What is the defining characteristic of tetracycline stains?

The defining characteristic of tetracycline stains is a grayish brown color. Tetracycline is an antibiotic that, when ingested during tooth development in children, can lead to permanent discoloration of the teeth. This discoloration occurs because the drug binds to the calcium ions in the teeth, affecting the enamel and dentin. The resultant staining is typically a grayish brown, which can vary in intensity depending on the timing and duration of the exposure to the antibiotic.

Other staining options, such as white spots, yellowish-green colors, or black discoloration, are not associated with tetracycline. White spots are often indicative of decalcification or enamel hypoplasia, while yellowish-green stains are more commonly linked to conditions like chronic fluorosis or certain dietary pigments. Black discoloration might indicate conditions like a particular type of dental caries or use of certain medications over time, but it does not relate to tetracycline exposure. Therefore, the grayish brown color is distinctly associated with the effects of tetracycline on developing teeth.