THE PROTECTIVE EFFECT OF ZINC ON ROSIN AND RESIN ACID TOXICITY IN HUMAN POLYMORPHONUCLEAR LEUKOCYTES AND HUMAN GINGIVAL FIBROBLASTS IN-VITRO

Combinations of rosin and zinc are used in dentistry as components of periodontal dressings and cements and as root canal sealers. The compo sition and properties of rosins differ largely depending on source and refinement processes. Rosin (colophony) is composed of approximately 70% resin acids. In order to study the toxic effects of different natu ral rosins and purified resin acids and the detoxifying effects of zin c, these compounds were analyzed and tested on human polymorphonuclear leukocytes (PMN cells) and human gingival fibroblasts using the radio chromium release method. The rosins and the pure resin acids showed a strong dose-related cytotoxicity, which was inhibited by increased zin c concentrations. The purified resin acids (isopimaric, levopimaric, a nd neoabietic acid) were more toxic than the natural rosins. The conte nts of these resin acids might explain the difference in toxicity of t he rosins tested. It is concluded that rosin and zinc are not to be co nsidered inert compounds and that the cytoprotective effects of zinc a nd its role in dentistry products merit further investigations. (C) 19 97 John Wiley & Sons, Inc.