Reconstruction of a Demineralized Dentin Matrix via Rapid Deposition of CaF₂ Nanoparticles In Situ Promotes Dentin Bonding

Abstract

Dentin bonding based on a wet-bonding technique is the fundamental technique used daily in clinics for tooth-restoration fixation and clinical treatment of tooth-related diseases. Limited bonding durability led by insufficient adhesive infiltration in the demineralized dentin (DD) matrix is the biggest concern in contemporary adhesive dentistry. This study proposes that the highly hydrated noncollagenous protein (NCP)-formed interfacial microenvironment of the DD matrix is the root cause of this problem. Meanwhile, the endogenous phosphate groups of the NCPs are used as pseudonuclei to rapidly induce the formation of amorphous CaF2 nanoparticles in situ in the interfacial microenvironment. The DD matrix is thus reconstructed into a novel porous structure. It markedly facilitates the infiltration of dentin adhesives in the DD matrix and also endows the DD matrix with anticollapsing capability when water evaporates. Whether using a wet-bonding or air-drying mode, the bonding effectiveness is greatly promoted, with the 12 month bonding strength being about twice that of the corresponding control groups. This suggests that the nanoreinforced DD matrix eliminates the dependence of bonding effectiveness on the moisture status of the DD surface controlled only by experiences of dentists. Consequently, this bonding strategy not only greatly improves bonding durability but also overcomes the technical sensitivity of bonding operations of the total-etched bonding pattern. This exhibits the potential to promote dentin bonding and is of great significance to dentistry.

Release of Interface Confined Water Significantly Improves Dentin Bonding

“…Consistent with our previous reports (Xu et al 2021; Lei et al 2022; Shu et al 2022), the treatment of the Ca 2+ or Cu 2+ solution significantly decreased water sorption (Fig. 2A).…”

“…Surface tension of the DDM was simulated by a 0.2 M sodium polyacrylate solution. To trace the infiltration of hydrophobic monomers, a Nile red labeling method was employed (Xu et al 2021). The nanomechanical property of the hybrid layer was tested by AFM under the peak-force tapping mode.…”

Construction of an antibacterial low-defect hybrid layer by facile PEI electrostatic assembly promotes dentin bonding

“…26 Nile Red was used as a hydrophobic adhesive monomer tracer due to its comparable size and hydrophobicity. 15,27 The distribution and relative content of hydrophobic adhesive monomers in the hybrid layer were indicated by the intensity of fluorescence measured by confocal laser scanning microscopy (CLSM, Fig. 4).…”

“…Based on our findings that rapid dehydration of the amorphous NCP-formed hydrogel-like DDM interface can greatly improve adhesive infiltration and form low-defect hybrid layers fundamentally promoting dentin bonding, 9,15 in this work, the water replenished DDM with a highly anionic hydrogel-like surface is firstly used as a template for electrostatic adsorption of polyethyleneimine (PEI), a polymer with the highest cationic charge density and potent antibacterial characteristics. Electrostatic assembly is a molecular assembly technology that is not limited by the shape, size or surface topography of the template.…”

Guided tissue remineralization and its effect on promoting dentin bonding

“…In addition, collagen fibrils exposed during the aging of the dentin bonding interface for various reasons are weak structures. These weak structures compromise the stability of the bonding interface (Xu et al, 2021). This makes dentin bonding a challenge even today.…”