Sealing properties of mineral trioxide aggregate orthograde apical plugs and root fillings in an in vitro apexification model.

One-visit mineral trioxide aggregate (MTA) apexification is gaining in popularity over the use of calcium hydroxide barriers. This study examined the sealing properties of two MTA apexification procedures using an in vitro apexification model. White MTA was introduced into instrumented single-rooted canals with standardized artificially created open apices to form 3- to 5-mm-thick orthograde apical plugs or complete orthograde fillings of the root segments. The remaining canal spaces in the former group were backfilled with thermoplasticized gutta-percha without a sealer. A Flodec fluid filtration device was used to record fluid flow across filled root canals at 48 hours and after 4 weeks of immersion in phosphate-buffered saline (PBS). Although MTA root fillings exhibited a better seal than MTA apical plugs at 48 hours, seals of these two groups were not significantly different after 4 weeks. Interaction of MTA with PBS may result in apatite deposition that improves the seal of MTA apical plugs with time.