Functional Remineralization of Dentin Lesions Using Polymer-Induced Liquid-Precursor Process

Abstract

It was hypothesized that applying the polymer-induced liquid-precursor (PILP) system to artificial lesions would result in time-dependent functional remineralization of carious dentin lesions that restores the mechanical properties of demineralized dentin matrix. 140 µm deep artificial caries lesions were remineralized via the PILP process for 7–28 days at 37°C to determine temporal remineralization characteristics. Poly-L-aspartic acid (27 KDa) was used as the polymeric process-directing agent and was added to the remineralization solution at a calcium-to-phosphate ratio of 2.14 (mol/mol). Nanomechanical properties of hydrated artificial lesions had a low reduced elastic modulus (ER = 0.2 GPa) region extending about 70 μm into the lesion, with a sloped region to about 140 μm where values reached normal dentin (18–20 GPa). After 7 days specimens recovered mechanical properties in the sloped region by 51% compared to the artificial lesion. Between 7–14 days, recovery of the outer portion of the lesion continued to a level of about 10 GPa with 74% improvement. 28 days of PILP mineralization resulted in 91% improvement of ER compared to the artificial lesion. These differences were statistically significant as determined from change-point diagrams. Mineral profiles determined by micro x-ray computed tomography were shallower than those determined by nanoindentation, and showed similar changes over time, but full mineral recovery occurred after 14 days in both the outer and sloped portions of the lesion. Scanning electron microscopy and energy dispersive x-ray analysis showed similar morphologies that were distinct from normal dentin with a clear line of demarcation between the outer and sloped portions of the lesion. Transmission electron microscopy and selected area electron diffraction showed that the starting lesions contained some residual mineral in the outer portions, which exhibited poor crystallinity. During remineralization, intrafibrillar mineral increased and crystallinity improved with intrafibrillar mineral exhibiting the orientation found in normal dentin or bone.

Recovery after PILP remineralization of dentin lesions created with two cariogenic acids

“…For group 3~6, each block was placed in 40 ml of remineralizing buffer containing Tris, 4.5 mM calcium and 2.1 mM phosphate, at pH 7.4 for 14 days in an incubator at 37°C, with agitation provided by a rocker platform for remineralizing treatment. 100 μg/ ml of Poly-L-aspartic acid (PASP) sodium salt, with molecular weight of 27 kDa (Alamanda polymers, Huntsville, AL) was added to A-PIL and L-PIL groups (Burwell et al, 2012; Jee, Thula, et al, 2010). Negative control groups (A-CAP and L-CAP) were treated in the remineralizing buffer prepared in the same way except without PASP.…”

“…Gower & Odom, 2000; L. B. Gower, 2008; Olszta et al, 2003) has been shown to be particularly effective at remineralization of collagen matrices (Jee, Thula, & Gower, 2010), so we have applied this polymer-induced liquid precursor (PILP) mineralization process to artificial caries lesions in coronal dentin prepared from acetate buffer at pH = 5, and have shown that it provided complete recovery of mineral content throughout the lesion depth (as seen in micro-CT), while nanomechanical testing found the reduced elastic modulus (E r ) recovered to 50–60% of normal dentin in the severely demineralized outer zone and fully recovery of the inner zone (Burwell et al, 2012). …”

Efficacy and micro-characterization of pathophysiological events on caries-affected dentin treated with glass-ionomer cements

“…3A). Intrafibrillar mineralization is the key factor to ensuring that collagen fibrils have the same mechanical properties as occurs in natural biomineralized dentin [54].…”

“…Therefore, the increase of Hi and Ei of the partially demineralized collagen at the HL is directly related to the precipitation of minerals at the resin-dentin interface [55], and more specifically at the intrafibrillar compartment [1,54], leading to functional remineralization. Functional remineralization, therefore, is the result of a process that yields recovery of physical and chemical properties otherwise lost due to disease [56].…”

Remineralization Potential of Mints Containing Bioactive Agents in Artificially Induced Root Caries

“…In this context, biomimetic remineralization strategies of dentin have gained considerable interest for the treatment of carious and noncarious lesions [Tay and Pashley, 2008;Xu et al, 2011b;Burwell et al, 2012;Zhang et al, 2012;Chen et al, 2016]. These approaches utilize specific analogs of extracellular matrix proteins (e.g., polyelectrolyte and poly (amino) acid macromolecules) that mimic the functional biomineralization of native noncollagenous proteins to stabilize and mediate mineral deposition within the collagen scaffold [Tay and Pashley, 2008].…”