An overbite is how much your upper front teeth vertically overlap your lower front teeth. An overjet is how far those upper teeth stick out horizontally in front of the lower ones. Both are normal in small amounts. Both are treatable with braces or clear aligners when they are excessive.
The two terms get used interchangeably, including by people who should know better, and the confusion matters because they are corrected differently. Here is the distinction in plain terms.
Overbite vs. Overjet: The Core Difference
| Overbite | Overjet | |
|---|---|---|
| Direction | Vertical — up and down overlap | Horizontal — forward projection |
| What you see | Upper teeth cover much of the lower teeth | Upper teeth angle or sit out in front |
| Healthy range | Roughly 1 to 3 mm of overlap | Roughly 1 to 3 mm of horizontal gap |
| Excessive version called | Deep bite | Protrusion, sometimes called buck teeth |
| Main risks | Excess wear on lower teeth, gum irritation, jaw strain | Front tooth trauma, difficulty closing lips, speech effects |
A useful mental test: look in a mirror and bite together normally. If your upper teeth hide most of your lower front teeth, you are looking at an overbite. If they jut forward with a visible horizontal step, that is overjet. Many patients have some of both.
What Causes Each One?
Causes of a Deep Overbite
- Genetics and inherited jaw proportions
- Lower jaw that is smaller relative to the upper jaw
- Missing or worn back teeth, which lets the bite collapse
- Long-term clenching and grinding
Causes of Excessive Overjet
- Genetics and jaw relationship
- Prolonged thumb sucking or pacifier use in early childhood
- Tongue thrusting when swallowing
- Mouth breathing and its effect on tongue posture during growth
- Crowding that pushes upper front teeth forward
Note how many of these are habits established before age 7. That is precisely why the American Association of Orthodontists recommends an evaluation at that age — a habit interrupted early can prevent a much larger correction later. See early orthodontic treatment in Riverside, CA.
Why These Are Worth Correcting
Neither condition is purely cosmetic when it is significant:
- Uneven wear. A deep bite concentrates force on the front teeth, flattening and chipping them over decades.
- Gum damage. Lower teeth biting into the upper palate, or upper teeth into the lower gums, causes chronic irritation and recession.
- Trauma risk. Protruding upper front teeth are considerably more likely to be broken in a fall or a collision.
- Jaw muscle strain. A bite that does not seat evenly makes the jaw muscles work to find a comfortable position.
- Speech and lip closure. Significant overjet can affect certain sounds and make lips difficult to close at rest.
How Orthodontists Correct an Overbite
Fixing a deep bite means opening it — reducing the vertical overlap. Common approaches:
- Leveling the arches. Wires or aligner stages designed to bring the front teeth up and the back teeth into better contact.
- Bite ramps or turbos. Small stops that prevent the front teeth from over-closing while the back teeth settle.
- Elastics. Rubber bands that change how the arches relate vertically.
- Growth modification in children. Guiding lower jaw growth while a child is still developing.
- Restorative finishing. If years of a deep bite have worn the front teeth down, bonding or crowns may follow alignment.
How Orthodontists Correct an Overjet
- Retracting the upper front teeth, often after creating space through expansion or, less commonly, extraction.
- Advancing the lower jaw or teeth in growing patients using functional appliances or elastics.
- Habit correction first. Thumb-sucking and tongue-thrust habits must be addressed or the overjet returns.
- Surgical options in adults where the discrepancy is skeletal rather than dental and the patient wants full correction.
Can Braces or Aligners Fix Both?
Yes, in most cases. Braces offer the most direct control for significant vertical and horizontal correction, especially in growing patients where elastics and appliances do the heavy lifting. Clear aligners handle mild to moderate cases well, using precision cuts, elastics, and staged movements designed to open the bite.
What determines the answer is not the appliance brand but whether the problem is in the teeth or in the jaws. Only X-rays can tell you that.
How Long Does Correction Take?
| Case | Typical duration |
|---|---|
| Mild overbite or overjet, teeth-only | 6 to 12 months |
| Moderate case with elastics | 12 to 24 months |
| Growing child with appliance-assisted correction | 18 to 30 months, sometimes in two phases |
| Adult skeletal case with surgery | Typically 18 to 30 months of orthodontics around the surgical step |
How Orthodontists Measure Your Bite
Both conditions are measured in millimeters, not eyeballed, which is why records matter more than a mirror check:
- Overbite is recorded as the vertical overlap of the upper central incisors over the lower ones, often expressed as a percentage of the lower tooth height. Roughly 20 to 30 percent coverage is typical; 50 percent or more is generally called a deep bite.
- Overjet is measured horizontally from the front surface of the lower incisors to the front surface of the uppers. Around 1 to 3 mm is normal; beyond about 5 mm the risk of trauma to the front teeth climbs noticeably.
- Related findings that change the plan include an open bite (no overlap at all), a crossbite, and how the back teeth relate front to back.
Those numbers get compared against a cephalometric X-ray, which shows whether the problem lives in the teeth or the jaws. That single distinction determines whether treatment is straightforward, needs growth guidance, or needs a surgical conversation.
Overbite and Overjet in Children vs. Adults
| Growing child or teen | Adult | |
|---|---|---|
| Tools available | Growth guidance, expanders, functional appliances, elastics | Tooth movement, elastics, mini-screws, surgery if skeletal |
| Skeletal correction | Possible while growth remains | Requires surgery |
| Habit factors | Thumb sucking and tongue thrust can still be interrupted | Habits usually resolved; damage already established |
| Typical result | Full correction of the underlying relationship | Full correction of teeth; jaw relationship compensated |
This is the practical reason orthodontists sound impatient about early evaluations. In a child, an excessive overjet may be a growth-guidance case. In an adult, the same measurement is a compromise-or-surgery conversation.
What Happens If You Leave It Alone
- Deep bites tend to deepen. As back teeth wear or are lost, the front teeth take more load and the overlap increases.
- Front teeth chip and wear. Enamel does not regenerate, so a case that was purely orthodontic at 25 may need bonding or crowns at 45.
- Gum recession progresses where lower teeth strike the upper gums, or vice versa.
- Trauma risk stays elevated for as long as the front teeth protrude.
- Treatment gets longer, not shorter. Compensations accumulate, and so does the work required to undo them.
Frequently Asked Questions
Is a small overbite normal?
Yes. About 1 to 3 mm of vertical overlap is normal and desirable; it protects the lower front teeth. Zero overlap is its own problem, called an open bite.
Can an overbite get worse over time?
It can. Worn or lost back teeth let the bite collapse further, which deepens the overbite and accelerates wear on the front teeth.
Does fixing an overjet change my profile?
It can soften the appearance of protruding front teeth and improve lip closure. Changes to the jaw itself require growth guidance in children or surgery in adults.
Can adults fix a deep bite without surgery?
Often yes, when the problem is dental. When it is skeletal, non-surgical treatment is a compromise, and a good orthodontist will tell you exactly what that compromise is.
Will my child grow out of it?
Sometimes crowding resolves as the jaw grows; excessive overjet and deep bites usually do not resolve on their own. An evaluation by age 7 answers the question for your child specifically.
Not sure which one you are looking at? Learn about orthodontic care for kids in Riverside, CA or schedule a free consultation.