Abstract: :　Objective　To investigate the relationship between the speed of shrinkage (SS) and the intracapsular pressure during indicated time after decompression. Methods Twenty-five patients who were diagnosed with cystic lesions of jaw bone by both imaging and pathological examination from April 2018 to October 2019 in the Affiliated Stomatological Hospital, Nanjing Medical University were enrolled in this study. Pressure sensors were utilized to measure the intracapsular pressure before operation. The volume of the cyst lesions was determined using mimics17.0 software before operation and 3, 6, 12 months after the surgery. Then the speed of shrinkage was calculated at different time periods (SS0-3: the rate of volume reduction in the first 3 months after surgery, SS3-6: the rate of volume reduction during 3 to 6 months after surgery, SS6-12: the rate of volume reduction during 6 to 12 months after surgery). The Student’s ANOVA and linear correction analysis were utilized to evaluate the statistical significance of the results and p < 0.05 was considered significant. Results 1. ANOVA statistical analysis showed that there were significant differences between SS0-3, SS3-6 and SS6-12. 2. SS0-3 was negatively correlated with intracapsular pressure (r = -0.5295, n=25, P<0.01). 3. SS0-3 was negatively correlated with age (r = -0.5866, n=25, P <0.01). 4. The intracapsular pressure was negatively associated with preoperative volume (r = -0.4487，n = 25，P<0.05). 5. The preoperative cystic volume of adults was positively correlated with SS0-3 (r =0.4546, n=20 ,P<0.05). Conclusion The intracapsular pressure of cystic lesions is closely related to the speed of shrinkage in different time periods after decompression.

Key words: cystic lesion of jaw bone , intracapsular pressure, decompression, speed of shrinkage