Abstract
Orthopantomography is recently used not only in dentistry but also in otorhinolaryngology. The orthopantomograph, which is manufactured by the Siemens Corporation, has two different mechanical systems ; N projection and S projection. N projection means a normal projection which is used as a routine technique, and S projection means a special projection which is used for examination of the maxillary sinus or the temporomandibular joint. The purpose of this study is to compare the S projection with the N projection regarding the roentgen anatomy of the maxillary sinus. The results obtained are as follows : 1. The roentgen anatomy of the maxillary sinus is different in N projection and S projection ; the anterior wall and the posterior wall are superimposed upon the medial wall in the N projection, but in the S projection only the anterior wall is superimposed upon the medial wall. 2. In the N projection, the inferior nasal concha and the zygomatic bone are superimposed upon the maxillary sinus but are hardly superimposed in the S projection. 3. The S projection is a better technique than the N projection for the roentgenological examination of the maxillary sinus.
