Risk of maxillary fungus ball in patients with endodontic treatment on maxillary teeth: a case-control study.

Background. Maxillary sinus fungus ball (FB) is a noninvasive fungal disease commonly associated with symptoms of recurrent maxillary rhinosinusitis and/or extrusion of root canal filling material into the sinus. Chronic periapical inflammatory processes of dental origin are believed to be the risk factors in the pathogenesis of FB. The aim of this study was to determine whether endodontic treatment performed on maxillary molar, premolar, and canine teeth was a risk factor in the development of FB. Methods. We designed a case-control study in which the cases were patients with FB admitted to the Department of Otorhinolaryngology at the University of Brescia between January 1990 and April 2005. For each case, 3 age-matched controls were randomly selected from the admission registry of the University Dental Clinic. Orthopantomography was used to detect endodontically treated maxillary molar, premolar, and canine teeth in both patients and controls. Results. Of 102 patients with FB who were admitted during the study period, 91 (89.2%) had had endodontic treatment compared with 113 (36.9%) of 306 controls (chi square _ 83.6601, P _ 0.000; OR 14.13; 95% CI 7.25- 27.54). The mean number (standard deviation; interquartile range [IQR]) of endodontic procedures was 1.39 (0.86; 1-2) in patients and 0.53 (0.81; 0-1) in controls (Mann-Whitney U test _ –9.138, P _ 0.0000). The interval between the endodontic treatment and the diagnosis of FB was available for 37 (36.3%) patients, and the median was 4 years (IQR 2-10). Interpretation. Endodontic treatment on maxillary teeth is a strong risk factor for FB of the maxillary sinus.