According to the American Dental Association (ADA), bacteria start attacking teeth within 20 minutes of eating or drinking, and the assault begins with the tooth enamel. Bacteria form as food is broken down, and foods with sugar and starch are especially efficient at forming strong and stubborn corrosives.
Starchy and sugary drinks and foods form a sticky bond with teeth, keeping the acids on the tooth surface longer. Eating throughout the day, especially when combining acidic drinks and sweet or starch-based foods, adds layer after layer of plaque and bacteria that interact to attack enamel, leading to decay. Soft drinks and candy are some of the more obvious foes, but others are less well-known.
Lemons are extremely acidic and can do some serious damage to tooth enamel. Studies have shown that people who suck on lemons or use powdered citrus sweeteners have considerable wear to their tooth enamel. While drinking a full glass of water with a lemon slice or with lemon juice likely won't cause extensive damage to enamel, doing so regularly without rinsing or brushing off the citric acid can eat at enamel over time [source: TIME]. Other fruits and fruit juices can have a similar effect but are not as highly acidic as lemons.
Other sour foods also take a toll on teeth, including sour candy, which is more damaging than the purely sweet, sugary candy. Even sports and energy-boosting drinks are very high in acids and sugars -- another double-whammy that can demineralize the teeth, breaking through the enamel into the dentin and causing cavities [source: Madrigal]. Teeth also need healthy foods coming into the body to help fight the bad bacteria, so diet can play a role as well.
Brushing and rinsing after eating and/or drinking is highly effective at getting the plaque and acids off of the teeth, but overdoing it is another story. When too much pressure is exerted while brushing, not only does the force cause gum tissue damage and wear and tear on the teeth, but it also leaves the mouth dirty. Bristles don't spread out and reach particles on the teeth when a toothbrush is pressed against them too hard. Using gentle pressure and a soft versus a hard-bristled brush prevents gum issues and sloughs away the acids and bacteria lying in wait on the enamel surface [source: ADA].
Cutting back on some of these foods, drinks and brushing habits prevents a lot of enamel wear, so all of the above are controllable, but sometimes it's more than just what we put into our mouths. Damage to the outer teeth can come from the inside out, too. How? We'll take a look inside, next.