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Why Do People Have Crooked Teeth?

By Lan Pham, Kaelyn Johnson, MPH, RD
Have you wondered why people have crooked teeth? There isn’t one single answer to that question.

If you have crooked teeth, you might wonder what caused the misalignment. According to experts, crooked teeth can arise due to a number of factors—from poor dental hygiene to a facial injury. Read on for some of the most common causes of crooked teeth.

Genetics and Environment

Most cases of malocclusion, or a misaligned bite, arise from a combination of genetic and environmental factors, according to a 2019 article published by the Journal of Advanced Clinical & Research Insights.

In other words, the way that your teeth and bones grow is a result of the interaction between your inherited genetic traits and your environment. 

Malocclusion can cause a number of dental issues, including crooked teeth. It can even cause crooked teeth to irritate your lips and gums as your mouth opens and closes—and snowball into problems with eating, drinking, speaking, and breathing. 

Genetic factors can play a particularly key role in bite patterns, arch width, and tooth size and shape. A number of genetic diseases—including Treacher Collins Syndrome, Apert Syndrome, and Pierre Robin’s Syndrome—can also influence the formation of the bones and tissues of the face. 

Teeth or jaw alignment issues with a genetic cause may be more resistant to treatment, but visiting an orthodontist can be a vital step in identifying the cause of your crooked teeth and developing a treatment plan to help. 

Not Wearing Retainers as Prescribed

Completing a successful treatment with braces or invisible dental aligners does not guarantee straight teeth for life. 

“When we bite down, the forces are transmitted from front to back, which causes the front teeth to shift and overlap over time,” Joseph Field, DDS, tells WebMD Connect to Care. This is true whether or not you’ve had orthodontic treatment. 

That’s why wearing a retainer after your teeth have been straightened is crucial for keeping your teeth in their new, healthy position.

Poor Nutrition

What you eat can contribute to the proper development of your teeth

It’s especially crucial for children to obtain adequate nutrition to support healthy tooth development. The online book Diet and Nutrition to Prevent Dental Problems, published by StatPearls, notes that the following developmental issues can be particularly impactful:

  • Vitamin A deficiency can lead to impaired tooth formation and problems with enamel
  • Vitamin D and calcium deficiency can cause low bone mineral in the teeth and delay the proper emergence of teeth from the gums
  • Vitamin C deficiency can cause poor formation of the second layer of the tooth (dentin) 

These nutritional deficiencies during childhood can contribute to crooked teeth later in life. 

Facial Injury

If you experience trauma or injury to the face that knocks your teeth out of place, this can result in crooked teeth. According to the American Association of Endodontists (AAE), accidents and sports-related injuries are common causes of dental trauma. 

It is uncommon, but still possible, for one of your teeth to become dislodged or knocked out completely due to injury. If this happens, the AAE recommends visiting a dentist or endodontist —a doctor that specifically specializes in treating traumatic dental injuries—immediately. Your endodontist will be able to assess the extent of the damage and help prevent any possible resulting misalignment. 

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