W e compared findings obtained by rotational panoramic radiography and computed tomography in postoperative maxillary cyst diagnosed histopathologically. The results were as follows;
1. Twenty two patients (13 males and 9 females) were studied, the average age was 45.8 years and the average period after initial surgery of maxillary sinus was 24.6 years.
2. In the rotational panoramic radiographs, the lesion had well-defined margin in 17 cases, slightly diffuse margin in 4 cases and diffuse margin in 1 case.
In the 21 cases with well-defined and slightly diffuse margin the lesion occupied the maxillary sinus horizontally in 14 cases and the inferior border extended to the alveolar area in 20 cases. The forms of the lesions were classified into four types; round type, partially round type, simular sinus type and unsettled type. The lesion was unilocular in 14 cases.
3. The location of the lesion obtained by different procedures agreed in 18 cases. 70% of lesions grouped round or partially round types in the rotational panormamic radiography were classified into the absorbed type in the computed tomography.