1,720,994 research outputs found
Nanoleakage and marginal quality of direct composite veneering system for cervical fillings.
Full text linkAim of this study was to evaluate the marginal adaptation and nanoleakage in class V bonded restorations before and after thermo- mechanical loading using Componeer Class V (CCV) compared to con- ventional composites. The null-hypothesis tested was that marginal adap- tation and nanoleakage of CCV was not significantly different compared to conventional composites before and after thermo-mechanical loading. Standardized Class V cavities (width 2.0mm, length 3.0mm, depth 1.5mm) were created in 40 human premolars and molars at the cement- enamel junction. Cavity dimensions were standardized using a digital caliper. Teeth were divided in four groups (N=10): Group 1 One- coat- Bond-Self-etching bonding agent with Synergy-D6+CCV (Coltene); Group 2 One- coat-Bond-Self-etching bonding agent Synergy-D6- flow+CCV (Coltene), Group 3 Scotchbond Universal adhesive system with Filtek-Supreme-XTE (3M ESPE); (Group 4) Scotchbond Universal adhesive system with Filtek-Supreme-XTE-flow (3M ESPE). Restorations were placed according to manufacturers’ instructions. Marginal quality was analyzed under a SEM using epoxy resin replicas before and after thermo-mechanical loading (240,000 mechanical cycles x 50N with a frequency of 1HZ and 7800 thermo-cycles between 5° and 55C° with chewing simulator CS4-Mechatronik). Data were statistically analyzed by two-way ANOVA and Tukey’s post-hoc test (α=0.05).Specimens were then processed to investigate nanoleakage expression under SEM.
The null hypothesis was partially accepted since no significant statistical differences were found in marginal adaptation with CCV compared to mar- gins obtained with conventional composite both before and after thermo- mechanical cycling (p>0.05). Conversely the nanoleakage analysis showed only significant differences between group 1 and group 4 (p<0.05).
The marginal quality of class V cavities restored with CCV was similar to conventional composite restorations, both before and after thermo- mechanical cycling. Nanoleakage expression was dependent on the restor- ative material type. Further clinical research is essential to confirm that composite shells for direct veneering can be a valid restorative procedure
Estado actual de institucionalización y regulación de la evaluación y gestión ambiental de las obras de transporte en Argentina
Full text linkLa incorporación de la componente ambiental en las obras de transporte en Argentina se ha dado en las últimas décadas del siglo XX, con un desarrollo heterogéneo según el medio del que se trate. En ese sentido se destaca el estudio de las relaciones causales (planteadas generalmente en términos de "impactos") del transporte sobre el ambiente. Su ejemplo más concreto está dado por las Evaluaciones de Impacto Ambiental, entendidas como herramientas jurídico-administrativas basadas en informes técnicos, como los Estudios de Impacto Ambiental. Se presenta el estado de situación de la consideración de la dimensión ambiental en la evaluación y gestión de proyectos y construcción de obras de infraestructura para los distintos medios de transporte en la Argentina, a través del marco institucional y normativo ambiental vinculado a cada medio de transporte, acompañado por un conjunto de estudios de caso.Fil: Daniele, Claudio. Universidad de Buenos Aires. Facultad de Filosofía y Letras. Departamento e Instituto de Geografía; Argentina.Fil: Mereb, Juan Francisco. Universidad de Buenos Aires. Facultad de Filosofía y Letras. Departamento de Geografía; Argentina.Fil: Frassetto, Andrea. Universidad de Buenos Aires. Facultad de Filosofía y Letras. Departamento e Instituto de Geografía; Argentina.Fil: Pérez, Jimena. Aves Argentinas. Carrera de Naturalista de Campo e Intérprete de la Naturaleza; Argentina
Influence of Chewing Simulation on the Bond-Strengths of Self-Etch/Self-Adhesive Cements.
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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