Evaluation of Nanocomposite Incorporation into a NOVEL Endodontic Retrofill Material

The goal of endodontic surgery is to excise peri-radicular pathology and seal the apical portion of the root to prevent post-operative infection. Current root-end sealing materials although effective, may display certain disadvantages such as shrinkage, technique sensitivity, and moisture contamination. Polymer nanocomposites(PNCs) are a new class of polymeric materials composed of nanoparticles such as carbon nanotubes or organoclays dispersed at a nano-scale in a polymer matrix. PNC's offer substantial improvements in mechanical and thermal properties as well as drug elution characteristics and make potentially promising candidates as root-end sealing materials. Objectives: The aim of this pilot study was to evaluate the apical seal of two polymer/monomer matrix(PMM) combinations containing C18-nanocomposite(NC) with a commonly used retrofilling material, Geristore®. Methods: Root ends of thirty-six teeth were resected, prepared, then sealed with a PMM material. Group 1(PMM1) consisted of monomers: 2,2-bis[p-(2-hydroxy-3-methacryloxypropoxy)phenyl]propane(Bis-GMA), triethylene-glycol-dimethacrylate(TEGDMA), and hydroxyl-ethyl-methacrylate(HEMA); photoinitiatiors: camphorquinone(I2), and ethyl-4-N,N-dimethylaminobenzoate(I3); and polymethylmethacrylate as the polymer. Group 2(PMM2) consisted of HEMA, urethane-dimethacrylate(UDMA), I2, I3, and polymer. Group 3(PMM1/NC) consisted of PMM1 and NC. Group 4(PMM2/NC) consisted of PMM2 and NC. Group 5 was Geristore®. Positive and negative controls were also used(3 each). Each root was placed in a leakage apparatus and inoculated with Enterococcus faecalis. Turbidity as a sign of leakage was assessed daily for two weeks. Results: Results were statistically analyzed using ANOVA and Tukey t-tests. All groups displayed varying degrees of leakage except for PMM1/NC which displayed no leakage (P < 0.01). Groups with NC showed significantly less leakage then groups without NC including Geristore®. However, Geristore® showed significantly less leakage than groups without NC(PMM1,PMM2).The addition of NC was suggested as the reason for the significant decrease in leakage. Conclusion: Within the confines of this study PMM1/NC should be further investigated for its use as an endodontic root-end sealing material.