Development, Characterization, and Influence of Proanthocyanidin Loaded PLGA Nanoparticles on Push out Bond Strength of Glass Fibre Posts Bonded with Resin Cement to Root Dentin: In Vitro Study

Partial or an incomplete penetration of bonding agent into the demineralized dentin can leave the denuded collagen fibres susceptible to degradation by photolytic enzymes. It is well known that the demineralized dentin and its collagen network is susceptible to degradation with time which can significantly affect the bond strength between root canal and sealer materials. The current study attempts assess the protective effect of proanthocyanidin (PA) loaded PLGA nanoparticles in minimizing the deterioration of demineralized dentin over a period. This is realized by determining/evaluating the push out bond strength between a glass fibre post cemented to root canal using resin luting cement. Ninety human mandibular premolars with single root canals were randomly divided into nine groups (n=10) after endodontic treatment and post space preparation. The root canal dentin of the control group was left unconditioned and the experimental groups i.e. proanthocyanidin and PA loaded PLGA nanoparticles (PA-NP) were conditioned respectively with the test solutions. The glass fibre posts (GFP) were cemented into the root canal with dual cure resin cement (RC). The push out bond strength (POBS) was measured at 30, 60, and 90 days. The mode of failure was evaluated with the help of stereomicroscope. The POBS were statistically analysed and evaluated with the help of paired t-test, ANOVA test and post hoc Bonferroni test at a confidence interval of 95% (α = 0.05). Unloaded NP's average particle size was found to be 237 16 nm, and its zeta potential was -54±4 mV. There was a statistically significant difference between the mean POBS at all time intervals among the groups tested. PA-NP showed a statistically significant higher bond strength compared to control at all time intervals, while it showed significantly better POBS compared to PA at 180 days. All the experimental groups showed higher POBS at all intervals of time compared to control group. Application of natural cross-linkers such as PA improves POBS of GFP bonded to root canal dentin. PA loaded PLGA nanoparticles (PA-NP) as a conditioning liquid prior to root canal cementation not only improved POBS significantly, but also reduced the time dependent reduction in the bond strength.