An in vitro study with various vehicles of diffusion of formocresol and its components.

Pulpotomy in primary teeth using the formocresol method results in varying degrees of devitalization of the root pulp. The extent of this devitalization depends on, among other things, the ability of the components of formocresol to leave the dressing. The purpose of this study was to evaluate the rate and duration of diffusion of the components of formocresol when incorporated in different vehicles. The antimicrobial effect of the drugs was used to assess the diffusion of the components of formocresol in blood agar, with a sensitive microorganism as an indicator. Evaluation of the MICs assessed in broth medium for formalin, formocresol and cresol, respectively, and the zone size of growth inhibition on blood agar from these components when incorporated in ZnO or ZnO-eugenol cement, suggested that the initial zone of inhibition from formocresol was due mainly to the diffusion of formaldehyde. Cresol diffused more slowly from the dressing. The presence of eugenol in the dressing, as in ZnO-eugenol cement, gave smaller initial release of formaldehyde, formocresol and cresol compared with the release from ZnO, but more prolonged diffusion. A higher initial release of formaldehyde was obtained when the formocresol was incorporated in ZnO alone compared with ZnO-eugenol cement or Pharmatec.