Precision Additive Manufacturing of Dental Scaffolds Using a Hydroxyapatite/Zirconia Bioceramic Composite Derived from Discarded Eggshells

With rising resource scarcity and environmental concerns, sustainable strategies like the 3R (reduce-reuse-recycle) concept are gaining importance. This study explores the precision manufacturing of dental scaffolds using zirconia/hydroxyapatite bioceramic composite. In order to emphasize sustainability in dental additive manufacturing, the hydroxyapatite used in this study was synthesized from the waste chicken eggshells. The custom slurry-based ceramic 3D printer was developed to handle the zirconia/hydroxyapatite composite. The self-developed 3D printer uses material in the form of slurry and works on the principle of vat photopolymerization technology. This study successfully demonstrates the working of the printer, thereby providing a sustainable route for manufacturing dental scaffolds. Furthermore, the study also focused on the precision of fabrication and sintering optimization. The optimized printing parameters resulted in excellent precision of the green bodies with the dimensional discrepancies of 0.21–0.27%, which is within the acceptable accuracy for dental models. Apart from the precision analysis, the study proposed two different approaches of sintering the roots and sockets: assembled-sintering and disassembled-sintering. Assembled-sintering approach proves to be more efficient with lesser dimensional deviation, thus providing dental scaffolds with clinically acceptable accuracy. Other than the manufacturability aspects, the biocompatibility analysis of the synthesized powder and its sintered specimen was carried out using L-929 and MG-63 cells. An interesting revelation was observed, which showed that the inclusion of 10% HAP enhances the cell growth by ~ 25% compared to pure zirconia samples. Moreover, the optimized pore diameter was found to be 0.4 mm, at which maximum cell proliferation was observed.