Malocclusion and Your Mouth: The Curious Causes of Crooked Teeth

tooth-366335_1920Did you know that humans are the only one out of 5,400 different species of mammals that gets crooked teeth? It’s true. And, we’ve only begun getting malocclusions within the past 200 years. Our ancestors had perfectly-aligned teeth, and 10mm of space behind their wisdom teeth. Many people today have to have wisdom teeth removed because they don’t fit.

If you’ve ever wondered why your teeth, your child’s teeth, or anyone else’s develops oddly – called a “malocclusion,” here’s what you need to know.

What Is It?

Malocclusion includes many different kinds of oral misalignment problems. According to Asian orthodontist Manhattan, a malocclusion may include crowded teeth, crossbite, overbite, underbite, or an open bite.

Any misalignment hinders the teeth from performing vital functions. If the misalignment is severe enough, it can cause pain and serious health complications.

The Symptoms

Symptoms and features include an improper alignment of the teeth, alteration in the appearance of the face, frequent biting of inner cheeks or tongue (accidental), discomfort when eating, biting, or chewing, speech problems and the development of a lisp, mouth-breathing, and other breathing problems.

Ideally, your teeth should fit inside your mouth without crowding or spacing problems. They should also overlap your lower teeth just slightly so the ridges of the molars fit into the grooves of the opposite molar.

The Causes

There are many suspected causes of malocclusion, including cleft lip and palate, a prolonged use of a bottle in childhood, frequent use of a pacifier after age 3, thumb sucking, injuries to the jaw at a young age, tumors of the jaw or mouth, poor dental health and hygiene, or abnormally-shaped or impacted teeth.

Some research now also suggests that exclusive breastfeeding may reduce the incidence of malocclusion by as much as 70 percent. Researchers at the University of Adelaide showed that breastfeeding dramatically reduced the incidence of moderate to severe malocclusion, especially when parents breastfed for at least 3 months. Better outcomes were seen at 6 months.

This only held true for exclusive breastfeeding. Meaning, parents who did not breast and bottle feed their children. The study, titled “Exclusive Breastfeeding and Risk Of Dental Malocclusion” was published in Pediatrics journal.


Malocclusion is usually diagnosed by your dentist doing a routine dental exam. Your dentist will examine your mouth and teeth and may perform a dental x-ray on you. If a malocclusion is found, he will classify it by its type and the severity of the misalignment.

A Class 1 malocclusion, for example, is when the upper teeth overlap the lower ones. The bite may be normal, and the overlap might be only very minor. Class 1 is the most common.

A Class 2 malocclusion is more severe. An overbite, called retrognathism, is when the upper teeth and jaw are significantly overlapping the lower the jaw and teeth. This can cause severe dysfunction and problems with everything from speaking to chewing. It can also cause what’s called “buck teeth.”

A Class 3 malocclusion is also very severe. This is when the lower jaw protrudes forward  and causes the lower teeth to overlap the upper ones. It’s called prognathism.

Malocclusions are typically treated with braces, removal of certain teeth, reshaping, bonding, surgery, and even wires to support the jaw bone.


Leo Reeves is a dental student in Baltimore. He is particularly interested in orthodontics and writes on this and other dental topics for a range of health related blogs in his spare time.