Proanthocyanidin-functionalized hydroxyapatite nanoparticles as dentin biomodifier

Objective. This study evaluated the potential combined effects of nanohydroxyapatite and proanthocyanidin on the remineralization and collagen stabilization of demineralized dentin. Methods. Seventy-five coronal dentin beams (6 x 1 x 1 mm(3)) were randomly allocated into five experimental groups (n = 15): Sound (no treatment), Control (pH-cycling), nHAp (nanohydroxyapatite), nHAp_PA (Proanthocyanidin-functionalized nanohydroxyapatite), and PA (proanthocyanidin) treatments. The sound group (negative control) were immersed in dis- tilled water over the experimental period. The remaining groups were submitted to a pH-cycling process for 14 days. Following the de-re mineralization process, specimens corresponding to the control group (positive control) were immersed in distilled water whereas the test groups were immersed in 1 mL of respective solution treatment (nHAp, nHAp_PA, or PA) for 1 min. The dentin samples were analyzed to determine their chemical composition (ATR-FTIR and Thermogravimetric) and mineralogical (XRD) characteristics as well as their mechanical response, obtained by three-point bending test. Results. Higher phosphate content (v(4) PO4: ATR-FTIR) and amount of mineral (XRD) was observed in the nHAp_PA group. Furthermore, a larger induction of collagen cross-links (ATR-FTIR) and %Organic Matter (TGA) would indicate the PA incorporation and the achievement of dentin matrix stability. These effects on dentin properties were related to increasing flexural strength (MPa), demonstrating that 15% w/v nHAp_PA treatment improved the mechanical properties of the samples. Significance. nHAp_PA shows significant potential for promoting remineralization while improving collagen stability into demineralized dentin in a clinically feasible period of 1 min. (C) 2021 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.

Automated summary

The combination of nanohydroxyapatite and proanthocyanidin shows significant potential for promoting remineralization and improving collagen stability in demineralized dentin within a clinically feasible period of 1 min. The effects on dentin properties were related to increasing flexural strength, indicating an improvement in mechanical properties.