Removability of three intracanal calcium hydroxide pastes from the root canal

The purpose of this study was to investigate the removability of calcium hydroxide dressed in root canals. Three types of calcium hydroxide pastes were used: Calfee paste ðF, Caicipex, ðF and Caicipex II ðF. Five single-rooted human extracted teeth were used. After removing the tooth crowns, the canals were prepared by NiTi files with 0.06 taper using the conventional method, and the roots were sectioned in the bucco-lingual direction so that repositionable root canal models could be obtained. After root canal dressing of the calcium hydroxide pastes, the root canals were irrigated by the following three methods: alternative irrigation with 1.5mL of 3% hydrogen peroxide and 1.5mL of 6 % sodium hypochlorite (NaClO), solely with 3.OmL of NaC1O, or 3.OmL of NaCIO with ultrasonics. Then, the canal model assemblies were dismantled, and the images of the canal wall surfaces were taken with a digital microscope. The ratio of the area occupied by calcium hydroxide pastes to the total canal wall surface area within 3 mm from the root apex was calculated as a percentage for each canal model. Statistical analysis showed that the removability of Calfee paste R was the highest among the three calcium hydroxide pastes (p < 0.05). There were no statistically significant differences among the irrigation methods used (p > 0.05).