Dentin Biomodification Induced by Proanthocyanidins from Rhodiola rosea
Objectives: To investigate the use of fractions from Rhodiola rosea (Rr), consisting of prodelphinidin-gallate esters as predominant proanthocyanidin sub-unit, with different degree of polymerization, for its potential to induce dentin biomodification. The study hypothesis was that Rr would induce sustained dentin biomodification and enhanced resin adhesion to dentin.
Methods: Fractions from Rr extract were produced by centrifugal partition chromatography - Armen-CPC-E, and named Rr1, Rr2, Rr3 and Rr4. Demineralized dentin specimens (0.5 × 1.7 × 7 mm) were treated with Rr1, Rr2, Rr3 and Rr4, at 0.65% w/v (pH 7.2). The dynamic mechanical properties (n = 5) were assessed immediately and after incubation in simulated body fluid (SBF) for 7 days, 1 and 3 months at 37°C. Microtensile bond strength (TBS) of the biomodified dentin-resin interfaces was assessed. Occlusal dentin surfaces (n = 6) were etched (35% Glycolic Acid for 15 s), primed (Rr1, Rr2, Rr3 and Rr4 at 6.5% w/v for 1 min) and bonded (experimental methacrylate adhesive). After 24 h and 3 months in SBF, specimens were tested under tensile at 1 mm/min. Statistical analysis was performed using Two-Way Anova and Tukey (α = 0.05).
Results: Rr biomodification resulted in statistically higher E* as compared to control at all time-points (p < 0.001). The highest E* was obtained by Rr2. Significant decrease in E* occurred after 1-month for all groups (p < 0.001). Higher TBS was observed following dentin priming with Rr2, as compared to Rr1, Rr4 and control (p = 0.040; 0.029 and 0.005, respectively); and no difference between Rr2 and Rr3 (p > 0.05). No statistically significant difference in TBS was observed between time-points (p > 0.05).
Conclusions: Rr increased dentin complex modulus, with Rr2 (galloylated dimers and trimers) as the most active fraction. Dentin priming with Rr2 improved dentin-resin bond strength.