The appearance of developing rat incisor enamel using a freeze fracturing technique

Robinson, C.; Fuchs, Patrick; Weatherell, J.A.

doi:10.1016/0022-0248(81)90062-2

Cited by 81 publications

(83 citation statements)

References 11 publications

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“…Roles in nucleation, growth, regulation of crystal size and shape, and control of crystal-crystal aggregation have been proposed [2][3][4][5]. Amelogenin is unique in that it self-assembles into nanospheres, supra-molecular structures observed in vitro [6][7][8] and in vivo [7,9] which are believed to be critical to the function of the protein. Several in vivo studies using antisense mice [10], knock out mice [11], transgenic mice [12], and hammerhead ribozymes [13] have investigated the role of amelogenin in regulating enamel nucleation and growth.…”

Section: Introductionmentioning

confidence: 99%

The nucleation and growth of calcium phosphate by amelogenin

Tarasevich

Howard

Larson

et al. 2007

Journal of Crystal Growth

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The nucleation processes involved in calcium phosphate formation in tooth enamel are not well understood but are believed to involve proteins in the extracellular matrix. The ability of one enamel protein, amelogenin, to promote the nucleation and growth of calcium phosphate was studied in an in vitro system involving metastable supersaturated solutions. It was found that recombinant amelogenin (rM179 and rp(H)M180) promoted the nucleation of calcium phosphate compared to solutions without protein. The amount of calcium phosphate increased with increasing supersaturation of the solutions and increasing protein concentrations up to 6.5 μg/mL. At higher protein concentrations, the amount of calcium phosphate decreased. The kinetics of nucleation was studied in situ and in real time using a quartz crystal microbalance (QCM) and showed that the protein reduced the induction time for nucleation compared to solutions without protein. This work shows a nucleation role for amelogenin in vitro which may be promoted by the association of amelogenin into nanosphere templates, exposing charged functionality at the surface.

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Section: Introductionmentioning

confidence: 99%

The nucleation and growth of calcium phosphate by amelogenin

Tarasevich

Howard

Larson

et al. 2007

Journal of Crystal Growth

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“…Smales [1975] described a helical structure in which 'the helices varied in overall width from 15 to 30 nm'. Robinson et al [1981] investigated developing rat incisor enamel using a freeze-fracture technique and indicated that 'the forming region seems to consist largely of spheres 300-500 Å in diameter'. Bai and Warshawsky [1985] found that 'globular particles observed in freeze-fracture replicas of fresh and fi xed enamel samples' can be 'removed by 4.0 M guanidine extraction'.…”

Section: Periodic Structures Of the Forming Enamel Organic Matrixmentioning

confidence: 99%

“…Freeze fracture replicas of unfi xed frozen forming enamel were prepared by Robinson et al [1981]. In the forming enamel, globular structures of 30-50 nm in diameter were present, fi rst randomly arranged and then aligned at a further stage.…”

Section: The Forming Enamel After Rapid Freezing and Freeze Substitutionmentioning

confidence: 99%

Amelogenin Supra-Molecular Assembly in vitro Compared with the Architecture of the Forming Enamel Matrix

Moradian‐Oldak

Goldberg

2005

Cells Tissues Organs

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Tooth enamel is formed in the extracellular space within an organic matrix enriched in amelogenin proteins. Amelogenin nanosphere assembly is a key factor in controlling the oriented and organized growth of enamel apatite crystals. Recently, we have reported the formation of higher ordered structures resulting from organized association and self-orientation of amelogenin nanospheres in vitro. This remarkable hierarchical organization includes self-assembly of amelogenin molecules into subunits of 4–6 nm in diameter followed by their assembly to form nanospheres of 15–25 nm in radii. Chains of >100 nm length are then formed as the result of nanosphere association. These linear arrays of nanospheres assemble to form the microribbons that are hundreds of microns in length, tens of microns in width, and a few microns in thickness. Here, we review the step by step process of amelogenin self-assembly during the formation of microribbon structures in vitro. Assembly properties of selected amelogenins lacking the hydrophilic C terminus will then be reviewed. We will consider amelogenin as a template for the organized growth of crystals in vitro. Finally, we will compare the structures formed in vitro with globular and periodic structures observed earlier, in vivo, by different sample preparation conditions. We propose that the alignment of amelogenin nanospheres into long chains is evident in vivo, and is an important indication for the function of this protein in controlling the oriented and elongated growth of apatite crystals during enamel biomineralization.

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“…Afterwards, stippled material condensed around the growing slender crystals and built a frame of "oriented" enamel proteins previously described as a "ghost" (Frank et al, 1960;Reith, 1960;Bonucci, 1979;Kallenbach, 1986;Warshawsky, 1989) which secondarily mineralizes to generate a complete enamel crystal (Aoba et al, 1996). Globular structures either randomly arranged or linearly oriented were initially described by Robinson et al (1981) using a freeze-fracturing technique. Recently, Brookes et al, in press) reported on the possible presence of bead-like structures which could form the precursors of enamel crystals.…”

Section: Discussionmentioning

confidence: 99%

Initial aspects of mineralization at the dentino-enamel junction in embryonic mouse incisor in vivo and in vitro: A tem comparative study

Meyer

Bodier-Houllé

Cuisinier

et al. 1999

In Vitro Cell.Dev.Biol.-Animal

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The frontier between the enamel organ and the dental papilla, the future dentino-enamel junction, undergoes coordinated modifications. The mineralization of the extracellular matrix starts within the predentine, which is a prerequisite for the formation of the first enamel crystallites in vivo. We investigated the dentino-enamel junction using the embryonic mouse incisor as a model. Our data showed that the notion of the dentino-enamel junction should not be restricted to the thin interface classically described. A temporo-spatial survey from the epithelio-mesenchymal junction to the dentino-enamel junction delineated a clear sequence of events characterized by the early deposition of electron-dense granules, followed by the appearance of patches of stippled material at the dentino-enamel junction. The first tiny enamel crystallites appeared in the vicinity of this material which presented a well-ordered alignment. The comparison of data obtained in vivo on 17-, 18-, 19-d-old embryonic incisors with those obtained in vitro using 15-d-old embryonic incisors cultured for 7 d emphasizes the relevance of this sequence. Helicoidal growing crystals were observed in cultured tooth germs but never in vivo.

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The appearance of developing rat incisor enamel using a freeze fracturing technique

Cited by 81 publications

References 11 publications

The nucleation and growth of calcium phosphate by amelogenin

The nucleation and growth of calcium phosphate by amelogenin

Amelogenin Supra-Molecular Assembly in vitro Compared with the Architecture of the Forming Enamel Matrix

Initial aspects of mineralization at the dentino-enamel junction in embryonic mouse incisor in vivo and in vitro: A tem comparative study

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