Manufacturing and bioactivity assessment of 3D printed composite scaffolds for guided bone regeneration procedures

Alveolar bone fractures and periodontal diseases, above all periodontitis, are an increasing social, medical, and economic issue of the new millennium ending in 7.5 million annual new cases of dentoalveolar issues worldwide and a total €149.52B loss in Europe alone. The clinical attention is drawn to the formation of alveolar bone defects, generated after a tooth loss and the consequent bone resorption process. An alveolar ridge augmentation technique is then essential as the lack of quality and bone volume may cause a collapse in dental implant placement while attempting to restore the missing teeth. The traditional treatments suggest the use of grafts or bone-filling particulate materials but, despite being a great approach for the biocompatibility, these classical strategies lack in reproducibility, bioactivity, and biodegradable properties. In this study, 3D printed multi-layers resorbable scaffolds for GBR procedures were fabricated with the Bioplotter system in 5 different composite biomaterial formulations designed to enhance the bone regeneration process with bioactive properties. Polycaprolactone was used as matrix with 10 % barium titanate, 10 % hydroxyapatite (HA), 20% HA, 10% Sr-doped HA and 10% Zn-doped HA. After the CAD phase, aimed to develop a model that mimics the complex bone inner structure, the optimization process of the 3D-printing parameters was performed for each composition leading to the successful manufacturing of all the scaffolds. Then, physicochemical characterizations were conducted to investigate the chemical composition’s materials, the thermal properties, and the morphology of the printed structures compared to the CAD architecture showing a high consistency of the computed design and fabrication method. Finally, in vitro biomineralization potential and the degradation effect on the mechanical properties were evaluated using the simulated body fluid (SBF). The formation of apatite’s precursors was detected on the samples’ surfaces containing HA, SrHA and ZnHA after 7 days of incubation while the presence of mature HA was confirmed since day 21, indicating the strong bioactive behaviour of the mentioned scaffolds. A slightly decrease in all the compressive modulus was registered as the materials degraded into the SBF solution while the 20%HA scaffold showed an improving due to the greater HA deposition. However, the scaffolds’ mechanical values met the objectives being comparable to the bone tissue ones concluding that these 3D printed composite scaffolds represent a promising solution in the progress of the guided bone regeneration (GBR) field development.