RESUMO
The aim of this study was to evaluate, using atomic force microscopy, the effect of two different bleaching agents on the modification of dental composites materials. This modification will be judged by analyzing the variation of surface roughness and surface morphology of two different composites: one containing nanoparticles and other consisting of microhybrid resin. The bleaching was performed by using two different concentrations of hydrogen peroxide: HP Blue (20% hydrogen peroxide) and Whiteness HP Maxx (35% hydrogen peroxide). Disks of Esthet X and Filtek™ Z350 composites were used. Atomic force microscopy was used for analyses of the same place of the sample before and after treatment. A total of 12 analyses were performed per group (n = 12). The samples were analyzed qualitatively by evaluating morphological changes in the images and quantitatively by using roughness parameters (Ra). Data were analyzed statistically using Kruskal-Wallis, Mann-Whitney, and Friedman tests (P < 0.05). Changes were observed both qualitatively and quantitatively only in the groups where Esthet X resin was used. The use of hydrogen peroxide bleaching agents caused changes only in the surface of microhybrid composites, with no changes being observed in the composite containing nanoparticles. Despite being even significant, these alterations are clinically slight and can be eliminated by polishing them.
Assuntos
Clareadores/farmacologia , Resinas Compostas , Propriedades de Superfície/efeitos dos fármacos , Peróxido de Hidrogênio/farmacologia , Microscopia de Força AtômicaRESUMO
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 ...
Dental bleaching is the simplest, the most common and conservative available way for dentists to offer their patients the standard color of teeth more desired. In some cases, the teeth that will be bleached may include restorations made of resin composites, which are more prone to chemical alteration compared with other restoration materials. Some studies have showed that different concentrations of bleaching gels might lead to a significant increase in surface roughness and amount of porosities in composite resins. This study evaluated the effect of two bleaching gels (Whiteness HP Blue 20%, Whiteness HP Max) on surface roughness of two resin composites, micro-hybrid (Esthet X, Denstply) and nanoparticled (Z350, 3M ESPE). A total of eight specimens (9 x 2 mm) were produced with a Teflon mold help, and were divided into four groups (Esthet X + Whiteness HP Blue 20%; Esthet X + Whiteness HP Max; Z 350 + Whiteness HP Blue 20%; Z 350 + Whiteness HP Max), with n=2. They were stored in neutral artificial saliva and, after 24 hours, were polished with aluminium oxide discs (Sof-lex, 3M ESPE). After seven days of salivary immersion, each specimen was taken to an atomic force microscope for recording initial value of surface roughness (Ra in nm). After that procedure, without removing the specimen from microscope, the bleaching gel was applied on the surface of the specimen, following manufacturers´ instructions, in order to allow posterior observation of the same area of the specimen initially observed, for recording the final value of surface roughness. Two-dimensional and 3D images were taken from each specimen group for observation of surface alterations. The results were statistically analyzed by ANOVA and the SNK test (p< 0.05). There were no statistically significant differences in the surface roughness (Ra) for specimens of micro-hybrid and nanoparticled composites, submitted to the bleaching agents Whiteness HP Blue 20% and Whiteness HP Maxx. ...