Which type of stain tends to be difficult to remove due to its association with metabolic changes?

The type of stain that tends to be difficult to remove due to its association with metabolic changes is black line stain. This stain is often closely related to certain conditions in the oral environment, such as changes in the composition of saliva or oral bacteria, which can lead to a more tenacious adhesion of the stain to the tooth surface. Black line stain typically forms along the gingival margin and can be more resistant to conventional cleaning methods, such as scaling or coronal polishing, requiring more specialized approaches for effective removal. Understanding the metabolic factors that contribute to the formation of this type of stain is crucial for dental professionals in developing appropriate dental hygiene practices tailored to maintain oral health.