tooth decay When you eat sugary food (just about everything you eat contains sugar!) your teeth will decay for 45 minutes. Bacteria and food particles form plaque on the surface of your teeth.  The bacteria produce acid that 'eats away' the calcium in the tooth's enamel and this causes the formation of minute holes (cavities).  It takes 6-8 hours for the damage done by this to be naturally  repaired by your saliva. So it's important to try and combine sugary foods with a meal to minimise the damage done and avoid snacking in between meals. If left untreated, the acid will eventually eat through the tooth enamel, and begin eroding the dentin beneath it.  As the dentin is porous, it is eroded much faster than the enamel which surrounds it so, a large cavity could be forming inside the tooth without showing many visible signs. As the decay continues, bacteria migrate through the porous dentin and infect the pulp.  When your body launches an immune response to the infection, the blood vessels around the tooth enlarge and press against the nerves entering the tooth causing the tooth to ache.  Modern dentistry has succeeded in reducing the incidence of tooth decay (dental caries) through water fluoridation, oral hygiene education, and preventive dental care that includes sealants, and conservative restorative treatment. “Cavities” are far less prevalent than they were several decades ago and may now be managed by advanced technology. Today real dental concern is periodontal disease (gum disease). If you want to know how much you'll pay for a filling, visit this page.