If you eat sugary and sticky foods or drink sweet beverages (candy, ice cream, cereals, sodas, coffee) and don’t brush and floss right away (or don’t do a good job of it when you do), bacteria form a sticky film called plaque, and this begins to eat away at the hard enamel surface of your teeth.
Once the bacteria reach the next layer of the tooth, the dentin, a cavity forms. There are also other risk factors for getting cavities, such as having a naturally dry mouth or having it as a side-effect of medication, or if you have frequent heartburn (because the acid erodes enamel). Infants may get cavities if they’re fed at bedtime.
If you do have a cavity, the dentist will first clear out the decay, clean the area, and fill it with material that will make it hard for bacteria to enter. The best material for dental fillings is gold (which can last 20 years) or porcelain inlays or onlays (for large cavities, custom-designed by a dental lab, which can be made to look like your natural teeth and are very durable). The most popular and affordable are made of composite resign, a plastic that can be made the color of your own teeth and last 3 to 10 years, but they stain easily from coffee, tea, and tobacco unless you clean them immediately afterward.
Any of these are increasingly requested to replace traditional silver amalgam fillings, out of concern for their mercury content.
If the cavity infection has gotten so deep that it has damaged the root nerves of the tooth, your dentist will explain the need to first do a root canal or a procedure called pulp capping, then repairing the top of the tooth according to its needs, which might include placing a crown to cover the natural tooth.
Unless cavities are treated as soon as possible, they can lead to periodontal disease, the gum infection that will result in the loss of teeth.
The best way to help prevent cavities is to spend a few minutes twice a day to thoroughly floss and brush (with fluoride toothpaste), which may mean bringing a dental kit to work and on trips. You may also want to use a high-grade mouthwash afterwards that does more than freshen breath. If you have problem areas, a dental mini-pick with bristles or a dental water pick can help. Chewing sugar-free gum can actually be helpful if it uses xylitol as the sweeteners since that has been shown to fight caries in several ways (stimulating saliva flow, raise the pH of plaque, and reducing bacteria).
Also, try to reduce sugar in your diet to 10% of calories and make sure what you eat afterward and the nutritional supplements you take provide adequate calcium, magnesium, and vitamin D, which are important in the formation of enamel.