This study investigates the synthesis of ZnSnO@SiO@5-FU nanoparticles as an additive for bone fillers in dental maxillofacial reconstruction. ZnSnO nanoparticles were synthesized and coated with a SiO shell, followed by the incorporation of 5-Fluorouracil (5-FU), aimed at enhancing the therapeutic properties of classical fillers. Structural analysis using X-ray diffraction confirmed that ZnSnO was the single crystalline phase present, with its crystallinity preserved after both SiO coating and 5-FU incorporation. SEM characterization revealed the micro-spherical particles of ZnSnO assembled by an agglomeration of nanorods, exhibiting dimensions and morphological characteristics that were consistent after the addition of both the SiO shell and 5-FU. Fourier-transformed infrared spectroscopy provided solid proof of the successful synthesis of ZnSnO, ZnSnO@SiO, and ZnSnO@SiO@5-FU, confirming the presence of expected functional groups. The SiO layer improved nanoparticle stability in the solution, as indicated by zeta potential measurements, while adding 5-FU significantly increased biocompatibility and targeting efficiency. The existence of the SiO shell and 5-FU is also confirmed by the hydrodynamic diameter, indicating an increase in particle size after incorporating both compounds. Antibacterial assays demonstrated a selective efficacy against Gram-positive bacteria, with ZnSnO@SiO@5-FU showing the strongest inhibitory effects. Biofilm inhibition studies further confirmed the nanoparticles' effectiveness in preventing bacterial colonization. Cytotoxicity tests on the A-431 human epidermoid carcinoma cell line revealed a dose-dependent reduction in cell viability, highlighting the potential of 5-FU for targeted cancer treatment. These findings highlight the potential of ZnSnO@SiO@5-FU nanoparticles as a multifunctional additive for bone fillers, offering enhanced antimicrobial and antitumor capabilities.