DIFFUSION BEHAVIOR OF EUGENOL FROM ZINC OXIDE-EUGENOL MIXTURES THROUGH HUMAN AND BOVINE DENTIN IN-VITRO

The objective of this in vitro study was to evaluate the long-term dif fusion behavior of eugenol from different zinc oxide-eugenol mixtures through thin dentin layers. In 24 freshly extracted, caries-free human teeth standardized cavities were prepared exhibiting a dentin surface area of 7 mm(2). The remaining thickness of the dentin close to the p ulp chamber amounted to at least 0.2 mm. In a second experiment standa rdized dentin disks (0.2 mm thick) were prepared from 24 bovine inciso rs. The disks were embedded in epoxy resin, thus exposing a resin-free , standardized area of 7 mm(2). Specimens from both experiments were i nserted into a screw cap of a vial. Cp-Cap, Temp Bond, and two zinc ox ide-eugenol mixtures (P/L ratios of 10:1 and 2:1) were applied to each of six specimens from both experiments. The opposing surface was in c ontact with 1 ml of Ringer solution. After 1 day, 7 days, and 21 days respectively, the amount of penetrated eugenol was determined with Hig h Performance Liquid Chromatography (HPLC). In both experiments we fou nd a persistent release and diffusion of eugenol, irrespective of the applied material. However, for the second experiment, we saw more pron ounced diffusion rates. Furthermore, the materials showed significant differences, particularly for low versus high P/L ratios.