Effect of Antioxidant on Coronal Seal of Dentin

Methods: Seventy single-root canals were enlarged and seven different treatment protocols were applied throughout the root canal treatment: The roots in Groups I, II and III were irrigated with sodium-hypochlorite. Group I was used as the negative control with only sodium-hypochlorite irrigation whereas in Group II, sodium-ascorbate was applied as an additional irrigation agent following sodium-hypochlorite. Irrigation procedure in Group III was same as in Group I. However, after the roots were obturated, cavities were cleaned off with a carbide bur (bur-finishing) to remove the effect of sodium-hypochlorite. Hydrogen-peroxide irrigation was used in Groups IV, V and VI; the procedural steps were similar to those of Groups I, II and III: hydrogen-peroxide in Group IV, sodium-ascorbate application in Group V, and bur-finishing in Group VI. Group VII was the positive control with saline irrigation alone. All roots were obturated with Diaket sealer and gutta-percha cones using cold lateral compaction technique. A self-etching priming adhesive plus resin composite was applied after the endodontic treatment. The microleakage of dentin margins was determined using dye-penetration technique with clearing process.

Results: The Kruskal-Wallis followed by Mann-Whitney test showed that both sodium-hypochlorite and hydrogen-peroxide deteriorated the marginal seal of the dentin adhesive (p<0.05). However, following both irrigation solutions the use of sodium-ascorbate reduced the microleakage (p<0.05). Additionally, when sodium-ascorbate or bur-finishing was applied to remove the deterioration caused by sodium-hypochlorite or hydrogen-peroxide, the microleakage scores obtained were not different from that of the positive control (p>0.05).

Conclusions: The adverse effects of sodium-hypochlorite and hydrogen-peroxide irrigation on marginal seal of the dentin adhesive might be alleviated with the application of sodium-ascorbate as additional irrigation agent.