While initiating an endo-antral syndrome, inside the endodontic system and the chronic apical lesions of upper teeth anatomicaly related to the maxillary sinus floor, may be found both endopathogenic bacteria and filamentous fungi. Similarly the improper root canal treatments may facilitate an emerging aspergillosis of maxillary sinus. By phenotype and genotype analysis in 10% of chronic apical periodontitis were disclosed filamentous fungi of Aspergillus genus (A. fumigatus, A. versicolor and A. niger). Accordingly might be also taken into consideration the hypothesis of mutual pathogenical relationship between pulpal and sinusal pathology, since at its turn the aspergillosis of maxillarx sinus can also promote the contamination of already filled or still untreated necrotic root canals with filamentous fungi.