, 2009.
Artículo en Inglés | MEDLINE | ID: mdl-19544819

RESUMEN

This in vitro study evaluated the effect of six different adhesive systems on the shear bond strength of resin composite to feldspathic and low-fusing porcelains. Sixty porcelain blocks were prepared for each low-fusing (Matchmaker) and feldspathic (MVK95) porcelain specimen. After surface preparation, the porcelain specimens were divided into six groups (n = 10) for different adhesive systems (Adper Prompt L-Pop, QuadrantUnil Bond, Te-Econom, PQ1, One-StepPlus and Prime&Bond NT). After adhesive application, a universal resin composite (FiltekZ250) was condensed on the specimens. The prepared specimens were then stored in distilled water at 37 degrees C for 24 hours, then all the samples were thermal cycled 1000 times between 5 degrees C and 55 degrees C. Shear testing was performed on a universal test machine using a crosshead speed of 0.5 mm/minute. The statistical analysis of the bond strength data included two-way ANOVA. Then, the means were compared by Tukey HSD test (alpha = 0.05). The lowest bond strength was observed in Adper Prompt L-Pop. No statistically significant difference was observed between One-Step Plus and Prime&Bond NT. The highest bond strength was observed in PQ1. When low-fusing or feldspathic porcelain restorations are repaired with resin composite, self-etching adhesive systems may not be indicated. If maximum bond strength is the goal in porcelain resin bonding, adhesive systems that have a high filler ratio should be used.


Asunto(s)
Resinas Compuestas/química , Recubrimiento Dental Adhesivo , Cementos Dentales/química , Materiales Dentales/química , Porcelana Dental/química , Silicatos de Aluminio/química , Análisis del Estrés Dental/instrumentación , Recubrimientos Dentinarios/química , Humanos , Ensayo de Materiales , Ácidos Polimetacrílicos/química , Compuestos de Potasio/química , Cementos de Resina/química , Resistencia al Corte , Estrés Mecánico , Propiedades de Superficie , Temperatura , Factores de Tiempo , Agua/química
7.
Sports (Basel) ; 7(2)2019 Feb 25.
Artículo en Inglés | MEDLINE | ID: mdl-30823528

RESUMEN

Debates about the conditions in which the frequency and intensity principles of regular exercise, depending on the fact that a sports background can be accepted as extremism, are still a controversial topic. The purpose of this research was to investigate the exercise dependence of athletes who practice Kickboxing, Taekwondo, and Muay Thai. The study included 141 athletes, consisting of 87 men and 54 women. The Exercise Dependence Scale-21 (EDS-21), composed of 21 items developed by Hausenblas and Downs and adapted into the Turkish version by Yeltepe and Ikizler, was applied to the athletes. As a result of the research, while athletes showed more sensitivity to the EDS (=71.41), this scale was also defined as symptomatic. It was found that five athletes (3.5%) were asymptomatic-nondependent, 117 athletes (83.0%) were symptomatic-nondependent, and 19 athletes (13.5%) were at risk for exercise dependence. It was determined that athletes were at risk for exercise dependence as follows: Eight athletes were doing Kickboxing, ten athletes were doing Taekwondo, and one athlete was doing Muay Thai. A significant difference was observed according to years of regular training and number of trainings per a day. Other variables presented no significant differences. It was possible to say that years of regular training could be effective in revealing exercise dependence.

8.
Environ Sci Pollut Res Int ; 25(36): 36589-36603, 2018 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-30377957

RESUMEN

This study examines the impact of economic growth, energy consumption, trade openness, financial development on carbon emissions for the case of Turkey by using annual time series data for the period of 1960-2013. The Lee and Strazicich test suggests that the variables are suitable for applying the bounds testing approach to cointegration. The cointegration analysis reveals that there exists a long-run relationship between the per capita real income, per capita energy consumption, trade openness, financial development, and per capita carbon emissions in the presence of structural breaks. The results show that in the long run, carbon emissions are mainly determined by economic growth, energy consumption, trade openness, and financial development. The VECM Granger causality analysis indicates a long-run unidirectional causality running from economic growth, energy consumption, trade openness, and financial development to carbon emissions. The findings also show that the EKC hypothesis is valid for Turkey both in the long run and short run. The study provides some implications for policy makers to decrease carbon emissions in Turkey.


Asunto(s)
Dióxido de Carbono/análisis , Comercio/economía , Conservación de los Recursos Energéticos/economía , Desarrollo Económico , Renta , Turquía
9.
J Ethnopharmacol ; 196: 236-241, 2017 Jan 20.
Artículo en Inglés | MEDLINE | ID: mdl-28011162

RESUMEN

ETHNOPHARMACOLOGICAL RELEVANCE: Topical formulations such as oily extracts or ointments prepared with the flowering aerial parts of St. John's wort (Hypericum perforatum L., Hypericaceae) have been used in the management of a wide range dermatological problems including superficial wounds and burns, bruises, contusions and many others in the worldwide traditional medicines. AIM OF THE STUDY: This is the first case study reporting the beneficial effects of an oily extract of St. John's wort in the treatment of pressure sores in a intensive care unit (ICU) patient. MATERIAL AND METHODS: The oily extract of St. John's wort was applied to a volunteer patient at ICU daily for forty successive days for wound care and treatment. Healing status was monitored macroscopically by measuring the wound size and stages at certain intervals as well as histopathological evaluation of the tissue sections taken at the initial and final dates of treatment. RESULTS: Evaluation of the results obtained from the macroscopical and histopathological experimentation have shown that oily extract of St. John's wort provided significant efficacy for the treatment of pressure sore wounds. CONCLUSION: St. John's wort oily extract may be suggested as a cost-effective option for the prevention or treatment of pressure sores in ICU patients.


Asunto(s)
Hypericum , Fitoterapia , Extractos Vegetales/uso terapéutico , Aceites de Plantas/uso terapéutico , Úlcera por Presión/tratamiento farmacológico , Anciano de 80 o más Años , Humanos , Masculino , Componentes Aéreos de las Plantas , Úlcera por Presión/patología , Piel/efectos de los fármacos , Piel/patología
10.
J Endod ; 32(12): 1214-6, 2006 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-17174686

RESUMEN

The purpose of this case presentation is to describe nonsurgical retreatment of anterior teeth with gemination. A 21-year-old male patient was referred for endodontic treatment of his maxillary left lateral incisor. In the clinical examination, a large crown was observed in the left maxillary incisor region when compared with the right maxillary lateral incisor. In the present case, a tooth gemination of a maxillary lateral incisor has been described. A periapical radiograph showed that the tooth had partially separated two crowns having a single root and one root canal, but the access cavity of the distal crown had not been opened, and the root canal had been obturated with single cone technique. Nonsurgical endodontic retreatment was decided for geminated lateral incisor. At the 6-month follow-up, the tooth was asymptomatic and there was no radiolucency around the apical region.


Asunto(s)
Dientes Fusionados/terapia , Incisivo/anomalías , Tratamiento del Conducto Radicular/métodos , Adulto , Humanos , Masculino , Maxilar , Retratamiento
11.
J Endod ; 32(9): 890-3, 2006 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-16934636

RESUMEN

The aim of this study was to compare bacterial penetration after obturation with lateral compaction technique using four different root canal sealers. This study was performed on 100 teeth including negative control (n = 10), positive control (n = 10), and experimental groups (n = 80). 80 teeth were randomly divided into five groups of 20 teeth each and obturated with AH 26 (A), AH Plus (AP), Sealapex (S), Ketac-Endo (K) root canal sealers. Evaluation was carried out for 60 days. After 30 days of comparing the bacterial penetration values, total penetration was observed in 85% of the Group AP, and group K, 80% of the group S, and 75% of the group A. According to the results of chi(2) test, there was no statistically significant difference observed between any groups (p > 0.05). After 60 days of comparing the bacterial penetration values, total penetration was observed in 100% of the group AP, group K, and group S and 95% of the group A. It may be concluded that under the conditions of this study, there was no difference in the bacterial penetration of the four root canal sealers tested at 30 and 60 days.


Asunto(s)
Filtración Dental , Materiales de Obturación del Conducto Radicular , Distribución de Chi-Cuadrado , Recuento de Colonia Microbiana , Enterococcus faecalis/aislamiento & purificación , Humanos , Ensayo de Materiales
12.
Dent Mater J ; 25(4): 713-8, 2006 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-17338305

RESUMEN

The purpose of this study was to examine the effect of thermal cycling on microleakage of a fissure sealant after it was bonded with different bonding agents and polymerized with different light curing units. To this end, two bonding agents (Xeno III, iBond), three light curing units (Astralis 3, Elipar free-light, Elipar free-light 2), and a fissure sealant (Fissurit FX) were used. Microleakage was then evaluated using a dye penetration method after thermal cycling. When the fissure sealant was polymerized with Elipar free-light and Elipar free-light 2, microleakage at 10,000 cycles was significantly increased compared with that at 5,000 cycles. In terms of comparison among the curing units, the best microleakage score was observed with Astralis 3 (p<0.05). In terms of comparison between the two bonding agents, no significant differences in microleakage score were observed (p>0.05). Further, it was concluded that in order to evaluate microleakage scores appropriately, it was necessary for specimens to be subjected to thermocycling of 10,000 times or more.


Asunto(s)
Recubrimiento Dental Adhesivo , Filtración Dental , Selladores de Fosas y Fisuras , Filtración Dental/diagnóstico , Filtración Dental/prevención & control , Análisis del Estrés Dental , Recubrimientos Dentinarios , Calor , Humanos , Luz , Ensayo de Materiales , Metacrilatos , Tercer Molar , Transición de Fase , Cementos de Resina , Estadísticas no Paramétricas
13.
Dent Mater J ; 25(2): 371-6, 2006 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-16916243

RESUMEN

The purpose of this study was to evaluate the discoloration of two nanohybrids, two microhybrids, and a posterior composite resin restorative material upon exposure to different drinks--namely tea, cola, coffee, red wine, and water. The colors of all specimens before and after storage in the solutions were measured by a colorimeter based on CIE Lab system, and the color differences thereby calculated. Data were analyzed by two-way analysis of variance (ANOVA) and Tukey's HSD test. According to ANOVA, the restorative material, staining agent, and their interaction were found to play a statistically significant role (P = 0.0001) in color change. Among the staining agents, water consistently showed the lowest deltaE* value for all materials, whereas red wine showed the highest deltaE* value. In other words, for all the materials tested, their color change in staining agents ranked in this increasing order: water < cola < tea < coffee < red wine. In terms of comparison among the five restorative materials, Filtek P60 and Z250 were observed to manifest less color change than the nanohybrids and Quadrant LC.


Asunto(s)
Bebidas , Color , Resinas Compuestas , Café , Cola , Colorimetría , Resinas Compuestas/química , Restauración Dental Permanente , Tamaño de la Partícula , Polietilenglicoles/química , Ácidos Polimetacrílicos/química , , Agua , Vino
14.
Agri ; 28(4): 183-189, 2016 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-28111731

RESUMEN

OBJECTIVES: The present study sought to compare the analgesic efficacy and adverse effects of intravenous (IV) lornoxicam and tramadol to investigate if lornoxicam is a reasonable alternative to a weak opioid for post-thyroidectomy pain. METHODS: Fifty patients of American Society of Anesthesiologists class I or II, 18 to 65 years of age, and who underwent thyroidectomy were assigned to 2 groups in a randomized manner. Group L received 8 mg of lornoxicam IV and Group T received 1 mg/kg of tramadol IV at conclusion of the operation. Pain intensity of patients was recorded at 15 and 30 minutes, and at 1, 2, 3, 4, 6, 12, and 24 hours after the initial dose with Numerical Rating Scale (NRS) and Ramsey Sedation Scale. Electrocardiogram, heart rate, systolic/diastolic and average artery pressure and peripheral oxygen saturations were monitored continuously during this period. Patients completed satisfaction questionnaires at 24th hour. RESULTS: Both drugs produced acceptable analgesia; however, significantly fewer patients reported 1 or more adverse events with lornoxicam than with tramadol. Most commonly seen in Group T was nausea/vomiting. NRS scores at 15 minutes, 30 minutes, and 1 hour were lower in Group L than in Group T (p<0.05), but there was no significant difference between groups after postoperative first hour. First analgesic requirement time was significantly longer in Group L compared to Group T (p<0.001). No serious complications were seen in either group. CONCLUSION: Lornoxicam is a safe and effective analgesic that may be used with fewer complications than low-dose tramadol for treatment of moderate to severe postoperative pain.


Asunto(s)
Analgésicos/uso terapéutico , Dolor Postoperatorio/prevención & control , Piroxicam/análogos & derivados , Tiroidectomía , Tramadol/uso terapéutico , Adolescente , Adulto , Anciano , Analgésicos/administración & dosificación , Femenino , Humanos , Infusiones Intravenosas , Masculino , Persona de Mediana Edad , Piroxicam/administración & dosificación , Piroxicam/uso terapéutico , Encuestas y Cuestionarios , Tramadol/administración & dosificación , Resultado del Tratamiento , Adulto Joven
15.
Am J Ophthalmol ; 138(3): 381-8, 2004 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-15364219

RESUMEN

PURPOSE: To describe the effect of coupling solutions used during laser photocoagulation on the ocular surface of patients with noninsulin-dependent diabetes mellitus (NIDDM). DESIGN: A prospective case-controlled study. METHODS: Ninety-two eyes of 46 NIDDM patients with clinically significant macular edema, poor metabolic control of diabetes, and peripheral neuropathy and 100 eyes of 50 normal control subjects were studied. The patients' eyes were assigned to argon green focal/grid laser photocoagulation using an applanation contact lens and one of the coupling fluids; 2% methocel, Thilo-Tears Gel, 1.4% sodium hyaluronate, or 0.9% simple saline. The control subjects received time-matched three-mirror contact lens fundus examinations. All subjects underwent corneal sensitivity measurements, Schirmer test, tear film breakup time, and corneal fluorescein staining before as well as 3 and 8 days after the laser procedures and contact lens examinations. Patients with corneal problems persisting after 8 days were followed longer. RESULTS: Diabetic eyes assigned to 2% methocel and 1.4% sodium hyaluronate had significantly lower mean corneal sensitivities and break-up time values as well as significantly higher mean fluorescein staining scores at all examination points after laser photocoagulation. All diabetic eyes with aqueous deficiency assigned to 2% methocel and 1.4% sodium hyaluronate developed delayed corneal epithelial healing. CONCLUSION: The use of viscous coupling solutions during applanation contact lens-aided laser procedures may be detrimental for the corneal epithelium in poorly controlled NIDDM patients with peripheral neuropathy and coexisting aqueous deficiency.


Asunto(s)
Lentes de Contacto , Enfermedades de la Córnea/inducido químicamente , Diabetes Mellitus Tipo 2/cirugía , Ácido Hialurónico/efectos adversos , Coagulación con Láser , Metilcelulosa/efectos adversos , Adulto , Anciano , Estudios de Casos y Controles , Enfermedades de la Córnea/metabolismo , Enfermedades de la Córnea/fisiopatología , Diabetes Mellitus Tipo 2/complicaciones , Retinopatía Diabética/etiología , Retinopatía Diabética/cirugía , Epitelio Corneal/efectos de los fármacos , Epitelio Corneal/metabolismo , Epitelio Corneal/fisiopatología , Femenino , Fluoresceína/metabolismo , Fluorofotometría , Humanos , Edema Macular/etiología , Edema Macular/cirugía , Masculino , Persona de Mediana Edad , Soluciones Oftálmicas/efectos adversos , Estudios Prospectivos , Lágrimas/fisiología , Cicatrización de Heridas/efectos de los fármacos
16.
Aust Endod J ; 39(3): 116-21, 2013 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-24279657

RESUMEN

The aim of this study was to compare new irrigation systems with a conventional irrigation technique for the removal of inter-appointment calcium hydroxide [Ca(OH)2 ]. Forty-seven extracted human single-rooted teeth were instrumented, and Ca(OH)2 paste was placed into root canals by using a lentulo spiral at the apical third. Teeth were randomly divided into three groups according to different irrigation protocols using a 30-gauge slot-tipped needle, EndoVac system and ProUltra® PiezoFlow™ ultrasonic irrigation system. Scanning electron microscopic images of the selected root canal surfaces (cervical, middle and apical third) were evaluated using a 5-grade scale. The influence of the irrigation system was evaluated using a two-way analysis of variance test and Tukey's test. The EndoVac and PiezoFlow groups demonstrated the lowest scale values (cleanest canals); however, there was no statistical difference between these two groups. The conventional irrigation group exhibited significantly higher scores (P < 0.05). The conventional needle irrigation was not sufficient to remove Ca(OH)2 from the root canal system. Irrigation with EndoVac and PiezoFlow™ ultrasonic irrigation systems improved the removal of the intracanal medicament resulting in cleaner root canal walls.


Asunto(s)
Hidróxido de Calcio/química , Materiales de Obturación del Conducto Radicular/química , Irrigantes del Conducto Radicular/química , Preparación del Conducto Radicular/métodos , Irrigación Terapéutica/métodos , Cavidad Pulpar/ultraestructura , Humanos , Ensayo de Materiales , Microscopía Electrónica de Rastreo , Agujas , Preparación del Conducto Radicular/instrumentación , Propiedades de Superficie , Irrigación Terapéutica/instrumentación , Ápice del Diente/ultraestructura , Cuello del Diente/ultraestructura , Ultrasonido/instrumentación , Vacio
17.
Braz Oral Res ; 27(4): 299-304, 2013.
Artículo en Inglés | MEDLINE | ID: mdl-23903858

RESUMEN

We investigated the effect of sodium ascorbate (SA) on the microtensile bond strengths (MTBSs) of different composites to bovine enamel after vital bleaching with hydrogen peroxide (HP) or carbamide peroxide (CP). Thirty bovine incisors were randomly divided into five groups and treated with no bleaching application (control), 35% HP alone, 35% HP+10% SA for 10 minutes (HP+SA), 16% CP alone, or 16% CP+10% SA for 10 minutes (CP+SA). Specimens were restored with Silorane adhesive and Filtek Silorane composite (designated as S/group) or with Clearfil SE bond and Filtek Supreme XT (designated as F/group). Composite build-up was created on the enamel. Sectioned specimens (n=10 per group; 1 mm2; cross-sectional area) were created and stressed in a universal testing machine at 1 mm/min crosshead speed. The application of 10% SA immediately after bleaching with 16% CP or 35% HP increased the enamel MTBS, regardless of the adhesive/composite resin used. The resulting MTBS values were similar to those of the control groups. Use of 16% CP and 35% HP alone decreased the enamel MTBS, regardless of the adhesive/composite resin used, with F/CP+SA=F/HP+SA=F/CP=S/CP+SA=S/HP+SA=S/C>S/CP=S/HP=F/CP=F/HP (p<0.05). We concluded that the application of SA for 10 minutes immediately after vital bleaching increases the enamel BS for dimethacrylate- and silorane-based composites.


Asunto(s)
Antioxidantes/farmacología , Ácido Ascórbico/farmacología , Resinas Compuestas/química , Recubrimiento Dental Adhesivo/métodos , Metacrilatos/química , Resinas de Silorano/química , Blanqueamiento de Dientes/métodos , Animales , Peróxido de Carbamida , Bovinos , Esmalte Dental/química , Esmalte Dental/efectos de los fármacos , Recubrimientos Dentinarios/química , Peróxido de Hidrógeno/química , Ensayo de Materiales , Peróxidos/química , Cementos de Resina/química , Propiedades de Superficie/efectos de los fármacos , Resistencia a la Tracción/efectos de los fármacos , Urea/análogos & derivados , Urea/química
18.
J Appl Oral Sci ; 19(5): 505-10, 2011 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-21922122

RESUMEN

OBJECTIVES: The purpose of this study was to investigate the effect of different air-polishing powders on the color stability of different types of composite resin restorative materials. MATERIAL AND METHODS: Thirty cylindrical specimens (15×2 mm) were prepared for each of 7 composite resin restorative materials. All specimens were polished with a series of aluminum oxide polishing discs (Sof-Lex). The prepared specimens of each composite resin were randomly divided into 3 groups of 10 specimens each, for control (Group-C) and two air-powder applications (Group-CP: Cavitron Prophy-Jet; Group-PS: Sirona ProSmile prophylaxis powder). A standard air-polishing unit (ProSmile Handly) was used. All specimens were air-powdered for 10 s at 4-bar pressure. The distance of the spray nosel from the specimens was approximately 10 mm and angulation of the nosel was 90°. Specimens were stored in 100 mL of coffee (Nescafe Classic) for 24 h at 37°C. Color measurement of all specimens was recorded before and after exposure to staining agent with a colorimeter (Minolta CR-300). Color differences (∆E*) between the 2 color measurements (baseline and after 24 h storage) were calculated. The data were analyzed with a 2-way ANOVA test, and mean values were compared by the Tukey HSD test (p<0.05). RESULTS: According to the 2-way ANOVA results, composite resin restorative materials, air-polishing powders, and their interaction were statistically significant (p<0.05) For Aelite Aesthetic Enemal, Filtek Z250, Grandio, CeramX Mono, and Quixfil composite resin restorative materials, no significant difference was observed between Group-PS and Group-CP (p>.05) and these groups demonstrated the highest ∆E* values. For Filtek Silorane and IntenS, the highest ∆E* values were observed in Group-PS. The lowest ∆E* values for all composite resin groups were observed in Group-C. When comparing the 7 composite resin restorative materials, Aelite Aesthetic Enemal demonstrated significantly less ∆E* values than the other composite resins tested. The highest ∆E* values were observed in Quixfil. CONCLUSION: Except for Quixfil, all control groups of composite resins that were polished Sof-Lex exhibited clinically acceptable ∆E values (<3.7). Air-polishing applications increased the color change for all composite resin restorative materials tested. Composite restorations may require re-polishing after air-polishing.


Asunto(s)
Color , Resinas Compuestas/química , Pulido Dental/métodos , Presión del Aire , Óxido de Aluminio/química , Análisis de Varianza , Colorimetría , Ensayo de Materiales , Polvos , Coloración de Prótesis , Distribución Aleatoria , Propiedades de Superficie , Factores de Tiempo
20.
J Appl Oral Sci ; 17(2): 108-12, 2009.
Artículo en Inglés | MEDLINE | ID: mdl-19274395

RESUMEN

The purpose of this study was to investigate the effect of different polishing methods on color stability of posterior, universal and nanohybrid composite resin restorative materials upon exposure to a staining agent. Twenty-five specimens were prepared for each of 5 different composite resins (Filtek Z250, Filtek P60, Quadrant LC, Grandio and Filtek Supreme). Specimens were divided into 5 groups and different polishing procedures, including polishing discs (Pd), polishing discs then diamond polishing paste (PdP), polishing discs then a liquid polishing system (Biscover) (PdB), and combinations of these (PdPB) were used. Unpolished specimens served as the control (C). The specimens were stored for 48 h in a coffee solution. The color of all specimens was measured before and after exposure with a colorimeter, and total color change (DeltaE*) were calculated. The data were analyzed with a two-way ANOVA and the means were compared by Tukey HSD test (alpha=0.05). The lowest color difference was observed in the groups PdP and C, while the highest color difference was observed in PdPB, and PdB. When comparing the five different restorative materials, no significant difference was observed between FiltekP60 and FiltekZ250, and these materials demonstrated significantly less color change than Quadrant LC and the nanohybrid materials (Grandio, Filtek Supreme). The posterior (Filtek P60) and universal (Filtek Z250) composite resin restorative materials, which do not contain tetraethyleneglycol dimethacrylate (TEGDMA), were found to be less stainable than the nanohybrid (Grandio, Filtek Supreme) and universal (Quadrant LC) composite resins, which contain TEGDMA. The use of diamond polishing paste after polishing with polishing discs significantly decreased staining when compared to the groups that used polishing discs alone, for all restorative materials tested. The highest color change values were obtained for the specimens that were polished with the Biscover liquid polish system (PdB and PdPB groups).


Asunto(s)
Resinas Compuestas , Pulido Dental , Color , Colorimetría , Resinas Compuestas/química , Ensayo de Materiales , Nanocompuestos , Tamaño de la Partícula
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA