Some degree of overbite is completely normal. Your upper front teeth are supposed to overlap your lower front teeth slightly, typically by 1 to 3 millimeters. This overlap helps you bite and chew efficiently. It only becomes a concern when the overlap exceeds about 4 millimeters, or when your upper teeth cover more than roughly 30% of your lower teeth.
What Counts as a Normal Overbite
A normal, healthy bite features a vertical overlap of 1 to 3 millimeters between the upper and lower front teeth. In a large study of children aged 10 to 12, about 48% had overbite values in the 0 to 2 millimeter range, while another 38% fell in the 3 to 4 millimeter range. So most people have at least a small overbite, and a mild one is extremely common.
An overbite becomes clinically significant, often called a “deep bite,” when the overlap exceeds 4 millimeters. In that same study, about 12% of children had an overbite of 5 to 6 millimeters, and only 1.5% had one greater than 7 millimeters. Overall, the prevalence of a true deep bite was around 22.6%. So while deep bites aren’t rare, they’re the minority.
Overbite vs. Overjet
These two terms get confused constantly, but they describe different things. Overbite is vertical: how much your upper teeth drop down over your lower teeth when you close your mouth. Overjet is horizontal: how far forward your upper teeth stick out past your lower teeth. A normal overjet is about 2 millimeters. When the horizontal gap is larger than that, you get what people commonly call “buck teeth,” which is a separate issue from a deep overbite. You can have one without the other, or both at the same time.
What Causes a Deep Overbite
Deep overbites have multiple causes, and genetics plays the biggest role. Research shows that skeletal factors, particularly the shape and rotation of the lower jaw, contribute more to overbite than the teeth themselves. A lower jaw that rotates slightly upward and forward, a steeper curve along the biting surfaces of the teeth, and a smaller jaw angle all push the bite deeper. These are inherited traits you can’t control.
The mechanics are straightforward: either the front teeth have erupted too far, the back teeth haven’t erupted enough, or the jawbones themselves are shaped in a way that creates excessive overlap. Often it’s a combination. Childhood habits like prolonged thumb sucking or pacifier use can worsen an existing tendency, but jaw structure is the primary driver. Orthodontists classify deep bites into two main patterns. In one, the upper front teeth protrude forward with a narrow, V-shaped upper arch. In the other, the upper central teeth tilt backward and the upper arch is broader, creating a deep overlap without the forward protrusion.
When an Overbite Needs Treatment
A small overbite in the 1 to 3 millimeter range rarely needs any treatment. Once the overlap moves beyond 4 millimeters, or once you start noticing symptoms, treatment becomes worth discussing. The decision isn’t purely about appearance. A deep bite can cause real problems over time.
The most common issues include:
- Tooth wear. Overbites greater than 4 millimeters are associated with higher levels of enamel loss. The upper and lower teeth grind against each other at steeper angles, wearing down surfaces faster than normal.
- Gum damage. In severe deep bites, the lower front teeth can contact the gum tissue behind the upper teeth, or vice versa. Over years, this repeated pressure causes irreversible damage to the gum and bone.
- Jaw pain. Severe overbites frequently occur alongside temporomandibular joint problems, including jaw clicking, stiffness, and pain. Among patients with severe bite problems referred for surgical correction, 43% to 73% also had jaw joint dysfunction.
If your overbite isn’t causing pain, wear, or gum issues, and it falls in a mild range, treatment is optional and primarily cosmetic. If you’re experiencing any of the symptoms above, or if a dentist has measured your overlap at 4 millimeters or more, correction can prevent worsening damage.
How Overbites Are Corrected
Treatment depends on severity. For mild to moderate deep bites, clear aligners can work well. They gradually shift teeth into better positions over roughly 6 months to 2 years. However, research indicates aligners are less effective at producing large changes, so they’re best suited for cases that need modest correction.
Traditional braces remain the standard for more significant overbites. They offer more precise control over tooth movement, particularly in the vertical dimension, and treatment typically lasts 1 to 3 years. Elastic bands are often added to braces (and sometimes to aligners) to help pull the bite into proper alignment more effectively.
For the most severe cases, where the overbite stems from a significant skeletal mismatch rather than just tooth position, jaw surgery may be recommended. This is relatively uncommon and reserved for situations where braces alone can’t achieve a stable result because the underlying bone structure is too far off.
What to Look for in Your Own Bite
You can get a rough sense of your overbite at home. Close your teeth together naturally and smile in a mirror. If you can see about a third or less of your lower front teeth peeking out below the upper ones, you’re likely in normal range. If your upper teeth cover most or all of your lower teeth, or if your lower teeth bite into the roof of your mouth, that suggests a deeper bite worth having evaluated.
Pay attention to symptoms more than appearance. Worn-down or chipped front teeth, soreness in the gum tissue behind your upper teeth, and jaw pain or clicking are the practical signals that an overbite is causing harm. Many people live their entire lives with a mildly deep bite and never need treatment. The bite only becomes a problem when it starts damaging other structures or causing discomfort.