Humans didn't get many cavities until we started farming a few thousand years ago.

  1. THE BEGINNING: At the end of the last ice age, we started growing wheat, barley, and rice and storing it for winter. Good idea right? These new carbohydrates gave us year-round energy, but also enabled a new type of harmful bacteria to live in our mouths.
  2. THE DESTRUCTION: During the Industrial Revolution 200 years ago, we began processing and refining our grains to make new foods and preserve them. Although these new foods are delicious, the refined grains further helped the new, harmful bacteria flourish and wreak havoc in our mouths.
  3. TODAY: With a completely different diet and the presence of harmful bacteria in our mouths, 90% of adults have had a cavity (making dental caries the most prevalent infectious disease on the planet).

Humans didn’t always get cavities; we did this to ourselves. Luckily, we now have the research, tools, and science to prevent and reverse cavities.



Cavity = Tooth + Bacteria + Carbohydrates + Time

There's an important distinction to make between an actual "cavity" and a "carious lesion".


  • Carious lesion (n.) - a weakened area of a tooth (reversible if small enough area)
  • Cavity (n.) - a hole in the tooth after the tooth has weakened to a great extent (irreversible)

How carious lesions and cavities form: Essentially, germs in our mouth tear our teeth apart. We have hundreds of different good & bad bacteria in our mouths, but the species Streptococcus mutans, Streptococcus sobrinus, and Lactobacilli are the main cavity-causing bacteria. These bacteria stick extremely well to our teeth and wait for us to eat food. Once we eat, they consume simple carbohydrates and produces an acid byproduct. This acid physically weakens & dissolves our teeth away for 20 minutes (until saliva washes away the acid). This weakened area of the tooth is called a carious lesion (termed "incipient caries" since it's just the start). If we remove the harmful acid, the tooth can reverse the process by re-hardening and regaining strength. But if the harmful acid remains on the tooth, the tooth continues to weaken and an actual hole forms, which we call a cavity.

It's almost impossible to tell if you have a carious lesion or cavity. If you see a white, brown, yellow, orange, or grey spot on your tooth, it may or may not be a carious lesion or cavity. Sometimes these spots are carious lesions or cavities, other times they're internal/external stains, hypocalcification, fluorosis, tooth wear, or fractures. Sometimes cavities hurt, and other times they don't. The most reliable way to tell if you have a cavity is to get a full examination, including x-rays, by a licensed Dentist.