Resistance of a 4-META-containing, methacrylate-based sealer to dislocation in root canals

The dislocation resistance of root fillings created with MetaSEAL, a self-adhesive 4-META-containing methacrylate resin-based sealer, was evaluated. Forty-six incisors were cleaned and shaped using NaOCl and EDTA as irrigants. They were filled with gutta-percha/MetaSEAL or gutta-percha/AH Plus sealer using either a single-cone technique or warm vertical compaction (n = 10). The roots were sectioned at the coronal and middle thirds to obtain thin slices, which were subjected to compressive loading to displace the set sealer/filling toward the coronal side of the slice. The remaining six teeth were filled with gutta-percha/MetaSEAL and cryofractured for scanning electron microscopic examination. The push-out strength of AH Plus was significantly higher than MetaSEAL irrespective of filling techniques (p < 0.05). A minimal hybrid layer was seen in radicular dentin, and resin tags were inconsistently identified from canal walls in the MetaSEAL-filled canals. The lower dislocation resistance in MetaSEAL-filled canals challenges the use of a self-adhesive bonding mechanism to create continuous bonds inside root canals.