Underbite vs. Overbite: Key Differences, Causes and Treatment

Bite problems are common in kids, with overbites being the most common type. Underbites, though less frequent, are still an important issue to address. 

The effects of bite issues go beyond just appearance. When the upper and lower jaws don’t line up properly, it can lead to problems like tooth wear, jaw pain, difficulty speaking and even trouble breathing. If left untreated, these issues can get worse, affecting both oral health and daily life.

By understanding the causes and risks of bite problems, you can better diagnose and treat them, whether that means using braces or, in more serious cases, surgery. Knowing these details helps you guide your patients to the best treatment plan for their unique needs.

What Is an Underbite?

Close your mouth and check if your lower teeth sit in front of your upper teeth. That’s an underbite. Your lower jaw has grown or positioned itself too far forward, creating a bite that’s the opposite of what most people have. In a normal bite, your upper jaw rests slightly ahead of your lower jaw, but with an underbite, your lower jaw takes the lead.

You’ll likely notice this condition in the mirror before you feel any problems. Your chin looks more prominent and your bite may appear edge-to-edge or completely reversed, where your lower teeth cover your upper teeth. The real issues start when you try to eat or speak. 

Chewing tougher foods becomes awkward, certain sounds might come out unclear and your jaw joints can feel sore after meals.

The severity depends on how far the lower jaw sticks out. In mild cases, the lower teeth barely overlap the upper teeth. In severe cases, the lower jaw extends far beyond the upper, often affecting speech and breathing.

Knowing where you fall on this spectrum helps determine whether you need treatment, from simple orthodontic work to jaw surgery, to restore comfort, function and facial balance.

What Is an Overbite?

When you close your mouth, your upper front teeth should rest just slightly in front of your lower teeth. An overbite occurs when the top teeth cover more of the bottom teeth than they should.

This differs from an overjet, which occurs when the top teeth protrude horizontally (similar to “buck teeth”). An overbite is all about how much the top teeth overlap the bottom teeth vertically.

A healthy bite shows a small amount of overlap, which helps protect your teeth when you chew. If the overlap is too much, it’s called a “deep bite.” In severe cases, the lower teeth can be hidden behind the upper ones, or even hit the roof of your mouth. A quick check: if you can’t see much of your lower teeth when your mouth is closed, you might have too much vertical overlap.

Since the issue is vertical, the signs usually show up in wear patterns rather than jaw sticking out. Look for flattened or chipped lower teeth, a gummy smile, or jaw discomfort after chewing. 

TMJ (temporomandibular joint) issues, which involve pain in the jaw joint, might cause headaches or ear pain. In extreme cases, the lower teeth can actually bite into the roof of your mouth, leading to gum damage.

This is fairly common and your dentist or orthodontist will check for it during regular exams. They may use X-rays to determine the extent of the overlap and whether it’s caused by tooth position or jaw structure. 

Key Differences and Similarities Between Overbites and Underbites

Overbites and underbites are two common types of bite issues, but while they are quite different in how the teeth align, they also share some similarities. Let’s explore both the key differences and the common traits between them.

What’s the Difference?

1. Overbite (Top Teeth Covering Too Much of the Bottom):

– An overbite occurs when the upper front teeth cover the lower teeth excessively vertically. – Visually, this often makes the face appear shorter and rounder, as the top teeth overlap more than they should.

1. Underbite (Bottom Teeth Sticking Out):

– An underbite occurs when the lower teeth jut out in front of the upper teeth, causing a horizontal misalignment. – This typically results in a more pronounced chin and a forward-leaning lower facial profile.

Similarities Between Overbites and Underbites

1. Both are Misalignments: Both an overbite and underbite occur when the teeth do not line up properly, either vertically (overbite) or horizontally (underbite).
2. Impact on Jaw and Teeth: Both can lead to jaw pain, tooth wear and difficulty chewing or speaking.
3. Health Risks: Both misalignments can cause or contribute to TMJ (temporomandibular joint) disorders, which cause pain in the jaw, head and ears.
4. Aesthetic Effects: While the exact visual impact differs (overbites make the face appear rounder and underbites create a more prominent chin), both can affect facial appearance and overall smile alignment.

What Happens If Left Untreated?

1. Jaw Strain: Misalignments in either case make the jaw muscles work harder, leading to discomfort, headaches and jaw fatigue.
2. Wear on Teeth: Both overbites and underbites can cause uneven wear on the teeth, which might lead to tooth damage or sensitivity.
3. Speech and Chewing Problems: Difficulty speaking and chewing is common in both cases.
4. Increased Risk of TMJ Disorders: Both issues can put strain on the TMJ, which can lead to chronic pain, headaches and earaches if untreated.

Causes of Overbites and Underbites

Both overbites and underbites can be influenced by genetics, but daily habits play a big role in shaping how these issues develop. Here’s a simpler breakdown of what causes these bite problems:

Causes of Underbites

1. Genetics: If someone in the family has a prominent lower jaw, there’s a good chance that trait will be passed down. This is the most common cause of an underbite.
2. Environmental Factors: Things like mouth-breathing, chronic tongue-thrusting, or a history of cleft palate can worsen a mild jaw issue, leading to a noticeable underbite.
3. Habits: Prolonged use of a bottle or pacifier beyond the toddler years can also contribute to bite issues, especially an open bite, though it’s less likely to push the lower teeth forward.
4. Genetic Variations: Certain populations, such as some East Asian and Pacific Island groups, tend to have higher rates of skeletal underbites due to genetics.

Causes of Overbites

1. Genetics: If a child inherits a smaller lower jaw or a larger upper jaw, the top teeth may overlap the bottom teeth more than usual.
2. Habits: Thumb-sucking and pacifier use past age 4 can push the upper teeth forward. Tongue-thrusting during swallowing can increase horizontal overlap but also worsen the vertical overlap.
3. Crowding of Teeth: When baby teeth fall out early or teeth are crowded, the bite may deepen.
4. Teeth Grinding: Bruxism (grinding teeth) in teens or adults can make the upper teeth appear even longer, deepening the bite.

While genetics plays a key role in both overbites and underbites, everyday habits like thumb-sucking, pacifier use and teeth grinding can make these issues worse. 

The good news is that by recognizing these habits early and addressing them, it’s possible to prevent mild bite problems from becoming more serious.

Health Risks and Complications of Bite Misalignments

Misaligned bites, whether it’s an underbite or overbite, can lead to various physical and emotional challenges. 

1. Impact on Teeth and Enamel

1. Underbite:

– Front teeth may collide edge-to-edge, causing enamel loss. – This leads to sensitive, chipped and flattened teeth that are more prone to fractures.

1. Overbite:

– Excessive vertical overlap can cause the upper teeth to dig into the gums or roof of the mouth, leading to painful sores and tissue damage.

2. Jaw and TMJ (Temporomandibular Joint) Strain

1. Underbite:

– The lower jaw is pushed forward, forcing the TMJ to work harder to find a comfortable position. – Over time, this can cause chronic jaw pain and TMJ disorders.

1. Overbite:

– An excessive vertical overlap puts strain on the lower teeth, leading to headaches and muscle fatigue in the face.

3. Speech and Chewing Problems

1. Underbite:

– Difficulties with chewing and pronouncing certain words due to misaligned teeth.

1. Overbite:

– The awkward bite mechanics make thorough chewing difficult, which can lead to digestive issues over time.

4. Long-Term Costs of Untreated Bite Issues

1. Waiting to treat bite problems can result in:

– Expensive restorative treatments like crowns, which can be as costly as repairing a major issue (e.g., replacing a car battery). – Nightguards for TMJ pain. – Jaw surgery in severe cases.

5. Impact on Oral Hygiene

1. Both bite issues make cleaning teeth more difficult:

– Crowded, overlapping, or edge-to-edge teeth are harder to clean, leading to: – Increased risk of cavities and gum disease. – Loose teeth as gum tissue breaks down.

6. Emotional and Social Effects

1. Underbite: A prominent chin can affect your appearance and self-confidence.
2. Overbite: A “gummy” smile can make you self-conscious about your smile.

– Many people avoid social situations or photos due to these concerns.

Both underbites and overbites, if left untreated, can cause serious problems with your teeth, jaw and overall quality of life. The longer you wait to treat these issues, the more expensive and complex the solutions become. 

Treatment Options

When considering treatment for bite misalignments, there is no one-size-fits-all solution. The right approach for you depends on factors such as your age, the severity of the misalignment and whether the problem lies with your teeth, jawbones, or both. 

Below is a breakdown of the various treatment options available.

Phase 1 Orthodontic Treatment

The first stage of treatment, often recommended between ages 7 and 10, is Phase 1 orthodontics. This phase typically uses growth-guided appliances, such as palatal expanders or reverse-pull face masks, to gently reshape the developing jaw. 

The goal is to help permanent teeth come in with a healthier bite. Early intervention can prevent the need for more complex procedures later on, taking advantage of the fact that children’s bones are still growing and highly adaptable. The timing of this treatment is crucial, as starting early can yield long-term benefits.

#### Traditional Braces

For most bite problems in children or adults, traditional braces are the go-to solution. Braces use metal or ceramic brackets, wires and elastics to apply steady pressure, gradually aligning teeth and positioning the jaw as needed. 

Braces can treat virtually any degree of misalignment, from mild crowding to more severe skeletal issues. The typical treatment time ranges from 18 to 36 months, with monthly adjustments to track progress. Traditional braces remain the gold standard for bite correction, offering a proven and reliable solution.

#### Clear Aligners (e.g., Invisalign)

For those seeking a more discreet option, clear aligners like Invisalign provide an almost invisible alternative to traditional braces. Clear aligners are custom-made trays that gradually move teeth into their desired positions. 

They are particularly effective for mild to moderate bite problems. However, to achieve results similar to those of braces, you need to wear the aligners for 20–22 hours a day. 

Clear aligners are a great option for those who want flexibility and discretion, but for more severe skeletal issues, aligners alone may not be sufficient.

#### Jaw Surgery

In cases where there is a jaw size mismatch, jaw surgery becomes necessary. This procedure repositions the upper or lower jaw to address the root issue. After surgery, braces or aligners are used to fine-tune the bite during the healing process. 

The entire treatment process, including surgery and orthodontic adjustments, can take between 12 to 24 months. While this is a more complex and lengthy option, it provides a permanent solution for problems that braces alone cannot fix.

#### Cosmetic and Non-Surgical Options

For very mild cases of bite misalignment, treatment might not require braces or surgery. Enamel reshaping or cosmetic veneers can adjust the proportions of teeth to improve the bite and appearance. 

Additionally, myofunctional therapy, which involves targeted exercises to improve tongue posture and swallowing, can complement orthodontic treatments or serve as an early intervention in young children.

Take Control of Your Bite Health Today

Understanding the causes of bite misalignments and recognizing their early signs are crucial steps in protecting your long-term oral health. 

By seeking treatment early, whether it’s with braces, clear aligners, or other solutions, you can prevent more complex issues from developing down the road.

If you’re noticing signs of a misaligned bite, such as jaw pain, difficulty chewing, or tooth wear, it’s important to consult with your dentist or an orthodontist as soon as possible. 

To find trusted dental professionals near you, explore Sunbit’s dental directory. Taking action now ensures a healthier, more comfortable bite and supports your overall dental well-being.