Fig. 3From: Cone-beam computed tomography-based analysis of maxillary sinus pneumatization extended into the alveolar process in different age groupsSchematic diagram of classification of maxillary sinus pneumatization. A Type I normal pneumatization; B and C Type II extensive pneumatization. Yellow dashed line: horizontal line at the sinus floor; blue dashed line: horizontal line at the root apex; white double-headed arrow: distance between the sinus floor and the root apexBack to article page