Estudio de biocompatibilidad de matrices poliméricas combinadas, responsivas al pH, con aplicación en Ingeniería de Tejido Óseo / Biocompatibility study of combined pH-responsive polymeric matrices with application in Bone Tissue Engineering

El presente trabajo muestra la obtención de un material a partir de un polímero sintético (TerP) y otro natural, mediante entrecruzamiento físico y su caracterización fisicoquímica y biológica, con el fin de emplearlos para regeneración de tejido óseo. Las membranas fueron obtenidas por la técnica de evaporación del solvente y caracterizadas por espectroscopia FTIR, ensayos de hinchamiento, medidas de ángulo de contacto y microscopia electrónica de barrido (SEM). Se encontró que la compatibilidad entre los polímeros que la constituyen es estable a pH fisiológico y que, al incorporar mayor cantidad del TerP a la matriz, esta se vuelve más hidrofóbica y porosa. Además, teniendo en cuenta la aplicación prevista para dichos materiales, se realizaron estudios de biocompatibilidad y citotoxicidad con células progenitoras de médula ósea (CPMO) y células RAW264.7, respectivamente. Se evaluó la proliferación celular, la producción y liberación de óxido nítrico (NO) al medio de cultivo durante 24 y 48 horas y la expresión de citoquinas proinflamatorias IL-1ß y TNF-α de las células crecidas sobre los biomateriales variando la cantidad del polímero sintético. Se encontró mayor proliferación celular y menor producción de NO sobre las matrices que contienen menos proporción del TerP, además de poseer una mejor biocompatibilidad. Los resultados de este estudio muestran que el terpolímero obtenido y su combinación con un polímero natural es una estrategia muy interesante para obtener un biomaterial con posibles aplicaciones en medicina regenerativa y que podría extenderse a otros sistemas estructuralmente relacionados. (AU)

In the present work, the preparation of a biomaterial from a synthetic terpolymer (TerP) and a natural polymer, physically crosslinked, is shown. In order to evaluate the new material for bone tissue regeneration, physicochemical and biological characterizations were performed. The membranes were obtained by solvent casting and characterized using FTIR spectroscopy, swelling tests, contact angle measurements, and scanning electron microscopy (SEM). It was found that the compatibility between the polymers is stable at physiological pH and the incorporation of a higher amount of TerP into the matrix increases hydrophobicity and porosity.Furthermore, considering the intended application of these materials, studies of biocompatibility and cytotoxicity were conducted with Bone Marrow Progenitor Cells (BMPCs) and RAW264.7 cells, respectively. Cell proliferation, NO production and release into the culture medium for 24 and 48 hours, and proinflammatory cytokine expression of IL-1ß and TNF-α from cells grown on the biomaterials while varying the amount of the synthetic polymer were evaluated. Greater cell proliferation and lower NO production were found on matrices containing a lower proportion of TerP, in addition to better biocompatibility. The results of this study demonstrate that the obtained terpolymer and its combination with a natural polymer is a highly interesting strategy for biomaterial preparation with potential applications in regenerative medicine. This approach could be extended to other structurally related systems. (AU)

The effects of monomers used in polymeric biomaterials on renal tissue / Efectos de los monómeros de los biomateriales poliméricos utilizados en tejido renal

SUMMARY: Biomaterials are mostly polymers and are used in artificial organ production in contemporary medicine. They are prepared by the polymerization reaction of many monomers. There are many monomers used in biomaterial production. In this study, we investigated whether acrylamide (AAm), methacrylamide (MAAm), N-isopropylacrylamide (NIPAm) and acrylic acid (AAc) used in polymeric biomaterial production had histopathological effects on renal tissue. In the present study, Wistar albino rats weighing ~ 250-300 g were used. Following the intramuscular injections of 1 mL aqueous monomer solutions at 50 mg/kg concentrations, acrylamide group animals were sacrificed at 1st, 2nd and 3rd weeks, the other monomer group animals were sacrificed at 1st, 2nd, 4th and 6th weeks. One mL serum physiologic were injected intramuscularly to the control group animals at the same time intervals with the experimental group animals. After histological follow-up, serial sections were prepared for evaluation under light microscope. In addition, the diameters of glomeruli and glomeruli space (Bowman's space) are measured, and the changes of the values of all groups with the exposure time were investigated. Acrylamide and its derivatives cause glomerular, arteriolar and tubule interstitial damage in the renal tissue. The narrowing glomeruli space, increasing diffuse mesangial matrix and tubular dilation was observed in some groups. In addition, dilatation, dissociation of tubular epithelium, thickening basement membranes and glycogenic vacuolization was also noted. These adverse results may be due to residual monomer. There should be no monomer residue in the polymer used as biomaterials.

RESUMEN: Los biomateriales en su mayoría son polímeros utilizados en la producción de órganos artificiales en la medicina contemporánea. Éstos son preparados mediante la reacción de polimerización de varios monómeros. Existe una gran cantidad de monómeros usados en la producción de biomateriales. En este estudio se investigó si la acrilamida (AAm), la metacrilamida (MAAm), la N-isopropilacrilamida (NIPAm) y el ácido acrílico (AAc) utilizados en la producción de biomateriales poliméricos tuvieron efectos histopatológicos en el tejido renal. En el presente estudio, se utilizaron ratas Wistar albinas que pesaban 250-300 g. Después de las inyecciones intramusculares (1 ml) de soluciones acuosas de monómero a concentraciones de 50 mg / kg, los animales del grupo de la acrilamida se sacrificaron a la 1ª, 2ª y 3ª semanas, los otros animales del grupo monómero se sacrificaron a las 1ª, 2ª, 4ª y 6ª semanas. Se inyectaron intramuscularmente 1 ml de suero fisiológico a los animales del grupo control en los mismos intervalos de tiempo que los animales del grupo experimental. Después del análisis histológico, se prepararon secciones en serie para su evaluación bajo microscopio óptico. Además, se midieron los diámetros de los glomérulos y el espacio glomerular, y se investigaron los cambios de los valores de todos los grupos con el tiempo de exposición. La acrilamida y sus derivados causaron daño intersticial glomerular, arteriolar y tubular en el tejido renal. El estrechamiento del espacio de los glomérulos, el aumento de la matriz mesangial difusa y la dilatación tubular se observó en algunos grupos. Además, también se observó dilatación, disociación del epitelio tubular, membranas basales espesantes y vacuolización glicogénica. Estos resultados adversos pueden deberse al monómero residual. No debe haber residuo de monómero en el polímero utilizado como biomateriales.

Cytotoxicity and genotoxicity of calcium silicate-based cements on an osteoblast lineage

Abstract Several calcium silicate-based biomaterials have been developed in recent years, in addition to Mineral Trioxide Aggregate (MTA). The aim of this study was to evaluate the cytotoxicity, genotoxicity and apoptosis/necrosis in human osteoblast cells (SAOS-2) of pure calcium silicate-based cements (CSC) and modified formulations: modified calcium silicate-based cements (CSCM) and three resin-based calcium silicate cements (CSCR1) (CSCR 2) (CSCR3). The following tests were performed after 24 hours of cement extract exposure: methyl-thiazolyl tetrazolium (MTT), apoptosis/necrosis assay and comet assay. The negative control (CT-) was performed with untreated cells, and the positive control (CT+) used hydrogen peroxide. The data for MTT and apoptosis were submitted to analysis of variance and Bonferroni's posttest (p < 0.05), and the data for the comet assay analysis, to the Kruskal-Wallis and Dunn tests (p < 0.05). The MTT test showed no significant difference among the materials in 2 mg/mL and 10 mg/mL concentrations. CSCR3 showed lower cell viability at 10 mg/mL. Only CSC showed lower cell viability at 50 mg/mL. CSCR1, CSCR2 and CSCR3 showed a higher percentage of initial apoptosis than the control in the apoptosis test, after 24 hours exposure. The same cements showed no genotoxicity in the concentration of 2 mg/mL, with the comet assay. CSC and CSCR2 were also not genotoxic at 10 mg/mL. All experimental materials showed viability with MTT. CSC and CSCR2 presented a better response to apoptosis and genotoxicity evaluation in the 10 mg/mL concentration, and demonstrated a considerable potential for use as reparative materials.

Radiopacity and cytotoxicity of Portland cement associated with niobium oxide micro and nanoparticles

Objective Mineral Trioxide Aggregate (MTA) is composed of Portland Cement (PC) and bismuth oxide (BO). Replacing BO for niobium oxide (NbO) microparticles (Nbµ) or nanoparticles (Nbη) may improve radiopacity and bioactivity. The aim of this study was to evaluate the radiopacity and cytotoxicity of the materials: 1) PC; 2) White MTA; 3) PC+30% Nbµ; 4) PC+30% Nbη. Material and Methods For the radiopacity test, specimens of the different materials were radiographed along an aluminum step-wedge. For cell culture assays, Saos-2 osteoblastic-cells (ATCC HTB-85) were used. Cell viability was evaluated through MTT assay, and bioactivity was assessed by alkaline phosphatase activity assay. Results The results demonstrated higher radiopacity for MTA, followed by Nbµ and Nbη, which had similar values. Cell culture analysis showed that PC and PC+NbO associations promoted greater cell viability than MTA. Conclusions It was concluded that the combination of PC+NbO is a potential alternative for composition of MTA. .

Human tooth germ stem cell response to calcium-silicate based endodontic cements

OBJECTIVE: The aim of this study was to compare the cytotoxic effects of endodontic cements on human tooth germ stem cells (hTGSCs). MTA Fillapex, a mineral trioxide aggregate (MTA)-based, salicylate resin containing root canal sealer, was compared with iRoot SP, a bioceramic sealer, and AH Plus Jet, an epoxy resin-based root canal sealer. MATERIAL AND METHODS: To evaluate cytotoxicity, all materials were packed into Teflon rings (4 mmµ3 mm) and co-cultured with hTGSCs with the aid of 24-well Transwell permeable supports, which had a pore size of 0.4 µm. Coverslips were coated with MTA Fillapex, iRoot SP and AH Plus Jet and each coverslip was placed onto the bottom of one well of a six-well plate for scanning electron microscopy (SEM) analysis. Before the cytotoxicity and SEM analysis, all samples were stored at 37ºC and at 95% humidity and 5% CO2 for 24 hours to set. The cellular viability was analyzed using MTS test (3-(4,5-dimethyl-thiazol-2-yl)-5-(3-carboxy-methoxy-phenyl)-2-(4-sulfo-phenyl)-2H-tetrazolium). The cytotoxic effects and SEM visualization of the tested materials were analyzed at 24-hour, 72-hour, one-week and two-week periods. RESULTS: On the 1st day, only MTA Fillapex caused cytotoxicity compared to negative control (NC) group (p<0.008). No significant difference was observed between the other tested materials at this period (p>0.05). After 14 days of incubation with the test materials, MTA Fillapex exhibited significantly higher cytotoxicity compared with iRoot SP, AH Plus Jet and the NC group (P<0.008). In the SEM analysis, the highest levels of cell attachment were observed for iRoot SP and the control group. After 24 hours, MTA Fillapex reduced the number of cells attached to the surface. CONCLUSIONS: Within the limitations of this study, sealers exerted different cytotoxic effects on hTGSCs. Although all materials ...

Estudo experimental da biocompatibilidade de novo material para implante orbitário / Experimental study of new material for biocompatibility as orbital implant

OBJETIVO:Avaliar a biocompatibilidade de material FullCure 720®, que é uma resina, na confecção de implante orbitário. Avaliou-se a resposta clínica dos animais, toxicidade sistêmica e a resposta inflamatória crônica. Os animais foram pesados, exames bioquímicos e resposta inflamatória foram avaliados. Foi efetuada evisceração e colocado implante esférico orbitário. Os animais foram acompanhados durante o período de 60 dias, onde se avaliou o comportamento clínico e sinais locais. Após este período, procedeu-se a eutanásia seguida da enucleação. Foi realizada análise macroscópica e histomorfométrica. Os resultados revelaram comportamento normal dos animais, com ausência de exposição ou extrusão dos implantes, morte de algum animal e ausência de toxicidade sistêmica. Houve formação de uma cápsula fibrosa entre a capa escleral e o implante orbitário, resposta inflamatória considerada normal quando em contato com o tecido do coelho. A resina FullCure 720® utilizada como implante orbitário, mostrou-se biocompatível neste estudo.

PURPOSE: To evaluate the resin FullCure 720® biocompatibility as orbital implant. Clinical response and signs of systemic toxicity to the resin were evaluated, local biocompatibility and microscopic analysis regarding chronic local inflammatory response to the implant. The animals were weighted, biochemical exams and inflammatory response were evaluated. All animals were eviscerated and implantation of the spheres was carried out. Animals were followed for 60 days. Clinical behavior of animals and local signals of inflammation had been observed. After this period animals underwent euthanasia followed by enucleation. Macroscopic and histomorphometric analysis were performed. The results showed normal behavior of the animals, without implant exposure, extrusion, death or systemic toxicity. Capsule tissue formation was observed between the sclera and the implant. Normal inflammatory response to the foreign material in contact with the rabbit soft tissue was observed. The resin FullCure 720®, demonstrated to be biocompatible as an orbital implant in this study.

Synthesis and cytotoxicity evaluation of granular magnesium substituted beta-tricalcium phosphate

Objective: The aim of this study was to produce dense granules of tricalcium phosphate (β-TCP) and magnesium (Mg) substituted β-TCP, also known as β-TCMP (Mg/Ca=0.15 mol), in order to evaluate the impact of Mg incorporation on the physicochemical parameters and in vitro biocompatibility of this novel material. Material and Methods: The materials were characterized using X-ray diffraction (XRD), infrared spectroscopy (FTIR), electron microscopy and inductively coupled plasma (ICP). Biocompatibility was assayed according to ISO 10993-12:2007 and 7405:2008, by two different tests of cell survival and integrity (XTT and CVDE). Results: The XRD profile presented the main peaks of β-TCP (JCPDS 090169) and β-TCMP (JCPDS 130404). The characteristic absorption bands of TCP were also identified by FTIR. The ICP results of β-TCMP granules extract showed a precipitation of calcium and release of Mg into the culture medium. Regarding the cytotoxicity assays, β-TCMP dense granules did not significantly affect the mitochondrial activity and relative cell density in relation to β-TCP dense granules, despite the release of Mg from granules into the cell culture medium. Conclusion: β-TCMP granules were successfully produced and were able to release Mg into media without cytotoxicity, indicating the suitability of this promising material for further biological studies on its adequacy for bone therapy.

Long-term cytotoxic effects of contemporary root canal sealers

Objectives: The aim of the present study was to investigate the effects of root canal sealers on the cytotoxicity of 3T3 fibroblasts during a period of 5 weeks. Material and Methods: Fibroblasts (3T3, 1×105 cells per well) were incubated with elutes of fresh specimens from eight root canal sealers (AH Plus, Epiphany, Endomethasone N, EndoREZ, MTA Fillapex, Pulp Canal Sealer EWT, RoekoSeal and Sealapex) and with elutes of the same specimens for 5 succeeding weeks after immersing in simulated body fluid. The cytotoxicity of all root canal sealers was determined using the MTT assay. Data were analyzed using ANOVA and Tukey's test. Results: RoekoSeal was the only sealer that did not show any cytotoxic effects (p<0.05). All the other tested sealers exhibited severe toxicity initially (week 0). MTA Fillapex remained moderately cytotoxic after the end of experimental period. Toxicity of the other tested sealers decreased gradually over time. The evaluated root canal sealers presented varying degrees of cytotoxicity, mainly in fresh mode.Conclusions: RoekoSeal had no cytotoxic effect both freshly mixed and in the other tested time points. MTA Fillapex was associated with significantly less cell viability when compared to the other tested root canal sealers.

Cytotoxicity of orthodontic elastics: in vitro investigation with on L929 mouse fibroblasts

Aim: To test the hypothesis that there is no difference in the cytotoxicity among natural latex elastics of different manufacturers using a L929 cell line culture. Methods: Different latex intra oral elastics (I.D. = 5/16", 4.5 oz.) were tested. The sample was divided into 7 groups of 15 elastic seach: Group AO (American Orthodontics), Group GAC (GAC International), Group TP (TP Orthodontics), Group AD (Aditek), Group AB (Abzil), Group MO (Morelli) and Group UN (Uniden).Cytotoxicity assays were performed by using cell culture medium containing L-929 line cells(mouse fibroblast). The cytotoxicity was evaluated by using the “dye-uptake” test, which wasemployed at two different moments (1 and 24 h). Data were compared by ANOVA and Tukey’s test(P < 0.05). Results: The results showed a significant difference (P < 0.05) between all groups and the group CC (cell control) at 1 and 24 h. Groups AD, AB, MO and UN were noticeably more cytotoxic than the groups AO, GAC and TP at 1 h. After 24 h, a significant decrease in cell viability was observed in all groups. Conclusions: Intraoral elastics from American Orthodontics, GACand TP Orthodontics trademarks induced less cell lysis than Aditek, Abzil, Morelli and Uniden trademarks.

In vitro cytotoxicity of latex orthodonticelastics / Citotoxicidad de los elásticos ortodònticos de látex

Natural latex does not fall into the category of materials known to be entirely inoffensive. The objective of the present in vitro study is to test the hypothesis that there is no difference in the cytotoxicity between natural latex elastics of different colours. The present article compared different latex intra-oral elastics (5/16 = 7.9 mm). The sample was divided into four groups according to their manufacturer: Group N (Natural latex elastic, Morelli), Group R (Red colour elastic, Morelli) Group Y (Yellow colour elastic, Morelli) and Group G (Green colour elastic, Morelli). Cytotoxicity assays were performed by using cell culture medium containing L-929 line cells (mouse fibroblast). The cytotoxicity was evaluated by using the “dyeuptake” test, which was employed at two different moments (1 and 24 h). Data were compared by analysis of variance (ANOVA) and Tukey’s test (p<0.05). The results showed a significant difference (p<0.05) between the groups N, R, Y, G and the negative cytotoxicity control at 1 and 24 h (p<0.05), it did not have presented significant difference between the groups N, R, Y, G tested (p>0.05) at 1 and 24 h. Morelli intra-oral elastics were found to be highly cytotoxic, regardless of their colour and immersion time.

El látex natural no entra en la categoría de materiales que se sabe del todo inofensivo. El objetivo del presente estudio in vitro es poner a prueba la hipótesis de que no hay diferencia en la citotoxicidad entre elásticos de látex natural de diferentes colores. El presente artículo compara diferentes elásticos intraorales de látex (5/16 =7,9 mm). La muestra se dividió en cuatro grupos según su fabricante: Grupo N (elástico látex, Morelli), Grupo I (elástico de color rojo, Morelli) Grupo Y (elástico de color amarillo, Morelli) y el Grupo G (elástico color verde, Morelli). Pruebas de citotoxicidad se realizaron mediante el uso de medio de cultivo celular que contiene líneas celulares L-929 (fibroblastos de ratón). La citotoxicidad se evaluó mediante el test “dye-uptake”, que se empleó en dos momentos diferentes (1 y 24 h). Los datos se compararon mediante análisis de varianza (ANOVA) y test de Tukey (p<0,05). Los resultados mostraron una diferencia significativa (p<0,05) entre los grupos N, R, Y, G y la negativa citotoxicidad del control en 1 y 24 h (p<0,05), no han presentado diferencias significativas entre los grupos N, R , Y, G probado (p>0,05) en 1 y 24 h. Elásticos intraorales Morelli resultaron ser altamente citotóxicos, independientemente de su color y tiempo de inmersión.

Cytotoxicity of latex and non-latex orthodontic elastomeric ligatures on L929 mouse fibroblasts

This study investigated the cytotoxicity exists between latex and non-latex Orthodontic elastomeric ligatures. Six elastomeric ligatures (1 latex, 2 latex-free and 3 polyurethane) from different manufacturers were divided into 6 groups of 15 elastics each: A (Latex-free, American Orthodontics), M (Polyurethane, Morelli), G (Polyurethane,GAC International), Te (Polyurethane, Tecnident), TP (Natural latex,TP Orthodontics) and U (Latex-free,3M Unitek). The cytotoxicity assay was performed using cell cultures (L929 mouse fibroblast cell line), which were subjected to the cell viability test with neutral red ("dye-uptake") at 1, 2, 3, 7 and 28 days. Data were analyzed statistically by ANOVA and Tukey's test (α=0.05). No statistically significant differences (p>0.05) were observed between Groups M and Te in all experimental periods, except at 2 days. No significant differences (p>0.05) in cell viability were found either among Groups A, G, TP and U or between Groups M and Te at 24 h or among Groups CC, A, G, TP and U at 2 and 28 days. It may be concluded that latex-free elastomeric ligatures from American Orthodontics and Unitek trademarks induced less cell lysis compared to latex and polyurethane ligatures.

Este estudo investigou a citotoxicidade entre ligaduras elásticas ortodônticas de látex e não-látex. Seis ligaduras elásticas de diferentes fabricantes (1 látex, 2 não-látex e 3 poliuretano) foram divididos em 6 grupos de 15 elásticos cada: Grupo A (látex-free, American Orthodontics), M (Poliuretano, Morelli), G (Poliuretano, GAC International), Te (Poliuretano, Tecnident), TP (látex natural, TP Orthodontics) e U (Látex-free, 3M Unitek). O ensaio de citotoxicidade foi realizado utilizando culturas de células (células da linhagem L929, fibroblastos de camundongo) que foram submetidos ao teste de viabilidade celular com vermelho neutro ("dye-uptake") em 1, 2, 3, 7 e 28 dias. A análise de variância (ANOVA), com comparações múltiplas e teste de Tukey foram empregados (α=0,05). Os resultados mostraram que não houve diferença estatisticamente significante entre os Grupos M e Te em todos os tempos experimentais (p>0,05), exceto em 2 dias. Não houve diferença estatisticamente (p>0,05) entre a viabilidade das células nos grupos A, G, TP e U ou entre os grupos M e Te em 24 h, ou entre os grupos CC, A, G, TP e U em 2 e 28 dias. Concluiu-se que as ligaduras elásticas látex-free das marcas American Orthodontics e Unitek induziram menor quantidade de lise celular comparado às ligaduras de látex ou poliuretano.

Cytotoxicity and biocompatibility of direct and indirect pulp capping materials

There are several studies about the cytotoxic effects of dental materials in contact with the pulp tissue, such as calcium hydroxide (CH), adhesive systems, resin composite and glass ionomer cements. The aim of this review article was to summarize and discuss the cytotoxicity and biocompatibility of materials used for protection of the dentin-pulp complex, some components of resin composites and adhesive systems when placed in direct or indirect contact with the pulp tissue. A large number of dental materials present cytotoxic effects when applied close or directly to the pulp, and the only material that seems to stimulate early pulp repair and dentin hard tissue barrier formation is CH.

Biosilicate® Ototoxicity and Vestibulotoxicity evaluation in guinea-pigs / Avaliação da ototoxicidade e vestibulotoxicidade do biosilicato® em orelhas de cobaias

Changes, destructions and interruptions in middle ear ossicular chain architecture may be caused by infection, trauma, tumors, congenital alterations or prior surgeries. Nonetheless, infectious and inflammatory processes, focal or generalized which affect the middle ear are the most prevalent, causing a great demand for ossiculoplasty. Biosilicato® is a new material which can be used in the middle ear with the goal of reconstructing the ossicular chain. It is a bioactive type A vitroceramic, in other words, it binds to bone or soft tissue in a matter of a few hours, thanks to the formation of hydroxy-carbonateapatatie in its contact surface when in contact with body fluids. AIMS: The goal of the present paper is to assess biosilicate ototoxicity and vestibular toxicity in experimental animals, for later use in humans. MATERIALS AND METHODS: This a clinical and experimental study in which otoacoustic emissions were performed before and after the placement of Biosilicate in the middle ear of experimental animals and a scanning electron microscopy was carried out in the cochlea, saccule, utriculus and macula of the semicircular canals after 30 and 90 days to assess oto and vestibular toxicity. RESULTS: There were no signs of oto or vestibular toxicity in any of the groups associated with biosilicate. CONCLUSION: Biosilicate is a safe material to be used in ossiculoplasties

As alterações, destruições e interrupções da arquitetura da cadeia ossicular da orelha média podem ser causadas por infecções, trauma, tumores, alterações congênitas ou cirurgias prévias. Entretanto os processos inflamatórios e infecciosos, focais ou generalizados que acometem a orelha média são os mais prevalentes, gerando uma enorme demanda de ossiculoplastias. O Biosilicato® é um novo material que pode ser usado em orelhas médias com o objetivo de reconstruir a cadeia ossicular. Constitui-se de uma vitrocerâmica bioativa do tipo A, ou seja, que se liga a tecido ósseo ou a tecido mole em algumas horas, devido à formação de hidroxicarbonatoapatita em sua superfície de contato quando em contato com fluidos corpóreos. OBJETIVO: O objetivo deste trabalho é avaliar a ototoxicidade e vestibulotoxicidade do Biosilicato em cobaias, para posterior utilização em humanos. MATERIAL E MÉTODO: Trata-se de um estudo clínico e experimental, onde foram realizadas emissões otoacústicas antes e após a colocação de Biosilicato na orelha média de cobaias e realizada microscopia eletrônica de varredura da cóclea, sáculo, utrículo e máculas dos canais semicirculares após 30 e 90 dias para avaliar a oto e vestibulotoxicidade. RESULTADOS: Não houve sinais de oto ou vestibulotoxicidade em nenhum dos grupos relacionados ao Biosilicato. CONCLUSÃO: O Biosilicato é um material seguro para ser usado em ossiculoplastias.

Effect of temperature variation on the cytotoxicity of cast dental alloys and commercially pure titanium

Cell culture system has been used to evaluate alloy cytotoxicity under different environments, testing the extracts, but the effect of temperature variation on the cytotoxicity of dental alloys has not been analyzed. OBJECTIVE: The aim of the present study was to investigate if temperature variation could affect dental alloy cytotoxicity, testing alloy extracts in an epithelial cell culture system. MATERIAL AND METHODS: Discs of Ni-Cr, Co-Cr-Mo, Ni-Cr-Ti, Ti-6Al-4V and commercially pure titanium (cp Ti) were cast by arc melting, under argon atmosphere, injected by vacuum-pressure. Discs were immersed in artificial saliva and subjected to different temperatures: 37ºC and thermocycling (37ºC/5ºC/37ºC/55ºC/37ºC). After thermocycling, extracts were put in a subconfluent culture during 6 h, and the number of cells and their viability were used to evaluate cytotoxicity in these temperatures. For each alloy, data from temperature conditions were compared by Student's t-test (α=0.05). RESULTS: The cytotoxicity tests with alloy/metal extracts showed that Ni-Cr, Co-Cr-Mo, Ti-6Al-4V and cp Ti extracts (p>0.05) did not affect cell number or cell viability, while Ni-Cr-Ti (p<0.05) extract decreased cell number and viability when the alloy was subjected to thermocycling. CONCLUSION: Within the limitations of the present study, the Ni-Cr-Ti alloy had cell number and viability decreased when subjected to temperature variation, while the other alloys/metal extracts did not show these results.

Avaliação in vitro da citotoxicidade de parafusos expansores palatinos / In vitro evaluation of the cytotoxicity of palatal expanders

Objetivo: Avaliar a citotoxicidade de parafusos expansores confeccionados com aço inoxidável ou compósito. Métodos: Foram avaliados 6 parafusos expansores divididos em 2 grupos de acordo com o material: expansor metálico e expansor de compósito. Três grupos controle foram utilizados: controle positivo (cilindro de amálgama), controle negativo (bastão de vidro) e controle de célula (células não expostas). Os expansores esterilizados foram imersos em meio mínimo essencial de Eagle por 24 h, onde se procedeu a remoção do sobrenadante e contato com fibroblastos L929. Após contato com o meio as células foram incubadas por 24 h, sendo adicionados 100 μL do corante vermelho neutro a 0,01%, seguido por incubação por 3 h e fixação das células. A citotoxicidade foi analisada em 4 períodos: 24, 48, 72 e 168 h. A contagem de células viáveis foi realizada com espectrofotômetro (λ = 492 nm) e os dados foram analisados por ANOVA. Resultados: Os grupos controle positivo (amálgama) foram estatisticamente diferentes dos demais grupos. Não houve diferença estatística na comparação entre os demais grupos e períodos. Conclusões: Os resultados sugerem que os parafusos expansores testados não apresentam citotoxicidade significativa conforme o desenho experimental utilizado.

Objective: To evaluate the cytotoxicity of two palatal expanders made of stainless steel or composite. Methods: Six expanders were divided into two experimental groups: metallic expander and composite expander. Three control groups also were assessed: positive control (amalgam), negative control (glass stick), and control cell (cells not exposed to any material). The sterilized expanders were immersed into Eagle's minimum essential medium for 24 h, and the contact assay was performed using L929 fibroblasts. The cells were incubated for 24 h, and 100 μL of 0.01% neutral-red staining solution were added followed by incubation for 3 h and cell fixation. Cytotoxicity was evaluated at four different periods of time: 24, 48, 72, and 168 h. Counting of viable cells was performed by using a spectrophotometer at a wavelength of 492 nm, and data were analyzed by ANOVA. Results: The positive control groups (amalgam) were statistically different from the other groups. No difference of cytotoxicity was found among the groups and periods of time. Conclusions: The tested metallic and composite expanders showed no significant cytotoxicity within this experimental design.

Propiedades biológicas de los materiales de obturación: III parte. Ensayos de uso clínico en animales de experimentación / Biological properties of root canal filling materials: part III. Usage tests in experimental animals

Una revisión exhaustiva de la bibliografía revela que existe una considerable cantidad de publicaciones relacionadas con las propiedades biológicas de los materiales de obturación endodóntica. La mayoría de las mismas están referidas a los ensayos preclínicos in vitro e in vivo de acuerdo a las normas establecidas por los diferentes organismos internacionales. Estas pruebas incluyen los ensayos de citotoxicidad in vitro y la implantación de materiales problema en el tejido celular subcutáneo, músculo o hueso de pequeños animales de laboratorio. Los resultados de estas diferentes metodologías no presentan una correlación definida. Como consecuencia de estas observaciones, los únicos ensayos de biocompatibilidad considerados como relevantes son los así denominados ensayos de uso clínico. En esta tercera entrega se hace un delineamiento de los ensayos requeridos para el análisis biológico de los materiales de obturación previos a su aceptación para ser utilizados rutinariamente en humanos.

Biocompatibility of EDTA, EGTA and citric acid

Este estudo in vivo avaliou o potencial irritativo do EDTA, EGTA, ácido cítrico e soro fisiológico (controle) durante a fase exsudativa do processo inflamatório. Aplicou-se, intravenosamente na veia caudal lateral de 32 ratos machos da linhagem "Wistar", variação albina, 20 mg/kg de azul de Evans 2%. Em seguida, no tecido subcutâneo da região dorsal dos animais injetou-se 0,01 mL das soluções testes. Após os intervalos de ½, 1, 3 e 6 horas, os animais foram sacrificados, suas peles dorsais foram excisadas e submetidas à análise do corante extravasado pela espectrofotometria de absorção de luz. Os dados obtidos foram avaliados pela análise de variância a 2 critérios e teste de Tukey. Em todos os períodos de tempo estudados, os maiores valores de corante extravasado foram observados no grupo do EDTA seguido pelos grupos do EGTA e ácido cítrico, em comparação ao grupo controle. Houve diferença estatisticamente significante entre todas as soluções testadas (p<0.01). Quando considerado o fator tempo, notou-se diferença significante entre os grupos de 3 e 6 horas (p<0.05). Entretanto, não houve diferença entre os grupos de tempo de ½ e 1 hora. Dentre os ácidos orgânicos avaliados, os resultados demonstraram que o ácido cítrico apresentou o menor potencial irritativo.

Cell death induced by hydroxyapatite on L929 fibroblast cells

Biomaterials intended for end-use application as bone-graft substitutes have to undergo safety evaluation. In this study, we investigated the in vitro cytotoxic effects especially to determine the mode of death of two hydroxyapatite compounds (HA2, HA3) which were synthesized locally. The methods used for cytotoxicity was the standard MTT assay whereas AO/PI staining was performed to determine the mode of cell death in HA treated L929 fibroblasts. Our results demonstrated that both HA2 and HA3 were not significantly cytotoxic as more than 75% cells after 72 hours treatment were viable. Furthermore, we found that the major mode of cell death in HA treated cells was apoptosis. In conclusion, our results demonstrated that these hydroxyapatite compounds are not cytotoxic where the mode of death was primarily via apoptosis.

DNA damage evaluation of hydroxyapatite on fibroblast cell L929 using the single cell gel electrophoresis assay

Hydroxyapatite is the main component of the bone which is a potential biomaterial substance that can be applied in orthopaedics. In this study, the biocompatibility of this biomaterial was assessed using an in vitro technique. The cytotoxicity and genotoxicity effect of HA2 and HA3 against L929 fibroblast cell was evaluated using the MTT Assay and Alkaline Comet Assay respectively. Both HA2 and HA3 compound showed low cytotoxicity effect as determined using MTT Assay. Cells viability following 72 hours incubation at maximum concentration of both HA2 and HA3 (200 mg/ml) were 75.3 +/- 8.8% and 86.7 +/- 13.1% respectively. However, the cytotoxicity effect of ZnSO4.7H2O as a positive control showed an IC50 values of 46 mg/ml (160 microM). On the other hand, both HA2 and HA3 compound showed a slight genotoxicity effect as determined using the Alkaline Comet Assay following incubation at the concentration 200 mg/ml for 72 hours. This assay has been widely used in genetic toxicology to detect DNA strand breaks and alkali-labile site. The percentage of the cells with DNA damage for both substance was 27.7 +/- 1.3% and 15.6 +/- 1.0% for HA2 and HA3 respectively. Incubation of the cells for 24 hours with 38 microg/ml (IC25) of positive control showed an increase in percentage of cells with DNA damage (67.5 +/- 0.7%). In conclusion, our study indicated that both hydroxyapatite compounds showed a good biocompatibility in fibroblast cells.

Chromosome aberration test for hydroxyapatite in sheep

The present study is aimed at finding the mutagenicity and cytotoxicity of dense form of synthetic hydroxyapatite (Source: School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia) in the blood of sheep. The biomaterial was implanted in the tibia of Malin, an indigenous sheep breed of Malaysia. Blood was collected from the sheep before implantation of the biomaterial, cultured and a karyological study was made. Six weeks after implantation, blood was collected from the same animal, cultured and screened for chromosome aberrations. The mitotic indices and karyological analysis indicated that the implantation of synthetic hydroxyapatite (dense form) did not produce any cytotoxicity or chromosome aberrations in the blood of sheep.