Effects of bleaching with carbamide peroxide gels on microhardness of restoration materials

The objective of this in vitro study was to quantitatively assess the effects of bleaching with 10 and 15% carbamide peroxide (CP) on restoration materials by performing superficial microhardness analysis. Acrylic cylindrical containers (4 x 2 mm) were filled with the following restoration products: Charisma (Heraues Kulzer, Vila Santa Catarina, São Paulo, Brazil), Durafill VS (Heraeus Kulzer), Vitremer (3M, Sumaré, São Paulo, Brazil), Dyract (Dentsply, Petrópolis, Rio de Janeiro, Brazil), and Permite C (SDI, São Pauio, São Paulo, Brazil). Sixty samples were prepared of each restoration material. Twenty samples received bleaching treatment with 10% CP, 20 samples received bleaching treatment with 15% CP, and 20 samples were kept submerged in artificial saliva, which was replaced daily. The treatment consisted of immersion of the specimens in 1 cm3 of CP at 10 and 15% for 6 hours per day during 3 weeks, whereupon the test specimens were washed, dried, and kept immersed in artificial saliva for 18 hours. Then the test and control specimens were analyzed using a microhardness gauge. The Knoop Hardness Number (KHN) was taken for each test and control specimen at five different locations by applying a 25 g force for 20 seconds. The values obtained were transformed into KHNs and the mean was calculated. The data were submitted to statistical analysis by analysis of variance and Tukey test, p < .05. The means/standard deviations were as follows: Charisma: CP 10% 38.52/4.08, CP 15% 34.31/6.13, saliva 37.36/4.48; Durafill VS: CP 10% 18.65/1.65, CP 15% 19.38/2.23, saliva 18.27/1.43; Dyract AP: CP 10% 30.26/2.81, CP 15% 28.64/5.44, saliva 33.88/3.46; Vitremer: CP 10% 28.15/3.04, CP 15% 17.40/3.11, saliva 40.93/4.18; and Permite C: CP 10% 183.50/27.09, CP 15% 159.45/5.78, saliva 215.80/26.15. A decrease in microhardness was observed for the materials Dyract AP, Vitremer, and Permite C after treatment with CP at 10 and 15%, whereas no effect on either of the two composites (Charisma and Durafill) was verified. CLINICAL SIGNIFICANCE: The application of the carbamide peroxide gels at 10 and 15% did not alter the microhardness of the composite resins Charisma and Durafill. In situ and clinical studies are necessary to enable one to conclude that the reduction in microhardness of the materials effectively results in clinical harm to the restorations.

Effects of three current provisional restoration materials on fibroblast viability

Poster presented at the First international Congress of CiiEM - From Basic Sciences to Clinical Research. Egas Moniz, Caparica, Portugal, 27-28 November 2015

Extended CT scale overcomes restoration caused streak artifacts for dental identification in CT--3D color encoded automatic discrimination of dental restorations

OBJECTIVE: Besides DNA, dental radiographs play a major role in the identification of victims in mass casualties or in corpses with major postmortem alterations. Computed tomography (CT) is increasingly applied in forensic investigations and is used to scan the dentition of deceased persons within minutes. We investigated different restoration materials concerning their radiopacity in CT for dental identification purposes. METHODS: Extracted teeth with different filling materials (composite, amalgam, ceramic, temporary fillings) were CT scanned. Radiopacities of the filling materials were analyzed in extended CT scale images. RESULTS: Radiopacity values ranged from 6000-8500HU (temporary fillings), 4500-17000HU (composite fillings) and >30710HU (Amalgam and Gold). The values were used to define presets for a 3D colored volume rendering software. CONCLUSIONS: The effects of filling material caused streak artifacts could be distinctively reduced for the assessment of the dental status and a postprocessing algorithm was introduced that allows for 3D color encoded visualization and discrimination of different dental restorations based on postmortem CT data.

Influência de agentes clareadores na rugosidade de compósitos dentários

O clareamento dental é o meio disponível mais simples, comum e conservador para o cirurgião-dentista proporcionar aos pacientes o padrão de cor de seus dentes mais desejado. Em alguns casos, os dentes que vão ser clareados podem apresentar restaurações realizadas com compósitos dentais, que são mais suscetíveis a alterações químicas, quando comparados a outros materiais restauradores. Alguns estudos mostraram que diferentes concentrações de agentes clareadores levaram a um aumento significativo da rugosidade superficial e das porosidades em compósitos dentais. Este estudo avaliou o efeito de dois agentes clareadores (Whiteness HP Blue 20%, Whiteness HP Max) sobre a rugosidade superficial de dois compósitos dentais, um micro-híbrido (Esthet X, Denstply) e outro nanoparticulado (Z 350, 3M ESPE). Um total de oito corpos de prova (9 x 2 mm) foram confeccionados com auxílio de uma matriz de teflon, sendo divididos em 4 grupos (Esthet X + Whiteness HP Blue 20%; Esthet X + Whiteness HP Max; Z 350 + Whiteness HP Blue 20%; Z 350 + Whiteness HP Max), sendo n=2. Os corpos de prova foram armazenados em saliva artificial neutra e, após 24 horas, foram polidos com discos de óxido de Alumínio (Sof-lex, 3M ESPE). Após sete dias de imersão salivar, cada corpo de prova foi levado a um microscópio de força atômica para obtenção do valor inicial de rugosidade superficial (Ra em nm). Em seguida, sem remover o corpo de prova do microscópio, o agente clareador foi aplicado sobre a superfície do corpo de prova, segundo as instruções do fabricante, de modo que permitisse uma posterior observação da mesma área do corpo de prova observada inicialmente, para obtenção do valor final de rugosidade superficial. Imagens em duas e três dimensões foram obtidas de cada corpo de prova para observação de alterações da topografia. Os resultados foram tratados estatisticamente por ANOVA e pelo teste de contraste Student-Newman-Keuls (p < 0,05). Não houve alteração significativa na rugosidade superficial (Ra) dos corpos da prova de compósitos micro-híbrido e nanoparticulado, submetidos aos agentes clareadores Whiteness HP Blue 20% e Whiteness HP Maxx. No entanto, independente do agente clareador utilizado, foram observadas maiores alterações topográficas nas imagens de microscopia de força atômica da superfície do compósito micro-híbrido do que nas imagens do nanoparticulado.

Desgaste abrasivo e dureza de seis resinas compostas expostas a diferentes tempos de fotopolimerização com aparelhos de LED e lâmpada incandescente

Pós-graduação em Ciência e Tecnologia de Materiais - FC

Effects of conservation interventions on the archaeological Roman site of Merida (Spain). Advance of research.

Research on the assessment of the effects of conservation/restoration treatments on stone material has been significant in recent years, with focus on the early observation of decay caused by the application of these treatments. However, in the case of archaeological sites, research is still scarce and few studies on the subject have been published. Restoration, as everything else, has changed according to trends, mainly guided by the release of new products and technologies, an experimental field where scientific assessment of suitability, efficacy and durability pre-evaluations of treatments are not always conducted. Some efforts have been made to solve this problem in the architectural field, where functional needs and technical requirements force to set clear standards. Unfortunately, archaeological sites, unlike historic buildings, have specific features that preclude the extrapolation of these results. A critical review of the methodologies, products and restoration materials is necessary, coupled with deeper research on degradation mechanisms caused by these treatments in the mid- and long-term. The aim of this paper is to introduce the research on the above issues using Merida as a case study.

Restauración del sonido fílmico

La restauración fílmica del audio es un proceso bastante complejo y se ha indagado poco en este campo. Antes de restaurar cualquier archivo, se debe preservar y conservar los archivos de la mejor manera posible. La preservación son las medidas que se deben tomar para garantizar el acceso permanente y la conservación asegura le existencia del archivo en su forma más original. Mientras que la restauración se basa en el estudio de los posibles deterioros que sufren los soportes fílmicos en el tiempo y los procesos que existen para corregirlos. La restauración siempre debe conservar la mayor originalidad posible, es decir debe mantener el audio como originalmente se expuso por primera vez. En la primera etapa, se identifican los posibles deterioros que se producen en los archivos, si conocemos en qué momento fue grabada la películas y cómo fue grabada, es decir con que máquina se realizó la grabación y el soporte fílmico en el que está grabado. Tanto las máquinas como los soportes han ido evolucionando a lo largo de la historia. El estudio de los soportes fílmicos nos permite conocer las degradaciones que sufren a lo largo del tiempo los archivos y por consecuencia, conocer las posibles restauraciones. Para intentar evitar degradaciones mayores, se intenta preservar y conservar en condiciones óptimas para el soporte. Según el soporte del archivo, tendrá unas condiciones típicas de temperatura, humedad, ventilación… en las cuales el material se conserva de la mejor manera. Tras estos pasos, se procede a restaurar. La restauración más típica es con materiales fotoquímicos, pero es bastante compleja y por tanto, en el proyecto se analiza la restauración tras digitalizar los archivos fílmicos. Para poder digitalizar correctamente los archivos, debemos tener presentes las normas y reglas de digitalización que están establecidas. La digitalización permite identificar las alteraciones típicas que aparecen en los materiales fílmicos, gracias a la herramienta del espectrograma podemos conocer las posibles soluciones de restauración para cada alteración. Las alteraciones que podemos encontrar e identificar son: · Zumbidos e Interferencias. · Siseo y Silbido. · Crujidos. · Pops y Clics. · Wow. · Lagunas o Abandonos. · Ruidos intermitentes. · Reverberación. La última parte del proyecto, una vez que se tienen todas las alteraciones típicas de los archivos fílmicos identificadas, se procede al estudio de cada una de ellas con las herramientas del espectrograma y se realiza el estudio de una manera más técnica. Con el espectrograma se determinan las herramientas que solucionan cada alteración como Reverb para la reverberación, Decrackle para los crujidos… y en el marco técnico se determina las características que tiene cada herramienta, es decir el tipo de filtro, ventana… que se puede utilizar para poder restaurar el audio de cada alteración. La restauración digital es un campo aún por investigar, pero se debería de empezar a concienciar que es una solución factible. Que este tipo de restauración puede mantener el sonido original y no va a modificar los archivos, como muchas veces se piensa. Ya que el paso del tiempo, poco a poco, ira degradando y destruyendo los soportes fílmicos en los que se encuentran, y el principal objetivo que se pretende conseguir es que los materiales fílmicos perduren a lo largo de la historia. ABSTRACT. The film audio restoration is a fairly complex process and little research has been done in this field. Before restoring any files, you must preserve and keep the files in the best way possible. The preservation is the measures to be taken to ensure continued access to and preservation ensures existence of the file in its original form. The restoration is based on the study of possible damage suffered by the film media in time and the processes that exist to correct them. The restoration must always retain the most original as possible, i.e. to keep the audio as originally discussed for the first time. In the first stage, potential impairments that occur in the files are identified, if you know what time it was recorded the movies and how it was recorded, i.e. that machine recording and film media on which is recorded took place. Both machines as media have evolved throughout history. The study of film media lets us know the suffering degradations over time and result files, make possible restorations. To try to prevent further degradation, are intended to preserve and keep in good condition for support. Depending on the media file, will have typical conditions of temperature, humidity, ventilation... in which the material is preserved in the best way. After these steps, we proceed to restore. The most typical is with photochemical restoration materials, but is rather complex and therefore the restoration project is analyzed after scanning film archives. To successfully scan the files must be aware of the rules and regulations are established digitization. Digitization allows identifying the typical alterations that appear in the film materials, thanks to the tool spectrogram we know the possible restoration solutions for each alteration. The alterations that can find and identify are: · Buzz and Interference. · Hiss and Hissing. · Crackle. · Pops and Clicks. · Wow and Flutter. · Audio Dropouts. The last part of the project, when we have all the typical alterations identified film archives, proceed to the study of each of them with the tools of spectrogram and the study of a more technical way is done . With the spectrogram tools that solve every alteration as Reverb for reverb, Decrackle for cracks... and the technical framework the features that each tool is determined, i.e. the type of filter, window... that can be used are determined for to restore the audio of each alteration. Digital restoration is an area for future research, but should start aware that it is a feasible solution. This type of restoration can keep the original sound and will not modify files, as is often thought. Since the passage of time, gradually degrading and destroying anger film media in which they are, and the main objective to be achieved is that the film materials endure throughout history.

Respuesta pulpar a materiales de restauración tipo resina

Las resinas compuestas y adhesivos dentales se utilizan ampliamente para la restauración de dientes con pulpas vitales. La preferencia en el uso de estas resinas compuestas podría estar atribuida a que son materiales con buenos resultados estéticos y se consideran materiales de restauración estables. Sin embargo se ha demostrado que son susceptibles a la degradación y liberación de la fracción de sus componentes y que cierta cantidad de los monómeros de su composición permanecen sin polimerizar por un largo periodo de tiempo, pudiendo estos filtrarse hacia el tejido pulpar y causar alteraciones de la actividad fisiológica de las células de la pulpa (DPCs) (1). Además, estudios in vitro han demostrado que los componentes de las resinas compuestas tienen potenciales tóxicos, generando respuestas inmediatas y a largo plazo luego de su aplicación. Identificar el potencial tóxico y deletéreo de los materiales de restauración sobre el tejido pulpar es de gran interés y relevancia clínica, por ello este estudio comprende en una revisión de la literatura acerca de la respuesta pulpar a los materiales de restauración tipo resina.

Contributions of labile and resistant organic materials to the immobilization of inorganic soil N when used in the restoration of abandoned agricultural fields

We have examined the contributions sucrose and sawdust make to the net immobilization of inorganic soil N and assimilation of both C and N into microbial biomass when they are used as part of a restoration plan to promote the establishment of indigenous vegetation on abandoned agricultural fields on the Central Hungarian Plain. Both amendments led to net N immobilization. Sucrose addition also led to mobilization of N from the soil organic N pool and its immobilization into microbial biomass, whereas sawdust addition apparently immobilized soil N into a non-biomass compartment or a biomass component that was not detected by the conventional biomass N assay (CHCl3 fumigation and extraction). This suggests that the N was either cycled through the biomass, but not immobilized within it, or that it was immobilized in a protected biomass fraction different to the fraction into which N was immobilized in response to sucrose addition.

Contributions of labile and resistant organic materials to the immobilization of inorganic soil N when used in the restoration of abandoned agricultural fields

We have examined the contributions sucrose and sawdust make to the net immobilization of inorganic soil N and assimilation of both C and N into microbial biomass when they are used as part of a restoration plan to promote the establishment of indigenous vegetation on abandoned agricultural fields on the Central Hungarian Plain. Both amendments led to net N immobilization. Sucrose addition also led to mobilization of N from the soil organic N pool and its immobilization into microbial biomass, whereas sawdust addition apparently immobilized soil N into a non-biomass compartment or a biomass component that was not detected by the conventional biomass N assay (CHCl3 fumigation and extraction). This suggests that the N was either cycled through the biomass, but not immobilized within it, or that it was immobilized in a protected biomass fraction different to the fraction into which N was immobilized in response to sucrose addition.

Study of the effects of exposure to ionizing irradiation on the materials used for dental restoration

A quantitative study was made about the effects caused by ionizing irradiation on materials used for dental restoration (amalgams, compound resins and compomere), aiming to alleviate in bearers of head and neck cancer, the possible harmful effects of radiotherapy perceived when the repaired teething is within the radiation field. Research also encourages further studies for new alternative materials to be used in dental repair of patients submitted to radiotherapy for head and neck cancer. Test samples were submitted to a gamma radiation beam coming from a cobalt-therapy source and analyzed according to the X-ray fluorescence technique, comparing the chemical composition of the samples before and after irradiation. Radiation detectors such as an ionization chamber and a Geiger-Muller were used to measure the rate of residual dose. Gamma spectrometry with Nal detectors was also performed on the same samples. Results showed that there was no significant change in the chemical composition and that at post-irradiation, samples did not exhibit radiation emission, that is to say they had not become radioactive.

Clinical evaluation of two materials in the restoration of abfraction lesions

Aim: To evaluate the clinical performance of a composite resin (CR) and a resin-modified glassionomer cement (RMGIC) for the treatment of abfraction lesions. Methods: Thirty patients with abfraction lesions in at least two premolar teeth were selected and invited to participate in this study. All restorations were made within the same clinical time frame. One tooth was restored with CR Z100TM (3M, St. Paul, MN, USA), and the other was restored with RMGIC VitremerTM (3M). The restorations were assessed immediately and 1, 6 and 12 months after the restoration, using modified US Public Health Service (USPHS) criteria: marginal integrity, marginal discoloration, wear, retention, secondary caries and hypersensitivity. The statistical analysis was based on Friedman ANOVA test and Mann-Whitney test, considering p<0.05 for statistical significance. Results: Both materials demonstrated satisfactory clinical performance after one year. In the individual analysis of each material, there was a significant difference (p<0.05) in the criteria marginal integrity and wear, for both CR and RMGIC. RMGIC exhibited more damage one year after the restoration. Comparing both materials, it was found a significant difference only for marginal discoloration, while the RMGIC restorations showed the worst prognosis after a year of evaluation. There was no significant difference in the number of retentions, caries or hypersensitivity between CR and RMGIC. Conclusions: It was concluded that CR exhibited the best clinical performance according to the cost-effectiveness and evaluation criteria used in this study.

Cytotoxic Effects and Biocompatibility of Antimicrobial Materials

The rising demand for medical implants for ageing populations and ongoing advancements in medical technology continue to drive the use of implantable devices. Higher implant usage has a consequent increased incidence of implant-related infections, and associated prolonged patient care, pain and loss of limb and other organ function. Numerous antibacterial surfaces have been designed that prevent the onset of biofilm formation, thus reducing or preventing implant-associated infections through inhibiting bacterial adhesion or by killing the organisms that successfully attach to the surface of the implant. Other surfaces have been designed to stimulate a local immune response, promoting the natural clearing of the invading pathogen. The desired antibacterial effects are typically achieved by modulating the surface chemistry and morphology of the implant material, by means of the controlled release of pharmacological agents and bioactive compounds from the surface of the material, or by a combination of both processes. An important issue for any type of antibacterial surface modification lies in balancing the non-fouling, bacteriostatic or bactericidal effects against local and systemic biocompatibility. In this chapter, we will first describe the concept of biocompatibility and its evolution, from devices that do not evoke a negative host response to those that actively drive host regeneration. We will then review the challenges associated with merging the need for an implant material to withstand a bacterial load with those associated with supporting function restoration and tissue healing.

Restoration Mechanisms During the Friction Stir Processing of Aluminum Alloys

In the current study, correlation of microstructure evolution with bulk crystallographic texture formation during friction stir processing (FSP) of commercial aluminum alloys has been attempted. Electron back-scattered diffraction and X-ray diffraction techniques were employed for characterizing the nugget zone of optimum friction stir processed samples. Volume fraction of measured texture components revealed that the texture formation in aluminum alloys is similar irrespective of the alloy composition. Recrystallization behavior during FSP was more of a composition dependent phenomenon.