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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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Topological features of collagen type I. (A) Tapping mode AFM image obtained in liquid of an individual gap zone of a dentin collagen fibril and the adjacent overlap zones. (B) Section analysis across the diameter of a fibril overlap zone reveals “bumps” at about 4 nm distance that have been associated with collagen microfibrils (A and B adapted from Habelitz et al. [37]). (C) Molecular model of the microfibrillar arrangement of collagen type I. (D) The same arrangement is shown in a freezefracture micrograph of hydrated, unfixed collagen type I from rat tail tendon with a horizontal field of view of 500 nm (C and D adapted from Ottani et al. [142]). (E) Schematic representation of the radial packing of collagen molecules (adapted from Hulmes et al. [71]) showing a fibril surrounded by the polymeric matrix illustrating the difficult hermetic enveloping of collagen by viscous monomers due to the presence of ∼4 nm surface “bumps”.
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f0010: Topological features of collagen type I. (A) Tapping mode AFM image obtained in liquid of an individual gap zone of a dentin collagen fibril and the adjacent overlap zones. (B) Section analysis across the diameter of a fibril overlap zone reveals “bumps” at about 4 nm distance that have been associated with collagen microfibrils (A and B adapted from Habelitz et al. [37]). (C) Molecular model of the microfibrillar arrangement of collagen type I. (D) The same arrangement is shown in a freezefracture micrograph of hydrated, unfixed collagen type I from rat tail tendon with a horizontal field of view of 500 nm (C and D adapted from Ottani et al. [142]). (E) Schematic representation of the radial packing of collagen molecules (adapted from Hulmes et al. [71]) showing a fibril surrounded by the polymeric matrix illustrating the difficult hermetic enveloping of collagen by viscous monomers due to the presence of ∼4 nm surface “bumps”.

Mentions: Surface features suggestive of the presence of collagen substructural units, commonly described as either microfibrils or subfibrils, have also been identified in dentin. We contend that microfibrils may be a more appropriate nomenclature for these thinner structures, as the features identified as subfibrils by microscopy generally refer to microfibrils earlier identified by XRD studies, which offer a much broader and earlier range of reports. Habelitz et al. [37] used AFM to report features of about 4 nm in width on the surface of dentin collagen, consistent with the longitudinal microfibrils found in collagen type I of a fully hydrated tendon [53] (Fig. 2A). These surface features are difficult to quantify but have been reported to wind axially along the fibrils at a shallow angle close to 5° (Fig. 2) [53,54].


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

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

Topological features of collagen type I. (A) Tapping mode AFM image obtained in liquid of an individual gap zone of a dentin collagen fibril and the adjacent overlap zones. (B) Section analysis across the diameter of a fibril overlap zone reveals “bumps” at about 4 nm distance that have been associated with collagen microfibrils (A and B adapted from Habelitz et al. [37]). (C) Molecular model of the microfibrillar arrangement of collagen type I. (D) The same arrangement is shown in a freezefracture micrograph of hydrated, unfixed collagen type I from rat tail tendon with a horizontal field of view of 500 nm (C and D adapted from Ottani et al. [142]). (E) Schematic representation of the radial packing of collagen molecules (adapted from Hulmes et al. [71]) showing a fibril surrounded by the polymeric matrix illustrating the difficult hermetic enveloping of collagen by viscous monomers due to the presence of ∼4 nm surface “bumps”.
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Related In: Results  -  Collection

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f0010: Topological features of collagen type I. (A) Tapping mode AFM image obtained in liquid of an individual gap zone of a dentin collagen fibril and the adjacent overlap zones. (B) Section analysis across the diameter of a fibril overlap zone reveals “bumps” at about 4 nm distance that have been associated with collagen microfibrils (A and B adapted from Habelitz et al. [37]). (C) Molecular model of the microfibrillar arrangement of collagen type I. (D) The same arrangement is shown in a freezefracture micrograph of hydrated, unfixed collagen type I from rat tail tendon with a horizontal field of view of 500 nm (C and D adapted from Ottani et al. [142]). (E) Schematic representation of the radial packing of collagen molecules (adapted from Hulmes et al. [71]) showing a fibril surrounded by the polymeric matrix illustrating the difficult hermetic enveloping of collagen by viscous monomers due to the presence of ∼4 nm surface “bumps”.
Mentions: Surface features suggestive of the presence of collagen substructural units, commonly described as either microfibrils or subfibrils, have also been identified in dentin. We contend that microfibrils may be a more appropriate nomenclature for these thinner structures, as the features identified as subfibrils by microscopy generally refer to microfibrils earlier identified by XRD studies, which offer a much broader and earlier range of reports. Habelitz et al. [37] used AFM to report features of about 4 nm in width on the surface of dentin collagen, consistent with the longitudinal microfibrils found in collagen type I of a fully hydrated tendon [53] (Fig. 2A). These surface features are difficult to quantify but have been reported to wind axially along the fibrils at a shallow angle close to 5° (Fig. 2) [53,54].

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