Dentin Remineralization Associating Peptide- and Particle-Assisted Strategies

This study investigated the efficacy of the polymer-induced liquid precursor (PILP) process and of an experimental composite containing dicalcium phosphate dihydrate (DCPD) particles for <i>in vitro</i> remineralization of artificial dentin lesions. The hypothesis was that pretreatment with the PILP solution associated with an external Ca²⁺/PO₄^3- source represented by the composite containing DCPD would increase dentin remineralization in comparison to each strategy alone. Dentin discs with a 2.5-mm × 2.5-mm demineralized window (acetic acid, pH 5, for 66 h) were assigned to one of four experimental conditions, defined by the pretreatment (20 μL for 20 s: PILP solution or deionized water) and by the composite placed on the dentin surface: "control" (50% barium glass, BG) or "DCPD" (40% DCPD and 10% BG). Specimens were placed in artificial pulp chambers with the lower compartment filled with simulated body fluid for 28 d. Remineralization was assessed by changes in the mineral-to-matrix ratio (MMR) at the dentin-composite interface (attenuated total reflection-Fourier transform infrared spectroscopy) and by nanoindentation. Data were analyzed by repeated-measures 2-way analysis of variance/Tukey test (α = 0.05). Selected specimens were observed under scanning electron microscopy/energy-dispersive X-ray spectroscopy (EDS) and transmission electron microscopy with selected area electron diffraction analysis (SAED). All groups recovered MMR to levels similar to sound dentin, but only PILP + DCPD reached MMR levels similar to sound dentin after 14 d (<i>P</i> > 0.05). At the external lesion (0-90 µm), both DCPD and PILP + DCPD groups showed an elastic modulus (EM) statistically higher than the control, but only PILP + DCPD showed EM similar to sound dentin at the internal lesion (90-160 µm, <i>P</i> < 0.001). In relation to sound dentin, EM recovery reached 18% in the PILP group (not different from the control), 31% in the DCPD group, and 57% in the PILP + DCPD group. Micro- and ultramorphological analyses confirmed the increase in mineral content in the latter 2 groups. In conclusion, the association of both remineralization strategies improved dentin remineralization compared to either approach separately.