What Causes Crooked Teeth? A Portland Orthodontist Explains

If you’ve ever looked in the mirror and wondered why your teeth came in the way they did, you’re not alone. It’s one of the most common questions we get at Garfinkle Orthodontics. Some patients want to know if they did something wrong. Others want to know if their kid’s crooked smile is their fault. Some are just curious.

The truth is, crooked teeth are incredibly common, and there’s rarely just one reason for them. Here’s a straightforward look at what actually causes teeth to come in crooked.

The Short Answer

Most crooked teeth are caused by a combination of factors, but genetics is by far the biggest one. The size and shape of your jaw, the size of your teeth, and how everything fits together are mostly determined by DNA. Everything else (habits, injuries, environmental factors) plays a smaller role on top of that foundation.

In other words, if your parents had crowded teeth, there’s a good chance you will too. That’s not your fault. It’s just biology.

Genetics: The Main Driver

Your genes determine a lot about your mouth:

• The size of your upper and lower jaws
• How your jaws fit together
• The size and shape of your individual teeth
• How many teeth you have
• When your baby teeth fall out and adult teeth come in

When your jaw is small but your teeth are large, there’s not enough room for everything to come in straight. That’s crowding. When your jaw is big but your teeth are small, you get gaps. When your upper and lower jaws don’t line up the way they should, you get an overbite, underbite, or crossbite.

Most of these things are inherited. You might have your mom’s small jaw and your dad’s big teeth, which is a classic recipe for crowded teeth.

Jaw Size vs. Tooth Size

This is one of the most common reasons for crooked teeth, especially in modern humans. Over the past few thousand years, our jaws have gotten smaller while our teeth have stayed roughly the same size. The result? Not enough room for all our teeth to fit comfortably.

This is why so many people need wisdom teeth removed. It’s also why crowding of the front teeth is so common. It’s less about anything you or your parents did wrong and more about the mismatch between modern jaw size and the teeth we still have.

Early Habits in Kids

Certain habits during childhood can contribute to crooked teeth or bite issues:

• Thumb sucking past age 5 can push front teeth forward and affect the shape of the roof of the mouth
• Prolonged pacifier use can cause similar issues to thumb sucking
• Tongue thrusting (pushing the tongue against the teeth when swallowing) can shift teeth over time
• Mouth breathing can affect how the jaw develops
• Prolonged bottle use past the typical weaning age can affect tooth position

Most of these habits are easy to address when they’re caught early. If you’re a parent and your child still has one of these habits, it’s worth bringing up at their first orthodontic evaluation.

Losing Baby Teeth Too Early (or Too Late)

Baby teeth do more than help kids chew. They also hold space for the adult teeth that are coming in behind them. When a baby tooth is lost too early (from decay, injury, or extraction), the surrounding teeth can shift into that empty space. When the adult tooth tries to come in, there’s no room, and it comes in crooked.

The opposite can happen too. If baby teeth hang around too long, they can block adult teeth from coming in properly.

This is one of the reasons we recommend a first orthodontic evaluation around age 7. We can spot these issues early and sometimes use a small space maintainer to prevent future crowding. Our post on signs your child may need early orthodontic treatment has more detail.

Injuries to the Mouth or Jaw

A hard hit to the face or mouth can affect tooth alignment, either immediately or over time. This can happen from:

• Sports injuries
• Falls
• Car accidents
• Playground mishaps

Sometimes a tooth that was knocked out of place in childhood never fully recovers. Other times, an injury to the jaw during growth years can affect how everything develops. This is one more reason we recommend mouthguards for any contact sport.

Diet and Jaw Development

There’s some interesting research suggesting that modern diets, which are heavier on soft, processed foods, may contribute to smaller jaw development over time. Humans used to chew tough, fibrous foods regularly, which gave our jaws more of a workout and encouraged them to develop fully.

Today’s softer diets mean less chewing, which may be one small factor in why jaw sizes have gotten smaller. This doesn’t mean you need to put your kid on a tough-food diet. Just something interesting to think about.

Tooth Shifting in Adults

Even if your teeth were perfectly straight as a teenager, they can shift as you get older. This is called mesial drift, and it happens to pretty much everyone throughout life. Causes of adult tooth shifting include:

• Natural aging of the jaw and surrounding tissues
• Pressure from your tongue, lips, and cheeks
• Loss of bone density
• Grinding or clenching
• Gum disease
• Tooth loss
• Not wearing a retainer after past orthodontic treatment

This is why so many adults who had braces as teens come back years later. Teeth want to move, and without something holding them in place (like a retainer), they will.

Gum Disease

Gum disease (periodontitis) can affect tooth position in adults. When the gums and bone supporting your teeth are damaged, teeth can shift, loosen, or drift. This is one of many reasons why good gum care matters, especially as you get older.

If you’ve noticed your teeth shifting and you also have signs of gum disease (bleeding gums, bad breath, tender gums), it’s worth seeing your dentist as well as your orthodontist.

Missing Teeth

When one tooth is missing, the surrounding teeth tend to shift toward the gap. This can cause your bite to change, your other teeth to lean, and your smile to look different over time. This is one reason dentists often recommend replacing missing teeth with implants or bridges, not just for appearance but for the health of all your other teeth.

Can You Prevent Crooked Teeth?

For the most part, no. Since genetics plays such a big role, you can’t fully prevent crooked teeth. But there are some things you can do to minimize other contributing factors:

• Address thumb sucking and pacifier habits by age 5
• Bring your child in for an orthodontic evaluation around age 7
• Watch for mouth breathing or snoring in kids
• See your dentist regularly to catch early decay in baby teeth
• Protect your mouth during sports with a mouthguard
• Keep up with great oral hygiene to prevent gum disease
• Wear your retainer if you’ve had past orthodontic treatment

Even with all of this, some crookedness is just going to happen. That’s where orthodontic treatment comes in.

What Can Be Done About Crooked Teeth?

The good news is that nearly every type of crooked teeth can be corrected, no matter the cause. Depending on the specific case, treatment might include:

• Traditional braces
• Clear aligners (Invisalign)
• Early intervention appliances for kids (expanders, space maintainers)
• Combination treatment for complex cases

For most patients, braces or Invisalign are the main options. Which one is best depends on your case, lifestyle, and preferences. Our post on braces vs. Invisalign, which is right for you walks through the comparison.

Is It Ever Too Late?

Nope. We treat adults all the time, and modern orthodontic treatment works just as well for adults as for teens. The only difference is that adult treatment can sometimes take a little longer because adult bone doesn’t remodel quite as fast as teen bone. But the results are just as impressive.

Our post on orthodontics for adults, it’s never too late covers what adult treatment looks like.

What If I Just Have One Crooked Tooth?

Even if your teeth are mostly straight and just one tooth bothers you, you have options. Some patients do a short round of Invisalign (sometimes just a few months) to fix one tooth. Others opt for cosmetic solutions through their dentist, like a veneer or bonding.

The best way to know what makes sense for your specific case is a quick consultation.

Crooked Teeth Are Normal

Here’s the biggest takeaway. If you have crooked teeth, you are not alone, and you did not do anything wrong. The vast majority of people have some kind of tooth or bite imperfection. Modern orthodontics has made it easier than ever to correct these issues at any age.

Whether you want to understand what’s going on with your smile, bring your child in for an evaluation, or finally do something about teeth that have bothered you for years, we’re here to help.

Come Learn More About Your Smile

The best way to understand what’s going on with your teeth is to come in and let us take a look. We can walk you through what we see, explain what caused it (if we can tell), and talk through your options.

Dr. Judah, Dr. Thrower, and our team love answering questions about how teeth and jaws develop. There are no silly questions, and we’re happy to go as deep into the details as you want.

We’re located in SW Portland and serve families throughout Beaverton, Lake Oswego, Tigard, Milwaukie, and the surrounding area. Your first consultation is always complimentary. Come see what we can do for your smile.