Improved Sealing and Remineralization at the Resin-Dentin Interface After Phosphoric Acid Etching and Load Cycling

Abstract

The purpose of this study was to investigate micro-morphology of the resin-dentin inter-diffusion zone using two different single-bottle self-etching dentin adhesives with and without previous acid-etching, after in vitro mechanical loading stimuli. Extracted human third molars were sectioned to obtain dentin surfaces. Two different single-bottle self-etching dentin adhesives, Futurabond U and Experimental both from VOCO, were applied following the manufacturer's instructions or after 37% phosphoric acid application. Resin-dentin interfaces were analyzed with dye assisted confocal microscopy evaluation (CLSM), including the calcium-chelation technique, xylenol orange (CLSM-XO). CLSM revealed that resin-dentin interfaces of unloaded specimens were deficiently resin-hybridized, in general. These samples showed a Rhodamine B-labeled hybrid complex and adhesive layer completely affected by fluorescein penetration (nanoleakage) through the porous resin-dentin interface, but thicker after PA-etching. Load cycling promoted an improved sealing of the resin-dentin interface at dentin, a decrease of the hybrid complex porosity, and an increment of dentin mineralization. Load cycled specimens treated with the XO technique produced a clearly outlined fluorescence due to consistent Ca-mineral deposits within the bonding interface and inside the dentinal tubules, especially when the experimental adhesive was applied.

A zinc chloride-doped adhesive facilitates sealing at the dentin interface: A confocal laser microscopy study

“…2D). These findings may be interpreted as dentin remineralization (Toledano et al, 2015a). The Xo dye is commonly employed in bone remineralization studies due to the ability to form complexes with divalent calcium ions (Profeta et al, 2013).…”

Influence of Acid Etching and Universal Adhesives on the Bond Strength to Dentin

“…However, in spite of the excellent longevity, problems related to dentin adhesion have been reported (4). Some factors, such as overdrying of dentin after acid etching, excess moisture, and excessive acid demineralization or acid undercorrosion, may decrease the flow of resinous monomers along the intertubular dentin, compromising the longevity of restorations (5).…”

“…Some factors, such as overdrying of dentin after acid etching, excess moisture, and excessive acid demineralization or acid undercorrosion, may decrease the flow of resinous monomers along the intertubular dentin, compromising the longevity of restorations (5). Although the conventional approach for adhesive restorations, including dentin etching with phosphoric acid (35-37%), is an established and predictable clinical procedure, the acid corrosion of dentin is a definitive factor for adhesion quality, increasing wettability and surface roughness, and allowing the penetration of adhesives and resin cements through the smear layer (4).…”

Determining Optimal Fluorescent Agent Concentrations in Dental Adhesive Resins for Imaging the Tooth/Restoration Interface

“…In dental research, confocal laser scanning microscopy (CLSM) has been utilized to acquire high-resolution optical sections of the dentin/adhesive interface (Watson & Boyde, 1991;Watson, 1997;D'Alpino et al, 2006a;Sauro et al, 2008;Toledano et al, 2014Toledano et al, , 2015. This interface is obtained when a dental adhesive-a fluid multi-monomer system used to make the dental composite adhere to the tooth-penetrates an acid-etched dentin surface, entangles the exposed collagen fibrils and undergoes in situ polymerization, forming a bio-engineered interlocked structure called the hybrid layer (Spencer et al, 2010;Pashley et al, 2011;Tjäderhane et al, 2013).…”