Transversal CT image section of maxillary cheek tooth 209 and adjacent sinonasal structures. 0.6mm slice thickness; W3100/C500. Buccodistal root of 209 showing severe periapical bone loss and enlarged periodontal space (open arrowheads) as well as apical gas inclusion (arrowhead). Filling of the rostral maxillary sinus (asterisk). Apiconasal fistula tract (arrow path) and accompanying swelling of the nasal mucosa (arrow). The ventral concha (VC) appears deformed