What condition can cause a "hairy tongue" appearance?

The condition known as "hairy tongue" is primarily caused by the elongation of the filiform papillae on the surface of the tongue. These tiny, thread-like structures are normally present and serve a role in the sensation of taste and aiding in the mechanical aspects of chewing and swallowing. When they become elongated, they can trap food particles, bacteria, and dead cells, leading to a discolored and sometimes dark appearance that resembles hair, hence the term "hairy tongue."

Factors contributing to the elongation of filiform papillae include poor oral hygiene, dry mouth, smoking, certain medications, and the use of some alcohol-based mouthwashes. The overall appearance associated with this condition can lead to discomfort and may also serve as an indicator of underlying health issues.

The other papillae types mentioned, such as fungiform, circumvallate, and foliate, do not typically contribute to the "hairy tongue" appearance. Each type serves different functions, primarily related to taste, and their elongation does not create the same visual effect as that of the filiform papillae. Therefore, understanding the role and characteristics of filiform papillae is crucial in recognizing the etiology of hairy tongue.