The bond strength of root canal sealers to dentin seems to be an important property for maintaining the integrity of the seal of root-canal fillings. In the few studies published, various assessment methods were used so quantitative comparison is not possible. The purpose of this study was to develop an effective and easily reproducible model and to test it with nine contemporary, commercially available endodontic sealers. After slicing off the coronal 2 mm of extracted third molars, the exposed dentin served as test surfaces. The teeth were fixed with plaster in 1-inch phenolic rings. Five-mm long sections of polyethylene tubing, filled with freshly mixed sealer, were placed on the dentin and tested for shearing bond strength after setting. A custom-made holder allowed the rings to be attached to an Instron machine, activated at a cross-arm speed of 0.5 mm/min. The mean bond strength, ranged from 0 to 4.9 MPa. The sealers were ranked and those that did not differ statistically in their bond strength were grouped together. This model provides a simple and reproducible means for measuring the in vitro bond strength of endodontic sealers.

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Strength of the bond of root canal sealers to gutta-percha seems to be an important property for maintaining the integrity of the apical seal. In the few studies published, different models and assessment methods were used. The purpose of our study was to adapt an effective and easily reproducible model and to test it on nine contemporary commercially available endodontic sealers. Gutta-percha disks with a diameter of 10 mm and thickness of 2 mm were prepared by warming gutta-percha cones and then fixed with plaster in 1-inch phenolic rings. Five-millimeter long sections of polyethylene tubing, filled with freshly mixed sealer, were placed on the gutta-percha and tested for shearing bond strength after setting. A custom-made holder was attached to the rings and placed in an Instron machine, which was activated at a cross-arm speed of 0.5 mm per minute. The bond strength ranged from 0 MPa to 6.4 MPa. The sealers were ranked, and those that did not differ statistically in their bond strength were grouped together. This model provides a simple and reproducible means for measuring the in vitro bond strength of endodontic sealers.

The long-term effect on periapical healing (8-14 months) of CRCS and Sealapex was compared with that of AH 26. Vital pulpectomy and root canal filling by the hybrid thermomechanical method were performed in teeth of 3 young monkeys. Ten roots with CRCS, 10 with Sealapex and 7 roots with AH 26 were examined after demineralization and routine histological processing. Hematoxylin and eosin and Brown & Brenn staining for micro-organisms were employed. Mild to severe inflammatory lesions were found at the apical foramina of the roots filled with AH 26 and CRCS. Most of the Sealapex specimens showed no inflammatory cells, except macrophages with sealer particles. A striking finding was a tendency towards apical obliteration with calcified tissue in roots filled with Sealapex, apparently following resorption of the sealer. Such a tendency was seldom observed with the other sealers. However, both AH 26 and Sealapex were irritating for a long time when pushed into bone. Despite the interesting results with Sealapex, additional research is needed before its use can be unconditionally recommended. This sealer has not yet been tested in infected cases and its ability to be resorbed, which is an advantage when it precedes replacement by calcified tissue, may become a disadvantage if it is not followed by apical obliteration.