Characterization of the chemical and viscoelastic properties of dentin treated with bromelain and bioactive glass-ceramic

To evaluate the effects of bromelain associated with Biosilicate (BrBio) on the chemical and viscoelastic properties of sound (SD) and caries-affected dentin (CAD), specifically on intertubular and peritubular regions.

Mid-coronal dentin discs were prepared, with half being demineralized using Streptococcus mutans to create CAD. Specimens (n = 5 per group) were treated with: Control (no treatment), 10% bromelain (Br), 10% Biosilicate (Bio), or their association (BrBio). Complex modulus (E*) and damping capacity (tan δ) were measured using nano-dynamic mechanical analysis (nano-DMA) at baseline, immediately after treatment, and after 3 months of aging. Immediate chemical composition was assessed by micro-Raman spectroscopy (n = 3). Data were analyzed using a general linear model, followed by Scheffé's post hoc test (α = 0.05).

Dentin substrates exhibited distinct chemical and viscoelastic profiles. CAD showed loss of peritubular dentin, restricting analyses to intertubular dentin. In intertubular SD, BrBio showed higher E* than Control and reduced tan δ after 3 months. In peritubular SD, Br presented higher tan δ than Bio and BrBio immediately after treatment. In intertubular CAD, BrBio displayed decreased E* immediately after treatment. In SD, BrBio presented higher crystallinity than Control, whereas in CAD, BrBio had lower crystallinity than Br.

The association of treatments preserved the viscoelastic properties of SD over time, likely by enhancing mineral content, increasing crystallinity, and stabilizing the organic matrix. In CAD, the association produced an immediate reduction in tan δ, suggesting early matrix stabilization mediated by Biosilicate.