Bioactivity means a material has an interaction with or causes a response when in contact with living tissue. Over the last few years the concept of bioactive dental materials has been widely discussed. Materials like MTA (mineral trioxide aggregate) have come to the forefront and reopened our curiosity about bioactivity. Bioactive dental materials are designed to cause the body to lie down new tooth structure, particularly dentin or cementum.
In the field of endodontics bioactive materials are used for procedures like apexification, treatment of a root perforation or internal root resorption. Restoratively we use bioactive materials to prevent pulpal death and initiate the formation of a dentinal bridge during direct or indirect pulp capping. There are a number of factors that contribute to the effectiveness of bioactive materials. Alkalinity or having a high pH is a critical factor. At one point we felt like this created an irritation tot he pulpal tissue and the response was the formation of new dentin.
We now believe that the effect is the result of two proteins being dissolved from the surrounding dentin, Bone Morphogenic Protein (BMP) and Transforming Growth Factor-Beta One (TBF-β1). Both have been demonstrated to contribute to pulp repair. Another factor is the creation of an antibacterial seal over the pulp exposure.
The active ingredient in all bioactive dental materials is calcium hydroxide. The new generation of materials that include Theracal LC (Bisco), Biodentine (Septodont) and Pro Root (Tulsa/Dentsply) are modern, more effective delivery systems for calcium hydroxide.