Effect of flavonoids on the mechanical properties of demineralised dentine

Objectives: This study compared the effect of three flavonoids: proanthocyanidin, naringin and quercetin on the modulus of elasticity (MOE) and ultimate tensile strength (UTS) of demineralised dentine.

Methods: Thirty teeth were sectioned into 0.5mm×1.7mm×7mm beams for MOE measurement. Another 30 non-carious molars were sectioned into 0.5mm×0.5mm thick dentine beams for UTS testing. Demineralised specimens were divided into three groups according to treatments: 6.5% proanthocyanidin, 6.5% quercetin and 6.5% naringin. Specimens were kept in their respective solutions and tested at baseline, 10min, 30min, 1h and 4h. The MOE of each specimen was determined using a three-point bending test at a crosshead speed of 0.5mm/min. For UTS evaluation, each specimen was tested in tension until failure using a crosshead speed of 1mm/min. Means and standard deviation were calculated. Two-way ANOVA and Tukey test were used to evaluate the effect of flavonoid treatment and treatment duration on MOE and UTS.

Results: Both MOE and UTS were significantly affected by flavonoid treatment (p<0.001) and treatment duration (p<0.001). Interaction of the two factors was significant for MOE (p<0.001), but not for UTS (p>0.05). Flavonoid treatment improved the mechanical properties of demineralised dentine in the order: proanthocyanidin>quercetin>naringin. It took a longer time for the flavonoids to produce a significant change in UTS, when compared to MOE.

Conclusion: Proanthocyanidin was more effective than quercetin and naringin in improving biomechanical properties of dentine matrix, thereby enhancing preventive and reparative dental therapies.

Clinical significance: Despite its larger molecular size, proanthocyanidin was more effective than quercetin and naringin, in enhancing the biomechanical properties of demineralised dentine.