What is a common feature of green stains?

Green stains are typically found on the cervical third of maxillary anterior teeth, which is the area closest to the gum line. This location is significant because it often results from the accumulation of chromogenic bacteria, which produce green pigmentation due to the interaction of bacteria with dental plaque and saliva. These stains can be more prominent in children due to their diet and habits but can also occur in adults, particularly if oral hygiene is neglected.

This characteristic location helps dental professionals assess the type of staining present. The other options provided do not accurately reflect the common features associated with green stains. For instance, incisal edges do not commonly exhibit these stains, excessive fluoride use is linked to different types of dental discoloration (such as fluorosis), and while poor dental hygiene can contribute to stain development, green stains themselves are more specifically associated with certain bacteria rather than being a general indicator of hygiene in adults.