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 in vitro 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 (P > 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, P < 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.