Application Of Digital Technology In Total Mandibular Body Excision And Defect Repair And Reconstruction

Objective:Through three-dimensional reconstruction,computer aided design,3D printing and other digital technologies,the vascularized free bone flap is used to achieve accurate repair and reconstruction of patients with mandibular body defects.To explore the application value of digital technology combined with vascularized free bone flap in the repair of large mandibular defect,and to provide a preliminary exploration for improving the accuracy of operation,improving the postoperative facial type of patients with large mandibular defect,reducing postoperative complications and improving the quality of life of patients.Methods:A total of 21 patients with mandibular resection caused by benign and malignant tumors in our hospital from November 2016 to December 2020 were selected,including 5 patients with total mandibular body resection(2 males and 3 females),aged between 17 and 72 years old,with an average age of 44 years old.One patient had postoperative recurrence of mandibular ameloblastoma,two patients had mandibular ameloblastoma,and two patients had squamous cell carcinoma of the mandible.There were 16 patients(14 males and 2 females)with partial mandibular resection,aged from 23 to 70 years,with an average age of 46 years.There were 3cases of ameloblastoma,1 case of central mandibular carcinoma,3 cases of gingival squamous cell carcinoma,5 cases of oral squamous cell carcinoma and 4 cases of oropharyngeal squamous cell carcinoma.All patients were stable,no obvious systemic disease.The patients were divided into two groups.One group was the patients with total mandibular body resection.The preoperative digital technology was designed and the operation group was performed according to the design(hereinafter referred to as the design group).The other group was one patient with total mandibular body resection and 15 patients with partial mandibular body resection.The operation group was directly performed according to the experience of the surgeon(hereinafter referred to as the experience group),including five patients in the design group and 16 patients in the experience group.The maxillofacial CT and double lower limb angiography(CTA)were taken in the design group and the experimental group before operation.The design group imported the scanned data into Mimics software in DICOM format.The maxillofacial data were reconstructed to obtain three-dimensional visualization images of soft and hard tissues in the lesion area.According to clinical examination and three-dimensional image analysis after reconstruction,the soft tissue boundary and jaw osteotomy line needed to be removed were determined and marked,and the mandibular lesion was virtually removed.The mandibular osteotomy guide plate was designed.CAD technology was used to measure and calculate the corresponding anatomical landmarks of the patient’s skull,especially the cheekbone and upper collar,so as to design the“personalized”mandible that matches the patient.According to the results of CAD technology,the position,length and angle of the required fibula were determined,and the fibula plastic guide plate was designed to facilitate the accurate positioning of the fibula.The osteotomy guide plate,plastic guide plate,in situ guide plate and the designed ’ personalized ’ mandibular model were printed by 3D printing technology.The personalized metal reconstruction titanium plate was pre-bending according to the reconstructed mandibular model.The curved titanium plate,osteotomy guide plate,plastic guide plate and in situ guide plate were disinfected for intraoperative use.In the experimental group,the mandible model was printed with3 D printing technology according to the preoperative 3D CT of the maxillofacial region,and the metal titanium plate was prepared according to the model before operation for intraoperative use.Patients in the design group and the experimental group were operated by the same surgical team,and the operations were divided into two groups.Design group :One group used the mandibular osteotomy guide plate to remove the lesion area of the mandible.At the same time,the second group prepared the vascularized free fibula flap according to CTA and fibula plastic guide plate.According to the positioning guide plate,the plasticized fibula and the free end of the mandible were matched.The mandibular fracture end and fibula were fixed by the positioning hole on the positioning guide plate.Finally,the personalized titanium plate was used to connect and fix the mandible and fibula in situ.The positioning guide plate was removed and the blood vessels were anastomosed under the microscope to complete the repair and reconstruction of the whole mandible defect,close the wound and complete the operation.The experimental group:the surgeon performed the resection of the mandibular lesion according to the preoperative three-dimensional CT and intraoperative findings.At the same time,the second group prepared the vascularized free fibula flap according to CTA.Finally,the fibula was molded,and the metal titanium plate was used to fix the bone flap and the free end of the mandible.The blood vessels were anastomosed under the microscope to complete the repair and reconstruction of the whole mandibular defect,close the wound and complete the operation.The lateral pole of bilateral mandibular condyle and bilateral mandibular angle were selected as landmarks of mandibular shape.The preoperative and postoperative CT data were compared to measure the offset length of the distance between the lateral pole of bilateral condyle and the distance between the bilateral mandibular angle.The operation time,intraoperative blood loss,postoperative infection and recurrence,postoperative complications and postoperative facial recovery were recorded.SPSS 18.0 software was used to process the data of the design group and the empirical group.The measurement data were expressed as mean±standard deviation(x±s).One-way analysis of variance was used for comparison between groups.P <0.05 indicated that the difference was statistically significant.Results:The operation time of the design group was(9.07±1.25)h,the operation time of the experience group was(9.25±1.02)h,p > 0.05,there was no significant difference.Three-dimensional CT of mandible was taken before operation and one month after operation.The distance deviation between the lateral poles of bilateral condyles was(0.48±0.16)mm in the design group and(1.59±1.45)mm in the experimental group,p = 0.092.There was no significant statistical difference,but the difference between the two groups was obvious.Bilateral mandibular angle deviation compared with preoperative design group(3.32±1.87)mm,experience group(4.33±1.08)mm,p <0.05,the difference was statistically significant.After 6 months–5 years of follow-up,the flaps in the design group survived without obvious complications,and the tumors did not recur.The patients had symmetrical postoperative surface,good subjective feeling of contour shape,no bounce and tenderness in the temporomandibular joint area,and the opening degree could reach 2–3 transverse fingers.The postoperative imaging data showed that the bilateral condyles were located in the articular fossa,and no obvious deviation was observed.The fibula and mandible were well combined,and no obvious abnormal absorption was observed.There were no obvious local and systemic complications.In the experimental group,6 patients had postoperative infection,and 3 patients underwent secondary surgery.Conclusion:1.Using three-dimensional reconstruction technology,computer-aided design technology,3D printing technology and other digital technology,we can scientifically plan the operation plan,accurately reproduce the soft and hard tissues of the mandibular lesion area,effectively improve the operation efficiency,reduce the blindness of operation,save the operation time,reduce the risk of operation,improve the aesthetics of the postoperative facial shape,and realize the accurate repair and reconstruction of the whole mandible defect.2.Computer-aided design technology plays an important role in the repair and reconstruction of large mandibular defects.It can accurately design the normal continuity and convexity of the reconstructed mandible,and ensure that the condyle is located in the normal anatomical position.It plays a great role in the recovery of facial shape and mandibular function after reconstruction.