Sealing ability of three coronal barriers in endodontically-treated teeth

Objective: To compare the ability of 3 barrier materials to prevent microleakage immediately after completion of the root canal treatment. Methods: 30 extracted premolars stored in 0.2% chloramine for up to 6 months after extraction were endodontically treated with gutta-percha and AH Plus sealer (Dentsply). The teeth were randomly divided into 3 groups (n=10): (1) Cavit (3M ESPE), a zinc oxide-based material; (2) Fuji IX (GC), a GIC-based material; and (3) Coroseal (Ivoclar Vivadent), a self-etch, resin-based material.  All materials were used as per manufacturers' instructions.  For each group, 5 specimens were thermocycled for 1,000 cycles (5-55^oC) while the other 5 were left in distilled water at 37^oC.  All teeth were immersed in 50% ammoniacal silver nitrate for 24h at 37^oC followed by 8h in a photodeveloping solution. The coronal aspect of each specimen was sectioned in four 1mm-thick slices perpendicular to the long axis of the tooth. Slices were processed for FE-SEM and evaporated with carbon. Silver penetration at the restoration-tooth interface was evaluated with a backscattered detector in rankings from 0 to 4, where 0=no infiltration and 4=infiltration down to slice 4 (deepest slice). Data were analyzed with nonparametric tests (Kruskal-Wallis and Mann-Whitney tests, P<0.05). Results: For non-thermocycled specimens, Cavit and Fuji IX resulted in significantly more leakage than Coroseal (P<0.006 and P<0.012, respectively). Cavit and Fuji IX resulted in statistically similar leakage scores (P>0.116). For thermocycled specimens there was no statistical difference between any pair of materials.  When scores were pooled for the variable “thermocycling”, Cavit resulted in significantly more leakage than Coroseal and Fuji IX (P<0.009 and P<0.018, respectively). Fuji IX resulted in significantly deeper leakage than Coroseal at P<0.023. Conclusions: Thermal fatigue resulted in similar leakage for all materials. Overall, the resin-based material Coroseal resulted in better marginal seal than Fuji IX and Cavit.