Effect of Additional Dry Heat Curing on Microflexural Strength in Three Types of Resin Composite: An In Vitro Study

Aim: Additional dry heat curing is a method that favorably influences the mechanical properties of an indirect resin composite restoration. Microflexural strength is a property currently applied for the evaluation of indirect resin composite restorations. The aim of the present study was to assess the effect of additional dry heat curing on microflexural strength in three types of direct-use resin composites. Materials and Methods: This in vitro study consisted of 70 resin composites samples made with a 6 × 2 × 1 mm metal matrix and divided into seven experimental groups, which included Gr1a: Tetric N-Ceram without additional dry heat curing (n = 10); Gr1b: Tetric N-Ceram with additional dry heat curing (n = 10); Gr 2a: Filtek Z350 XT without additional dry heat curing (n = 10); Gr2b: Filtek Z350 XT with additional dry heat curing (n = 10); Gr3a: Filtek Z250 without additional dry heat curing (n = 10); Gr3b: Filtek Z250 with additional dry heat curing (n = 10); and Gr4: SR Nexco Paste (control) without additional dry heat curing (n = 10). The samples were stored in distilled water at 37 °C for 24 h. A universal testing machine with a 2000 N load cell at a speed of 1 mm/min was used to assess flexural strength. The data were analyzed with a parametric ANOVA test with Tukey’s post hoc intergroup factor (for groups without heat treatment) and a nonparametric Kruskall Wallis test with Bonferroni’s post hoc (for groups with heat treatment). In addition, the comparison of independent groups in each resin composite type with and without heat treatment was performed with a Mann Whitney U test. A significance level of p < 0.05 was considered. Results: The Filtek Z250 resin composite with and without additional dry heat curing presented the highest microflexural strength values with 137.27 ± 24.43 MPa and 121.32 ± 9.74 MPa, respectively, while the SR Nexco Paste (control) resin composite presented the lowest microflexural strength values with 86.06 ± 14.34 MPa compared to all the resin composites with additional dry heat curing. The Filtek Z250 and Filtek Z350XT resin composites with and without additional dry heat curing presented significantly higher microflexural strength versus the SR Nexco (p < 0.05) and Tetric N-Ceram (p < 0.05) resin composites. In addition, the Filtek Z350XT and Tetric N-Ceram resin composites with additional dry heat curing showed significantly higher microflexural strength (p < 0.05) compared to those without additional dry heat curing. Conclusions: The Filtek Z250 and Z350XT resin composites had significantly higher microflexural strength values with and without additional dry heat curing. In addition, the Filtek Z350XT and Tetric N-Ceram resin composites subjected to additional dry heat curing showed significantly higher microflexural strength compared to when they did not receive the same procedure, a situation that did not occur with the Filtek Z250 resin composite.Revisión por pare

Evaluation of the mechanical properties of bricks made with glass and plastic waste. Analysis of carbon dioxide emissions

El uso de desechos no biodegradables como el vidrio y el plástico en la industria de la construcción ha recibido atención significativa para un medio ambiente más limpio. Este trabajo presenta un estudio de las propiedades mecánicas de ladrillos que contienen agregados, vidrio y pellets de tereftalato de polietileno. Los ladrillos se fundieron  a 240 °C durante 3 horas y se enfriaron por convección natural. Los resultados mostraron que un aumento en el contenido de vidrio y agregados genera un incremento en la densidad, que es superior en las muestras con mayor contenido de agregados. La misma tendencia se observó en la resistencia a la compresión: la muestra con mayor contenido de agregados mostró una mejora del 243 % comparada con la referencia (preparada solo con plástico). Los resultados indicaron que las emisiones de dióxido de carbono disminuyeron alrededor del 30 % en las muestras preparadas, en comparación con los ladrillos tradicionales. Se espera que el uso de residuos de plástico y vidrio en la producción de ladrillos se convierta en una ruta para su valorización.The use of non-biodegradable waste such as glass and plastic in the construction industry has received significant attention for a cleaner environment. This work presents a study of bricks’; mechanical properties containing aggregates, glass, and polyethylene terephthalate pellets. The bricks were melted at a temperature up to 240 ° C for 3 hours and cooled by natural convection. The results showed that an increase in the content of glass and aggregates generates an increase in density, being higher in the samples with a higher aggregates content. The same trend was observed in compressive strength. The sample with the highest aggregates’; content showed an improvement of 243% compared to the reference (preparedonly with plastic). The results indicated that carbon dioxide emissions decreased by around 30% in the prepared samples, compared to traditional bricks. The use of plastic and glass waste in brick production is expected to become a recovery route

Dibujo Asistido Por El Computador-CI161-201502

Curso de especialidad en la carrera de Ingeniería Civil de carácter teórico-práctico dirigido a los estudiantes del 1er. ciclo que busca desarrollar la competencia general de Manejo de la Información y la competencia especifica K de ABET:Utiliza las técnicas habilidades herramientas modernas de ingeniería necesarias en la práctica de la ingeniería civil. El dibujo en ingeniería es un medio importante de comunicación entre ingenieros técnicos y profesionales que participan en el diseño y la producción. El propósito del diseño en ingeniería es preparar un plan para la transformación de conceptos e ideas en productos concretos y tangibles usando recursos disponibles. El dibujo en ingeniería es el lenguaje común entre los ingenieros pues plasma a través de los planos la asignación de responsabilidades entre diseñadores propietarios y contratistas que implementan el diseño permitiendo la solución de problemas.El dibujo de ingeniería es la representación gráfica detallada de una idea. El lenguaje gráfico es importante en la ingeniería pues permite plasmar en un dibujo de manera ordenada y detallada proyectos de toda índole y gran complejidad.Es muy importante para los profesionales de ingeniería ser capaces de producir planos de ingeniería a nivel profesional y ser capaz de leer e interpretar correctamente los planos de ingeniería y la documentación producida por otros profesionales que participan en el diseño

Unidades de mampostería elaboradas con plástico reciclado, vidrio y arena

En muchos países del mundo, los residuos de plásticos de baja densidad, específicamente el PET (Polyethylene terephthalate) y el vidrio, son un problema, dado que no existen sistemas locales de recolección, gestión y reciclaje. Como resultado, el PET y el vidrio de desecho no tienen valor económico agregado y se deja de lado causando problemas estéticos, ambientales y de salud pública. La elaboración de bloques de mampostería, a partir de arena y PET se convierte en una alternativa de gestión de residuos. En este trabajo se presentan los resultados de la preparación de bloques a partir de PET reciclado, arena y vidrio reciclado. Se prepararon bloques prismáticos a partir de mezclas de estos tres componentes, con diferentes relaciones de arena y vidrio reciclado. Las propiedades de los especímenes se evaluaron mediante la densidad, la resistencia a la compresión y el módulo de elasticidad. De los resultados experimentales, se encontró que la adición de vidrio y de arena, modifica las propiedades mecánicas de los bloques. Se encontró que la densidad y la resistencia a la compresión aumentan con la incorporación de vidrio y de arena. El material preparado con un mayor contenido de vidrio presentó una mayor resistencia a la compresión (30.5 MPa). Los resultados encontrados muestran el potencial de este tipo de materiales como una tecnología de gestión de residuos, en la implementación de estudios adicionales, por ejemplo, el estudio del módulo de elasticidad de forma [email protected]@[email protected]@campusucc.edu.c

Sociodemographic factors associated with the level of knowledge about management of epileptic patients in Peruvian dental students: a cross-sectional study under a multivariable analysis

Background: Epilepsy is a chronic neurological disease that could indirectly affect oral health, and it is necessary for dentists to be familiar with the specific needs of patients with epilepsy. Therefore, aim of the present study was to assess the factors associated with the level of knowledge about management of epileptic patients in Peruvian dental students. Methods: This analytical, observational, cross-sectional and prospective study assessed 312 dental students from a Peruvian university during February to April 2022. A validated questionnaire of 20 closed multiple-choice questions was used to measure the level of knowledge about dental management in epileptic patients. A logit model was used to assess the influence of variables: gender, age, year of study, marital status, place of origin and area of residence, with the level of knowledge in dental students considering a significance level of p 0.05). Conclusion: Most of the students showed a poor and fair level of knowledge about the dental management of epileptic patients, with gender, academic year and place of origin being influential factors. It is advisable that authorities and teachers in the dental profession organize recurrent training programs on the care of patients with chronic diseases requiring special attention, since knowing general concepts, pharmacological management and dental care of epileptic patients will allow future dentists to develop competencies to improve and implement good quality care protocols for this group of patients.Revisión por pare

Evaluación de las propiedades mecánicas de ladrillos elaborados con residuos de vidrio y plástico. Análisis de las emisiones de dióxido de carbono

The use of non-biodegradable waste such as glass and plastic in the construction industry has received significant attention for a cleaner environment. This work presents a study of bricks’; mechanical properties containing aggregates, glass, and polyethylene terephthalate pellets. The bricks were melted at a temperature up to 240 ° C for 3 hours and cooled by natural convection. The results showed that an increase in the content of glass and aggregates generates an increase in density, being higher in the samples with a higher aggregates content. The same trend was observed in compressive strength. The sample with the highest aggregates’; content showed an improvement of 243% compared to the reference (prepared only with plastic). The results indicated that carbon dioxide emissions decreased by around 30% in the prepared samples, compared to traditional bricks. The use of plastic and glass waste in brick production is expected to become a recovery route.El uso de desechos no biodegradables como el vidrio y el plástico en la industria de la construcción ha recibido atención significativa para un medio ambiente más limpio. Este trabajo presenta un estudio de las propiedades mecánicas de ladrillos que contienen agregados, vidrio y pellets de tereftalato de polietileno. Los ladrillos se fundieron a 240 °C durante 3 horas y se enfriaron por convección natural. Los resultados mostraron que un aumento en el contenido de vidrio y agregados genera un incremento en la densidad, que es superior en las muestras con mayor contenido de agregados. La misma tendencia se observó en la resistencia a la compresión: la muestra con mayor contenido de agregados mostró una mejora del 243 % comparada con la referencia (preparada solo con plástico). Los resultados indicaron que las emisiones de dióxido de carbono disminuyeron alrededor del 30 % en las muestras preparadas, en comparación con los ladrillos tradicionales. Se espera que el uso de residuos de plástico y vidrio en la producción de ladrillos se convierta en una ruta para su valorizació

Effect of 16% Carbamide Peroxide and Activated-Charcoal-Based Whitening Toothpaste on Enamel Surface Roughness in Bovine Teeth: An In Vitro Study

Background: Activated charcoal is a nanocrystalline form of carbon with a large specific surface area and high porosity in the nanometer range, having consequently the capacity to absorb pigments, chromophores, and stains responsible for tooth color change, while carbamide peroxide is unstable and breaks down immediately upon contact with tissue and saliva, first dissociating into hydrogen peroxide and urea and subsequently into oxygen, water, and carbon dioxide. Therefore, the aim of the present study was to assess the effect of 16% carbamide peroxide and activated-charcoal-based whitening toothpaste on enamel surface roughness in bovine teeth. Materials and Methods: The present experimental in vitro, longitudinal, and prospective study consisted of 60 teeth randomly distributed in six groups: A: artificial saliva, B: conventional toothpaste (Colgate Maximum Protection), C: whitening toothpaste with activated charcoal (Oral-B 3D White Mineral Clear), D: 16% carbamide peroxide (Whiteness Perfect 16%), E: 16% carbamide peroxide plus conventional toothpaste (Whiteness Perfect 16% plus Colgate Maximum Protection), and F: 16% carbamide peroxide plus whitening toothpaste with activated charcoal (Whiteness Perfect 16% plus Oral-B 3D White Mineral Clear). Surface roughness was assessed with a digital roughness meter before and after each treatment. For the statistical analysis, Student’s t test for related samples was used, in addition to the ANOVA test for one intergroup factor, considering a significance level of p p = 0.041), whitening toothpaste with activated charcoal (p = 0.001), and 16% carbamide peroxide plus whitening toothpaste with activated charcoal (p = 0.002) significantly increased their surface roughness values. On the other hand, significant differences were observed when comparing the variation in surface roughness between the application of artificial saliva (control) and the whitening toothpaste with activated charcoal (p = 0.031), and the 16% carbamide peroxide plus whitening toothpaste with activated charcoal (p = 0.030). Conclusion: The use of whitening toothpaste with activated charcoal and in combination with 16% carbamide peroxide significantly increased enamel surface roughness in bovine teeth

Adhesive Strength in Dentin Conditioned with 18% Ethylenediaminetetraacetic Acid versus 35% Phosphoric Acid: In Vitro Study with 1-Year Artificial Aging

The success and longevity of a resin composite restoration is determined by its good bonding to the tooth structure, with the adhesion being a challenge to dentin due to its complexity and structural heterogeneity. The present study aimed to compare the adhesive strength of dentin conditioned with 18% ethylenediaminetetraacetic acid (EDTA) versus 35% phosphoric acid (H3PO4) in human premolars. Materials and Methods: This in vitro experimental study was performed on 40 human premolars. The occlusal thirds were sectioned and randomly placed into four groups according to the type of dentin conditioning: Group 1 (control), Group 2 (18% EDTA), Group 3 (35% H3PO4) and Group 4 (18% EDTA plus 35% H3PO4). Then, 10,000 thermocycles between 5 +/&minus; 2 &deg;C and 55 +/&minus; 2 &deg;C were applied. Adhesive strength was tested by shearing with a digital universal testing machine at a crosshead speed of 0.75 mm/min. The values obtained were analyzed in megapascals (MPa). The mean and standard deviation were used as measures of central tendency and dispersion. In addition, a one-factor intergroup ANOVA test was applied with Tukey&rsquo;s post hoc test considering a significance level of p &lt; 0.05. Results: The 18% EDTA and 18% EDTA plus 35% H3PO4 showed significantly higher adhesive strength compared to the control group that did not receive dentin conditioning (p = 0.047 and p &lt; 0.001, respectively). However, the group conditioned with 18% EDTA did not present significant differences compared to the group conditioned with 35% H3PO4 (p = 0.997). In addition, the group conditioned with 18% EDTA plus 35% H3PO4 showed significantly higher adhesive strength compared to the groups conditioned with 18% EDTA (p = 0.002) and 35% H3PO4 (p = 0.001). Conclusion: The adhesion of bulk fill resin composite to dentin was favorable when preconditioning was performed using 18% EDTA followed by 35% H3PO4. In contrast, when both etchants were used separately, the bulk fill resin composite showed similar bond strength values in both cases, but significantly lower compared to their sequential application

Surface Microhardness of Bulk-Fill Resin Composites Handled With Gloves

ABSTRACT: Aim: It has been reported that resin composites may experience alterations in their mechanical properties when they come into contact with glove powder. Therefore, the present study aimed to compare the surface microhardness of 3 bulk-fill resin composites handled with latex and nitrile gloves prior to light curing. Methods: This in vitro experimental study consisted of 90 resin composite specimens with a 6-mm diameter and a 4-mm height divided equally and randomly into 9 groups. Prior to light curing, the resin composites were handled with latex gloves, nitrile gloves, or only a spatula (control). Subsequently, the surface microhardness was measured with an Electronic Vickers Hardness Tester. The Kruskal–Wallis nonparametric H test with Bonferroni correction was used for comparisons. A significance level of 5% (P < .05) was considered. Results: When comparing surface microhardness of each resin composite according to type of handling received, significant differences were observed in Filtek One Bulk Fill (P < .001) and Opus Bulk Fill (P < .001). In addition, these resin composites presented significantly higher surface microhardness than Tetric N-Ceram Bulk Fill resin (P < .05) when handled with latex gloves, nitrile gloves, and only a spatula. Finally, Filtek Bulk Fill resin presented significantly higher surface microhardness compared to Opus Bulk Fill resin when handled with nitrile gloves (P = .038) and a spatula only (P = .033). Conclusions: The surface microhardness of Filtek One Bulk Fill and Opus Bulk Fill resin composites decreased significantly when handled with latex or nitrile gloves, showing no variation in Tetric N-Ceram Bulk Fill resin composite. In addition, Filtek One Bulk Fill resin composite showed significantly higher surface microhardness than Opus Bulk Fill and Tetric N-Ceram Bulk Fill resin composites when handled with nitrile gloves. It is recommended that bulk-fill resin composites be handled with a spatula, because the use of latex or nitrile gloves could adversely affect their clinical performance

Escuela y educación superior: temas para la reflexión

Este libro presenta avances de proyectos de tesis doctorales del Énfasis de Historia de la Educación, Pedagogía y Educación Comparada del Doctorado Interinstitucional en Educación de la Universidad Distrital Francisco José de Caldas, la Universidad Pedagógica Nacional y la Universidad del Valle. El libro se articula en cuatro partes: Escuela y currículo; Escuela y violencia; Formación de maestros y pedagogías críticas y Educación superior