Absence of DNA damage in multiple organs after oral exposure to fluoride in Wistar rats

Effects of Fluoride on Submandibular Glands of Mice: Changes in Oxidative Biochemistry, Proteomic Profile, and Genotoxicity

Although fluoride (F) is well-known to prevent dental caries, changes in cell processes in different tissues have been associated with its excessive exposure. Thus, this study aimed to evaluate the effects of F exposure on biochemical, proteomic, and genotoxic parameters of submandibular glands. Twenty one old rats (n = 30) were allocated into three groups: 60 days administration of drinking water containing 10 mgF/L, 50 mgF/L, or only deionized water (control). The submandibular glands were collected for oxidative biochemistry, protein expression profile, and genotoxic potential analyses. The results showed that both F concentrations increased the levels of thiobarbituric acid–reactive substances (TBARS) and reduced glutathione (GSH) and changed the proteomic profile, mainly regarding the cytoskeleton and cellular activity. Only the exposure to 50 mgF/L induced significant changes in DNA integrity. These findings reinforce the importance of continuous monitoring of F concentration in drinking water and the need for strategies to minimize F intake from other sources to obtain maximum preventive/therapeutic effects and avoid potential adverse effects.

Putative mechanisms of genotoxicity induced by fluoride: a comprehensive review

Genotoxicity is the ability of an agent to produce damage on the DNA molecule. Considering the strong evidence for a relationship between genetic damage and carcinogenesis, to elucidate the putative mechanisms of genotoxicity induced by fluoride are important to measure the degree of risk involved to human populations. The purpose of this article is to provide a comprehensive review on genotoxicity induced by fluoride on the basis of its mechanisms of action. In the last 10 years, all published data showed some evidence related to genotoxicity, which is due to mitochondrial disruption, oxidative stress, and cell cycle disturbances. However, this is an area that still requires a lot of investigation since the published data are not sufficient for clarifying the genotoxicity induced by fluoride. Certainly, the new information will be added to those already established for regulatory purposes as a safe way to promote oral healthcare and prevent oral carcinogenesis.

Sodium fluoride promotes apoptosis by generation of reactive oxygen species in human lymphocytes

Fluoride generated the attention of toxicologists due to its deleterious effects at high concentrations in human populations suffering from fluorosis and with in vivo experimental models. Interest in its undesirable effects has resurfaced due to the awareness that this element interacts with cellular systems even at low doses. This study focused on examining the adverse effects of inorganic fluoride (NaF) on human lymphocyte cells in vitro. Mitochondrial function, oxidative stress, cell cycle progression, and mode of cell death were combined with genotoxic endpoints. Data demonstrated that NaF at lower concentrations, although not significantly cytotoxic and genotoxic, induced oxidative stress leading to apoptotic cell death. The results also suggested that at low concentrations (<1 μg/ml), NaF may affect cell cycle progression. Taken together, our findings confirm earlier reports on mechanisms involved in NaF-induced apoptosis.

Fluoride content of soft drinks, nectars, juices, juice drinks, concentrates, teas and infusions marketed in Portugal

A potentiometric method using a fluoride combination ion-selective electrode was validated and used to analyse 183 samples, including soft drinks, juices, nectars, juice drinks, concentrates, teas and infusions marketed in Portugal. The fluoride levels were higher in extract-based soft drinks, juice drinks and juice, with fluoride values of 0.86 ± 0.35, 0.40 ± 0.24 and 0.37 ± 0.11 mg l⁻¹, respectively. The lowest fluoride concentration was found in infusion samples (0.12 ± 0.01 mg l⁻¹), followed by teas and carbonated soft drinks with fluoride concentrations of 0.16 ± 0.12 and 0.18 ± 0.07 mg l⁻¹, respectively. Nectars, concentrates and juice-based drinks had similar fluoride concentrations of 0.33 ± 0.16, 0.29 ± 0.12 and 0.25 ± 0.14 mg l⁻¹, respectively. The fluoride concentrations in all these samples would only contribute intakes below the acceptable daily intake (ADI = 0.05 mg kg⁻¹ body weight day⁻¹), indicating that, individually, these beverages cannot induce fluoride toxicity in the population group of children.

Biocompatibility of a porous alumina ceramic scaffold coated with hydroxyapatite and bioglass

This study aimed to evaluate the osteointegration and genotoxic potential of a bioactive scaffold, composed of alumina and coated with hydroxyapatite and bioglass, after their implantation in tibias of rats. For this purpose, Wistar rats underwent surgery to induce a tibial bone defect, which was filled with the bioactive scaffolds. Histology analysis (descriptive and morphometry) of the bone tissue and the single-cell gel assay (comet) in multiple organs (blood, liver, and kidney) were used to reach this aim after a period of 30, 60, 90, and 180 days of material implantation. The main findings showed that the incorporation of hydroxyapatite and bioglass in the alumina scaffolds produced a suitable environment for bone ingrowth in the tibial defects and did not demonstrate any genotoxicity in the organs evaluated in all experimental periods. These results clearly indicate that the bioactive scaffolds used in this study present osteogenic potential and still exhibit local and systemic biocompatibility. These findings are promising once they convey important information about the behavior of this novel biomaterial in biological system and highlight its possible clinical application.

Genetic damage in human peripheral lymphocytes exposed to antimicrobial endodontic agents

OBJECTIVE

Formocresol, paramonochlorophenol, or calcium hydroxide have been widely used in dental practice to eradicate bacteria and consequently to produce root canal disinfection. Taking into consideration strong evidence for a relationship between DNA damage and carcinogenesis, the purpose of the present study was to evaluate the genotoxic effects of antimicrobial endodontic compounds in human peripheral lymphocytes by single-cell gel (comet) assay. This technique detects DNA strand breaks in individual cells.

STUDY DESIGN

A total of 10 microL of the tested substance solution (formocreso1, paramonochlorofeno1, and calcium hydroxide at 100-microg/mL concentration) was added to human peripheral lymphocytes from 10 volunteers for 1 hour at 37 degrees C. The negative control group was treated with vehicle control (PBS) for 1 hour at 37 degrees C, as well. For the positive control group, lymphocytes were exposed to hydrogen peroxide at 100 microM during 5 minutes on ice.

RESULTS

No DNA breakage was detected after a treatment of peripheral lymphocytes by formocresol, paramonochlorophenol, or calcium hydroxide at 100 microg/mL.

CONCLUSIONS

In summary, our results indicate that exposure to formocresol, paramonochlorophenol, or calcium hydroxide may not be a factor that increases the level of DNA lesions in human peripheral lymphocytes as detected by single-cell gel (comet) assay.