3D Reconstruction Technology Based On CBCT Data Applied In Effectiveness Evaluation After Decompression On Large Jaw Cystic Lesions

1.BackgroundWith functional surgery progress,decompression has been widely applied in treating large jaw cystic lesions because of recognized safety and effectiveness.It was reported that decompression showed different effect between patients in different ages and lesions with different pathological types,locations and treatment periods.2.Objectives:It was aimed to establish quantitative method to evaluate decompression effectiveness of large jaw cystic lesions.3D reconstruction technology based on CBCT data was applied in effectiveness evaluation of decompression on large jaw cystic lesions.Regression model of cystic extent was built by quantitative analysis of CBCT data,and theoretical timing of secondary curettage was then computed.It was also performed to analyze factors influencing decompression effectiveness.2.Materials and methods(1)32 patients received decompression treatment on jaw cystic lesions and got both CBCT and PTG examination in same period(less than 1 week)were included into first section of study.Series of CBCT and PTG evaluations before and after decompression(64 CBCT and 64 PTG totally)were collected and analyzed using OsiriX software.3D reconstruction based on CBCT data was performed to measure the lesion volumes.Size shrinkage and gray level histogram(GLH)characters were compared between CBCT-based 3D reconstruction and PTG-based 2D evaluation.(2)42 patients received decompression and complete CBCT examination until secondary curettage were included in second section of study.3D reconstruction was performed to evaluate lesion extent change and mandibular buccolingual diameter reduction after decompression.Possible factors influencing decompression effectiveness were analyzed.Regression model between cystic lesion extents,decompression durations and original volumes was established.3.Results(1)3D reconstruction method reflect much more lesion reduction(75.5%)than traditional PTG-based 2D evaluation method(47.7%,P<0.001).3D reconstruction method distinguished edges of cystic lesions exactly than PTG-based 2D method.Before decompression,all grey level histograms(GLHs,32/32)of cystic lesion showed well unimodality in 3D reconstruction method.Besides,most of GLHs(31/32)of cystic lesions showed well bimodality in 3D reconstruction method.(2)Cystic lesion extent after decompression was associated with decompression duration and original extent.The regression model was built as follows:Vt=V0 ×0.7333×e-0.01851×t+0.2656×V0(t:decompression duration/day,V0:original extent/cm3,Vt:lesion extent t days after decompression/cm3)(3)Jaw cyst showed larger reduction ratio than keratocystic odontogenic tumor(KCOT)after decompression(P=0.040).Cystic lesion in mandible revealed faster reduction than which in maxilla after decompression(P=0.019).Buccolingual reduction ratio was negatively associated with patient’s age significantly(r=-0.35,P=0-.039).Jaw cyst in mandible had faster buccolingual reduction rate than KCOT(P=0.039).4 Conclusions(1)3D reconstruction technology based on CBCT data could be applied in effectiveness evaluation of decompression on jaw cystic lesions,which is sensitive and precise.(2)Lesion volume after decompression showed linear correlation with original lesion and exponential correlation with treatment duration.(3)Decompression effect was influenced by location and pathological type of cystic lesions and patients’ages.