Commonly used root conditioning materials include all of the following EXCEPT:

Root conditioning materials are used in dental procedures to prepare the root surface for optimal bonding and healing, often in conjunction with periodontal therapy. The correct answer is hydrogen peroxide because it is not typically used as a root conditioning agent.

Citric acid, tetracycline, and EDTA are well-established for their effectiveness in modifying the root surface. Citric acid serves as an effective chelating agent that decalcifies the dentin and enhances the removal of smear layers, revealing a more favorable bonding surface. Tetracycline is employed for its antibacterial properties and can also facilitate root surface conditioning through protein removal. EDTA is another chelating agent that efficiently removes inorganic components and debris from the root surface, contributing to good bonding outcomes.

In contrast, hydrogen peroxide is primarily known for its antiseptic qualities and is more commonly used for teeth whitening and disinfection rather than as a root conditioning material. Hence, its inclusion in the list does not align with common practices in root conditioning, making it the exception among the options provided.