Dataset Information

Nano-hydroxyapatite in oral care cosmetics: characterization and cytotoxicity assessment.

ABSTRACT: Nano-hydroxyapatite has been used as an oral care ingredient, being incorporated in several products for the treatment of dental hypersensitivity and enamel remineralisation. Despite its promising results, regulatory and safety concerns have been discussed and questioned by the European Scientific Committee on Consumer Safety (SCCS) regarding the usage of hydroxyapatite nanoparticles in oral care products. In this work, a commercially available nano-hydroxyapatite was characterized and its cytocompatibility towards human gingival fibroblasts was evaluated, as well as its irritation potential using the in vitro HET-CAM assay. All the conditions chosen in this study tried to simulate the tooth brushing procedure and the hydroxyapatite nanoparticles levels normally incorporated in oral care products. The commercial hydroxyapatite nanoparticles used in this study exhibited a rod-like morphology and the expected chemical and phase composition. The set of in vitro cytotoxicity parameters accessed showed that these nanoparticles are highly cytocompatible towards human gingival fibroblasts. Additionally, these nanoparticles did not possess any irritation potential on HET-CAM assay. This study clarifies the issues raised by SCCS and it concludes that this specific nano-hydroxyapatite is cytocompatible, as these nanoparticles did not alter the normal behaviour of the cells. Therefore, they are safe to be used in oral care products.

SUBMITTER: Coelho CC

PROVIDER: S-EPMC6667430 | biostudies-literature | 2019 Jul

REPOSITORIES: biostudies-literature

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Nano-hydroxyapatite in oral care cosmetics: characterization and cytotoxicity assessment.

Coelho Catarina C CC Grenho Liliana L Gomes Pedro S PS Quadros Paulo A PA Fernandes Maria H MH

Scientific reports 20190730 1

Nano-hydroxyapatite has been used as an oral care ingredient, being incorporated in several products for the treatment of dental hypersensitivity and enamel remineralisation. Despite its promising results, regulatory and safety concerns have been discussed and questioned by the European Scientific Committee on Consumer Safety (SCCS) regarding the usage of hydroxyapatite nanoparticles in oral care products. In this work, a commercially available nano-hydroxyapatite was characterized and its cytoc ...[more]

PMID: 31363145

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Project description:Nano-hydroxyapatite is used in oral care products worldwide. But there is little evidence yet whether nano-hydroxyapatite can enter systemic tissues via the oral epithelium. We investigated histologically the ability of two types of nano-hydroxyapatite, SKM-1 and Mi-HAP, to permeate oral epithelium both with and without a stratum corneum, using two types of three-dimensional reconstituted human oral epithelium, SkinEthic HGE and SkinEthic HOE respectively with and without a stratum corneum. Both types of nano-hydroxyapatite formed aggregates in solution, but both aggregates and primary particles were much larger for SKM-1 than for Mi-HAP. Samples of each tissue model were exposed to SKM-1 and Mi-HAP for 24 h at concentrations ranging from 1,000 to 50,000 ppm. After treatment, paraffin sections from the samples were stained with Dahl or Von Kossa stains. We also used OsteoSense 680EX, a fluorescent imaging agent, to test for the presence of HAP in paraffin tissue sections for the first time. Our results for both types of nano-hydroxyapatite showed that the nanoparticles did not penetrate the stratum corneum in SkinEthic HGE samples and penetrated only the outermost layer of cells in SkinEthic HOE samples without stratum corneum, and no permeation into the deeper layers of the epithelium in either tissue model was observed. In the non-cornified model, OsteoSense 680EX staining confirmed the presence of nano-hydroxyapatite particles in both the cytoplasm and extracellular matrix of outermost cells, but not in the deeper layers. Our results suggest that the stratum corneum may act as a barrier to penetration of nano-hydroxyapatite into the oral epithelium. Moreover, since oral epithelial cell turnover is around 5-7 days, superficial cells of the non-keratinized mucosa in which nanoparticles are taken up are likely to be deciduated within that time frame. Our findings suggest that nano-hydroxyapatite is unlikely to enter systemic tissues via intact oral epithelium.

Project description:Magnesium (Mg) and its alloys have shown attractive biocompatibility and mechanical strength for medical applications, but low corrosion resistance of Mg in physiological environment limits its broad clinical translation. Hydroxyapatite (HA) nanoparticles (nHA) are promising coating materials for decreasing degradation rates and prolonging mechanical strength of Mg-based implants while enhancing bone healing due to their osteoconductivity and osteoinductivity. Conformal HA coatings with nano-to-submicron structures, namely nHA and mHA coatings, were deposited successfully on Mg plates and rods using a transonic particle acceleration (TPA) process under two different conditions, characterized, and investigated for their effects on Mg degradation in vitro. The nHA and mHA coatings enhanced corrosion resistance of Mg and retained 86-90% of ultimate compressive strength after in vitro immersion in rSBF for 6 weeks, much greater than non-coated Mg that only retained 66% of strength. Mg-based rods with or without coatings showed slower degradation than the respective Mg-based plates in rSBF after 6 weeks, likely because of the greater surface-to-volume ratio of Mg plates than Mg rods. This indicates that Mg-based plate and screw devices may undergo different degradation even when they have the same coatings and are implanted at the same or similar anatomical locations. Therefore, in addition to locations of implantation, the geometry, dimension, surface area, volume, and mass of Mg-based implants and devices should be carefully considered in their design and processing to ensure that they not only provide adequate structural and mechanical stability for bone fixation, but also support the functions of bone cells, as clinically required for craniomaxillofacial (CMF) and orthopedic implants. When the nHA and mHA coated Mg and non-coated Mg plates were cultured with bone marrow derived mesenchymal stem cells (BMSCs) using the in vitro direct culture method, greater cell adhesion densities were observed under indirect contact conditions than that under direct contact conditions for the nHA and mHA coated Mg. In comparison with non-coated Mg, the nHA and mHA coated Mg reduced BMSC adhesion densities directly on the surface, but increased the average BMSC adhesion densities under indirect contact. Further long-term studies in vitro and in vivo are necessary to elucidate the effects of nHA and mHA coatings on cell functions and tissue healing.

Dataset Information

Nano-hydroxyapatite in oral care cosmetics: characterization and cytotoxicity assessment.

Publications

Nano-hydroxyapatite in oral care cosmetics: characterization and cytotoxicity assessment.

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