Maxillary sinus cysts include mucus cysts, plasma cysts, tooth-containing cysts, and root cysts. Mucous cysts are caused by obstruction of mucus gland ducts or by mucus retention due to obstruction of the sinus cavity outlet after inflammation of the maxillary sinus. Plasma cysts are formed when fluid exuded from capillaries is retained in the submucosal connective tissue. Ungrown teeth stimulate proliferation and secretion of enamel-forming cells in the alveoli, producing tooth-containing cysts, which are associated with defects in tooth development. X-rays are important in the diagnosis of maxillary sinus cysts because they not only determine the presence of an abscess, but also allow observation of the nature and extent of the cyst. The paranasal sinus nasal-chin (Waters’ position) film and the mouth cap film are generally used as routine photographs for the examination of maxillary sinus cysts, which in most cases can be shown on the nasal-chin and mouth cap films and are not difficult to diagnose. However, in some cases, the diagnosis cannot be made only from the nasal chin and mouth cap films, so it is necessary to take additional photographs of other locations or high voltage photographs, body layer photographs, cyst puncture imaging, etc. to determine the diagnosis. (1) Oblique and lateral position of maxillary sinus: Mucus cysts and plasma cysts of maxillary sinus occur in the soft tissue of maxillary sinus. Sometimes the diagnosis is difficult because the cyst is larger or less dense, and the contour of the cyst does not show well in the nasal chin position. At this time, in order to make a clear diagnosis, we believe that adding an oblique photograph of the maxillary sinus at 10-20 degrees (i.e., the patient is placed in the position of the nasal chin position film, and then the patient’s head is rotated 10-20 degrees to the affected side) can often show the edge of the cyst, which is helpful for a clear diagnosis. This oblique view is also useful for observing tooth-containing cysts and tooth root cysts. In lateral photographs, both maxillary sinuses overlap each other, which is unfavorable for observation, but if the maxillary sinus cyst causes a significant forward expansion of the anterior wall of the maxillary sinus, its bony changes can be clearly shown on the lateral film. (2) High voltage photography : Tooth-containing cysts and tooth root cysts of the maxillary sinus occur within the bone of the maxillary sinus, the symptoms are usually obvious, and larger cysts can cause facial enlargement and deformity, the mouth cover is convex underneath, and there is a sense of ping-pong ball when touched ……. However, sometimes due to the small size of the cyst or its special location, it may not show up on the conventional nasal chin radiograph. In this case, it is often helpful to increase the voltage when taking nasochin radiographs to observe the structures within the cyst that overlap with the teeth (ectopic teeth, for example). (3) Body layer photography: Orthoptic body layer photography of the maxillary sinus is more helpful to show the lesion, which can clearly show the cystic cavity or ectopic teeth. For example, we have encountered a case of maxillary cyst occurring in the inner wall of the maxillary sinus, near the inferior turbinate and the inferior nasal tract, and clinical examination revealed that the outer wall of the inferior nasal tract was internally protruding and no abnormality was seen in the nasal chin position. Later, orthoptic body photography of the maxillary sinus was performed, which clearly showed the contour of the cyst and ectopic teeth. (4) Cyst perforation angiography and maxillary sinus angiography: When there is a clinical manifestation of cyst, even if the cyst is clearly shown on the X-ray of the above-mentioned positions, the existence of the cyst cannot be denied at the risk, and cyst perforation angiography and maxillary sinus angiography can be performed when necessary. We have encountered a case in which a focal bony bulge in the alveolus was found on palpation, but the cyst outline was not clearly shown on the nasal chin position and other position photographs, and the diagnosis was later confirmed by cyst puncture. Occasionally, some of the contrast agent may be mistakenly injected into the submucosa during the cyst puncture angiography. When analyzing the cyst angiography film, care should be taken not to regard the mistakenly injected contrast agent into the submucosa as a cystic cavity, and the contrast agent can be clearly seen in the submucosa by turning the patient to the tangential position under fluoroscopy. Maxillary sinus cysts appear as filling defects on maxillary sinus radiographs.