Behavior of mineral trioxide aggregate apical plugs and root fillings under cyclic loading

The aim of the present study was to develop a methodology for constant monitoring of the resistance to fluid flow during functional loading and to then compare the efficacy of 4-mm mineral trioxide aggregate (MTA) apical plugs and full-length MTA root fillings.

The root canals of 24 single-rooted teeth were instrumented and assigned into two groups: group 1 (filled with a 4-mm MTA apical plug and gutta percha) and group 2 (filled with MTA to cementoenamel junction level). All teeth were subjected to stepwise cyclic loading with a constant simulated interstitial pressure of 25 cm H₂ O applied apically. A Flodec machine (De Marco Engineering, Geneva, Switzerland) constantly monitored the rate and direction of fluid flow. Student's t-test, Kruskal-Wallis test, Fisher's exact test, and Newcombe-Wilson test were used for statistical analysis, with P < 0.05.

Crown fractures occurred in 21 teeth with no change in the rate of fluid flow. Three teeth (filled with full-length MTA) showed sudden change in the rate of fluid flow through the root canal after cyclic loading.

The methodology reliably monitored fluid flow during cyclic loading. There was no difference between a 4-mm MTA apical plug and full-length MTA root filling after cyclic loading using a dynamic fluid-flow monitoring technique.