Comparative Evaluation of Coronal Microleakage Associated with Different Intra-Orifice Barrier Protocols in Endodontically Treated Maxillary Anterior Teeth

Preventing coronal microleakage is crucial for long-term endodontic success; this ex vivo study compared the sealing performance of five intra-orifice barrier (IOB) material application protocols with that of a no-IOB control. Sixty maxillary anterior teeth were randomly assigned to six groups (n = 10): control, flowable composite, universal composite, resin-modified glass ionomer cement (RMGIC), high-viscosity bulk-fill composite, and flowable bulk-fill composite. Following endodontic treatment, 2 mm-thick barriers were placed in five groups. All specimens underwent 1000 thermocycles and 24 h immersion in 2% methylene blue. Linear dye penetration was measured at ×50 using stereomicroscopy and ImageJ. Data were analyzed using one-way ANOVA with Tukey's HSD test (α = 0.05). Microleakage differed significantly among groups (F (5, 54) = 12.473; p < 0.001). The lowest mean microleakage was observed with the Estelite Sigma Quick (EQ) (1.85 ± 0.59 mm), followed by the Estelite Bulk Fill Flow (EF) (2.28 ± 0.91 mm) and Filtek One Bulk Fill Restorative (FR) (2.48 ± 1.18 mm). No statistically significant differences were detected among these materials; however, each demonstrated significantly less microleakage than the Tetric N-Flow (TNF), Ionoseal (IS), and no-IOB control (p < 0.05), among which no differences were detected (p > 0.05). Under the experimental conditions of this ex vivo study, the protocols involving the EQ and both bulk-fill resin composites (FR, EF) resulted in significantly lower coronal dye penetration than the protocols involving the TNF, IS and the no-IOB control.