Toughening and strengthening of visible light-cured hydroxyapatite thiol-ene resin composite intended as bone fixation using 2D textile

Metals plates and screws are the gold standard in metacarpal and phalangeal fracture fixation as they provide high stability to complex fractures. However, incidence rates of complications ranging from 42 to 92 % have been reported. Bone bioadhesive fixation based on light-cured thiol-ene technology and reinforced with hydroxyapatite (HA) is a promising solution for customizable devices with tailored mechanical properties and reduced soft tissue adhesion. The reinforcement of these thiol-ene composites with 2D textiles or meshes has been proposed; however, their role in the mechanical performance has not been explored. In this study, structural and mechanical behavior properties of a light-cured resin composite with thiol-ene precursors and HA in the presence and absence of one and three-layer of poly(ethylene terephthalate) (PET) meshes were assessed. The lack of effect of the meshes on the light-cure efficiency and the structural homogeneity of the cured composite is shown using Raman spectroscopy, water uptake measurements, and micro-computed tomography. The insertion of meshes increased the strength and energy to fracture of resin-based composite. The woven geometry of the PET meshes enables frictional sliding behavior, and reduced crack propagation ensuring integrity after matrix failure. This effect increases with the number of meshes and was significantly higher in bending than in tensile stress conditions. Related to hand and wrist fractures, the design of composite fixation devices, based on HA and meshes fillers can significantly increase the strength and toughening of those medical devices with a potential impact on post-operation by reducing mechanical mismatch of stress shielding and prevent complications due to material disintegration, resulting from the compliant and personalized bone bioadhesive fixation application.