A Two-Scale Multi-Resolution Topologically Optimized Multi-Material Design of 3D Printed Craniofacial Bone Implants.

Tareq Zobaer,Jaejong Park,Alok Sutradhar

doi:10.3390/mi12020101

Tareq Zobaer, Jaejong Park + Show 1 more

Open Access

https://doi.org/10.3390/mi12020101

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Abstract

Bone replacement implants for craniofacial reconstruction require to provide an adequate structural foundation to withstand the physiological loading. With recent advances in 3D printing technology in place of bone grafts using autologous tissues, patient-specific additively manufactured implants are being established as suitable alternates. Since the stress distribution of these structures is complicated, efficient design techniques, such as topology optimization, can deliver optimized designs with enhanced functionality. In this work, a two-scale topology optimization approach is proposed that provides multi-material designs for both macrostructures and microstructures. In the first stage, a multi-resolution topology optimization approach is used to produce multi-material designs with maximum stiffness. Then, a microstructure with a desired property supplants the solid domain. This is beneficial for bone implant design since, in addition to imparting the desired functional property to the design, it also introduces porosity. To show the efficacy of the technique, four different large craniofacial defects due to maxillectomy are considered, and their respective implant designs with multi-materials are shown. These designs show good potential in developing patient-specific optimized designs suitable for additive manufacturing.

Highlights

The main function of the skeletal system is to provide a stable foundation for body support and to facilitate human movement [1], with bones being the primary components of this system
Since the multi-material topology optimization approach does not carry any units during the process, it is the ratio of the 3D Cartesian axial lengths that are input to the algorithm
Acquired numbers from the measurement are carefully rounded into integers which essentially represent the dimensions of the design domain of the topology optimization in their respective directions

Summary

Introduction

The main function of the skeletal system is to provide a stable foundation for body support and to facilitate human movement [1], with bones being the primary components of this system. A surgical procedure to include bone replacements is usually necessary when this skeletal system is damaged This process becomes complicated if the defect site is large or located near the region where functionality like biting as well as aesthetic appearance are significant factors (e.g., midface) [3]. Through decades of research efforts, it has been established that Titanium and its alloys are more suitable than other metal alloys for bone implants due to their superior biocompatibility, bioactivity, and mechanical properties [5] Another advantage of Titanium-based materials compared to bone grafting is that they provide limited geometric freedom since they are usually machined from sheets or billets.

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