Chemical analyses of a self-etch adhesive root canal sealer

Objectives:  MetaSEAL^TM (Parkell; USA) was a newly developed self-etch adhesive resinous sealer containing 4-META.  To evaluate the morphological and chemical characteristics in the vicinity of resin-dentin interface of roots obturated with MetaSEAL^TM, SEM observations, Energy-dispersive X-ray spectroscopy (EDS) microanalysis and Fourier transform infrared (FT-IR) analysis were executed.

Methods:  The extracted single-rooted human teeth were used.  After enlargement of root with Ni-Ti file, root canal was irrigated with the combination of EDTA and NaClO.  Then, the canals were filled with MetaSEAL^TM and gutta-percha points.  The specimens were stored in 100% humidity at 37°C for 14 days, and were cut horizontally against tooth axis using 2000-grid SiC paper under water irrigation.  The polished specimens were treated with HCl and NaClO.  Specimens were observed with SEM due to evaluate the interface between resinous sealer and radicular dentin.  Quantitative element analysis of calcium, phosphorus, carbon, silica and zirconium in the vicinity of resin-dentin interface was carried out by EDS, and FT-IR was used to compare the absorption peaks in the same areas.    

Results:  SEM observation indicated that the surface of radicular dentin after endodontic treatment was collagen-rich fibrous network with different thickness, and there were formation of resin tags and hybrid-like layer in resin-dentin interface.  The thickness of hybrid-like layer was 10-30 µm, the gaps were not observed in all the resin-dentin interfaces.  EDS element analysis showed different calcium, phosphorus, calcium and silica contents in radicular dentin, hybrid-like layer and MetaSEAL^TM, respectively.  FT-IR analysis showed that the absorption peaks of hybrid-like layer were similar to these of radicular dentin and MetaSEAL^TM.

Conclusion:  It was concluded that hybrid-like layer at resin-dentin interface of root obturated with MetaSEAL^TM was a real 'hybrid layer'.  Furthermore, it was observed that hybrid layer had different thickness because MetaSEAL^TM adequately infiltrated and polymerized into fibrous network formed after endodontic treatment.