This chapter examines the use of polymer nanocomposites in 3D and 4D printing for medical applications. Integrating nanomaterials into polymers improves their electrical, thermal, and magnetic characteristics. 3D printing facilitates the production of personalized medical devices, enhancing their compatibility and their mechanical durability. The chapter focuses on using nanotechnology to improve the process of three-dimensional and four-dimensional printing in biomedical sciences. The addition of shape memory capability offers an additional dimension and introduces a fourth dimension, allowing for adaptive reactions to stimuli. This property is vital for various medical applications, including dental implants, biosensors, occluders, and stents, where accurate and responsive reactions are necessary for optimal performance. This chapter also highlights different types of polymer-nanocomposites used in biomedical printing. Additionally, it examines the developing applications of 4D printing and highlights their potential to transform the manufacturing of medical devices.