What needs to be done for regular care in a screw-retained full-arch maxillary implant prosthesis?

For SCREW-RETAINED implant prostheses, a critical maintenance requirement is PERIODIC TIGHTENING OF THE PROSTHETIC SCREWS. Screws can loosen over time due to: occlusal forces, micromotion, and material fatigue. Loose screws → screw fracture, abutment damage, implant complications. Regular recall appointments include: screw torque verification (to manufacturer's specifications), checking screw access holes, cleaning around implants, and radiographic assessment. C is correct.