Final answer:
Composite fillings would have a different radiopaque appearance compared to other dental restorations.
Step-by-step explanation:
The radiopaque appearance of dental restorations refers to their visibility on X-ray images. In this case, all restorations mentioned (Amalgam, Composite, Gold, Porcelain) would appear radiopaque except for Composite. Composite fillings are made of a resin material that contains a high amount of radiolucent components, making them less visible on X-rays compared to other restorations.