Quantitative radioactive analysis of microleakage of four different retrograde fillings.

Sealing properties of four different retrograde filling materials were investigated in vitro. Radioactive isotopes were applied in the root canal, and leakage into an extraradicular fluid was measured at regular intervals. The method permitted repeated observation of the specimens over prolonged periods of time. Forty single-rooted human teeth were biomechanically instrumented and obturated using calcium-hydroxide paste. Following obturation, an apicectomy was performed and retrograde cavities were filled with four different materials: group 1, non gamma 2 amalgam (Amalcap); group 2, glass ionomer cement (Ketac Silver); group 3, calcium-hydroxide-based root canal sealer (Sealapex); group 4, composite resin (Palfique Light-S). After removal of the calcium hydroxide, the teeth were immersed in a fluid. An isotope solution was then placed in the root canals. Samples were taken from the fluid at 0, 3, 7, 28, 56, 105, 210, 285 and 376 days to determine the radioactivity. It was found that Sealapex and Palfique Light-S showed significantly less leakage than amalgam and glass ionomer cement, which had the highest apical leakage.