Cytotoxic Effects of Resin Components on Cultured Mammalian Fibroblasts

The objectives of this study were to determine the cytotoxic concentrations of 11 components of resin composites on monolayers of cultured Balb/c 3T3 fibroblasts, to study the inhibitory effects of these components on DNA synthesis, total protein content, and protein synthesis, and to determine whether effects were reversible when the components were withdrawn from the medium. These data were reported as concentrations which inhibited 10% (ID10) and 50% (ID50) of a particular metabolic process as well as the range of concentrations over which cell metabolism was irreversibly inhibited. For any individual component, the ID50 values for all three metabolic parameters were of the same magnitude. The same was true for the ranges of irreversibility. Ethoxylated Bis-phenol A dimethacrylate (E-BPA) was the most toxic molecule of the group (ID50 being between 1 and 10 μmol/L). The ID50 concentrations for three of the components, including Bis-GMA, UDMA, TEGDMA, and Bis-phenol A, ranged between 10 and 100 μmol/L, while the ID 50 values of three components (N,N dihydroxyethyl-p-toluidine, camphoroquinone, and N,N dimethylaminoethyl methacrylate) were above 100 μmol/L. The concentrations to which the cells and tissues are exposed in uiuo are not known. This study should help to identify the concentrations of organic composite components which pose clinical cytotoxic hazards.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66623/2/10.1177_00220345910700111201.pd

Estrogenicity of resin-based composites and sealants used in dentistry.

We tested some resin-based composites used in dentistry for their estrogenic activity. A sealant based on bisphenol-A diglycidylether methacrylate (bis-GMA) increased cell yields, progesterone receptor expression, and pS2 secretion in human estrogen-target, serum-sensitive MCF7 breast cancer cells. Estrogenicity was due to bisphenol-A and bisphenol-A dimethacrylate, monomers found in the base paste of the dental sealant and identified by mass spectrometry. Samples of saliva from 18 subjects treated with 50 mg of a bis-GMA-based sealant applied on their molars were collected 1 hr before and after treatment. Bisphenol-A (range 90-931 micrograms) was identified only in saliva collected during a 1-hr period after treatment. The use of bis-GMA-based resins in dentistry, and particularly the use of sealants in children, appears to contribute to human exposure to xenoestrogens

Effect of starch-based biomaterials on the in vitro proliferation and viability of osteoblast-like cells

The cytotoxicity of starch-based polymers was investigated using different methodologies. Poly-L-lactic acid (PLLA) was used as a control for comparison purposes. Extracts of four different starch-based blends (corn starch and ethylene vinyl alcohol (SEVA-C), corn starch and cellulose acetate (SCA), corn starch and polycaprolactone (SPCL) and starch and poly-lactic acid (SPLA70) were prepared in culture medium and their toxicity was analysed. Osteoblast-like cells (SaOs-2) were incubated with the extracts and cell viability was assessed using the MTT test and a lactate dehydrogenase (LDH) assay. In addition DNA and total protein were quantified in order to evaluate cell proliferation. Cells were also cultured in direct contact with the polymers for 3 and 7 days and observed in light and scanning electron microscopy (SEM). LDH and DNA quantification revealed to be the most sensitive tests to assess respectively cell viability and cell proliferation after incubation with starch-based materials and PLLA. SCA was the starch blend with higher cytotoxicity index although similar to PLLA polymer. Cell adhesion tests confirmed the worst performance of the blend of starch with cellulose acetate but also showed that SPCL does not perform as well as it could be expected. All the other materials were shown to present a comparable behaviour in terms of cell adhesion showing slight differences in morphology that seem to disappear for longer culture times. The results of this study suggest that not only the extract of the materials but also their three-dimensional form has to be biologically tested in order to analyse material-associated parameters that are not possible to consider within the degradation extract. In this study, the majority of the starch-based biomaterials presented very promising results in terms of cytotoxicity, comparable to the currently used biodegradable PLLA which might lead the biocompatibility evaluation of those novel biomaterials to other studies.Fundação para a Ciência e a Tecnologia (FCT

Réactions biologiques indésirables des patients et pathologies professionnelles en orthodontie

L'exercice de l'orthodontie amène des biomatériaux exogènes de différentes compositions au contact de la muqueuse ou de la peau. Le processus de vieillissement des matériaux conduit à la libération de petites quantités d'ions métalliques ou de composés organiques à partir des appareils. La concentration des substances libérées est trop faible pour être toxique, sauf si une exposition répétée est associée à une irritation mécanique. Cependant, les réactions allergiques représentent un risque chez les patients préalablement sensibilisés à une substance allergisante particulière. Les réactions sont essentiellement des éruptions cutanées ou des lésions muqueuses, leur incidence a été évaluée entre 0,3 et 0,4 % chez les patients suivis en orthodontie. L'autre aspect de ces réactions indésirables est le risque pour le personnel, exposé de manière répétée à des facteurs similaires, de développer des pathologies. Le risque est plus élevé chez les professionnels que chez les patients. La plupart de ces manifestations sont des dermatoses, leur incidence a été évaluée à environ 20%. Une faible partie de ces maladies professionnelles est constituée de réactions autres que cutanées, telles que des affections respiratoires, des nausées ou des maux de tête, mais la difficulté est de les différencier des problèmes liés au stress ou à l'environnement intérieur

An assessment of the physical properties and biocompatibility of three silicone elastomers

The physical properties of two room-temperature vulcanizing (RTV) silicones, A-2186 and Silbione 71556, and one high-temperature vulcanizing (HTV) material, Mollomed, were compared. The potential cytotoxicity of the silicone materials was assessed with the agarose overlay test. The properties that were investigated were tensile strength, percentage elongation, modulus, permanent set, tear strength, and hardness. The properties tested were selected because of their clinical significance for fabricating facial prostheses. The results of this study indicate that the A-2186 material has a better combination of high tear strength and elongation at break with a softer surface compared with Mollomed silicone, and Silbione 71556 silicone proved to be the weakest material. All materials demonstrated absence of cytotoxicity in the cell culture tests. © 1994