Biomechanics of Dentin Altered by Bromelain and Preserved by Biosilicate

Objectives: Bromelain, a natural deproteinizing agent, and Biosilicate, a fully crystallized glass-ceramic, have shown promising results in enhancing the bond strength to dentin and inhibiting endogenous proteases. This study evaluated the effect of both treatments on the viscoelastic behavior of intertubular and peritubular dentin.
Methods: Mid-coronal dentin discs were obtained from sound human molars (2 mm-thick), embedded in epoxy resin, and polished. Specimens were then randomly divided into three groups (n = 3), based on the surface treatment: Control – No treatment; Br – 10% Bromelain extract; Bio – 10% Biosilicate. The viscoelastic properties of the intertubular and peritubular dentin were determined before and after treatment using nano-dynamic mechanical analysis, under hydrated conditions, using a customized Ubi 1 nanoindenter (Hysitron Bruker) with a Berkovich tip. A lock-in amplifier was used to apply a sinusoidal dynamic load. Measurements were obtained immediately after the treatments at five different locations (number of indentations = 15, per sample and constituent). Complex modulus (E*), storage modulus (E’), loss modulus (E”), and damping capacity (tan δ) were recorded as a function of frequency (10-100 Hz). Data were statistically analyzed using two-way ANOVA and student’s t test (p = 0.05).
Results: Peritubular dentin presented significantly higher dynamic mechanical properties than intertubular dentin (p < 0.05). Dentin treated with bromelain exhibited a higher damping capacity of both the intertubular (p < 0.05) and peritubular (p < 0.05) dentin when compared to control. Conversely, the application of Biosilicate did not result in any significant changes in the damping capacity. Additionally, the complex modulus remained unaffected by either treatment.
Conclusions: The deproteinizing effect of bromelain increased the damping capacity of sound dentin, indicating a greater potential for energy dissipation. In contrast, Biosilicate had no impact on its dynamic mechanical properties.