Figure 2.

Authors’ proposal on maxillary sinuses with Underwood bone septa classification based on CBCT 20 × 20 axial scans. (A) Maxillary sinus without any bone/septal disturbances; (B) one septa in the anterior part of the sinus; (C) one septa in the posterior part of the sinus; (D) a single septa in the middle of the sinus; (E) two septa dividing the sinus into three components; (F) a vertical septa that divides the sinus into right and left, equal or not, parts; (G) located in part of the sinus, either anterior/posterior/middle part with some septa mimicking a clover leaf appearance; (H) maxillary sinus divided with multiple septa in a chaotic matter, like the spider-web appearance; (I) a single not full septa but a half septa in the maxillary sinus; (J) two half septa; (K) three half septa; (L) four or more half septa placed randomly in the maxillary sinuses. Red line – possible shape and location of a full or partial bony septa within the maxilalry sinus.