Thursday, June 04, 2015

Influence of phosphoproteins’ biomimetic analogs on remineralization of mineral-depleted resin–dentin interfaces created with ion-releasing resin-based systems

Dental Materials
April 22, 2015

Abstract

Objective

The study aimed at evaluating the remineralization of acid-etched dentin pre-treated with primers containing biomimetic analogs and bonded using an ion-releasing light-curable resin-based material.

Methods

An experimental etch-and-rinse adhesive system filled with Ca2+, PO43−-releasing Ca-Silicate micro-fillers was created along with two experimental primers containing biomimetic analogs such as sodium trimetaphosphate (TMP) and/or polyaspartic acid (PLA). Dentin specimens etched with 37% H3PO4 were pre-treated with two different aqueous primers containing the polyanionic biomimetic analogs or deionized water and subsequently bonded using the experimental resin-based materials. The specimens were sectioned and analyzed by AFM/nanoindentation to evaluate changes in the modulus of elasticity (Ei) across the resin–dentin interface at different AS storage periods (up to 90 days). Raman cluster analysis was also performed to evaluate the chemical changes along the interface. The phosphate uptake by the acid-etched dentin was evaluated using the ATR-FTIR. Additional resin–dentin specimens were tested for microtensile bond strength. SEM examination was performed after de-bonding, while confocal laser microscopy was used to evaluate the interfaces ultramorphology and micropermeability.

Results

Both biomimetic primers induced phosphate uptake by acid-etched dentin. Specimens created with the ion-releasing resin in combination with the pre-treatment primers containing either PLA and TMA showed the greatest recovery of the Ei of the hybrid layer, with no decrease in μTBS (p  > 0.05) after 3-month AS storage. The ion-releasing resin applied after use of the biomimetic primers showed the greatest reduction in micropermeability due to mineral precipitation; these results were confirmed using SEM.

Significance

The use of the ion-releasing resin-based system applied to acid-etched dentin pre-treated with biomimetic primers containing analogs of phosphoproteins such as poly-l-aspartic acid and/or sodium trimetaphosphate provides a suitable bonding approach for biomimetic remineralization of resin–dentin interfaces.


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