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This paper presents an experimental methodology to determine plated and intact femur strains using fiber Bragg gratings and strain gauges. A plated and an intact synthetic femur were used and loaded under a simplistic static load of 600 N. A stainless steel (316L) plate was used to fixate a simulated 45°fracture on one femur. Strains were recoded at the same sites on both femurs. Strain shielding is shown to be more pronounced at the distal region of the plated femur. The experimental methodology based on fiber Bragg grating sensors is a novel approach to assess bone plate strains, which could also be used to obtain biologic tissue and implant surface strains in locations where conventional strain gauge use is not technically feasible.

This study aimed to validate a numerical model of an intact mandible for further development of a new TMJ implant. Numerical and experimental models of the biomechanics of the mandible were elaborated to characterize the human temporomandibular joint and to approach the development of a condyle implant. The model of the mandible was obtained through the use of a polymeric replica of a human cadaveric mandible and through 3D geometry acquisition. The three-dimensional finite element model was generated as a tetrahedral finite element mesh. The level of mesh refinement was established via a convergence test and a model with more than 50,000 degrees of freedom was required to obtain analysis accuracy. The functional loading cases included muscle loading in four different load boundary conditions. The same boundary conditions were applied to the experimental model. The strains were measured with an experimental procedure using electric resistance strain gauges applied on the external surface of the mandible. The mechanical response is shown and discussed in terms of strains, principal numerical and measured strains. This study proved that FE models of the mandible can reproduce experimental strains within an overall agreement of 10%. The FE models correctly reproduced bone strains under different load configurations and therefore can be used for the design of a novel TMJ implant considering other load configurations and bone mechanical properties.

OBJECTIVE: To study the effects of an oronasal interface (OI) for noninvasive ventilation, using a three-dimensional (3D) computational model with the ability to simulate and evaluate the main pressure zones (PZs) of the OI on the human face. METHODS: We used a 3D digital model of the human face, based on a pre-established geometric model. The model simulated soft tissues, skull, and nasal cartilage. The geometric model was obtained by 3D laser scanning and post-processed for use in the model created, with the objective of separating the cushion from the frame. A computer simulation was performed to determine the pressure required in order to create the facial PZs. We obtained descriptive graphical images of the PZs and their intensity. RESULTS: For the graphical analyses of each face-OI model pair and their respective evaluations, we ran 21 simulations. The computer model identified several high-impact PZs in the nasal bridge and paranasal regions. The variation in soft tissue depth had a direct impact on the amount of pressure applied (438-724 cmH2O). CONCLUSIONS: The computer simulation results indicate that, in patients submitted to noninvasive ventilation with an OI, the probability of skin lesion is higher in the nasal bridge and paranasal regions. This methodology could increase the applicability of biomechanical research on noninvasive ventilation interfaces, providing the information needed in order to choose the interface that best minimizes the risk of skin lesion.

is a research fellow in nanostructures at Cranfield University. His areas of interest are synthesis of novel nanomaterials and systems and their integration into other products, including sensors. He has a PhD in nanomaterial synthesis and two Master's degrees, one in advanced automation and the other in nanotechnology and microsystems.

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Orthodontic forces are measured using a polymer photonic crystal fibre sensor. Transversal pressure deforms the fibre structure proportionally to the applied load causing light to leak out. The characterization for transversal pressure demonstrates linear behaviour within the studied load range 0.09 to 4.7 N. For the orthodontic measurements the sensor is placed between the orthodontic appliance and only one tooth. Loads ranging over 0.98 to 8.82 N, simulating extra oral appliances, are applied over the orthodontic system at the first molar region. The surface of the tooth experiences forces ranging from 0 to ~0.63 N compatible with forces required for dental movement.