Push-Out Bond Strength of A Novel Hydroxyapatite Coated Gutta Percha

Objective: A novel nano hydroxyapatite coated Gutta percha (GP) has been developed for root canal filling. The aim of this study is to evaluate the push-out bond strength of different types of coated GP root filling materials compared to conventional GP. Methods: Fifty extracted teeth were selected and instrumented using ProTaper rotary files to size F4. The canals were assigned into five groups (n=5 each) and obturated using matching single cone technique as follows:  EndoRez coated GP and EndoRez sealer, Endosequence coated GP (BC GP) with Endosequence BC sealer, Active GP with Endosequence BC sealer (ActiV GP), conventional GP with Endosequence BC sealer and nanohydroxyapatite coated GP (HA GP) with Endosequence BC sealer. Each root was sectioned horizontally at the thickness of 1 mm ± 0.1 to obtain 5 sections. The specimens were subjected to the push-out test using a Universal Test Machine at a loading speed of 0.5 mm/ min. Failure modes after push-out test was examined under stereomicroscope. The push-out data were analyzed using ANOVA and the post hoc Dunnett T3 test (p = 0.05). Results: The highest bond strength yielded by HA GP (6.18 ± 2.70) followed by BC GP (5.77 ± 2.78), ActiV GP (5.38 ± 3.21), conventional GP (4.65 ± 2.86) and EndoReZ (0.48 ± 0.20). There were significant differences between EndoReZ and all other groups (p < 0.001). The failure mode of conventional GP was equal of both cohesive and mixed (40%). EndoRez and HA GP exhibited mixed failure mode; 56% and 52% respectively, whereas ActiV GP and BC GP showed cohesive failure; 48% and 44% respectively. Conclusion: EndoReZ system exhibited the lowest push-out bond strength to root dentine compared with other materials. HA GP showed promising results to be used as root canal filling material.