Apical marginal adaptation of orthograde and retrograde root end fillings: a dye leakage and scanning electron microscopic study.

A few studies have attempted to examine the correlation between clinical success of root canal therapy and in vitro examinations. In this case report we examined the apical adaptation of three orthograde fillings and four retrograde amalgam root end fillings from four radiographically successful teeth and one unsuccessful case by using dye leakage and scanning electron microscopic methods. Despite the radiographic appearance of successful root canal therapy, these examinations showed penetration of methylene blue dye through the apical foramina to the levels of the root canal filling materials in the roots treated nonsurgically and the presence of small gaps between filling materials and the dentinal walls. The methylene blue dye also penetrated through the interface between amalgam and root end cavities, and there were varying size gaps between the root end cavities and amalgam. Similar examinations on the radiographically unsuccessful retrograde filling showed the presence of gaps between the amalgam and the root end cavity preparation and complete penetration of methylene blue dye between amalgam, root canal filling materials, and the dentinal walls.