Antagonism of fluoride toxicity by high levels of calcium but not of inorganic phosphate during secretory amelogenesis in the hamster tooth germ in vitro

Bronckers, A.L.J.J.; Bervoets, T.J.M.; Lyaruu, D.M.; Wöltgens, J.H.M.

doi:10.1016/0003-9969(89)90017-4

Cited by 4 publications

(10 citation statements)

References 32 publications

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“…The effect of F, given the previous day, was still detectable as a slight reduction in amelogenin deposition in explants recovering at low and moderate calcium levels. Light microscopy confirmed recovery of the explants and showed that ameloblasts postcultured in normal and high levels of calcium looked normal and had deposited thicker layers of enamel than at low and very low calcium levels (data not shown; similar examples have been published previously [17].…”

Section: Resultssupporting

confidence: 80%

“…Some of these effects were reversible; when F was removed from the media – mimicking clearance of plasma F – the ameloblast structure was restored and crystals were seen to grow in the fluorotic matrix (16). Interestingly, the adverse effects of F on fluorotic matrix and ameloblast structure, but not hypermineralization, could be prevented by simultaneously increasing calcium levels in the medium (17). These data suggested that F did not change the intrinsic properties of the fluorotic matrix to mineralize (16,17) but indicated that the failure to initiate or foster crystals was caused by local, temporary changes, probably of a physico–chemical nature.…”

mentioning

confidence: 99%

“…Interestingly, the adverse effects of F on fluorotic matrix and ameloblast structure, but not hypermineralization, could be prevented by simultaneously increasing calcium levels in the medium (17). These data suggested that F did not change the intrinsic properties of the fluorotic matrix to mineralize (16,17) but indicated that the failure to initiate or foster crystals was caused by local, temporary changes, probably of a physico–chemical nature. One possibility, that F is less effective at inducing fluorotic enamel formation near a thick layer of (pre‐exposure) enamel, is that the higher mineral content of a thick layer provides a faster clearance of F than that of a thin layer.…”

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confidence: 99%

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Effect of calcium, given before or after a fluoride insult, on hamster secretory amelogenesis in vitro

Bronckers

Bervoets

Wöltgens

et al. 2006

European J Oral Sciences

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We tested the hypothesis that high-calcium medium given prior to or immediately after exposure to fluoride (F) reduces the negative effects of F on secretory amelogenesis. Hamster molar tooth germs were grown in organ culture in media with different calcium levels. Deposition of enamel matrix and matrix mineralization were monitored by incorporation of [3H]proline and uptake of 45Ca and acid-soluble 32PO4. Ameloblast structure and the occurrence of a fluorotic enamel matrix were examined by light and electron microscopy. A preculture of explants in high-calcium medium partially prevented the formation of fluorotic (non-mineralizing) enamel matrix, increased matrix secretion but could not prevent F-induced hypermineralization of the pre-exposure enamel. High-calcium medium, applied after F insult, accelerated the recovery of fluorotic matrix, improved ameloblast structure, enhanced amelogenin secretion, and increased enamel thickness. The data indicate that it might be the balance between the amount of mineral deposition and that of matrix secretion which is critical for the mineralization of newly secreted enamel. Exposure to F disturbs this balance by enhancing mineralization of the pre-exposure enamel, probably generating an excess of protons. High calcium may protect against F exposure by enhancing amelogenin secretion into the enamel space, thereby increasing the local buffering capacity at the mineralization front.

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Section: Resultssupporting

confidence: 80%

mentioning

confidence: 99%

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confidence: 99%

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Effect of calcium, given before or after a fluoride insult, on hamster secretory amelogenesis in vitro

Bronckers

Bervoets

Wöltgens

et al. 2006

European J Oral Sciences

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“…In vitro, these effects are more severe when calcium levels in the culture media, during exposure to fluoride, are low. At high media calcium levels, the fluoride effects on matrix and on cell structure are much less severe, or absent (Bronckers et al, 1989). These results suggest that, in vivo, the drop of plasma calcium associated with injection of a high dose of fluoride may enhance the severity of fluorotic lesions.…”

Section: Early-secretory Ameloblastsmentioning

confidence: 83%

The Impact of Fluoride on Ameloblasts and the Mechanisms of Enamel Fluorosis

Lyaruu²,

2009

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Intake of excess amounts of fluoride during tooth development cause enamel fluorosis, a developmental disturbance that makes enamel more porous. In mild fluorosis, there are white opaque striations across the enamel surface, whereas in more severe cases, the porous regions increase in size, with enamel pitting, and secondary discoloration of the enamel surface. The effects of fluoride on enamel formation suggest that fluoride affects the enamelforming cells, the ameloblasts. Studies investigating the effects of fluoride on ameloblasts and the mechanisms of fluorosis are based on in vitro cultures as well as animal models. The use of these model systems requires a biologically relevant fluoride dose, and must be carefully interpreted in relation to human tooth formation. Based on these studies, we propose that fluoride can directly affect the ameloblasts, particularly at high fluoride levels, while at lower fluoride levels, the ameloblasts may respond to local effects of fluoride on the mineralizing matrix. A new working model is presented, focused on the assumption that fluoride increases the rate of mineral formation, resulting in a greater release of protons into the forming enamel matrix.

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“…Histoiogically, IL-la and TGF-P were detected in both normal and osteopetrotic tissues but variation in their distribution was observed (24). Suitable culturing techniques permit monitoring of the developing tooth in isolation and allow metabolic and biochemical aspects of development to be documented (25)(26). Hence, substances secreted by the developing tooth may be analysed.…”

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confidence: 99%

Interleukin‐1 (IL‐1) bioactivity and inhibition of IL‐1 bioactivity in supernatant fluid from cultured microphthalmic (mi) mice teeth of different ages

Symons¹,

Polak²,

Powell³

et al. 1995

J Oral Pathology Medicine

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A functioning dental follicle and bone resorption are necessary for tooth eruption. In the microphthalmic (mi) mouse, bone resorption is defective and teeth fail to erupt. Local bone metabolism involves the production of cytokines such as interleukin-1 alpha (IL-1 alpha) and transforming growth factor-beta (TGF-beta). The production of these cytokines by dental tissues during eruption may be fundamental to tooth movement. Molars from mi mice were cultured and supernatants tested for the presence of these cytokines using bio-dot blotting and ELISA. A thymocyte bioassay was used to test supernatants for IL-1 bioactivity and IL-1 inhibition bioactivity. IL-1 alpha and TGF-beta were detected in all supernatants. Supernatants demonstrated no IL-1 bioactivity but inhibited IL-1 bioactivity which varied with concentration of supernatant, age and animal. This study demonstrated that cultured developing teeth secrete IL-1 alpha and TGF-beta however, concentrations varied in normal and pathological states. While IL-1 alpha was present in the supernatants, all demonstrated a variable ability to inhibit IL-1 bioactivity. This ability may influence local bone metabolism and hence tooth eruption.

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Antagonism of fluoride toxicity by high levels of calcium but not of inorganic phosphate during secretory amelogenesis in the hamster tooth germ in vitro

Cited by 4 publications

References 32 publications

Effect of calcium, given before or after a fluoride insult, on hamster secretory amelogenesis in vitro

Effect of calcium, given before or after a fluoride insult, on hamster secretory amelogenesis in vitro

The Impact of Fluoride on Ameloblasts and the Mechanisms of Enamel Fluorosis

Interleukin‐1 (IL‐1) bioactivity and inhibition of IL‐1 bioactivity in supernatant fluid from cultured microphthalmic (mi) mice teeth of different ages

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