The Mechanical Properties Of The 3D Printed Mandibular Scaffold And Finite Element Analysis Of The Implanted Bone Defect

Many factors such as tumor,trauma,inflammation or congenital malformations can cause mandibular defects.Traditional repair methods use reconstruction titanium plates combined with ilium or fibula grafts,which are limited in source and cause damage to the donor site,which is greatly affected by subjective factors.The repair effect is different when the position of transplantation is different.With the rapid development of 3D printing technology in tissue engineering,scaffolds made of a variety of different materials prepared by 3D printing have been widely used in mandibular defect repair.First,we used single-pass 3D printing technology to prepare silk fibroin/type I/hydroxyapatite scaffolds and polycaprolactone/hydroxyapatite scaffolds of 30°,45°,and 90° with different printing angles.Uniaxial compression,creep,and relaxation mechanics experiments were carried out for the two stents.The results show that at the same compression rate and strain,for the two types of stents,the Young's modulus of the 90° stent is higher than that of 30° and 45°.As the creep time increases,the two types of stents the creep strain of the stent increases.With the increase of the relaxation time,the stress of the stent decreases rapidly and then slowly.Secondly,a 90° silk fibroin/type I collagen/hydroxyapatite and polycaprolactone/hydroxyapatite composite scaffold was prepared using low-temperature dual-channel 3D printing technology,and the dual-channel composite scaffold was subjected to uniaxial compression.Creep,relaxation,and ratchet mechanics experiments,and a theoretical model of creep and relaxation has been established.The results show that at the same compression rate and strain,for the two types of stents,the Young's modulus of the 90° stent is higher than that of 30° and45°.As the creep time increases,the two types of stents the creep strain of the stent increases.With the increase of the relaxation time,the stress of the stent decreases rapidly and then slowly.Then,the finite element simulation method was used to study the mechanical properties between the layers of the dual-channel stent under uniaxial compression of10% strain.The results show that when the stent undergoes 10% compressive strain,the stress range of each layer of the stent is 0.2?0.6N,and the maximum deformation occurs on the wire harness between the second layer and the third layer of the stent,and the maximum displacement is 0.315 mm.The wire harness has undergone torsional deformation.It is found that the simulation results are in good agreement.With the experimental results,that is to say,the finite element model can predict the mechanical properties of the stent in uniaxial compression.Finally,the finite element simulation method was used to study the force of the dual-channel stent implanted in the rabbit mandible under different binding conditions.The results showed that the maximum mises stress of the rabbit mandible was 7.40 MPa,which appeared in the area of the posterior teeth of the rabbit mandible.When the left side of the stent was bound to the bottom surface,the maximum mises stress of the composite stent was 300 Pa.When the upper side of the stent was bound to the bottom surface,the maximum mises stress of the composite bracket is 129 Pa.In this paper,three methods of experimental testing,theoretical prediction and finite element simulation are used to obtain the mechanical properties of different types of mandibular scaffolds and the force after implantation of the bone defect from the macro to the micro level.The research results can be used for subsequent clinical observations.It provides a basis for mandibular injury repair and helps promote the clinical application of tissue engineering techniques to repair mandibular defects.