Computed tomographic evaluation of cystic volume changes of the jaws after decompression

Abstract

The treatment for cystic lesions can be determined depending on the size, location, patients'' age, perforation of cortical layer and proximity to vital structures. If the cysts are large or containing vital structures, conservative treatment such as decompression or marsupialization should be considered for preservation of oral tissues and avoidance of surgical damage to important anatomical structures. Decompression and marsupialization are very similar surgical procedures aimed to decrease the cystic size by reducing pressure of the cystic fluid and inducing bony apposition to the cystic walls. There has been many studies on the effects of marsupialization or decompression for cystic lesions of the jaw using panoramic radiographies. The disadvantages of plain radiographic examination are that it is impossible to objectively evaluate the degree of bony healing parallel to cystic wall and interval changes in size of cystic lesions. The aim of this study is to evaluate the effectiveness of decompression according to reduction parameters by measuring the cystic volume changes using computed tomography(CT).We had chosen the patients who underwent decompression for a cystic lesion of the jaw at the Department of Oral and Maxillofacial Surgery of Yonsei university dental hospital from 2006 to 2010. All the patients had been examined by CT before and after decompression at intervals 6 months. We had measured the volume cystic lesions by threshold method and evaluated the volumetric changes after decompression according to various parameters. The average reduction rates (RR) of 29 cystic cases was 56%. There was statistically significant difference in RR by age and initial volume. The group with younger age and large initial volume showed higher RR. There was no statistically significant difference in reduction rates by sex, location, expansion of cortical layer, radiographic finding and pathologic diagnosis. In conclusion, decompression is more effective in younger patients, larger initial lesions. Computed tomography is an efficient method in evaluating the bony healing within the cyst cavity by measuring the changes of cystic volume after decompression. However, due to its high economic cost and radiation dose, an additional comparative study using another reasonable diagnostic radiographic tool should be considered.