Bioactive
Thomas E. Dudney, DMD
As new technology and advancements in dental materials continue to change the face of dentistry, the terms "bioactive" and "bioactivity" are frequently encountered. Merriam-Webster's Dictionary defines bioactive (the adjective form) as: "having an effect on a living organism." Taken literally, this definition could actually be referring to both positive and negative effects, but as it relates to dental materials, manufacturers are continually striving through research and development to develop new products that elicit positive biologic responses and have beneficial effects. However, confusion is often created by the different interpretations of what is actually required for a material to be considered bioactive. Some people maintain that any product that releases ions is bioactive; therefore, they would consider glass ionomers bioactive because they release fluoride ions. However, there are others who say that to be considered bioactive, a material must be able to form hydroxyapatite in the presence of oral fluids and release not only fluoride ions but also calcium and phosphate ions as well. As the debate continues to unfold, it is possible that the significance is not in which definition is correct or the most accurate but in what the potential benefits are in the use of these products. Instead of debating whether materials are or are not bioactive based on their properties, which is more about extoling the virtues of particular products, it is more useful to illustrate the different categories of materials that might be considered bioactive and the clinical conditions that could benefit from their application.
Presently, the different categories of ma-ter-ials that are claiming to offer bioactivity or bioactive properties include bases, liners, restoratives, pulp capping agents, cements, and root canal fillers. Beyond conventional root canal treatment, other endodontic procedures in which these materials might also be used include apexification and the treatment of perforations and internal resorption. For the most part, bioactive materials are either calcium silicates or calcium aluminates-both of which set with an acid-base chemical reaction that produces an alkaline pH. This elevated pH is believed to play a significant role in the benefits imparted by these materials. Some of the clinical benefits attributed to bioactive materials include the release of ions (eg, fluoride, calcium, phosphate), acid neutralization due to elevated pH, remineralization, and hydroxyapatite formation. The use of products with some or all of these properties could greatly benefit all dental patients, but especially children, the elderly, and those who demonstrate a high risk of developing caries or decreased salivary flow. In fact, it is well known that decreased salivary flow is a double-edged sword that contributes greatly to an increase in acid erosion as well as dental caries. Any products that can elevate pH have the ability to neutralize the acids that cause dental erosion. Furthermore, the use of bioactive materials could potentially prevent or deter recurrent decay, especially in patients with decreased salivary flow, by providing protection against microleakage, which increases the longevity of both direct and indirect restorations.
As dental materials continue to be developed and improved, it is incumbent upon dentists to educate themselves about which ones might be beneficial to their patients and why. Although there is some confusion and controversy when it comes to defining bioactivity and what products are considered truly bioactive, it is hard to ignore the potential benefits that may be realized with their use. As dental manufacturers continue to heavily invest in research and development, a better understanding of bioactive materials and their benefits should be achieved. There is still much to be learned and understood with respect to bioactivity and bioactive dental materials, but the future appears to be bright. When making clinical decisions about which products to use, the potential benefits offered by bioactive materials should weigh heavily in the decision-making process. Only by arming themselves with facts and credible information will dentists be able to make sound choices regarding product selection.
About the Author
Thomas E. Dudney, DMD, is a diplomate of the American Board of Aesthetic Dentistry and a clinical director for the Pacific Aesthetic Continuum hands-on programs. He maintains a private practice in Alabaster, Alabama.
