Teeth are made up of complex interconnected minerals. The enamel is made up mostly of fluoride, calcium, magnesium and trace amounts of nitrogen. These elements are bonded together, but these bonds can be broken, and the minerals can be leached out of the teeth. Usually it is one of two things that do this; food or bacteria.
Many bacteria living in the mouth secrete acidic by products when they chow down on carbohydrates. Coming into contact with acidic remains causes the bonds to break and for your enamel to lose fluoride and calcium, eventually creating a cavity. Usually, with this kind of demineralization, it will be limited to one tooth or one spot on a tooth, and this is how you get cavities. But a bacterial infection of the gum can cause demineralization on a more massive scale, causing all of your teeth to lose some amount of minerals. This can cause massive discoloration and white splotches to appear.
Besides carbs and sugars that feed bacteria and cause them to proliferate and break down your enamel, acidic foods can also eat away at the protective enamel layer of your teeth. Foods naturally high in acid content, like citrus fruits, red berries and cheeses high in lactic acid will cause your teeth to deteriorate even without a bacterial infection present. The same can be said of vinegary foods, as wella s coffee and tea. Brushing your teeth right after eating something of this nature is a bad idea, as you will literally brush little bits of your enamel off of your tooth.
Anorexia and bulimia can also cause the demineralization and eventual rot of the teeth. With bulimic patients, the teeth frequently come into contact with acid, and the acid will dissolve the enamel, leaving the cementum and the inner structures exposed. With anorexic patients, the loss of food means that the minerals that are being used up are not being replenished, and the teeth start to lose their luster, than their color, and finally will break away or just fall out altogether. The use of party drugs like amphetamines and alcohol will also dissolve the calcium and magnesium from your teeth, and ruin them eventually.
Orthodontic treatment also leaches out the calcium and fluoride from your body, because the metal reacts with the tooth surface and breaks the bonds that hold it together.
If your teeth are collectively turning a grayer or more yellow color, and not because of plaque, than you have an issue. The enamel you have is being destroyed, and you should do something about it. Usually, though, demineralization only happens in small pockets, and will appear as white splotches on the teeth. The enamel will be thinner, sometimes more raised, and much whiter than the tooth around it. These spots are much more likely to become cavities that any other site on your teeth, as the protective layer is thinnest there.
Luckily, enamel lost is not lost forever, and you can replenish and remineralize your teeth. Buy some fluoride foam or gel, possibly a fluoride ointment, and apply to your teeth. Do NOT brush it off, just let it become a part of your teeth. Repeat as often as necessary. Eat plenty of dairy products or, if you are a vegan, lots of beans and lentils. Take a calcium supplement with magnesium, otherwise your body will not soak it up.
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