Limits...
The dentin organic matrix - limitations of restorative dentistry hidden on the nanometer scale.

Bertassoni LE, Orgel JP, Antipova O, Swain MV - Acta Biomater (2012)

Bottom Line: Research has shown, however, that this interaction imposes less than desirable long-term prospects for current resin-based dental restorations.Finally, we discuss the relation of these complexly assembled nanostructures with the protease degradative processes driving the low durability of current resin-based dental restorations.We argue in favour of the structural limitations that these complexly organized and inherently hydrated organic structures may impose on the clinical prospects of current hydrophobic and hydrolyzable dental polymers that establish ultrafine contact with the tooth substrate.

View Article: PubMed Central - PubMed

Affiliation: Biomaterials Science Research Unit, Faculty of Dentistry, University of Sydney, United Dental Hospital, NSW, Australia. luiz.bertassoni@sydney.edu.au

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Increasing complexity of the organizational hierarchy of collagen type I (modified from Orgel et al. [62]). (A) Collagen molecules are composed of three α polypeptide chains; one chain is shown. The repeating (X–Y–Gly)n pattern in which the X and Y positions are frequently occupied by proline and 4-hydroxyproline residues is represented by X, Y and G. (B) A not to scale (shortened) illustration of the collagen monomeric molecular structure depicting the non-helical N- and C-telopeptides bordering the long, central, helical domain. (C) Molecules are approximately 303 nm long (the relaxed length is a straight line measurement from end to end). Four collagen–ligand binding sites are indicated. (D) Simplified collagen molecular lateral packing: each molecule is staggered from its neighbour by a multiple of ∼67 nm. The gap region is where there are four collagen molecular segments and the overlap region where there are five. (D-ii) Schematic two-dimensional representation of the lateral molecular packing (D) and microfibril topology (light grey) illustrating the quasi-hexagonal arrangement. The intermolecular separation is slightly more or slightly less than 1.3 nm inside the hydrated fibrils, yielding a molecular packing that is quasi-hexagonal. (D-ii) Each collagen molecule in the microfibril is coloured so that it is obvious that each D-period contains molecular segments from five different molecules. (E) Three interdigitated microfibrils where each red and grey microfibril bundle represents a single microfibril, as shown in D(ii), forming an intermolecular association that would resemble thinner microfibrillar bundles (provided that these are not a random disaggregation event) (F) The type I collagen fibril exhibits a characteristic periodic banded pattern originating from the presence of a gap (black) and an overlap region (white) in the collagen axial packing (D). (F-i) AFM micrograph of a collagen fibril. (F-ii) Lateral view of the molecular packing within a single fibril, where each circle represents the estimated position of each collagen molecule in cross-section (adapted from Hulmes et al. [71]).
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f0005: Increasing complexity of the organizational hierarchy of collagen type I (modified from Orgel et al. [62]). (A) Collagen molecules are composed of three α polypeptide chains; one chain is shown. The repeating (X–Y–Gly)n pattern in which the X and Y positions are frequently occupied by proline and 4-hydroxyproline residues is represented by X, Y and G. (B) A not to scale (shortened) illustration of the collagen monomeric molecular structure depicting the non-helical N- and C-telopeptides bordering the long, central, helical domain. (C) Molecules are approximately 303 nm long (the relaxed length is a straight line measurement from end to end). Four collagen–ligand binding sites are indicated. (D) Simplified collagen molecular lateral packing: each molecule is staggered from its neighbour by a multiple of ∼67 nm. The gap region is where there are four collagen molecular segments and the overlap region where there are five. (D-ii) Schematic two-dimensional representation of the lateral molecular packing (D) and microfibril topology (light grey) illustrating the quasi-hexagonal arrangement. The intermolecular separation is slightly more or slightly less than 1.3 nm inside the hydrated fibrils, yielding a molecular packing that is quasi-hexagonal. (D-ii) Each collagen molecule in the microfibril is coloured so that it is obvious that each D-period contains molecular segments from five different molecules. (E) Three interdigitated microfibrils where each red and grey microfibril bundle represents a single microfibril, as shown in D(ii), forming an intermolecular association that would resemble thinner microfibrillar bundles (provided that these are not a random disaggregation event) (F) The type I collagen fibril exhibits a characteristic periodic banded pattern originating from the presence of a gap (black) and an overlap region (white) in the collagen axial packing (D). (F-i) AFM micrograph of a collagen fibril. (F-ii) Lateral view of the molecular packing within a single fibril, where each circle represents the estimated position of each collagen molecule in cross-section (adapted from Hulmes et al. [71]).

Mentions: A feature that distinguishes collagen from other fibrillar macromolecules is that they are most easily recognized by their axial 67 nm periodicity [45], which can be seen by AFM [37,40] and electron microscopy [10,35,36] and can also be inferred from X-ray diffraction (XRD) data [46–52]. The 67 nm periodicity (corresponding to one D-period) stems from the staggered arrangement of collagen molecules in a given fibril, where the staggered spaces between the ends of successive collagen molecules yield the so-called gap zones and the areas where multiple molecules are superimposed represent the overlap zone (Fig. 1).


The dentin organic matrix - limitations of restorative dentistry hidden on the nanometer scale.

Bertassoni LE, Orgel JP, Antipova O, Swain MV - Acta Biomater (2012)

Increasing complexity of the organizational hierarchy of collagen type I (modified from Orgel et al. [62]). (A) Collagen molecules are composed of three α polypeptide chains; one chain is shown. The repeating (X–Y–Gly)n pattern in which the X and Y positions are frequently occupied by proline and 4-hydroxyproline residues is represented by X, Y and G. (B) A not to scale (shortened) illustration of the collagen monomeric molecular structure depicting the non-helical N- and C-telopeptides bordering the long, central, helical domain. (C) Molecules are approximately 303 nm long (the relaxed length is a straight line measurement from end to end). Four collagen–ligand binding sites are indicated. (D) Simplified collagen molecular lateral packing: each molecule is staggered from its neighbour by a multiple of ∼67 nm. The gap region is where there are four collagen molecular segments and the overlap region where there are five. (D-ii) Schematic two-dimensional representation of the lateral molecular packing (D) and microfibril topology (light grey) illustrating the quasi-hexagonal arrangement. The intermolecular separation is slightly more or slightly less than 1.3 nm inside the hydrated fibrils, yielding a molecular packing that is quasi-hexagonal. (D-ii) Each collagen molecule in the microfibril is coloured so that it is obvious that each D-period contains molecular segments from five different molecules. (E) Three interdigitated microfibrils where each red and grey microfibril bundle represents a single microfibril, as shown in D(ii), forming an intermolecular association that would resemble thinner microfibrillar bundles (provided that these are not a random disaggregation event) (F) The type I collagen fibril exhibits a characteristic periodic banded pattern originating from the presence of a gap (black) and an overlap region (white) in the collagen axial packing (D). (F-i) AFM micrograph of a collagen fibril. (F-ii) Lateral view of the molecular packing within a single fibril, where each circle represents the estimated position of each collagen molecule in cross-section (adapted from Hulmes et al. [71]).
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3473357&req=5

f0005: Increasing complexity of the organizational hierarchy of collagen type I (modified from Orgel et al. [62]). (A) Collagen molecules are composed of three α polypeptide chains; one chain is shown. The repeating (X–Y–Gly)n pattern in which the X and Y positions are frequently occupied by proline and 4-hydroxyproline residues is represented by X, Y and G. (B) A not to scale (shortened) illustration of the collagen monomeric molecular structure depicting the non-helical N- and C-telopeptides bordering the long, central, helical domain. (C) Molecules are approximately 303 nm long (the relaxed length is a straight line measurement from end to end). Four collagen–ligand binding sites are indicated. (D) Simplified collagen molecular lateral packing: each molecule is staggered from its neighbour by a multiple of ∼67 nm. The gap region is where there are four collagen molecular segments and the overlap region where there are five. (D-ii) Schematic two-dimensional representation of the lateral molecular packing (D) and microfibril topology (light grey) illustrating the quasi-hexagonal arrangement. The intermolecular separation is slightly more or slightly less than 1.3 nm inside the hydrated fibrils, yielding a molecular packing that is quasi-hexagonal. (D-ii) Each collagen molecule in the microfibril is coloured so that it is obvious that each D-period contains molecular segments from five different molecules. (E) Three interdigitated microfibrils where each red and grey microfibril bundle represents a single microfibril, as shown in D(ii), forming an intermolecular association that would resemble thinner microfibrillar bundles (provided that these are not a random disaggregation event) (F) The type I collagen fibril exhibits a characteristic periodic banded pattern originating from the presence of a gap (black) and an overlap region (white) in the collagen axial packing (D). (F-i) AFM micrograph of a collagen fibril. (F-ii) Lateral view of the molecular packing within a single fibril, where each circle represents the estimated position of each collagen molecule in cross-section (adapted from Hulmes et al. [71]).
Mentions: A feature that distinguishes collagen from other fibrillar macromolecules is that they are most easily recognized by their axial 67 nm periodicity [45], which can be seen by AFM [37,40] and electron microscopy [10,35,36] and can also be inferred from X-ray diffraction (XRD) data [46–52]. The 67 nm periodicity (corresponding to one D-period) stems from the staggered arrangement of collagen molecules in a given fibril, where the staggered spaces between the ends of successive collagen molecules yield the so-called gap zones and the areas where multiple molecules are superimposed represent the overlap zone (Fig. 1).

Bottom Line: Research has shown, however, that this interaction imposes less than desirable long-term prospects for current resin-based dental restorations.Finally, we discuss the relation of these complexly assembled nanostructures with the protease degradative processes driving the low durability of current resin-based dental restorations.We argue in favour of the structural limitations that these complexly organized and inherently hydrated organic structures may impose on the clinical prospects of current hydrophobic and hydrolyzable dental polymers that establish ultrafine contact with the tooth substrate.

View Article: PubMed Central - PubMed

Affiliation: Biomaterials Science Research Unit, Faculty of Dentistry, University of Sydney, United Dental Hospital, NSW, Australia. luiz.bertassoni@sydney.edu.au

Show MeSH
Related in: MedlinePlus