The Cessation of Fluoridated Water Administration and the Fluoride Distribution Profiles in Rat Molar Cementum

Ito, Tatsuaki; Nakagaki, H; Kato, Kazúo; Kondo, Karina Yuri; Isogai, A; Adachi, Keiko; Negoro, Michie; Huang, Aisheng; Nguyen, Tung; Robinson, Campbell W.

doi:10.1159/000262424

Cited by 2 publications

(2 citation statements)

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“…It is known that the best method for the systemic absorption of NaF is via the gastrointestinal tract. Hence, deionized water mixed with NaF to a concentration of 100 ppm [7,11,12] was used to feed the mice. This meant that they were exposed to 5 mM NaF every day from week 12 to week 58, which covered their adult and aging periods.…”

Section: Discussionmentioning

confidence: 99%

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Oral toxicity to high level sodium fluoride causes impairment of autophagy

Oka

Zhang

et al. 2020

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Background: Gingival recession and concomitant alveolar bone resorption are hallmarks of periodontal diseases and excessive fluoride intake has some deleterious effects on teeth, bone and soft tissues. Autophagy is a highly conserved intracellular digestion process that degrades damaged proteins and organelles but the biological roles of autophagy in pathological aspects of oral tissues remain largely unknown. We sought to elucidate the function of autophagy, especially its interplay with apoptosis and oxidative stress, in the oral toxicity induced by exposure to 5 mM sodium fluoride (NaF). Methods: HCEM2 cementoblast cells in culture were exposed to 5 mM NaF for 5 min, after which cell viability and cell apoptosis were assessed using the MTS assay and an Annexin V-FITC/PI apoptosis detection kit, respectively. Real-time quantitative RT-PCR and Western blotting were performed to characterize the mRNA and protein expression levels of markers for autophagy, apoptosis, and oxidative stress. C57BL/6 mice were exposed to 5 mM NaF in their drinking water from 12 to 58 weeks. Micro-computed tomography was used to measure changes in their alveolar bone while immunohistochemistry and immunofluorescence staining was used to evaluate protein expression levels of autophagy, apoptosis, and oxidative stress markers.Results: Cementoblasts exposed to 5 mM NaF had decreased levels of autophagy, as shown by reduced expression levels of ATG5, Beclin1 and LC3-II, elicited excessive apoptosis, which in turn induced oxidative stress and inflammation, as manifested by elevated levels of Bax, cleaved caspase-3, SOD1 and phospho NF-κB. Consistently, the in vivo results verified the findings of the in vitro study and treatment of mice with 5 mM NaF resulted in histological abnormalities in periodontal tissues, induced excessive oxidative stress and apoptosis, and reduced autophagy. These results correlated with the immunofluorescence observations, thus confirming the pivotal role of autophagic flux dysfunction in 5 mM NaF-induced cell death. Micro-computed tomography analysis demonstrated that 5 mM NaF caused a decrease in bone areas of mice compared with controls. Exposure to 5 mM NaF induced RANKL (receptor activator of nuclear factor κB ligand) and cathepsin K expression in periodontal tissues, while ATG5 and Beclin1 expression was abrogated by 5 mM NaF.Conclusion: Taken together, our findings suggest that 5 mM NaF elicits oral toxicity that contributes to excessive apoptosis, oxidative stress, and defective autophagy, which aggravates periodontal tissue damage.

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Section: Discussionmentioning

confidence: 99%

“…The highest concentration of uoride has been observed in the cementum of roots in animal [7] and human [8] studies. That concentration has also been found to increase with age [9][10][11][12][13] and is dependent upon the level of uoride in the water consumed [10,12].…”

Section: Introductionmentioning

confidence: 92%