Variations in the composition of developing rat incisor enamel

Hiller, Christopher R.; Robinson, C.; Weatherell, J.A.

doi:10.1007/bf02546222

Cited by 133 publications

(100 citation statements)

References 15 publications

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“…with Hiller et al (1975) as a consistent thickness of " 110 µm (apart from some apical slices) was found (Fig. 1).…”

Section: mentioning

confidence: 93%

“…The proposal by Starkey (1971) that this increase in mineral concentration is due to a contraction in enamel volume was rejected by Hiller et al (1975) who found no systematic reduction in enamel thickness along rat incisors. The present study agrees Fig.…”

Section: mentioning

confidence: 99%

“…These stages were shown to be related to changes in the chemistry and histology of the enamel organ (Robinson et al 1981). Analyses of dissected enamel particles along rat incisors (Hiller et al 1975) showed that both the Ca and P concentrations increase from the growing root apex towards the more mature incisal end. The steepest increase is from the opaque region (stage 3) and approaches a maximum in the hard translucent region (stage 4).…”

Section: mentioning

confidence: 99%

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X‐ray microtomographic study of mineral distribution in enamel of mandibular rat incisors

et al. 2000

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 X-ray microtomography was used to study the mineral concentrations in sequential slices of enamel of 5 mandibular incisors which showed an increase from " 1n0 to " 2n7 g cm V $ from the apex towards the incisal end. For points at the same distance from the apex, there were differences up to 0n6 g cm V $ between the teeth. The change of mean concentrations in the slices with distance could be modelled as (different) saturating exponentials. Under the assumption of a uniform growth rate of a mandibular incisor of 0n6 mm per day and a common time origin for the start of maturation (taken as a mineral concentration of 1 g cm V $), the distances were transformed to a common time frame to give a pooled data set. A single saturating exponential could be fitted to this pooled transformed data ; this was : C m l 2n84k1n94 exp (k0n18d ) where C m is the mean mineral concentration (g cm V $) and d the time (days) from the start of maturation. This gives an asymptotic concentration of 2n84 g cm V $ towards the incisal end, with a time constant of 7n7 days. The mineral concentration distribution functions were found to be more positively skewed closer to the apex, but more negatively skewed towards the incisal end. The difference between the higher mineral concentration in the outer enamel and the enamel near the amelodentinal junction (ADJ) was " 3 %. The direction of maximum increase in concentration from the outer enamel surface to the ADJ meets the boundary of the ADJ at " 80m. Three dimensional surface rendering of isodensity contours showed that the previously described C-shaped pattern of mineralisation is not solely a surface phenomenon, but extends through the depth of the enamel.

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“…with Hiller et al (1975) as a consistent thickness of " 110 µm (apart from some apical slices) was found (Fig. 1).…”

Section: mentioning

confidence: 93%

Section: mentioning

confidence: 99%

Section: mentioning

confidence: 99%

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X‐ray microtomographic study of mineral distribution in enamel of mandibular rat incisors

et al. 2000

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“…Also, the presumed hetero-ionic substitutions associate with other types of substitutions to accommodate the created charge imbalance, further increasing the strain in the crystal structure. It is now established that most of the carbonate in enamel mineral is incorporated in the process of mineralization during tooth formation (Hiller et al, 1975) and that the carbonate content and substitution types in enamel mineral change markedly during amelogenesis . It is worth noting that the carbonate incorporation into calcium apatites is a common phenomenon in the formation of fish enameloid having high amounts of fluoride (Lowenstam and Weiner, 1989 lattice occurs at 866 cm-', with apparent sharpening.…”

Section: Carbonatoapatite As the Most Appropriate Prototype Of Biominmentioning

confidence: 99%

The Effect of Fluoride On Apatite Structure and Growth

Aoba

1997

Critical Reviews in Oral Biology & Medicine

181

120

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Fluoride participates in many aspects of calcium phosphate formation in vivo and has enormous effects on the process and on the nature and properties of formed mineral. The most well-documented effect of fluoride is that this ion substitutes for a column hydroxyl in the apatite structure, giving rise to a reduction of crystal volume and a concomitant increase in structural stability. In the process of enamel mineralization during amelogenesis (a unique model for the cell-mediated formation of well-crystallized carbonatoapatite), free fluoride ions in the fluid phase are supposed to accelerate the hydrolysis of acidic precursor(s) and increase the driving force for the growth of apatitic mineral. Once fluoride is incorporated into the enamel mineral, the ion likely affects the subsequent mineralization process by reducing the solubility of the mineral and thereby modulating the ionic composition in the fluid surrounding the mineral, and enhancing the matrix protein-mineral interaction. But excess fluoride leads to anomalous enamel formation by retarding tissue maturation. It is worth noting that enameloid/enamel minerals found in vertebrate teeth have a wide range of CO3 and fluoride substitutions. In the evolutionary process from elasmobranch through teleost enameloid to mammalian enamel, the biosystems appear to develop regulatory functions for limiting the fluoridation of the formed mineral, but this development is accompanied by an increase of carbonate substitution or defects in the mineral. In research on the cariostatic effect of fluoride, considerable emphasis is placed on the roles of free fluoride ions (i.e., preventing the dissolution and accelerating the kinetics of remineralization) in the oral fluid bathing tooth mineral. Fluoride also has been used for the treatment of osteoporosis, but much still remains to be learned about maximizing the benefit and minimizing the risk of fluoride when used as a public health measure.

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“…The contribution of magnesium to biomineralization is unclear. In a number of calcified tissues, such as rat incisor enamel (Hiller et al, 1975), cutaneous calcinosis (Tochon-Danguy et al, 1978), fracture callus, and turkey tendon (Quint et al, 1980), the magnesium concentration strongly diminished as the mineralization process evolved. The presence of magnesium in the early stages was accompanied by an elevated carbonate content (Hiller et al, 1975;Quint et al, 1980).…”

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confidence: 99%

The Distribution of Magnesium in Developing Rat Incisor Dentin

et al. 1991

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Previous studies have shown that rat incisor dentin contains a considerable amount of magnesium that is distributed heterogeneously. The cementum-related dentin, especially its incisal portion, is richest in magnesium. It was the purpose of the present study to investigate the changes that occur in the magnesium content during dentin maturation.Cross-sections were prepared from rat incisors at the apical, middle, and incisal levels. By means of an electron microprobe, tracings were made of the Ca-, Mg-, and P-signal frequencies. Comparison of corresponding dentin layers within and between the cross-sections showed that the Mg/P molar ratio was always higher in the cementum-related dentin (CRD) than in the enamel-related dentin (ERD) and increased from the apex toward the incisal edge. Especially in the incisal crosssection, an increase in Mg/P was found from the older (peripheral) toward the younger (central) dentin layers. As the Mg/P ratio varied from 0.07 to 0.33, the Ca/P ratio was found to fluctuate from 1.48 to 1.15. The two ratios appeared to be highly correlated (r = -0.97; p<0.001), suggesting that Mg replaces Ca and is bound to phosphate. overdose of Nembutal injected intracardially. Their lower right jaws were dissected out and stored frozen. Cross-sectional slices (1 mm in thickness) of the incisors, together with the surrounding tissues, were prepared at an apical, middle, and incisal level (Fig. 1) by use of a Microslice 2 MR (Metals Research Ltd., Cambridge, England) with a diamond saw blade under constant water cooling. After removal of the surrounding bone, the cross-sections of the incisors were dehydrated through a graded series of ethanol and propyleneoxide and embedded in epoxy resin (Epon LX112, Ladd), which was polymerized at 60°C. All specimens were embedded simultaneously in the same piece of epoxy resin, in such a way that the slices obtained from one tooth were next to each other. The incisal aspect of each slice was then serially polished with silicon carbide abrasive paper (nos. 240 to 600), followed by a 0.03-,um aluminum oxide micropolisher.Electron microprobe analysis. -After the slices were coated with a carbon layer in a Balzer BEA 250 evaporator, the specimens were subjected to electron microprobe analysis in a JEOL Superprobe 733 (10 kV, 10 WxA, beam area 1 1Lm2, ten s per J Dent Res 70(3): 187-191, March, 1991

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Variations in the composition of developing rat incisor enamel

Cited by 133 publications

References 15 publications

X‐ray microtomographic study of mineral distribution in enamel of mandibular rat incisors

X‐ray microtomographic study of mineral distribution in enamel of mandibular rat incisors

The Effect of Fluoride On Apatite Structure and Growth

The Distribution of Magnesium in Developing Rat Incisor Dentin

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