The posterior wall of the maxillary sinus as seen in panoramic radiography.

The dental and sinus projection programs of the PM 2002cc panoramic x-ray unit were compared with regard to the visualization of the maxillary sinus posterior wall of a dried skull. The posterior wall of the maxillary sinus appeared different on each program. In the sinus projection program the posterior wall appeared narrower than that in the dental projection program. The main cause for the difference of the maxillary sinus posterior wall image was the projection angle. In the sinus projection x-rays entered more tangentially to the posterior wall of the sinus than in the dental projection, but in the dental projection x-rays entered more tangentially to the mediosuperior and medioinferior region of the maxillary sinus posterior wall. Thus a large, widely destructive lesion in the posterior wall of the maxillary sinus would be more easily detected with the sinus projection. On the other hand, lesions confined to the mediosuperior and medioinferior regions of the posterior wall will be depicted more clearly with the dental projection program.