Short-term periradicular tissue response to mineral trioxide aggregate (MTA) as root-end filling material.

Aim: The aim of the present study was to evaluate the short-term response of periradicular tissues to MTA when used as a root-end filling material in ideal tissue conditions.
Methodology: The experimental procedures were performed on the healthy teeth of dogs. Pulps were removed and root canals prepared and filled with gutta-percha and sealer. At the same session, buccal mucoperiosteal flaps were reflected and the root ends resected. MTA or IRM were used as root-end filling materials. The periradicular tissue reactions were evaluated histologically from 1 to 5 weeks. Hard tissue formed on the MTA surface was further examined by scanning electron microscopy.
Results: The most characteristic tissue reaction to MTA was the presence of connective tissue after the first postoperative week. Inflammation was seen occasionally. Early tissue healing events after MTA root-end filling were characterized by hard tissue formation, activated progressively from the peripheral root walls along the MTA-soft tissue interface. In contrast, hard tissue was not seen over the IRM root-end filling.
Conclusions: MTA is a biocompatible material that stimulates periradicular tissue repair at the root-end situation; however, the nature of the newly formed tissues requires further elucidation.