ABSTRACT
Abstract The aim of this study was to evaluate the degree of conversion (DC) and the thermal stability of bulk-fill and conventional composite resins. Eleven composite resin samples were prepared to evaluate the DC, Vickers microhardness (VMH), mass and residue/particle loss, glass transition temperature (Tg), enthalpy, and linear coefficient of thermal expansion (CTE) using infrared spectroscopy (FTIR), microdurometer analyses, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and dilatometry (DIL). The data were subjected to statistical analysis, with a significance level of 95%. DC and VMH were not influenced by the polymerized side of the sample, and statistical differences were recorded only among the materials. Decomposition temperature, melting, and mass and residue loss were dependent on the material and on the evaluation condition (polymerized and non-polymerized). Tg values were similar between the composites, without statistically significant difference, and CTE ranged from 10.5 to 37.1 (10-6/°C), with no statistical difference between the materials. There was a moderate negative correlation between CTE and the % of load particles, by weight. Most resins had a DC above that which is reported in the literature. TGA, Tg, and CTE analyses showed the thermal behavior of the evaluated composites, providing data for future research, assisting with the choice of material for direct or semidirect restorations, and helping choose the appropriate temperature for increasing the DC of such materials.
Subject(s)
Surface Properties , Materials Testing/methods , Composite Resins/chemistry , Dental Materials/chemistry , Spectrophotometry, Infrared , Temperature , Composite Resins/analysis , Dental Materials/analysis , HardnessABSTRACT
Abstract The aim of this study was to evaluate the cytotoxic effect, degree of conversion (% DC), Vickers hardness (VH), and surface morphology of composite resins. Eleven resins, nine bulk-fill resins, and two conventional resins were evaluated. Each material was sampled to evaluate DC (using FTIR), VH, cytotoxicity (using MTT and Neutral Red - NR test), surface morphology (using SEM and AFM), and organic filler (using EDS). All statistical tests were performed with SPSS and the level of significance was set at 0.05. MTT revealed that the materials presented low or no cytotoxic potential in relation to the control. Opus was the resin with the lowest cell viability at a 1:2 concentration at 72 h (32%) and at 7 days (43%), but that significantly increased when the NR test was applied at a 1:2 concentration after 7 days. Thickness and surface subjected to polymerization had no influence on DC, and differences were observed only between the materials. In the microhardness test, statistical differences were observed between the evaluated thicknesses. The bulk-fill resins analyzed in this study exhibited low and/or no cytotoxicity to L929 cells, except for Opus, which showed moderate cytotoxicity according to the MTT assay. When the NR test was used, results were not satisfactory for all composites, indicating the need for different methodologies to evaluate the properties of these materials. The assessed resins demonstrated acceptable physicomechanical properties.
Subject(s)
Animals , Mice , Composite Resins/toxicity , Composite Resins/chemistry , Fibroblasts/drug effects , Reference Values , Spectrometry, X-Ray Emission , Surface Properties , Time Factors , Materials Testing , Cell Line , Cells, Cultured , Reproducibility of Results , Analysis of Variance , Statistics, Nonparametric , Microscopy, Atomic Force , Polymerization , Hardness TestsABSTRACT
Objetivo: Desenvolver esferas de quitosana/D. ambrosioides (mastruz) para aplicação como biomaterial. Material e Métodos: Para obtenção das esferas de quitosana e quitosana com extrato alcoólico bruto do mastruz (EAB) utilizou-se a técnica de GeleificaçãoIonotrópica. Foram formados quatro grupos: QO- quitosana; Q5; Q10 e Q20, quitosana com 5%, 10% e 20% de EAB, respectivamente. Foram caracterizadas por Microscopia Óptica (MO); Citotoxicidade e Biodegradação. Resultados: NoMO, observou-se esferas bem delimitadas e mais escuras, à medida que o percentual do EAB aumentou. Todos os grupos foram não citotóxicos. Na presença de lisozima, observou-se perda de massa, já na solução tampão fosfato salina (PBS) constatou-se ganho de massa. Conclusão: Conclui-se que as esferas apresentaram potencial para utilização como biomaterial.
Objective: This worked aimed to develop chitosan/D. ambrosioides (mastruz) spheres to be applied as a biomaterial. Material and Methods: To obtain the chitosan spheres and the chitosan with crude ethanolic extract of mastruz (CEE) the Ionotropic gelation technique was used. Four groups were formed: QO- Chitosan; Q5; Q10 and Q20, Chitosan with 5%, 10% and 20% of CEE, respectively. Were characterized by Optic Microscopy (OM); Cytotoxicity and Biodegradation.Results: InOM, well delimited and darker spheres were observed, as the CEE percentage increased. All groups were noncytotoxic. In the presence of lysozyme, mass loss was observed, as for in solution Phosphate Buffered Saline (PBS) the mass gain was found. Conclusion: It can be concluded that the spheres presented potential for use as a biomaterial.
ABSTRACT
O objetivo do presente trabalho foi avaliar o processo de regeneração óssea em coelhos através da utilização da hidroxiapatita e da quitosana isoladas e associadas à medula óssea. Foram utilizados 20 coelhos adultos, de ambos os sexos, da raça Nova Zelândia e pesando em média 3,0±0,4kg. Os animais foram divididos ao acaso de acordo com dois momentos experimentais, sendo que 10 animais foram submetidos à eutanásia 30 dias após a cirurgia, e 10, 60 dias após a cirurgia. Foram utilizados quatro implantes que constituíram os grupos. Os materiais foram introduzidos em defeitos criados cirurgicamente na metáfise proximal (MP) e distal (MD) de cada fêmur, de modo que a quitosana foi introduzida na MP e a hidroxiapatita na MD do membro esquerdo e, no membro direito, além dos implantes, foi adicionada medula óssea. Na avaliação histológica descritiva comparativa, constatou-se que os grupos QUI e QUIMO, em ambos os momentos estudados, estimularam reações mais acentuadas e aceleraram o reparo ósseo. Na análise morfométrica, os grupos QUI e QUIMO diferiram estatisticamente dos outros grupos, tendo sido observada maior formação óssea (P<0,05).
The aim of this research was to evaluate the process of bone regeneration in rabbits by the use of hydroxyapatite and chitosan only and associated with bone marrow. Twenty male and female rabbits, New Zealand breed and weighing in average 3.0±0.4kg were used. Animals were randomly divided according with two experimental moments, being 10 animals euthanized 30 days after surgery, and 10 euthanized 60 days after surgery. Four implants that constituted the groups were used. Materials were introduced into the proximal (MP) and distal metaphysis (MD) of each femur, so that chitosan was introduced into the MP and hydroxyapatite into the MD of the left limb, and in the right limb bone marrow was added beyond the implants. At the comparative descriptive histological evaluation, it was found that the QUI and QUIMO groups in both periods stimulated more pronounced reactions and accelerated bone repair. In morphometric analysis, QUI and QUIMO groups differed statistically from the other, has been shown greater bone formation (P<0.05).
ABSTRACT
O objetivo deste estudo foi avaliar os fosfatos de cálcio, pirofosfato de cálcio (CPP) com tratamento térmico a 70 0 e 900°C, fosfato tricálcio associado à hidroxiapatita (TCP/HA) e hidroxiapatita (HA) como substitutos ósseos. Foram utilizados 20 coelhos (Oryctolagus cuniculus), de ambos os sexos, da raça Nova Zelândia, pesando em média 2,5±0,41 kg. Os animais foram distribuídos, ao acaso, em dois grupos de 10 animais de acordo com o período em que foram eutanasiados (30 ou 60 dias). Os implantes foram introduzidos na metáfise proximal e distal de cada fêmur, de modo que os CPP 700 e 900 foram introduzidos no membro esquerdo, enquanto o TCP/HA e HA no membro direito. Foram realizadas avaliações clínico-cirúrgicas e radiográficas imediatamente após a cirurgia e aos 30 e 60 dias dopós-operatório. Os animais apresentaram evolução clínica normal. Na avaliação radiográfica observou-se diferença estatística entre os grupos com maior grau de radiopacidade nos animais do grupo 60 dias que utilizaram os implantes TCP/HA e HA. Na avaliação histológica, por meio de microscopia de luz e análise morfométrica, os materiais TCP/HA e HA proporcionaram maior neoformação óssea ao redor dos implantes do que com os CPP700 e CPP900 aos 30 e 60 dias de avaliação.
The aim of this study was to evaluate the calcium phosphate, calcium pyrophosphate (CPP) with heat treatment at 700 and 900 ° C, tricalcium phosphate combined with hydroxyapatite (TCP/HA) and hydroxyapatite (HA) as bone substitutes. We used 20 rabbits (Oryctolagus cuniculus) of both sexes, New Zealand breed, with mean weigh of 2.5 ± 0.41 kg. The animals were randomly divided into two groups of 10 animals in the period in which they were euthanized (30 or 60 days). The implants were placed on the proximal and distal metaphysis of each femur so that CPP 700 and 900 were introduced in the left, while TCP/HA and HA in the right. Clinical and radiographic-surgical evaluations were performed immediately after surgery, and 30 and 60 days post-surgery. The animals showed normal clinical evolution. In the radiographic evaluation there was statistical difference between groups with higher degree of radiopacity at group 60 days that used TCP/HA and HA implants. In the histological evaluation by light microscopy and morphometric analysis the materials TCP/HA and HA showed greater bone formation around the implants than CPP700 and CPP900 at 30 and 60-days evaluation.