Zinc as a growth factor for Aspergillus sp. and the antifungal effects of root canal sealants.

Noninvasive aspergillosis of the maxillary sinus is frequently associated with extrusion of root canal cements into the sinus, and it has been suggested that zinc oxide-based materials might promote infection because zinc is a growth factor for Aspergillus sp. To investigate this possibility pure zinc oxide-eugenol cement and five other cements were tested for antifungal activity against five strains of Aspergillus fumigatus, one strain of A. niger, and one strain of A. flavus by zone inhibition and by spectrophotometric measurement of growth rates at various zinc concentrations. All cements had antifungal activity. Eugenol-containing materials had the most activity, but this activity was reduced with mixing and setting. No growth enhancement attributable to zinc was detected by either method. To determine whether contaminated materials might introduce spores into the sinus, 63 samples taken from one clinic were cultured. Aspergillus sp. was isolated from two.