Readers' Round Table

Abstract

To the Editor: A recent article, “In Vitro Cytotoxicity Of Traditional Versus Contemporary Dental Ceramics,” appeared in your journal. It was with great concern we read the conclusions of this article indicating that “Lithium-disilicate material exhibited cytotoxicity that would not be deemed biologically acceptable.” Please be assured that in our development of new materials and specifically with IPS Empress 2 as well, we evaluate and test our products to meet or exceed all biologic, physical, and clinical requirements for safety and effectiveness. IPS Empress 2 has been evaluated by independent toxicologic laboratories and has been in clinical trials for more than 6 years with no adverse effects. Furthermore, this product has received 510K clearance by the Food and Drug Administration and has been reviewed and accepted by numerous regulatory authorities around the globe without issue. Biologic acceptability is based on a series of evaluations of cellular and tissue response. Cytotoxicity is, on the other hand, recognized as a screening test and one of several steps to assess biologic compatibility. Cytotoxicity results will vary depending on cell culture, ratio, and specimen fabrication techniques. Therefore it is inappropriate to make a definitive conclusion on biocompatibility on the basis of a single screening evaluation. We reconfirm the biologic safety of IPS Empress 2 based on FDA, ISO and Medical Device Standards and strongly disagree with the conclusions of the authors.