Endogenous stains are characterized by:

Endogenous stains are indeed characterized by being internal and non-removable. These stains originate from within the tooth structure, typically due to factors such as developmental issues, medications, or systemic conditions that affect the enamel and dentin during formation. Because these stains are embedded within the tooth's structure, they cannot be simply removed through surface cleaning like extrinsic stains, which are often the result of external factors like food, drinks, or smoking.

Understanding the nature of endogenous stains is crucial, particularly in a dental setting, as they require different treatment approaches compared to extrinsic stains. Treatments for endogenous stains may include various cosmetic procedures or restorative options rather than standard cleaning methods. This context highlights the importance of distinguishing between the types of dental stains to apply appropriate treatment and care.