The Study On Constructing 3D-printing Bone Tissue Engineering Scaffold Based On CT Data

Background:Bone defect is a common problem in surgical department. There are many reasons that can lead to bone defect, such as trauma, infection, tumors, osteomyelitis surgical debridement and congenital diseases. Therefore, more and more scholars and medical researchers started to study the bone defect. As a way of curing bone defect, bone tissue engineering has become the hot and difficult spot of the research. Compared to bone transplantation, bone tissue engineering has abundant resources and seldom causes rejection,it costs less to realize mass production as well.However, the osteogenic property of bone tissue engineering scaffolds is still limited by some unsolved problems. For example, The lack of bone formation; the mismatch between the manufactured scaffolds and the irregular bone damage area, the existing of gap can influence the osteogenesis; the poor connectivity among the pores.; the discordance between the internal structures; the uncontrollability of scaffolds’ degradation rate and so on.3D printing technology brings the light of hope for solving those problems. The 3D printing technology which is now applied into the manufacture of bone tissue engineering scaffolds,has subverted the traditional methods. Due to the designable scaffold structure and pore morphology, it can provide a better scaffold which has more morphological, physical and chemical properties and osteogenic activity. We can use this technology to match scaffold and bone defect area. This study mainly introduces a new designing method of 3D-printing scaffolds, which develops the three-dimensional reconstruction of bone defects based on the patients’ CT data. And we can construct scaffolds on the foundation of 3D data models. Objective:The objective of this paper is to precisely build bone defect modeling by Mimics software, determine the feasibility of 3D technology in the aspect of constructing tissue engineering bone, and explore the key points to build three-dimensional digital model of tissue engineering bone based on CT data. Methods:1. Obtaining the three-dimensional reconstruction on patient’s bone defect by using CT data.Choose 10 odontogenic cyst patients from the CT data from department of maxillofacial surgery in our hospital. And screen according to the condition of the bone defect area,which has XYZ axial diameter more than 5mm in order to facilitate the design and processing. Then put the digital imaging and communications in medicine data into MIMICS, and finish the three-dimensional reconstruction in bone defect area.2. Design the 3D model of the scaffold which is highly matched with the bone defect area.Edit the mask of bone defect area, and restore normal morphology of the target area and do the three-dimensional reconstruction. Get the outside structure by using boolean operations.3.Design and choose of Scaffolds’ internal morphology.Use the Pro/E to design 3 different basic structural units of the scaffold. Then choose one from them according to the actual situation.4.The stress and total deformity in different scaffolds tested by finite element analysis.Test the models of different structures by finite element analysis in Solidworks Simulation software. Define the elastic modulus of 11 GPa, poisson’s ratio of 0.3, load of 90 N, and constraint models to the ground. Analyze the stress and deformation.5.Export and construction of customize scaffolds’ three-dimensional model.Import the 3D data of the assembled scaffold model into MIMICS. Then compare them and export to the STL file. At last, print the PLA scaffold with a FDM printer and models with a SLA printer. Results1.The three-dimensional reconstruction of patient’s bone defect area.2.Scaffold models which used the boolean operations can highly match the bone defect area successfully.3.Building three different basic unit internal structures of the scaffold.4. Finite element analysis of the designed three structures of scaffold.5.Assembling the external morphology and internal structure of scaffolds; constructing scaffolds by using a 3D printer. Conclusions:Based on the CT data, we can construct digital three dimentional model of bone defect scaffold by using Mimics software and computer aided design. Also, FEA proved that the cubic basic structure had better mechanical properties.