Clinical And Preclinical Study Of Individualized Titanium And PEEK Meshes For Complex Alveolar Bone Augmentation

With the development of computer-aided design and fabrication technology,individualized mesh implants can be digitally designed and fabricated for personalized reconstruction of complex alveolar bone defects.At present,3D-prining individualized titanium mesh(3D-PITM)and milled individualized polyetheretherketone(PEEK)mesh are the main two types of individualized mesh implants.The application of3D-PITM shows excellent clinical results,but is still rare,especially for Asian populations.In addition,it is unclear whether 3D-PITM can achieve the pre-designed bone contour and volume to realize personalized reconstruction.Individualized polyetheretherketone(PEEK)mesh(IPM)are widely used in orthopedics because of their good biocompatibility and mechanical properties similar to human bone.Although there have been studies showed that the application of milled patient-specific PEEK mesh for alveolar bone augmentation can achieve comparable clinical outcomes to that of titanium mesh,individualized PEEK mesh(IPM)implant with lattice structure similar to 3D-PITM have not yet been made.Therefore,the first part of this study designed and produced3D-PITMconforms to the alveolar bone contour of Asians,and applied it for alveolar bone augmentation.A set of digital technologies was used to retrospectively evaluated the clinical outcomes and dimensional accuracy of bone grafting in 25 implants of 16 patients.The second part of this study used computer-aided design(CAD)and computer numerical control(CNC)technology to design and fabricate an individualized PEEK mesh implant with a minimum thickness.Three-point bending test,three-dimensional finite element analysis and beagle experiment were used to compare the difference in biomechanical properties and osteogenesis between IPM and 3D-PTIM.The purpose of this part is to evaluate the feasibility of IPM for complex alveolar bone augmentation and select a proper individualized mesh implant.In the first part of study,clinical results indicated that the maximum vertical bone gainwas up to 12.53 mm,with an average bone resorption less than 0.5 mm at 10 to 18 months postoperatively.But there is 25% of patients still have titanium mesh exposure.On the other hand,the superimposition of the digital models shows that the maximum deviation between the actual and virtual bone augmentation was about 3.4 mm.In the two-dimensional analysis,the actual gained bone height was about0.5mm less than the preoperative virtual design.But,the actual gained bone width were about 0.5mm more than the preoperative design.In the second part of the study,the minimum thickness can be manufactured of the IPM was 0.6mm,and the bending strength of PEEK mesh with the minimum thickness was 1/3 of that of titanium mesh with the thickness of 0.3mm.In the three-dimensional finite element analysis,the two kinds of meshes will not break under the physiological load of30 N above the mesh and can remain spatial stability with the displacement less than 0.05 mm.The equivalent elastic strain values of bone grafts under IPM(4120microstrain)was higher than that of3D-PITM,which means more mechanical stimulation under IPM.In beagle animal experiments,the clinical observation,Micro-CT evaluation and histological analysis have demostrated that IPM has similar biocompatibility,space maintenance and osteogenic ability compared with 3D-PITM,but no statistical difference was found.Therefore,the following conclusions can be drawn:1.The application of 3D-PITM for alveolar bone augmentation shows a promising clinical results and bone resorption,but there are still complications such as exposure of the titanium mesh.2.The dimensional accuracy of bone grafting with 3D-PITM needs to be further improved by optimizing the preoperative design and surgical technology;3.Compared with 3D-PITM,the rigidity of milled IPM is lower,and it can maintain spatial stability with no break under physiological load with more mechanical stimulation;4.IPM can maintain the osteogenesis space to and meet needs of complex alveolar bone augmentation.