A bigger problem arises if plaque is allowed to remain on your teeth and harden. That can happen after just 26 hours. When this occurs, the plaque hardens into tartar, or dental calculus. Because it has mineralized onto your teeth, tartar is far more difficult to remove than plaque.
Once tartar forms on teeth, it may be more difficult for you to brush and floss effectively. If this is the case, the acids released by the bacteria in your mouth are more likely to break down tooth enamel. That leads to cavities and tooth decay.Tartar that develops above the gum line can be especially serious. That's because the bacteria it harbors may irritate and damage gums. Over time, this inflammation can lead to progressive gum disease. Gum disease can have serious consequences if left untreated. According to the CDC, between 5% and 11% of the adult population suffers from advanced gum disease.The mildest form of gum disease is called gingivitis. This is the initial stages of gum inflammation caused by the presence of plaque and tartar on the teeth. Gingivitis can usually be stopped and reversed with careful brushing, flossing, and regular cleanings by dental professionals.If tartar is not removed and gingivitis is left untreated, it can progress into a more serious form of gum disease. That more serious form is known as periodontitis. With this gum disease, pockets form between the gums and teeth. Those pockets become infected by bacteria beneath the gums. The body's immune system releases chemicals to fight the bacteria. These chemicals along with the substances the bacteria release can damage the bone and other tissues that hold the teeth in place. This can lead ultimately to tooth loss and bone degradation. In addition, studies have shown that bacteria in gum disease may contribute to heart disease as well as other conditions.
If found early enough, decay can be reversible (i.e. it goes away itself) without treatment. This is only the case when the decay is small and still within the enamel (the outside shell of the tooth).