Effect Of Decompression On Cystic Lesions Of The Mandible:CBCT 3-dimensional Volumetric Analysis

Objectives: The aim of this research was to investigate the quantitative analysis of the factors affecting the decompression of cystic lesions of the mandible by 3D volumetric reconstruction.In this study,CBCT data were used to perform 3D volumetric reconstruction to investigate the relationship between the change of cystic volume before and after decompression and the age of the patient,the patient’s gender,the presence of impacted teeth in the cyst,and histopathological types.METHODS: 43 patients with cystic disease of the mandible who were treated in our hospital from July 2015 to February 2018 were randomly collected(including 12 cases of dentigerous cysts,19 cases of keratocytic odontogenic tumors and 12 cases of unicystic Ameloblastoma).The patient’s age,gender,the presence of impacted teeth in the cyst,the duration and histopathological type were recorded.Decompression was performed in all cases.CBCT was taken prior and after the decompression was performed.After the CBCT data were collected,the DICOM data were imported into Mimics 17.0 software.The cystic lesions were manually edited and segmented and the 3D reconstruction was performed.Mimics software was used to measure the volume of the cavity before and after the decompression surgery,calculate the absolute volume contraction velocity,relative volume contraction velocity,and total volume reduction value.The SPSS 20.0 statistical software was used to test normality among the variables of the 3 cystic lesions,chi-square test were performed.Performing the Pearson correlation analysis was to investigate the significance of the difference in the reduction patterns between two independent groups.Simple linear regression and multiple linear regression models were used to further explore the linear function relationship between cystic pathological type independent variables and multiple dependent variables.Probabilities of <0.05 were accepted as a statistically significant difference.Result: There was no significant difference in the speed of shrinkage among the 3 groups,but there was a significant correlation between the initial volume of the lesion and the absolute speed of shrinkage within each group(p < 0.05).Initial volume was also significantly associated(p<0.05)with a total volume reduction in each type of cyst.Age may be negatively correlated with the speed of shrinkage in dentigerous cysts,which means that the older the patient is,the less the reduction.Treatment seemed to last longer as the speed of shrinkage was decreased in the keratocystic tumors and dentigerous cysts(p<0.05)as shown in multiple regression.The relative speed of shrinkage of unicystic ameloblastomas seemed to be slower when there was a presence of impacted tooth in the lesion(p<0.05).Conclusion:By the three-dimensional reconstruction of jaw cystic lesions,accurate measurement of its volume,and correlation analysis of the influencing factors,it can be concluded that different influencing factors play a significant role in a speed of shrinkage of cystic lesions.Decompression can be considered as a primary treatment method and conservative approach for the treatment of large jaw cystic lesion.