In vitro leakage associated with three root-filling techniques in large and extremely large root canals.

This study assessed the apical leakage of ultrasonically condensed root fillings in extremely large canals, compared to cold lateral condensation and thermoplastic compaction. Ninety single-rooted teeth were used. In 45 teeth canals were enlarged to size 70 (large). The remaining 45 canals were enlarged to size 140 (extremely large). Each set of teeth was subdivided into three root-filling groups (n = 15): (1) cold lateral condensation (LC); (2) thermoplastic compaction (TC); and (3) ultrasonic lateral condensation (UC). Teeth in all six subgroups were subjected to drawing ink penetration, cleared, and evaluated for linear apical dye leakage. Significantly deeper dye penetration (p < 0.04, Wilcoxon rank-sum test) was observed for LC than for UC. TC did not differ significantly from LC and UC. Dye penetration was significantly deeper (p < 0.0001) in canals enlarged to size 140 than to size 70, independent of root-filling method. Apical leakage associated with ultrasonically condensed root fillings was less than that with cold lateral condensation. It was consistently greater in extremely large canals than that in large ones.