What stains on teeth are typically associated with poor oral hygiene?

Yellow or brown stains on teeth are commonly associated with poor oral hygiene as they typically result from plaque accumulation and the buildup of tartar. These stains can occur because inadequate brushing and flossing allow food particles, bacteria, and stained substances from food and beverages to adhere to the enamel of the teeth. Over time, without proper cleaning, these substances can discolor the teeth, leading to the yellow or brown appearance.

While other types of stains do exist, such as red or green stains, they are usually linked to distinct causes, like specific types of food, beverages, or even certain health conditions. White stains can indicate early stages of demineralization due to acid exposure, but they are not necessarily a direct reflection of poor hygiene. Thus, yellow or brown stains are the most indicative of a lack of proper oral care and maintenance.