Before going on about remineralization, just what is the mineral part of teeth and how does it get demineralized?
Teeth are made up of four kinds of tissues: pulp, cementum, enamel and dentin. Pulp is the softest, deepest part of the tooth and contains the nerves and blood vessels that bring nutrients to the tooth. Cementum is a hard covering around the pulp down into the roots, and dentin is an inner covering that is also very hard but fills most of the inside rather than outside of the tooth. Enamel crowns the tooth, making up the visible part and adding strength for chewing. Three of the four tooth tissues are hard, but all can be compromised and become worn down or soft and weak. Pulp is already soft, but as long as it's covered, it serves its purpose painlessly and efficiently beneath the harder coatings. Once exposed, however, the network of nerve endings throughout and surrounding the pulp are open to air, liquid and bacteria contact, all of which can cause significant pain.
Cells in the body multiply to form teeth tissues, and the hard parts are made up mostly of minerals. Crystals of calcium phosphates grow close together in a network to form the enamel, and although it is stronger even than bone or concrete, once it starts to break down through acid erosion or injury, it doesn't grow back in its original, hardest enamel form. But in the short term, and as part of the ongoing process mentioned earlier, enamel can retain strength if remineralization keeps happening to neutralize acids and bacteria [source: Madrigal].
Our bodies support remineralizing teeth as long as there are minerals available to send as needed. Saliva carries calcium and phosphates to the sites of demineralization naturally, but the mouth can only compensate so much when it's overcome with bacteria and plaque for too long. Plaque can start to harden on teeth if it's not removed after eating, and when this hardening starts, enamel begins breaking down from the overactive bacteria in the plaque growth. Demineralization then wins out and cavities can run rampant.
When plaque gets out of control, remineralization of the hard tissues below the gum line is affected too, and the risk of gum inflammation and disease increases. Saliva needs to be present and circulating, often through moving the jaw or chewing. Diet, hygiene and overall physical health also impact how well teeth can remineralize and protect themselves naturally. Dry mouth from medications and tooth decay from over-consumption of soda and starchy and sugary foods are just two enemies of remineralization [source: ADA].
If teeth can't remineralize enough to outpace the loss of minerals, can anything be done to regain balance, or do the bad guys in your mouth win? We'll look at some artificial means of remineralizing, next.