What is a characteristic of yellow stains on teeth?

Yellow stains on teeth are often associated with certain dietary habits, smoking, or the consumption of beverages like coffee or tea. The characteristic of appearing primarily on the buccal surfaces of maxillary molars is accurate because these areas are more exposed to staining agents from food and drinks. The buccal surfaces of these teeth are also more prone to plaque accumulation, which can lead to discoloration.

Other options do not accurately describe yellow stains. For instance, yellow stains are less likely to be found on those with excellent oral hygiene, as regular brushing and flossing can help minimize or prevent such discoloration. Additionally, while excessive fluoride exposure can lead to enamel fluorosis, which results in white or brown spots rather than yellow stains, younger adults are not specifically known for having yellow stains more than other demographics. Thus, the statement regarding the appearance of yellow stains primarily on the buccal of maxillary molars stands out as the most characteristic feature.