Cytotoxicity and genotoxicity of natural resin-based experimental endodontic sealers.

OBJECTIVES: The development of endodontic sealers based on natural resins seems to be promising, given their improved biological properties. This study evaluated the cytotoxic and genotoxic effects of two experimental root canal sealers, based on extracts from Copaifera multijuga and Ricinus communis (castor oil polymer), comparing them to synthetic resin-based sealers: a single methacrylate-based, a multi-methacrylate-based, and an epoxy resin-based sealers. MATERIALS AND METHODS: Sealers were prepared, set, and exposed to cell culture medium for 24 h at 37 °C with CO2. V79 cells were exposed to serial dilutions of the extracts of each sealer for 24 h. Cell viability was measured by the MTT assay and genotoxicity was assessed by the formation of micronuclei. RESULTS: The single methacrylate-based sealer had the most cytotoxic effects, with significant reduction in cell viability in all dilutions of the extract. The castor oil polymer-based sealer was, on the other hand, the most biocompatible sealer, with no cytotoxic effects at any concentration. All tested sealers were not genotoxic, excepting the single methacrylate-based sealer. CONCLUSIONS: The tested natural resin-based sealers presented low cytotoxic and no genotoxic effects on cell cultures. CLINICAL RELEVANCE: These results may suggest a good alternative to develop new endodontic sealers, in order to achieve better biological response and healing, when compared to commercially available sealers.

Setting time affects in vitro biological properties of root canal sealers.

INTRODUCTION: Biocompatibility of root canal sealers is important because of the long-term contact of their eluates and/or degradation products with periapical tissues. The literature still lacks studies about the genotoxic effects of these materials and the influence of setting time on biological properties. The cytotoxicity and genotoxicity of an epoxy resin-based sealer (AH Plus), a single methacrylate-based sealer (EndoRez), and a silicone-based sealer (RoekoSeal) were assessed. METHODS: Chinese hamster fibroblasts (V79) were cultured and exposed to different dilutions of extracts from the sealers that were left to set for 0, 12, and 24 hours before contact with culture medium. Cell viability was measured by the methyl-thiazol-diphenyltetrazolium assay. Genotoxicity was assessed by the comet assay. Data were statistically analyzed by Kruskal-Wallis and Dunn tests (P < .05). RESULTS: Root canal sealers were statistically more cytotoxic than the untreated control group, except for the silicon-based sealer. Cell viability ranking was the following (from the most to the least cytotoxic): methacrylate-based > epoxy resin-based > silicone-based. The setting time influenced the epoxy resin-based sealer cytotoxicity (decreased at 12 hours) and the general genotoxicity (increased at 24 hours). DNA damage ranking was the following (from the most to the least genotoxic): methacrylate-based > silicone-based = epoxy resin-based. CONCLUSIONS: The setting time had influence on the cytotoxicity of the epoxy resin-based sealer and genotoxicity of all tested sealers. The methacrylate-based sealer was the most cytotoxic, and the silicone-based sealer was not cytotoxic. Genotoxicity was observed for all sealers.

A hydrogel scaffold that maintains viability and supports differentiation of dental pulp stem cells.

OBJECTIVES: The clinical translation of stem cell-based Regenerative Endodontics demands further development of suitable injectable scaffolds. Puramatrix™ is a defined, self-assembling peptide hydrogel which instantaneously polymerizes under normal physiological conditions. Here, we assessed the compatibility of Puramatrix™ with dental pulp stem cell (DPSC) growth and differentiation. METHODS: DPSC cells were grown in 0.05-0.25% Puramatrix™. Cell viability was measured colorimetrically using the WST-1 assay. Cell morphology was observed in 3D modeling using confocal microscopy. In addition, we used the human tooth slice model with Puramatrix™ to verify DPSC differentiation into odontoblast-like cells, as measured by expression of DSPP and DMP-1. RESULTS: DPSC survived and proliferated in Puramatrix™ for at least three weeks in culture. Confocal microscopy revealed that cells seeded in Puramatrix™ presented morphological features of healthy cells, and some cells exhibited cytoplasmic elongations. Notably, after 21 days in tooth slices containing Puramatrix™, DPSC cells expressed DMP-1 and DSPP, putative markers of odontoblastic differentiation. SIGNIFICANCE: Collectively, these data suggest that self-assembling peptide hydrogels might be useful injectable scaffolds for stem cell-based Regenerative Endodontics.

Células-tronco na saúde e na doença / Stem cells in health and disease

Células-tronco foram recentemente caracterizadas como componentes fundamentais parao desenvolvimento e função de órgãos e tecidos do corpo humano. O descontrole nos processos de diferenciação e sobrevivência das células-tronco tem sido caracterizado como fator etiológico importante em alterações de desenvolvimento do complexo crânio-facial. O conhecimento gerado através de estudos feitos nesta área levantaram a possibilidade de se utilizar células-tronco terapeuticamente para regeneração de tecidos da cavidade oral. Por outro lado, células-tronco também foram caracterizadas em patologias importantes como o câncer. Em câncer, células-tronco participam dos processos de progressão tumoral, bem como na resistência a terapias uma vez que estas células são resistentes a quimioterapia convencional. Tanto em regeneração de tecidos quanto em câncer, é fundamental que se tenha uma compreensão profunda dos mecanismos que governam o comportamento das células-tronco para que se possa desenvolver terapias que sejam seguras e eficazes para os pacientes. O objetivo principal desta revisão é discutir o papel das células tronco em saúde e na doença, usando a regeneração de tecido pulpar e o câncer oral como exemplos de relevância no contexto de Odontologia.

Stem cells were recently characterized as critical components of the development and function of most tissues and organs in humans. Indeed, deregulated survival and differentiation of stem cells have been characterized as important etiological factors of developmental anomalies in the craniofacial region. This knowledge raised the possibility that stem cells could be useful for the therapeutic regeneration of oral tissues. On the other hand, stem cells appear to have an important role in tumor progression, as well as in the resistance of cancer to therapy. This might be due to the fact that stem cells are resilient, long-lived, and tend to survive to conventional chemotherapeutic drugs. Both, in tissue regeneration and in cancer, it is critical to have a profound understanding of the mechanisms that regulate the behavior of stem cells to develop therapies that are safe and effective for patients. The main objective of this review is to discuss the role of stem cells in health and disease, using dental pulp tissue regeneration and oral cancer as examples of relevance to Dentistry.

The effects of low-level diode laser treatment and dental pulp-capping materials on the proliferation of L-929 fibroblasts.

Low-level laser therapy (LLLT) has been reported to improve tissue healing and might therefore be useful in dental pulp capping after trauma. We evaluated the effects of a low-level diode laser (lambda = 680 nm) and dental pulp-capping substances on cell proliferation. Calcium hydroxide and adhesive resin were applied as conditioned media to cultures. Half of the samples received irradiation with the diode laser at a fluence of 4 J/cm(2) for 60 s. Using a hemocytometer, cells were counted at 1, 3, 5, and 7 days, and the data were analyzed by ANOVA. All cultures exhibited continuous growth, except those treated with adhesive resin. As compared to the other two groups, cell proliferation was significantly lower in cultures treated with adhesive resin; it was also significantly lower in cultures treated with calcium hydroxide, as compared to the control group. When combined with dental pulp-capping materials, LLLT had no effect on L-929 cell proliferation.

Effect of laser phototherapy on the release of TNF-alpha and MMP-1 by endodontic sealer-stimulated macrophages.

OBJECTIVE: Our aim was to analyze the effect of laser phototherapy on the secretory activity of macrophages activated by interferon-gamma (IFN-gamma) and lipopolysaccharide (LPS), and stimulated by substances leached from an epoxy resin-based sealer (AH-Plus) and a calcium hydroxide-based sealer (Sealapex). BACKGROUND DATA: Laser phototherapy can modulate the inflammatory process, improving wound healing. This type of therapy could be useful for modulating postoperative symptoms seen after endodontic treatment. MATERIALS AND METHODS: Cytotoxicity was indirectly assessed by measuring mitochondrial activity. Macrophages were stimulated by the leached substances or not (controls), and the groups were then irradiated or not. The secretion of pro-inflammatory cytokines (TNF-alpha and MMP-1) was analyzed using ELISA. Two irradiations at 6-h intervals were done with an As-Ga-Al diode laser (780 nm, 70 mW, spot size 4.0 mm(2), 3 J/cm(2), for 1.5 sec) in contact mode. RESULTS: The sealers were non-cytotoxic to macrophages. The production of TNF-alpha was significantly decreased by laser phototherapy, regardless of experimental group. The level of secretion of MMP-1 was similar in all groups. CONCLUSION: Based on the conditions of this study we concluded that in activated macrophages, laser phototherapy impairs the secretion of the pro-inflammatory cytokine TNF-alpha, but has no influence on MMP-1 secretion.