RESUMO

Abstract Bioactive cements based on tricalcium silicate have been introducedto the market for use in dentistry, with a variety of clinical applications. These cements are in contact with vital tissues such as dental pulp or periodontium in cases of unintentional extrusion; thus, it is important to know the genotoxicity and cytoxicity of these materials. The objective of this study was to evaluate the cytotoxicity and genotoxicity of bioactive sealers, Bio-C® Sealer and MTA Repair HP®, in human fibroblasts. Discs of bioactive sealers Bio-C® Sealer, and MTA Repair HP®, were prepared and set for 24h under sterile conditions. The discs were placed in culture medium at 2.5mg/mL inside a SRT6D roller mixer (Stuart, UK) at 60rpm for 24h. The eluates obtained were incubated for 24h with previously activated and cultured ATCC cell line fibroblasts at 80% confluence. The cytotoxicity was evaluated by Alamar Blue® and LIVE/ DEAD assays, as well as the analysis of the Tunel and Mitotracker assays to evaluate genotoxicity using the confocal laser-scanning microscope. In the Alamar Blue® assay, the Bio-C® Sealer presented a cell proliferation of 87%, while the MTA Repair HP® Sealer was 72%. A statistically significant difference was found between the MTA Repair HP® Sealant and the negative control (p=<0.001). Regarding the genotoxicity tests, in the Tunel assay, both materials stain the nucleus of the fibroblast cells exposed to the eluates, while in the Mitotracker assay, the MTA Repair HP® Sealer showed greater mitochondrial function than the Bio-C® Sealer. Calcium silicate-based sealers, Bio-C® Sealer and MTA Repair HP®, are not cytotoxic and have low genotoxicity.

Resumen Los cementos bioactivos a base de silicato tricálcico se introdujeron en el mercado para uso en odontología, con una variedad de aplicaciones clínicas. Estos cementos pueden estar en contacto con tejidos como la pulpa dental o el periodonto, en caso de extrusión no intencionada. Por lo tanto, es importante conocer la genotoxicidad y la citoxicidad de estos materiales. El objetivo de este estudio fue evaluar la citotoxicidad y genotoxicidad de los selladores bioactivos Bio-C® Sealer y MTA Repair HP® en fibroblastos humanos. Se prepararon discos de selladores bioactivos Bio-C® Sealer y MTA Repair HP® y se colocaron durante 24h en condiciones de esterilidad. Los discos se colocaron en medio de cultivo a 2,5mg/mL dentro de un mezclador de rodillos SRT6D (Stuart, Reino Unido) a 60rpm durante 24h. Los eluidos obtenidos se incubaron durante 24h con fibroblastos de la línea celular ATCC previamente activados y cultivados al 80% de confluencia. La citotoxicidad se evaluó mediante ensayos Alamar Blue® y LIVE/DEAD; así como el análisis de los ensayos Tunnel y Mitotracker para evaluar la genotoxicidad, utilizando el microscopio confocal láser de barrido. En el ensayo Alamar Blue®, el Sellador Bio-C® presentó una proliferación celular del 87%, mientras que el sellador MTA Repair HP® fue del 72%. Se encontró una diferencia estadísticamente significativa entre el sellador MTA Repair HP® con respecto al control negativo (p=<0.001). En cuanto a las pruebas de genotoxicidad, en el ensayo Tunel, ambos materiales tiñen el núcleo de las células fibroblásticas expuestas a los eluidos, mientras que el ensayo Mitotracker, el sellador MTA Repair HP®, mostró una mayor función mitocondrial que el Bio-C® Sealer. Los selladores a base de silicato de calcio, Bio-C® Sealer y MTA Repair HP® no son citotóxicos y tienen una baja genotoxicidad.

RESUMO

STATEMENT OF PROBLEM: Prefabricated dowels do not always provide intraradicular sealing in the root canal dentin, and the lack of sealing predisposes the dowel to adhesive failure and debonding. It is unclear if fiber-reinforced composite resin dowels provide better sealing. PURPOSE: The purpose of this in vitro study was to evaluate the intraradicular sealing and morphological fit of prefabricated dowels and fiber-reinforced composite resin dowels in root canal dentin. The thickness of the resin cement layer and push-out bond strength were determined to assess their effects on the sealing of the dowels. MATERIAL AND METHODS: A total of 50 permanent maxillary central incisors were endodontically treated and divided into 2 subgroups (n=25). In one group, prefabricated dowels were cemented; in the second group, fiber-reinforced composite resin dowels were placed. The thickness of the resin cement layer was assessed in 3 different locations: coronal, middle, and apical of the root canal dentin with fluorescence confocal laser microscopy. The push-out bond strength was then determined, and intraradicular sealing observed by using scanning electron microscopy. RESULTS: Fiber-reinforced composite resin dowels showed a closer intraradicular fit and seal in the root canal dentin, and the morphology of the apical portion of the fiber-reinforced composite resin dowels showed a sealing area with the gutta percha in the apical portion. The mean thickness of the resin cement layer was significantly reduced for the fiber-reinforced composite resin dowels compared with the prefabricated dowels (P<.05) in the cervical area (197.0 µm versus 311.0 µm) and in the apical portion of the root canal (57.3 µm versus 131.6 µm). The mean push-out strength was higher for the fiber-reinforced composite resin dowels (22.98 N/mm2) than that for the prefabricated dowels (16.49 N/mm2) (P<.05). CONCLUSIONS: The morphological fit of fiber-reinforced composite resin dowels provides better intraradicular sealing in the cervical and apical portions, reducing the resin cement thickness. The increased push-out strength can therefore be assumed to result from increased frictional retention compared with prefabricated dowels.

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RESUMO

The engineering of bone tissues represents an area of opportunity for the development of new polymeric compounds. In this context, the objective of this work is the generation and evaluation in vitro of supports obtained from mixtures of starch with poly (lactic acid) (PLA), treated with arginine-glycine-aspartic acid peptides (RGD). For this, non-woven fibers of PLA with different starch content (0.0, 2.5, 5.0 and 10.0%wt) were obtained using the electrospinning technique. Then the physical absorption of RGD was carried out, with the aim of increasing the cellular adhesion of the polymeric material. Subsequently, in vitro biocompatibility tests were performed, and viability (LIFE/DEAD), proliferation (MTS assay) and cell adhesion were carried out with osteoblasts incubated for 48 h. Regarding biocompatibility results, only viable cells were found for all the compositions, and the biocompatibility of the materials was validated by the morphological analysis of the cultured cells, where extended cells were observed. Proliferation assays show that osteoblasts proliferate better on the surfaces of PLA and PLA with 5.0% starch scaffolds. Therefore, it is concluded that the scaffolds obtained by electrospinning of PLA with starch and functionalized with RGD are promising for its use in the regeneration of bone tissue.

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