Bacteria Induced Discoloration in Mineral Trioxide Aggregate

Objectives: The present study investigated the effect of the bacteria induced discoloration in Mineral Trioxide Aggregate.
Methods: In this study, four types of MTA were used: RetroMTA (BioMTA, Seoul, Korea), ProrootMTA (Dentsply, Tulsa Detal, Tulsa, UK), MTA Angelus (Angelus, Londrina, PR, Brazil), and White Portland Cement (Union Cement, Korea). Coronal portions of 80 mature bovine upper incisors were cut at the CEJ level to obtain dentin blocks, and a cavity of 3.5 mm diameter and 1.7 mm depth was prepared using a diamond round bur. The cavity was filled with MTA, and MTA was set for 24 hrs. Each type of MTA specimens (n=5) were submerged in four different media for seven days. After seven days, photos were taken and shade change was evaluated using a spectrophotometer.
Results: In BHI solution with E. faecalis, Proroot MTA and MTA Angelus showed statistically significant black discoloration. These two MTAs contain bismuth oxide as a radiopacifier. Tooth discoloration did not occur in the RetroMTA and White Portland Cement groups. When BHI solution containing E. faecalis was sterilized through autoclave, there was no tooth discoloration.
Conclusions: E. faecalis induced the discoloration in MTAs containing bismuth oxide.