There are multiple causes for this to occur. It could be a trauma to the tooth when the tooth was forming, exposure to too much digestive fluid (if its generalized), a stain, an old filling, or a breakdown of the enamel due to decay.
There are multiple causes for this to occur. It could be a trauma to the tooth when the tooth was forming, exposure to too much digestive fluid (if its generalized), a stain, an old filling, or a breakdown of the enamel due to decay.