Remineralization of Dentin Using PILP-Activating Glass-Ionomer Cements

Objectives: Remineralization of dentin lesions requires not only recovering apatite mineral, but also incorporation of the mineral within collagen fibrils for mechanical reinforcement of the dentin matrix facilitating functional remineralization (FR). The polymer-induced liquid-precursor (PILP) process induces FR, by applying treatments of artificial lesions in solutions comprised of poly-Aspartic acid (pAsp). Here we have developed glass-ionomer cements (GICs) that set in clinically-relevant times and release PILP ingredients to induce FM.
Methods: A Box-Behnken experimental design was used to evaluate setting characteristics of novel GICs from bioactive glass, polyacrylic acid, maleic acid, pAsp, and/or phosvitin. Artificial lesions (n=3) were created by 66h demineralization followed by rinsing, drying, and rehydrating before restoring with experimental GICs (n=3) and sealing with flowable composite. Remineralization treatments were performed by soaking in simulated-body-fluid for 2 weeks. The lesion shrinkage after dehydration (indicating remineralization) and elastic modulus (indicating FM) were measured and compared to cement controls (n=3) using Analysis of Variance (ANOVA).
Results: About 50 cement systems were evaluated and enabled finding cements that set quickly (<10 min). Treatments that included pAsp or phosvitin significantly reduced shrinkage (p£0.05, CI=95%), while no substantial improvement was observed without these molecules or when commercial GICs were used. The modulus of the demineralized zone (E~0.5GPa) increased within 2 weeks of treatments when PILP-activating cements were applied. Phosvitin-based cements showed the highest recovery of properties, with modulus E=13±3GPa, and was comparable to 200 measurements made in sound dentin (E=14±4GPa).
Conclusions: Novel PILP-activating GICs have been designed that could function in a clinical setting and provide remineralization that reinforces the dentin matrix. These GICs have the potential to become an intricate part of minimally invasive dental treatments that repair portions of natural caries lesions and conserve natural tissue, thus extending the lifetime of the tooth.