RESUMO
INTRODUCTION: In this study, we evaluated the cellular viability of various esthetic, metallic, and nickel-free orthodontic brackets. METHODS: The sample was divided into 11 groups (n = 8): cellular control, negative control, positive control, metallic, polycarbonate, 2 types of monocrystalline ceramic, 3 types of nickel free, and polycrystalline ceramic brackets. Cell culture (NIH/3T3-mice fibroblasts) was added to the plates of 96 wells containing the specimens and incubated in 5% carbon dioxide at 37°C for 24 hours. Cytotoxicity was analyzed qualitatively and quantitatively. Cell growth was analyzed with an inverted light microscope, photomicrographs were obtained, and the results were recorded as response rates based on modifications of the parameters of Stanford according to the size of diffusion halo of toxic substances. Cell viability was analyzed (MTT assay); a microplate reader recorded the cell viability through the mitochondrial activity in a length of 570 nm. The values were statistically analyzed. RESULTS: All tested brackets had higher cytotoxicity values than did the negative control (P <0.05), with the exception Rematitan and Equilibrium (both, Dentaurum, Ispringen, Germany) (P >0.05), suggesting low toxicity effects. The values showed that only polycarbonate brackets were similar (P >0.05) to the positive control, suggesting high toxicity. CONCLUSIONS: The brackets demonstrated different ranges of cytotoxicity; nickel-free brackets had better biocompatibility than the others. On the other hand, polycarbonate brackets were made of a highly cytotoxic material for the cells analyzed.
Assuntos
Ligas Dentárias/toxicidade , Materiais Dentários/toxicidade , Braquetes Ortodônticos , Alumínio/toxicidade , Animais , Compostos Benzidrílicos , Materiais Biocompatíveis/toxicidade , Dióxido de Carbono/administração & dosagem , Técnicas de Cultura de Células , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Cerâmica/toxicidade , Ligas de Cromo/química , Corantes , Estética Dentária , Fibroblastos/efeitos dos fármacos , Camundongos , Células NIH 3T3 , Níquel/toxicidade , Fenóis/toxicidade , Cimento de Policarboxilato/toxicidade , Temperatura , Sais de Tetrazólio , Tiazóis , Fatores de Tempo , Titânio/toxicidadeRESUMO
INTRODUCTION: Ceramic brackets are chemically inert in the oral cavity, whereas polycarbonate and polyoxymethylene brackets can degrade and release bisphenol-A and formaldehyde, respectively. More reliable tests are needed to assess the potential toxicity of these materials. In addition to traditional cytotoxicity tests, the study of nitric oxide (NO) cellular production stimulated by a specific material has been shown to be a reliable tool for evaluating cytotoxic potential. The purpose of this study was to assess, with esthetic brackets, cellular viability by 3,(4,5-dimethylthiazol-2-yl)-2,5diphenyltetrazolium bromide assay (Sigma, St. Louis, Mo) in the macrophage cell line J774 stimulated with interferon gamma. Interferon gamma is a key cytokine in the activation of macrophages, plays an important role in immunologic processes, and also quantifies NO production by these macrophages. METHODS: Well plates were seeded with 2 x 104 J774 cells per well, in a volume of 100 microL, resuspended in Roswell Park Memorial Institute Supplemented Medium 1640. The macrophage cell line J774 was stimulated with interferon gamma. Ceramic, polycarbonate, and polyoxymethylene brackets were added and kept in the culture for 24, 48, or 72 hours in 5% carbon dioxide at 37 degrees C; the control samples did not include brackets. At the end of each incubation period, the supernatant was collected for posterior NO quantification, and the cells were evaluated for cytotoxicity. RESULTS: Cellular viability in all groups was higher at 72 hours than at 24 hours. The final means in the bracket groups did not show significant differences compared with the control group. NO production was significantly greater in all groups at the final time than at the initial time. However, the brackets with the interferon gamma stimulation did not result in greater NO production than did the cells in the control group.
Assuntos
Cerâmica/toxicidade , Materiais Dentários/toxicidade , Interferon gama/farmacologia , Macrófagos/efeitos dos fármacos , Óxido Nítrico/biossíntese , Braquetes Ortodônticos , Cimento de Policarboxilato/toxicidade , Resinas Sintéticas/toxicidade , Animais , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Corantes , Ativação de Macrófagos/efeitos dos fármacos , Macrófagos/citologia , Teste de Materiais , Camundongos , Óxido Nítrico/análise , Temperatura , Sais de Tetrazólio , Tiazóis , Fatores de TempoRESUMO
INTRODUCTION: Studies show that ceramic brackets are chemically inert in the oral cavity, whereas polycarbonate and polyoxymethylene brackets can degrade, releasing bisphenol-A and formaldehyde, respectively. In addition to the traditional cytotoxicity tests, the study of nitric oxide cellular production stimulated by a specific material has been shown to be a reliable tool for evaluating its cytotoxic potential. METHODS: We aimed to assess cellular viability by MTT (Sigma, St. Louis, Mo): 3,(4,5-dimethylthiazol-2-yl)-2,5diphenyl tetrazolium bromide assay in a murine macrophage cell line J774 with esthetic brackets and quantify nitric oxide production by these macrophages. Cell cultures were evaluated at 3 times: 24, 48, and 72 hours. RESULTS: Cellular viability in all groups was higher at 72 hours compared with 24 hours. This increase was significant in the control and ceramic brackets groups. Final means in the bracket groups showed no significant differences compared with the control group. Nitric oxide production was significantly greater in all groups at final time. There was no significant difference between the final means of the bracket groups and the control group, although polyoxymethylene brackets showed significantly greater means at 24 and 48 hours. CONCLUSIONS: Final means in the bracket groups showed no significant differences compared with the control group.
Assuntos
Materiais Dentários/toxicidade , Macrófagos/metabolismo , Óxido Nítrico/metabolismo , Braquetes Ortodônticos , Animais , Contagem de Células/métodos , Sobrevivência Celular/efeitos dos fármacos , Células Cultivadas , Colorimetria/métodos , Materiais Dentários/química , Porcelana Dentária/química , Porcelana Dentária/toxicidade , Formazans , Macrófagos/efeitos dos fármacos , Teste de Materiais/métodos , Camundongos , Cimento de Policarboxilato/química , Cimento de Policarboxilato/toxicidade , Resinas Sintéticas/química , Resinas Sintéticas/toxicidade , Estatísticas não Paramétricas , Sais de TetrazólioRESUMO
Glass-ionomer cements are widely used in dentistry as restorative materials and adhesives for composite restorations. A number of genotoxicity studies have been conducted using these materials with results conflicting so far. Thus, the approach was aimed to look at the genotoxic and cytotoxic potential of three different glass-ionomer cements available commercially (Ketac Cem, Ketac Molar and Vitrebond) by the single cell gel (comet) assay and trypan blue exclusion test, respectively. For this, such materials were exposed to mouse lymphoma cells in vitro for 1 h at 37 degrees C. Data were assessed by Kruskall-Wallis non-parametric test. The results showed that all powders assayed did not show genotoxic effects. On the other hand, the liquid from Vitrebond at 0.1% dilution caused an increase of DNA injury. Significant statistically differences (P < 0.05) in cytotoxicity provoked by all powders tested were observed for exposure at 1,000 micro g mL(-1) concentration and 100 micro g mL(-1) for Ketac Molar. With respect to liquids of glass-ionomer cements evaluated, the major toxic effect on cell viability was produced at 1%, beginning at the dilution of 0.5% for Vitrebond. Taken together, these results support the notion that some components of glass-ionomer cements show both genotoxic and cytotoxic effects in higher concentrations.
Assuntos
Dano ao DNA , Materiais Dentários/toxicidade , Cimentos de Ionômeros de Vidro/toxicidade , Animais , Sobrevivência Celular/efeitos dos fármacos , Ensaio Cometa , Leucemia L5178 , Óxido de Magnésio/toxicidade , Teste de Materiais , Camundongos , Cimento de Policarboxilato/toxicidade , Estatísticas não Paramétricas , Azul Tripano , Óxido de Zinco/toxicidadeRESUMO
Glass ionomer cements are widely used in dentistry as restorative materials and adhesives for composite restorations. However, the results of genotoxicity studies using these materials are inconclusive in literature. The goal of this study was to examine the genotoxic and cytotoxic potential of three different glass ionomer cements available commercially (Ketac Cem, Ketac Molar and Vitrebond) by the single cell gel (comet) assay and trypan blue exclusion test, respectively. For this, such materials were exposed to Chinese hamster ovary (CHO) cells in vitro for 1 h at 37( composite function)C. Data were assessed by Kruskall-Wallis nonparametric test. The results showed that the powder from Ketac Molar displayed genotoxicity only in the maximum concentration evaluated (100 microg/mL). In the same way, the liquid from Vitrebond at 0.1% dilution caused an increase of DNA injury. Significant differences (P<0.05) in cytotoxicity provoked by all powders tested of glass ionomer cements were observed for exposure at 1,000 microg/mL concentration. With respect to liquids of glass ionomer cements evaluated, the major toxic effect on cell viability was produced at 10%, beginning at the dilution of 0.5% for Vitrebond. Taken together, we conclude that some components of glass ionomer cements show both genotoxic and cytotoxic effects.