Why Are So Many Teeth Crooked? What Ancient Skulls Suggest

Crowded and crooked teeth are much more common in people today than in skulls from earlier centuries. The main explanation is that soft, processed modern food gives the jaws less chewing work while children are growing, so jaws end up slightly smaller than the teeth they need to hold. Genes still matter, and diet is not the whole story, but the evidence for a dietary influence is consistent.

What do old skulls show?

A study from the University of Oslo compared 146 skulls from abandoned medieval graveyards in Oslo, Norway, with a modern Norwegian sample assessed with the same orthodontic index.

• About 36 percent of the medieval skulls showed an objective need for orthodontic treatment.

• In the modern sample, the figure was 65 percent.

• Severe cases were also more common today: 20 percent of the modern sample showed great need, compared with 7 percent of the medieval skulls.

The authors concluded that both how often malocclusion occurs and how severe it is have increased over the last several hundred years in that population.

Why would diet change jaw size?

Bone responds to the forces placed on it. Chewing tough, raw or lightly processed food puts more strain on the jaws and face than chewing soft, cooked food, and that strain helps drive growth.

• In 1984, anthropologist Robert Corruccini reviewed populations around the world and described a rapid rise in crooked teeth and bite problems as groups moved to urban, industrialized diets. He argued the speed of the change pointed to environmental causes rather than genetic ones.

• In 2004, a team led by Harvard's Daniel Lieberman raised rock hyraxes, small animals with a short face somewhat like ours, on either raw and dried food or cooked food. The animals fed cooked food had about 10 percent less growth in the lower and back parts of the face, where chewing strain was highest.

Lieberman later described this pattern for a general audience in his 2013 book The Story of the Human Body, as one example of a mismatch between modern life and the bodies we inherited.

What are the limits of this evidence?

• Skull studies compare populations, not individual people. They cannot tell you why your own teeth are crowded.

• Genes influence tooth size, jaw shape and bite. Habits such as thumb sucking and mouth breathing may also play a part.

• The animal research shows a plausible way diet affects jaw growth. It does not show that a tougher diet today would straighten an adult's teeth.

What does this mean for you?

Crowding is common, and having it does not mean anyone did something wrong. Crooked teeth can be harder to clean, which raises the risk of decay and gum disease, and a poor bite can wear teeth unevenly. Whether treatment makes sense depends on your teeth, your bite and your goals.

If you are weighing options, you can read about clear aligners, how smile design compares with orthodontics, and why wisdom teeth sometimes have too little room. In Jacksonville, a dental examination is the place to start.

Sources

1. Evensen JP, Øgaard B. Are malocclusions more prevalent and severe now? A comparative study of medieval skulls from Norway. Am J Orthod Dentofacial Orthop. 2007;131(6):710-716. doi:10.1016/j.ajodo.2005.08.037. Retrieved via PubMed.

2. Corruccini RS. An epidemiologic transition in dental occlusion in world populations. Am J Orthod. 1984;86(5):419-426. doi:10.1016/s0002-9416(84)90035-6. Retrieved via PubMed.

3. Lieberman DE, Krovitz GE, Yates FW, Devlin M, St Claire M. Effects of food processing on masticatory strain and craniofacial growth in a retrognathic face. J Hum Evol. 2004;46(6):655-677. doi:10.1016/j.jhevol.2004.03.005. Retrieved via PubMed.

4. Lieberman DE. The Story of the Human Body: Evolution, Health, and Disease. New York: Pantheon; 2013.

About the author. CJ Henley, DMD, is a general dentist in Jacksonville whose practice focuses on cosmetic and restorative dentistry, dental implants and dental care around head and neck cancer. Meet Dr. Henley.
CJ Henley, DMD, PA · 3675 Hendricks Avenue, Jacksonville, FL 32207 · 904-398-1549
Updated October 2026.

What Is eXciteOSA, the Daytime Device for Snoring and Mild Sleep Apnea?

eXciteOSA is a prescription mouthpiece that sends mild electrical pulses to the tongue muscles for 20 minutes a day while you are awake. The FDA authorized it in February 2021 for adults with snoring or mild obstructive sleep apnea. It is not meant for moderate or severe sleep apnea, and it should be considered only after a physician has diagnosed the problem.

How does it work?

In obstructive sleep apnea, the airway repeatedly narrows or closes during sleep. A relaxed tongue falling back toward the throat is often part of the problem. eXciteOSA is designed to train the tongue muscles so the tongue is less likely to collapse backward at night.

The mouthpiece has four electrodes, two above the tongue and two below it. The prescribed routine is 20 minutes once a day for six weeks, then once a week after that.

What did the FDA review?

The FDA looked at data from 115 people who snored, including 48 who also had mild sleep apnea. Everyone used the device daily for six weeks, stopped for two weeks and was then reassessed.

• In 87 of the 115 people, time spent snoring louder than 40 decibels fell by more than 20 percent.

• In 41 of the 48 people with mild sleep apnea, the average apnea-hypopnea index (the number of breathing pauses and shallow breaths per hour of sleep) fell from 10.21 to 5.27, a 48 percent drop.

The most common side effects were extra saliva, tongue or tooth discomfort, tongue tingling, sensitivity in fillings, a metallic taste, gagging and a tight jaw.

Who should not use it?

According to the FDA, the device should not be used by people who:

• have a pacemaker or implanted pacing leads

• are pregnant

• have braces, metal fillings or other metal dental work, or implants in the mouth

• have sores in or around the mouth

• have sleep apnea with an apnea-hypopnea index of 15 or higher

The FDA also says patients should have a comprehensive dental examination before using it, because the device sits against the teeth and gums and is not suitable for some dental work.

How is sleep apnea diagnosed?

Sleep apnea is diagnosed by a physician, usually after a sleep study done in a lab or at home. Snoring alone does not tell you whether you have sleep apnea or how severe it is. Untreated sleep apnea is linked to heart disease, daytime sleepiness and problems with memory and concentration, so loud snoring, pauses in breathing or waking unrefreshed are worth raising with your physician.

Continuous positive airway pressure (CPAP) remains a first-line treatment. Depending on the diagnosis, physicians may also consider other options. The right choice depends on the severity of your sleep apnea, your anatomy and your other health conditions.

Where does a dentist fit in?

A dentist cannot diagnose sleep apnea. A dental examination can check whether your teeth, gums and dental work are healthy enough for any device worn in the mouth, and a dentist may notice signs worth mentioning to your physician, such as heavy tooth wear from grinding.

If you live in Jacksonville and want your mouth checked before trying a device your physician has recommended, you can arrange a dental examination or contact our office.

Sources

1. U.S. Food and Drug Administration. FDA authorizes marketing of novel device to reduce snoring and mild obstructive sleep apnea in patients 18 years and older. News release, February 5, 2021. Reproduced by BioSpace. Retrieved October 6, 2026.

2. American Academy of Sleep Medicine. FDA authorizes eXciteOSA device for snoring and mild sleep apnea. February 5, 2021. Retrieved October 6, 2026.

About the author. CJ Henley, DMD, is a general dentist in Jacksonville whose practice focuses on cosmetic and restorative dentistry, dental implants and dental care around head and neck cancer. Meet Dr. Henley.
CJ Henley, DMD, PA · 3675 Hendricks Avenue, Jacksonville, FL 32207 · 904-398-1549
Updated October 2026.