Early monitoring for 3D-printed patient-specific mandible reconstructive implant biomechanical behavior under different occlusal conditions using a wireless module system

Three-dimensional (3D) printing technology used to manufacture patient-specific, large-scale medical implants has become increasingly prevalent. Nevertheless, early biomechanics monitoring can enhance the implantation success rate. This study developed a wireless module system (WMS) for strain gauge measurement that can be placed within the implant to achieve early biomechanical behavior detection for an experimental 3D-printed metal model of a patient-specific segmental implant (MMPSI) after surgery. This WMS includes a chip, a circuit board, and a battery, all with dimensions smaller than 20 mm × 12 mm × 8 mm. This system can connect to strain gauges and interface with a mobile application for measuring and transmitting strain data. The WMS functionality was confirmed through cantilever beam experiments. Premature failure was detected using this WMS installed in an experimental 3D-printed MMPSI and through in vitro fatigue biomechanical testing under different occlusal forces applied on the plastic-simulated mandibular model. The WMS validation results indicated that the strain gauge measurement error compared to theoretical values was within 17%. Biomechanical fatigue results addressed the higher strain received and greater cyclic loads were recorded when occlusal force was applied onto the premolar under identical force application conditions because the premolar was closer to the strain gauge attachment location, resulting in a longer lever arm compared to the molar. This study concluded that the developed WMS for strain measurement can be installed in a patient-specific 3D-printed implant with enough internal space to detect early biomechanical behavior after surgery. Current results of in vitro fatigue test for segmental defect indicated that occlusal situation can be adjusted to reduce implantation failure risk.