A black line stain on the teeth is caused by an anaerobic bacteria known as chromogenous. This type of stain is typically seen in pediatric dentistry.
The most dominant species of bacteria responsible for causing black line stains on teeth are actinomyces. The black stains are actually ferrous deposits that are formed after the chemical interaction of sulphide of hydrogen and iron on the surface of the teeth. Sulphide of hydrogen is created when anaerobic bacteria produce hydrogen, while iron occurs naturally in the saliva. Saliva contains iron because of a typical healthy diet, or it is released by red blood corpuscles into the saliva. Bloody gums are one cause of the release of red blood corpuscles.
Black stains are viewed as a form of dental plaque because the flora responsible for the condition tend to calcify on the teeth. The black line stains that form on the teeth are unsightly, but they have a mild pathology, so they do not affect the vitality of the tooth's structure. A dentist typically diagnosis black line stains by their appearance. The stains generally have borders that measure approximately 1 millimeter, or they are constructed of unfinished lines that are formed by a dark exogenous substance. The exogenous substance follows the gingival festoon of bet coronary, which is also known as the cervical third of the crown of the tooth. The stains can also appear as points or dark spots on other portions of the tooth, and it occurs on both temporary and permanent teeth.