Density comparison of root canal obturation at apical one-third between single cone and downpack-backfill techniques using polidimetylsiloxane sealer

This study aimed to to compare the apical sealing ability in one-third apex between single cone (SC) and downpack-backfill (DB) techniques, using polydimethylsiloxane sealer. Forty extracted human mandibular premolars were divided into two groups: SC and DB. After they were obturated with polydimethylsiloxane sealer, the samples were stored in an incubator, coated with nail varnish, immersed in India ink, and then the specimens were cleaned, using Robertson's technique. The apical dye penetration was evaluated using a stereomicroscope. The lowest leakage score (0-0.5 mm) was found in the SC group and the highest score (>1 mm) was found in the DB group. The single cone technique exhibited better sealing ability than the downpack-backfill technique, although there was not a statistically significant difference between these two techniques.