The Importance of Intrafibrillar Mineralization of Collagen on the Mechanical Properties of Dentin

Abstract

It is widely held that the hardness and modulus of dentin increase in proportion to the mineral concentration. To test this belief, we measured hardness and modulus of normal dentin and an altered form of dentin without gap-zone mineralization in wet and dry conditions by AFM nanoindentation to determine if the modulus and hardness scale linearly with mineral concentration. Mineral concentrations in the mid-coronal location of the normal and altered dentins were 44.4 vol% and 30.9 vol%, respectively. Surrounding the pulp of the altered dentin was a region of higher mineralization, 40.5 vol%. The indentation modulus of normal dentin was 23.9 (SD = 1.1) GPa dry and 20.0 (SD = 1.0) GPa wet. In mid-coronal regions of the altered dentin, the indentation modulus was 13.8 (SD = 2.0) GPa dry and 5.7 (SD = 1.4) GPa wet. In the more mineralized regions of the altered dentin, the modulus was 20.4 (SD = 1.8) GPa dry and 5.3 (SD = 0.8) GPa wet; the properties of the altered wet dentin did not correlate with mineral concentration. The results of this study raise doubt as to whether mineral concentration alone is a sufficient endpoint for assessing the success or failure of remineralization approaches in restorative dentistry.

Effect of sterilization by gamma radiation on nano-mechanical properties of teeth

“…Another possible explanation is that dentin collagen is reinforced by intrafibrillar mineral and each fibril is surrounded by extrafibrillar mineral. The intrafibrillar mineral, which stiffens the collagen fibrils, dominates the elastic behavior under normal loading conditions [25].…”

Comparison of nanohardness between coronal and radicular intertubular dentin

“…The Young's modulus of coronal intertubular dentin was 26.60±2. 19 GPa, while that of radicular dentin was 20.89±1.10 GPa. Results showed that the hardness and Young's modulus of coronal intertubular dentin were greater than those ofradicularintertubulardentin.…”

“…Hence, the aim of this study wastodetermineandcomparethenanohardnessand Young's modulus of coronal and radicular intertubular dentin. Indentation is widely used to evaluate hardness and Young's modulus for dentin 1,[15][16][17][18][19][20][21][22][23] .Thisisbecausenanoindentationresults inverysmallindentedregions,makingitpossibleto clarifytheintertubulardentinpropertiesirrespective ofperitubulardentinorthedentinaltubules.…”

Zinc-modified nanopolymers improve the quality of resin–dentin bonded interfaces

“…Most of these tested materials have the ability of delivering calcium and phosphate ions to promote regrowth of remnant apatite crystals within the intrafibrillar zone of collagen fibrils (via classic nucleation) [6]. A second route to remineralization exists based upon biomineralization mediated by amorphous calcium and phosphate precursors (ACP) and polyanionic polymers [7].…”