How does green stain become intrinsic?

The process of green stain becoming intrinsic is primarily related to its incorporation with decalcified areas of the enamel. When green stain, often associated with certain bacterial deposits or materials like chromogenic bacteria, is present, it can penetrate the surface of the enamel where decalcification has occurred. This leads to the stain being absorbed into the tooth structure, thereby changing it from an extrinsic to an intrinsic stain.

Intrinsic stains are those that are embedded within the tooth structure itself, as opposed to merely sitting on the surface. The presence of decalcified areas allows for the stain to become trapped and a part of the tooth, leading to a more permanent coloration that cannot be removed by standard polishing or cleaning procedures. This contrasts with extrinsic stains, which remain on the surface and can typically be easily removed through dental hygiene practices.

Other options do not accurately describe the transformation of green stain into an intrinsic stain. While improper removal may lead to additional staining, it does not initiate the conversion to intrinsic staining. Similarly, while staining over time and dietary factors can certainly contribute to the overall appearance of teeth, they do not specifically explain the association between green stain and the intrinsic change related to decalcified areas.