A cavity is an area of the tooth that is permanently weaker and decayed, i.e. "demineralized". Cavities can be literal holes (cavitation), or soft spots.
Acid. Oral bacteria uses carbs in your diet to make acid. These acids can eat away at your teeth, forming weak spots and holes.
All of these can increase your risk for new tooth decay:
You may have one or some of the following:
Your dentist can diagnose cavities with a clinical examination and/or dental x-rays. The clinical diagnosis involves both visual and tactile examination, using special instruments meant for finding cavities. X-rays can show cavities in between teeth, which otherwise might not be found in the clinical examination. X-rays can also be used to determine the extent of the decay.
Not really. However, cavities-causing bacteria can be passed from one person to another. Mouths with active decay have an increased quantity of cavities-causing bacteria.
Generally, sugary foods and drinks can increase your risk for tooth decay (and diabetes!) but you should still be able to enjoy these things in moderation if you thoroughly brush and floss after consumption.
Maintaining a clean mouth and eating a healthy, balanced diet can reduce risk and possibly even slow down tooth decay. Once a tooth already has a brown, soft, or cavitated spot, the only way to definitively and esthetically restore the tooth would be with a filling placed by your dentist.
Certain caries risk factors can be inherited:
Acidic (low) pH increases ones risk for cavities. Our mouths contain both healthy bacteria and cavity-causing (acidogenic or acid-producing) bacteria. Many of the healthy bacteria are inhibited or killed by frequent or prolonged exposure to acidic conditions, enabling the bad bacteria to thrive.
Furthermore, when pH is low, minerals get pulled away from the tooth structure. After a while, the weaker demineralized spot becomes a hole. Remember high school chemistry class? Spilling acid = hole in your jeans. The same thing happens to teeth when they're exposed to very acidic conditions.Floss Now!