Black line stain on teeth is partially caused by dental plaque in the same manner as other topical stains on teeth are caused. However, the way the plaque was formed is the key to unlocking the mystery of black stains. All dental plaque is caused by bacteria. However, the type of bacteria that causes black stains is different than that which causes other stains. Black line stain is found near the gum line on both the front and back of the teeth and is more prevalent on the back teeth.
Chromogenic bacteria is the cause of the plaque on teeth that results in black line stain. This type of bacteria is known for causing calcification. In plaque caused by chromogenic bacteria the deposit of calcium along the gum line is the cause of children with black line stain to have a remarkably lower incidence of dental decay.
All dental plaque is caused by improper brushing, no routine brushing after meals and snacks, little or no flossing, improper flossing, snacking before bedtime, or a combination of these. Plaque causing bacteria breed rapidly during our sleep, feeding off of food particles and sugars from sweetened drinks. It is imperative to teach our youth how to properly brush and floss so they have healthy, unstained teeth.
Studies have been ongoing for years into the relationship between colored extrinsic dental stains and dental disease. It was during these early studies it was discovered that children with black line stain had fewer cavities than children with other colored extrinsic stains. The children in these studies varied in age and it was shown this was true both in children who still have their baby teeth and those with the adult teeth.
Gingival scrapings from the teeth of children with black line stain has been shown to contain an increased phosphate content as well as an increased calcium content mentioned earlier. The scrapings were also shown to contain iron. Other testing showed calcium carbonate, phosphates, and mucin. Other studies have suggested the black stain was caused by melanin.
Further testing has shown an insoluable iron compound in the black line stain. It has now been proven the chromogenic bacteria and insoluable iron compound to be the cause of black line stain. It is thought the iron compound is formed due to the interaction of hydrogen sulfide produced by the chromogenic bacteria and iron in the saliva or gingival fluids.
A child with a high iron content in their body is at great risk for black line stain if they are not taught proper brushing and flossing techniques or the child does not follow through with proper brushing and flossing. Ultimately, it is a parent or guardian's responsibility to oversee their child's dental hygeine routine. This should include an explanation of how plaque forms and the consequences of not taking care of our teeth.