Cyclic flexural fatigue of porous Ti6Al4V constructs for use in mandibular reconstruction

Abstract

Porous Ti6Al4V constructs have been developed to replace mandibular bone, however the flexural fatigue properties of these constructs must first be assessed. In this study, porous constructs were built by selective laser melting (SLM) and subjected to cyclic flexural loading using a three-point bending setup and a servo-hydraulic Instron machine. Maximum flexural stress was plotted against the number of cycles. Also, numerical models were developed to predict the fatigue strength of porous constructs. These models were validated using experimental test data and extended to account for bone ingrowth. Scanning electron microscopy was used to study the internal and surface structures of dynamically loaded constructs. We found that numerical models of the SLM-built constructs accurately predicted flexural fatigue strength within ≈10 % deviation. Numerical fatigue models and experimental tests demonstrated that fatigue strength of constructs were ≈30 % of their flexural yield strengths. Numerical models with bone ingrowth revealed that fatigue strength was doubled when compared to models without bone ingrowth. This may have been due to a damping effect of bone, resulting in reduction of fatigue failure. Overall, our study demonstrates the effectiveness of using numerical modeling in estimating the fatigue strength of SLM-built constructs intended for mandibular implant designs.