Leakage associated with single or multiple increment backfill with the Obtura II gutta-percha system

The purpose of this in vitro study was to compare dye leakage between canals backfilled in a single increment and canals backfilled in multiple increments using the Obtura II system with two different sealers. Sixty extracted single canal teeth were decoronated, cleaned, and shaped. After master cone fit and placement of either Roth 801 or AH26 sealers, the canals were down-packed to 4 mm from working length. The teeth were then divided into 4 groups of 15: group 1--Roth 801 sealer with 1 increment of Obtura II back-fill; group 2--Roth 801 sealer backfilled in 4- to 5-mm increments; group 3--AH26 sealer with 1 increment of backfill; and group 4--AH26 sealer backfilled in 4- to 5-mm increments. After sealer set, the teeth were apicected 5 mm from working length. The apices were discarded. The coronal segments were coated with two layers of fingernail polish, except for the resected apical end. The teeth were immersed in Pelikan ink for 5 days. The teeth were then decalcified, dehydrated, and rendered transparent in methylsalicylate. Dye penetration was measured on four surfaces of each root. The mean measurements of each tooth were averaged for each group. Leakage of group 1 was 6.69; group 2, 5.39; group 3, 5.71; and group 4, 5.02. Differences were not statistically significant (p > 0.05). This study suggests that it may be clinically acceptable to backfill canals up to 10 mm in a single increment using sealer and the Obtura II gutta-percha system.