Aim To investigate by means of a fluid filtration whether immediate or delayed post space preparation and post cementation may influence the apical seal associated with Thermafil Obturators (Dentsply Maillefer, Switzerland). Methodology Fifty-four single-rooted teeth were randomly divided into five experimental (n = 10) and two control (n = 2) groups. Crowns were removed with a diamond bur at the cemento-enamel junction. Canals were shaped with Mtwo (Sweden & Martina, Italy), smeared with Pulp Canal Sealer (SybronEndo, USA) and filled with Thermafil Obturators (Dentsply Maillefer). Filled canals were subjected to the following protocols: G1, no other treatment; G2, post space preparation with Thermafil Post Space Bur (Dentsply Maillefer); G3, post space preparation with Thermafil Post Space Bur and D.T. light post (RTD, France) cementation; G4 and G5, as G2 and G3, the same respectively, after one week saline storage. Specimens underwent fluid filtration testing in accordance with the Cobankara et al. model (2002) after 7 and 30 days. Results Mean microleakage values ± SD (μL) after 7 days were: G1, 0.22 ± 0.22; G2, 0.56 ± 0.89; G3, 0.52 ± 0.76; G4, 0.30 ± 0.38; G5, 0.26 ± 0.46; and after 30 days: G1, 0.03 ± 0.03; G2, 0.06 ± 0.07; G3, 0.02 ± 0.04; G4, 0.01 ± 0.02; G5, 0.04 ± 0.12. Positive controls leaked respectively 75 and 88 μL in a minute; negative controls did not show filtration. There was no significant difference amongst the groups. Conclusions Under the conditions of the present ex vivo study, immediate or delayed post space preparation and post cementation did not influence apical seal.
