You are a helpful, respectful, and honest assistant. Always answer as helpfully as possible, while being safe. Your answers should not include any harmful, unethical, racist, sexist, toxic, dangerous, or illegal content. Please ensure that your responses are socially unbiased and positive in nature. If a question does not make any sense or is not factually coherent, explain why instead of answering something not correct. If you don't know the answer to a question, please don't share false information.
What is All of the following materials are radiopaque in nature except: and explain in detail?
All given options are metallic (radiopaque) in nature except composite resins.
Generally, non-metallic radiopaque markers (gutta-percha, composite resin) are used in MDCT imaging and CBCT imaging studies to minimize the effect of image artifacts produced by metal markers.

 
Reference: White and Pharoah's Oral Radiology Principles and Interpretation 7th edition page no 637