Tetracyclines are known to cause permanent tooth discoloration and enamel hypoplasia because they bind to calcium ions during tooth development, leading to deposition within the dentin and enamel. This results in a characteristic yellow, brown, or gray discoloration that is irreversible. The risk is highest when tetracyclines are administered during pregnancy or early childhood, periods of active tooth formation. Other antibiotic classes do not bind calcium in this way and therefore do not produce these dental defects.

Reference: Harrison’s Principles of Internal Medicine, J. Larry Jameson et al., 20th Edition.