A Preliminary Study On The Effectiveness And Safety Of 3D Printed Titanium Plate In Mandible

Backgroud and Purpose:Mandible is located in the lower 1/3 part of the face.Because of its special location and anatomical characteristics,multiple fractures often occur when external force strikes.Mandibular fracture and bone defect are common diseases in maxillofacial surgery,which often occurred in patients with trauma,tumor,or congenital malformation of the jaws.The types of fractures in the mandible are different because of the different nature,direction,and strength of the external force in patients of trauma.In view of the anatomical characteristics of the mandible,when the external force strikes,the stress concentration area is more prone to fracture.The easy fracture area includes the median mandibular joint,the bilateral mental foramen,the mandibular angle and the bilateral condyle neck.In the comminuted fracture of the mandible caused by greater external force,the mandibular part is a common bone defect position.After mandibular fracture or bone defect,it will lead to loss of physiological functions such as swallowing,pronunciation and chewing.In addition,it will also bring defects to the facial appearance,which will bring adverse effects to the social life of patients and even cause psychological problems of patients.At present,for the patients with mandibular fracture and bone defect,titanium alloy plates are used for fracture fixation,reconstruction of bone defect area,and fixation of bone graft in reconstruction operation,so as to restore the continuity of mandible and restore its function.With the development of material injection technology in recent years,3D printing technology has been gradually applied to the medical field,which greatly promoted the accuracy of maxillofacial surgery,realized the personalized treatment of patients,and improved the operation effect.Especially in the field of medical material,combined with 3D printing technology and a variety of new materials,derived from the personalized prosthesis and implant treatment for a variety of new,has shown obvious advantages in the treatment of neurosurgery,orthopedics and craniofacial surgery,which is one of the main direction of the future development of precise surgery.Titanium alloy 3D printing technology is considered to be the most easy access to clinical application of manufacturing technology,which can meet the requirements of craniofacial surgery for complex three-dimensional shape of implant.At present,Germany,France,Holland,Belgium and other countries have initially started this application.They have been applied in jaw reconstruction and orthognathic surgery.But in China,the application is not widespread.The main reasons are not only national policy factors,but also different standards of titanium alloy material and manufacturing in China.Therefore,we used 3D printing titanium alloy plate to repair mandibular bone defects,aiming to repair mandibular bone defects quickly,accurately and individually,and to study the effect of this method in animal experiments.First,the three-dimensional model of the Beagle canine mandible was made,and the personalized titanium alloy plate was made by 3D printing.Then,bone defects were made in bilateral mandible.A personalized titanium alloy plate was used to repair the bone defect area of the mandible.The effectiveness and safety of the individualized titanium alloy plate in animals were observed,and the clinical effect was evaluated,which laid the foundation for the clinical application of the later period.Preparation of 3D printed titanium alloy mandible bone plate and mandible bone defectMethod:Twelve adult Beagle dogs,not limited to male and female,were randomly divided into three groups according to the time of taking material.First,the CT data of the Beagle dog head are input into the medical image control system software MIMICS19.0.Using the digital surgical technology,we designed the three-dimensional model of the metal plate matching the defect area and the transplanted bone block.After processing and designing,we used the industrial 3D printer Eos m290(Germany)and titanium alloy powder Ti-6Al-4V to make the mandibular plate.Then,the animal bilateral mandible bone defect was prepared and the transplant repair was performed.On this basis,the performance of 3D printing titanium alloy plate was tested.Results:The 3D printed titanium alloy plate was close to the bone defect area of the mandible,and had the prebending angle matching the shape of the mandible and the bone graft.Study on the effectiveness of 3D printing titanium alloy plate in mandible reconstructionMethod:On the basis of the first part,the reconstruction of the bone defect in the mandible was performed in the region.Animals were sacrificed 1 months,3 months and 6 months after operation.MicroCT scanning,hard tissue staining and three point bending test were used to observe the repair effect of the plate.Result:After the operation,CT showed that the combination of bone plate and bone was good.With the extension of the postoperative time,the bone density in the bone grafting area became more and more compact..The hard tissue slices showed that there was fibrous tissue formation between bone graft and adjacent bone suture 1 months after operation.After 3 months,fibrous tissue changed to cartilage.After 6 months,bony callus was formed in the group,and the shape of the osteogenic area was better.Three point bending experiments showed that the bone defect area of the flexural strength and compressive strength with time after operation was gradually increased.Bone microstructural parameters measurement showed that the new bone Haversian system was constantly reconstructed,and all indicators indicated that over time,the number of trabecular bone increased and the thickness increased,which was closer to the measurement value of bone microstructure parameters of normal mandible.Conclusion:3D printing plate of titanium alloy is a kind of good biocompatibility,good performance of repair materials,through 3D printing technology can not only produce all kinds of titanium alloy plate personalized,also can achieve stable fixation effect,induce bone tissue reconstruction in bone defect region.Study on the safety of 3D printing titanium alloy plate in mandible reconstructionMethod:In the preparation of mandibular bone defect and transplantation repair,the safety of 3D printing titanium alloy mandible bone plate was studied.After 1 month,3 months and 6 months after mandibular bone transplantation,blood routine examination and serum biochemical examination were performed.After execution of the animals,the liver and kidney tissues of the experimental animals were stained with H.E staining for histological observation.Result:After 1,3 and 6 months,there was no abnormality in blood routine and serum biochemistry before operation compared with that before operation.There was no abnormal change in HE staining of liver and kidney slices.Conclusion:3D printing titanium alloy plate of mandibular bone is a good safety plate.It can not only achieve stable retention effect,but also has no toxic effect on body tissues,and it can meet the requirements of clinical use.