Evaluation of setting properties and retention characteristics of mineral trioxide aggregate when used as a furcation perforation repair material.

Furcation perforations were created in 32 extracted maxillary and mandibular molars. The perforations were prepared in the center of the pulp chamber floor parallel to the long axis of each tooth and a saline-moistened Gelfoam matrix was placed below the perforation to simulate a clinical condition. The teeth were randomly divided into four groups, and the perforations were all repaired with mineral trioxide aggregate (MTA) and then covered with either a wet or dry cotton pellet for 24 or 72 h. Instron testing was used to measure the force required to displace the material from the perforation. The force measurements showed that MTA resisted displacement at 72 h to a significantly greater level than at 24 h (p < 0.05). When slight displacement occurred at 24 h the material demonstrated the ability to re-establish resistance to dislodgement from the dentin wall. The presence of some moisture in the perforation during placement was advantageous in aiding adaptation of MTA to the walls of the perforation, but there was no significant difference in MTA retention when a wet or dry cotton pellet was placed in the pulp chamber during the setting time (p > 0.05).