[Maxillary sinus by waters' view-superimposed structures]

The image of the maxillary sinus obtained by Waters' view contains such superimposed structures as lateral extensions of the sphenoidal sinus and posterior ethmoidal cells. Planimetric evaluations were done for the maxillary sinus itself and the two superimposed sinuses. The medial portion of maxillary sinus is occupied by these two sinuses and the areas covered by these amount to one third of the maxillary sinus' area. To properly interpret the radiolucency of the maxillary sinus, the areas covered by these two sinuses and the areas corresponding to the zygomatic recess should be avoided. The proper radiolucency of the maxillary sinus should be evaluated at the central portion, namely at and around the point where the vertical line passing the inferior orbital canal and the horizontal line passing the foramen rotundum meet each other.