Preliminary evaluation of a novel polymer nanocomposite as a root-end filling material

To evaluate two nanoparticle-enhanced polymer root-end filling materials (NERP1 and NERP2) on the initial apical seal as compared to a polymer-based commercial compomer.

One hundred and forty extracted roots with completely formed apices were resected 3 mm from the apex. Cavities were then prepared in the apical openings of the resected root ends using an ultrasonic handpiece to a depth of 3 mm. The roots were then randomly divided into five groups to receive one of five root-end filling materials. Roots in groups 1 and 2 received NERP1 and NERP2, whilst those in groups 3 and 4 received identical polymers as groups 1 and 2 but without nanoparticle addition (RP1 and RP2, respectively). The root-end cavities for the fifth group were filled with commercially available root-end filling compomer. Roots were mounted in a dual-chamber leakage apparatus and inoculated coronally with Enterococcus faecalis. Turbidity of the apical broth was assessed daily for 4 weeks as a sign of initial leakage. The results were statistically analysed using odds ratio and Fisher's chi-square analysis.

Nanoparticle-enhanced root-end filling polymer 1 displayed significantly fewer leaked samples compared to all other tested groups as early as 5 days, whilst NERP2 was not significantly different compared to other groups. Odds ratio analysis revealed leakage of the commercial compomer was 12 times more likely than NERP1.

Nanoparticle-enhanced root-end filling polymer 1 can reduce apical microleakage significantly under laboratory conditions.