INFLUENCE OF ZINC-OXIDE ON ASPERGILLUS SPECIES - A POSSIBLE CAUSE OF LOCAL, NONINVASIVE ASPERGILLOSIS OF THE MAXILLARY SINUS

Recently the appearance of radiopaque 'concrements' in the maxillary s inus was reported. These radiodense objects could be identified as roo t-filling material for teeth of the upper jaw containing zinc oxide. T his suggested that excess root-filling material containing zinc oxide in the maxillary sinus could favour the formation of a local, non-inva sive aspergillosis. To verify this hypothesis in vitro, we tested the influence of zinc oxide on Aspergillus fumigatus, A. flavus, A. terreu s, A. nidulans, A. niger and A. niveus. A geometric series of zinc oxi de diluted in 0.1 N H2SO4 was used. Czapek-Dox agar was inoculated wit h the six Aspergillus species. Circular cavities stamped into the cent re of each agar plate were filled with an equal amount of the dilution s and all plates were then incubated for 7 days at 37 degrees C. Readi ngs were taken on days 3, 5 and 7. Soluble zinc oxide promoted the gro wth of all the tested Aspergillus species, the effect diminishing with decreasing concentration. This effect could be observed on all days o f measurement. Only with A. niger was stimulation of growth minimal, p robably because this species already exhibits a high growth rate on Cz apek-Dox agar. Therefore, overfilling of maxillary teeth with a zinc o xide-containing root-filling material may favour the formation of loca l aspergillosis.