A western-blotting study of enamel glycoproteins in rat experimental fluorosis

Dajean, S.; Ménanteau, Jean

doi:10.1016/0003-9969(89)90119-2

Cited by 5 publications

(4 citation statements)

References 16 publications

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“…ment of nitrogen (40) and carbon (41,42) have shown an increase in the amount of organic material in fluorosed enamel compared to normal enamel. Studies of fluoride effects on developing rat enamel show that amelogenin proteins are retained longer in the maturation stage of fluorosed enamel (19,24,43). This prolonged retention of amelogenin as maturation progresses may slow the growth of the enamel crystals, resulting in the less mineralized enamel that occurs in enamel fluorosis.…”

Section: Secretory Stagementioning

confidence: 99%

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Mechanism and Timing of Fluoride Effects on Developing Enamel

Besten¹

1999

J Public Health Dent

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Fluoride appears to specifically interact with mineralizing tissues, causing an alteration of the mineralization process. In enamel, fluorosis results in a subsurface hypomineralization. This hypomineralized enamel appears to be directly related to a delay in the removal of amelogenins at the early-maturation stage of enamel formation. The specific cause for this delay is not known, although existing evidence points to reduced proteolytic activity of proteinases that hydrolyze amelogenin. This delay in hydrolysis of amelogenins could be due to a direct effect of fluoride on proteinase secretion or proteolytic activity, or to a reduced effectiveness of the proteinase due to other changes in the protein or mineral of the fluorosed enamel matrix. The formation of dental fluorosis is highly dependent on the dose, duration, and timing of fluoride exposure. The early-maturation stage of enamel formation appears to be particularly sensitive to the effects of fluoride on enamel formation. Although the risk of enamel fluorosis is minimal with exposure only during the secretory stage, this risk is greatest when exposure occurs in both secretory and maturation stages of enamel formation. The risk of fluorosis appears to be best related to the total cumulative fluoride exposure to the developing dentition.

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Section: Secretory Stagementioning

confidence: 99%

“…These changes in the mineral chemistry could affect mineral/matrix interactions and enzyme activity. For example, it has been suggested that enamel proteins produced in the presence of fluoride may be more tightly bound to fluorapatite, thereby making them less accessible to degradation by enamel proteinases (43,62).…”

Section: Secretory Stagementioning

confidence: 99%

Mechanism and Timing of Fluoride Effects on Developing Enamel

Besten¹

1999

J Public Health Dent

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“…Some investigators suspect that fluoride may alter the quantity or activity of extracellular enamel proteinases believed actively to degrade enamel proteins (amelogenins) during the maturation stage of amelogenesis (Crenshaw and Bawden, 1984;Den Besten and Crenshaw, 1987;Den Besten and Heffernan, 1989a,b). It is also possible that enamel proteins produced in the presence of fluoride may be chemically or structurally altered and/or more tightly bound to fluoridated apatite, thereby making them less accessible to degradation by the enamel proteinases (Tanabe et ah, 1988;Dajean and Menanteau, 1989;Robinson and Kirkham, 1990). Fluorosed enamel has been shown to have an increased magnesium and fluoride content (Robinson and Kirkham, 1990).…”

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confidence: 97%

Dental Fluorosis: Its Use as a Biomarker

Besten

1994

Adv Dent Res.

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Several epidemiological studies, beginning with those of Dean and co-workers in the 1940's, clearly demonstrate the relationship between dental fluorosis in humans and the level of fluoride in water supplies. These studies and others have shown that, in a population, there is a direct relationship among the degree of enamel fluorosis, plasma and bone fluoride levels, and the concentration of fluoride in drinking water. However, dental fluorosis is a reflection of fluoride exposure only during the time of enamel formation, somewhat limiting its use as a biomarker. In addition, the degree of fluorosis is dependent not only on the total fluoride dose, but also on the timing and duration of fluoride exposure. At the level of an individual response to fluoride exposure, factors such as body weight, activity level, nutritional factors, and the rate of skeletal growth and remodeling are also important. These variables, along with an individual variability in response to similar doses of fluoride, indicate that enamel fluorosis cannot be used as a biological marker of the level of fluoride exposure for an individual.

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“…Although the cause-and-effect relationships between these factors remain poorly understood at present, some investigators suspect that fluoride may alter, in a dose dependent manner, the quantity or activity of extracellular proteinases (Suga, 1970;Crenshaw and Bawden, 1984;DenBesten and Heffernan, 1989a) needed to degrade enamel proteins (amelogenins) during the maturation stage of amelogenesis (reviewed and reported in Overall and Limeback, 1988;Carter et al, 1989;DenBesten and Heffernan, 1989b;Smith et al, 1989a). Other workers suspect that enamel proteins produced in the presence of fluoride may be chemically or structurally altered, and/or more tightly bound to fluorapatite, thereby making them less accessible to degradation by the enamel proteinases (Tanabe et al, 1988;Dajean and Menanteau, 1989;Aoba et al, 1990;Robinson and Kirkham, 1990). It is possible that fluoride may also upset the local balance for ionic calcium such that the enamel crystals grow improperly and alternate cations such as magnesium become enriched in fluorosed enamel (Aoba et al, 1990;Robinson and Kirkham, 1990).…”

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confidence: 99%

Effects of chronic fluoride exposure on morphometric parameters defining the stages of amelogenesis and ameloblast modulation in rat incisors

1993

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The response of ameloblasts to long-term (6 weeks) exposure to 100 ppm fluoride was examined in continuously erupting mandibular incisors of female Sprague-Dawley rats as compared to control rats receiving a similar diet (Teklad L-356) but no sodium fluoride in their drinking water. After treatment, animals from both groups were perfused intravascularly with glutaraldehyde, and the incisors were removed and processed for light microscope morphometric analyses directly from 1 microns thick Epon sections. Other animals were injected intravenously with calcein (green fluorescence) followed 4 hours later by xylenol orange (red fluorescence) in order to reveal smooth-ended ameloblast modulation bands and thereby allow quantification of parameters related to the creation and movement of modulation waves within the maturation zone of these teeth. The results indicated that rat incisors expressed four major changes in normal amelogenesis which could be attributed to the chronic fluoride treatment. First, ameloblasts produced a thinner than normal enamel layer by the time they completed the secretory stage and entered the maturation stage of amelogenesis. Second, enamel organ cells within the maturation zone, especially those from the papillary layer, were shorter in height than normal. Third, ameloblasts related to maturing enamel in areas where it was partially soluble and/or fully soluble in EDTA modulated at a rate that was much slower than normal. In some locations ameloblasts remained ruffle-ended for as much as 30% longer than normal per cycle. This upset the usual pattern such that fewer total modulation cycles were completed per unit time by these ameloblasts. Fourth, enamel proteins were lost from the maturing enamel layer at a rate that was about 40% slower than normal. The data suggested that ameloblasts detected the delay in the extracellular breakdown and/or loss of enamel proteins and they responded by remaining ruffle-ended for longer intervals than usual (positive feedback).

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A western-blotting study of enamel glycoproteins in rat experimental fluorosis

Cited by 5 publications

References 16 publications

Mechanism and Timing of Fluoride Effects on Developing Enamel

Mechanism and Timing of Fluoride Effects on Developing Enamel

Dental Fluorosis: Its Use as a Biomarker

Effects of chronic fluoride exposure on morphometric parameters defining the stages of amelogenesis and ameloblast modulation in rat incisors

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