An overbite is the vertical overlap of the upper front teeth over the lower front teeth when the back teeth are closed. A small overlap is normal and healthy, measuring 2 to 4 millimeters and covering roughly 25 to 30 percent of the lower front teeth. Nearly everyone has an overbite, so the useful question is not whether your child has one but how deep it is. Overlap past about 50 percent is called a deep bite, and at 90 to 100 percent the lower teeth disappear from view and may strike the tissue behind the upper teeth. Below we define the term precisely, explain how it is measured, map it against the other bite problems it gets confused with, cover what causes it, and answer the questions parents ask most.
What Is the Definition of an Overbite?
An overbite is how far the upper front teeth come down over the lower front teeth when the mouth is closed. It is a vertical measurement, taken from the biting edge of the upper incisor down to the biting edge of the lower incisor, and some amount of it is present in almost every healthy mouth. The word describes a normal feature of human anatomy that only becomes a diagnosis at the extremes.
The overlap exists for a reason. Upper front teeth sit slightly outside the lower ones. That slight outside position lets the upper teeth shear past the lower ones when your child bites down. Shearing past is how front teeth cut food, in much the way two blades of a scissor pass each other rather than meeting edge to edge. Front teeth that met perfectly flat would chip rather than cut.
Orthodontists file excessive overlap under malocclusion, the umbrella term for teeth and jaws that do not fit together correctly. The World Health Organization ranks malocclusion the third most significant oral health problem worldwide, behind only tooth decay and gum disease, which places a deep bite in the same category of concern as a cavity rather than in the same category as a hairstyle. We evaluate it alongside the other bite problems at every developmental checkpoint.
Why Is an Overbite So Common?
An overbite is common because the overlap itself is a normal feature of how human teeth are built. Everyone has some vertical overlap, so the word applies to nearly every mouth, and only the depth separates a healthy bite from one that needs attention. Much of the confusion around the term comes from people using it to mean a problem when it usually describes something ordinary.
Excessive overlap is also genuinely widespread. Malocclusion prevalence in children and adolescents ranges from 39 to 93 percent across populations, according to a scoping review published through the National Library of Medicine, and Angle Class II malocclusion, the jaw relationship that most often produces a deep bite, occurs in 15 to 20 percent of U.S. children based on published epidemiological data. A common finding is not automatically a harmless one, which is why measurement matters more than the label.
What Does a Normal Overbite Look Like Compared to a Severe One?
A normal overbite covers roughly 25 to 30 percent of the lower front teeth and measures 2 to 4 millimeters, while a severe overbite covers 90 to 100 percent and hides the lower teeth entirely. The dividing line for a deep bite sits at about 50 percent coverage, which is the point where orthodontists begin watching for functional damage. Cleveland Clinic guidance places the healthy range at that 2 to 4 millimeter overlap.
A healthy bite is easy to recognize once you know what to look for. When your child bites together naturally, you should see the full height of the lower front teeth minus the top quarter or so. The lower incisal edges should rest lightly against the back surface of the upper front teeth without pressing into tissue. Nothing should feel strained when the back teeth come together, and this is the reference point we measure against for every child we see in Yorktown Heights.
Severity climbs from there in stages rather than jumping. Between 30 and 50 percent, the overlap is deeper than ideal but rarely causing damage. Past 50 percent, uneven wear on the front teeth becomes the concern. Past 90 percent, soft tissue contact becomes the more pressing problem, since gum damage is harder to reverse than tooth position. Our orthodontist grades each case against those bands rather than describing a bite as simply good or bad.
How Do Orthodontists Measure an Overbite?
Orthodontists measure an overbite with a periodontal probe placed against the upper central incisor while the back teeth are closed. The measurement records how many millimeters of the lower incisor the upper tooth covers, and that number is then converted to a percentage of the lower tooth’s total height. Both figures appear in a chart because each one tells a different part of the story.
Millimeters and percentages can disagree. A child with short lower incisors may show a modest millimeter reading that still amounts to more than half the tooth covered. A child with long incisors may measure 4 millimeters and still fall inside a healthy percentage. This is one of several reasons a mirror check at home is a reason to ask rather than an answer in itself.
What Does a Severe Overbite Look Like?
A severe overbite looks like upper front teeth that cover nearly all of the lower front teeth, leaving little or none of them visible. In the deepest cases the lower incisal edges contact the tissue behind the upper front teeth or the roof of the mouth itself, which is called an impinging bite. The smile reads as top heavy because only the upper arch shows.
Parents often notice the effects before the depth. Flattened or chipped edges on front teeth in a young child, a chin that looks set back in side-profile photographs, and lower teeth that vanish in every school picture all point toward a bite well past the healthy range.
Is a 70% Overbite Bad?
A 70 percent overbite is a deep bite and generally warrants evaluation. At that depth the upper teeth cover more than two thirds of the lower front teeth, which sits well past the 50 percent threshold where orthodontists start tracking for wear and jaw strain. It is not an emergency, and it is not something to leave unexamined either.
What happens next depends on the cause rather than the number. A 70 percent overlap driven by tooth position in a growing child is a straightforward case. The same percentage driven by a jaw relationship is a different conversation with a different timeline. Depth tells you to look; the examination tells you what to do.
What Is the Difference Between an Overbite and an Overjet?
An overbite is vertical overlap and an overjet is horizontal protrusion. Overbite measures how far down the upper front teeth sit over the lower ones, while overjet measures how far forward they stick out ahead of them. These two terms are the most frequently confused pair in orthodontics, and even dental professionals swap them in casual conversation.
Picture the difference by changing your viewing angle. Looking at a child straight on, a deep overbite hides the lower front teeth. Looking from the side, a large overjet leaves a visible horizontal gap between the upper and lower front teeth, which is the pattern people casually call buck teeth. A child can have one, the other, or both at once.
The distinction carries real consequences. Cleveland Clinic guidance considers an overjet greater than 2 millimeters increased, with 8 to 10 millimeters classified as severe. Injury risk attaches specifically to overjet rather than to vertical overlap, and a prospective study following 1,413 schoolchildren found that those with an overjet of 6 millimeters or more carried 3.37 times the risk of traumatic dental injury. Using the words precisely is what keeps that risk visible.
What Are the Different Types of Bite Problems?
The main bite problems are overbite, overjet, underbite, crossbite, open bite, crowding, and spacing. Each describes a specific relationship between the upper and lower teeth, and a child can have several at the same time in different parts of the mouth. Placing your child’s situation on this map is the fastest way to understand what an orthodontist is describing.
The table below lays out each one, with prevalence figures drawn from published systematic reviews and national survey data where research supports them.
| Bite problem | What it describes | How it looks | How common in children |
|---|---|---|---|
| Overbite | Vertical overlap of upper front teeth over lower front teeth | Lower front teeth partly or fully hidden when the mouth closes | Present in nearly everyone; excessive in a minority |
| Overjet | Horizontal distance the upper front teeth sit ahead of the lower ones | A visible gap between upper and lower front teeth in side view | Increased overjet of 3 mm or more found in 41.2 percent of three-year-olds in one birth cohort |
| Underbite | Lower front teeth closing in front of the upper front teeth | The lower jaw appears to sit forward of the upper | Class III relationship in roughly 12 percent in one national survey |
| Crossbite | Upper teeth sitting inside the lower teeth on one or both sides | The jaw often shifts sideways to find a comfortable bite | Posterior crossbite affects 5 to 15 percent of children |
| Open bite | Front teeth that do not touch even when the back teeth close | A visible gap between the front teeth with the mouth shut | Anterior open bite in 10.9 percent of three-year-olds in the same cohort |
| Crowding | Teeth competing for space in an arch too small to hold them | Overlapping, twisted, or stacked teeth | Mean prevalence of 33.8 percent across studies of children and adolescents |
| Spacing | Gaps between teeth that should be in contact | Visible spaces, often between the upper front teeth | Common in young children and frequently self-correcting |
Underbite sits at the opposite end of the scale from overbite, and the two get paired in searches constantly because they describe opposite versions of the same front-tooth relationship. Sorting which one a child has is the first step in any orthodontic treatment plan, since the two move in opposite directions.
What Is the Difference Between an Overbite and an Underbite?
An overbite means the upper front teeth close over the lower ones, and an underbite means the lower front teeth close in front of the upper ones. The two are opposite conditions, and an underbite almost always reflects jaw proportion rather than tooth position alone. A child cannot have both at the front of the mouth at the same time, though a child can have an underbite on one side and a normal relationship on the other.
Treatment timing differs sharply between them. An underbite usually involves a lower jaw growing further forward than the upper one, and guiding that relationship works best while growth is still active. Overbites driven by tooth position are far less time-sensitive. This is one of the clearest illustrations of why naming the condition precisely changes what happens next.
What Is a Class I, Class II, or Class III Bite?
Class I, Class II, and Class III describe how the upper and lower back molars line up with each other. Class I means the molars meet in a normal relationship, Class II means the lower molars sit behind where they should, and Class III means the lower molars sit ahead of where they should. This system is called Angle classification, and it appears on nearly every orthodontic chart and referral.
Parents encounter these terms most often on a treatment plan. A Class II bite is the one that most frequently produces a deep overbite or an increased overjet, since a lower jaw sitting back leaves the upper front teeth covering more than they should. Class II is further split into division 1, where the upper front teeth flare forward, and division 2, where they tip backward.
The distribution across children is well documented. One national survey found a Class I molar relationship in 65 percent of children, Class II division 1 in 17 percent, Class II division 2 in 6 percent, and Class III in 12 percent. Knowing your child’s classification tells you more about their treatment than the overbite percentage alone does.
Can a Child Have an Overbite and Crowding at the Same Time?
Yes, a child can have an overbite and crowding at the same time, and the combination is extremely common. Crowding and deep bites frequently share a root cause, since an arch too small to hold the teeth often accompanies a jaw relationship that deepens the front overlap. Treating them together in one plan is routine rather than exceptional.
Combinations extend further than that. A child may have a deep overbite at the front, a crossbite on one side, and crowding in the lower arch, all at once. An orthodontic examination catalogues every finding rather than naming a single diagnosis, which is why a treatment plan usually addresses several conditions in one sequence.
What Causes an Overbite?
An overbite is caused by inherited jaw proportions, tooth position, childhood oral habits, or missing teeth. Orthodontists sort every case into two groups: a dental overbite, where the jaws are proportioned reasonably and the teeth sit wrong, and a skeletal overbite, where the jaws themselves do not match. Those two groups look similar from the outside and respond to completely different treatment.
The causes behind each group:
- Genetics. Jaw size, jaw position, and tooth size are inherited, and a small or set-back lower jaw is the most common single cause of a skeletal overbite.
- Jaw growth patterns. The two jaws grow on separate schedules, and a mismatch in timing can deepen an overlap during childhood.
- Thumb and finger sucking. Steady pressure behind the upper front teeth tips them forward and holds the lower teeth back.
- Prolonged pacifier use. The same mechanism as digit sucking, with published research showing pacifier habits carry their own distinct malocclusion risks.
- Tongue thrusting. A tongue that presses forward during swallowing applies force to the front teeth thousands of times a day.
- Missing or lost lower teeth. When a lower tooth is absent, the opposing upper tooth over-erupts into the gap and deepens the overlap.
- Crowding. Teeth without room to sit upright tip and rotate, which changes how the front teeth meet.
Habits matter most when they persist. Research published in Pediatric Dentistry estimates that roughly 50 percent of infants suck a thumb or finger at age one, with average spontaneous cessation at 3.8 years, so habits ending in that normal window rarely leave a mark. Published etiology research associates chronic thumb sucking with roughly 4.25 times the malocclusion risk when it continues well past that point. When encouragement alone is not enough, custom habit appliances can interrupt the pressure gently.
Tooth loss deserves its own note because parents rarely connect it to bite development. Losing a baby molar years ahead of schedule lets neighboring teeth drift into the gap and blocks the permanent tooth beneath, which changes both the crowding picture and the bite. We treat early tooth loss as an orthodontic event for exactly this reason.
Jaw width contributes as well. A narrow upper arch crowds the teeth and often accompanies a deeper front overlap, and widening that arch during growth addresses both at once. A palatal expander is the appliance used for this, and it works best in younger children because the growth seam in the palate has not yet matured.
Can a Young Child Have an Overbite?
Yes, a young child can have an overbite, and some degree of overlap is normal even in baby teeth. What makes a young child’s bite different is that it is still forming, so some findings resolve as permanent teeth arrive while others deepen. Separating the two requires measurement rather than a guess.
Baby-tooth bites carry real information. A birth cohort study of three-year-olds found increased overjet of 3 millimeters or more in 41.2 percent of children and anterior open bite in 10.9 percent, and every child in that cohort with a thumb habit had some form of malocclusion. Findings at three are not predictions, but they tell us which children to watch closely.
The American Association of Orthodontists recommends a first orthodontic evaluation no later than age 7, which is when enough permanent teeth have arrived to read the developing bite reliably. Children who need earlier intervention move into Phase 1 treatment, and most children evaluated at seven need nothing more than a monitoring schedule.
What Does an Overbite Do?
A deep overbite wears down the front teeth, irritates the gum tissue behind the upper teeth, strains the jaw joints, and makes certain sounds and foods harder to manage. A normal overbite does none of these things, which is the entire reason depth matters more than the label. Each effect has its own mechanism and its own timeline.
Wear comes first and progresses quietly. Front teeth meeting at the wrong angle grind against each other rather than shearing past, which flattens and chips the incisal edges over years. Enamel does not regrow, so wear accumulated during childhood stays.
Tissue damage follows in deeper cases. Lower incisal edges striking the tissue behind the upper front teeth inflame that tissue with every closure, and chronic inflammation leads to gum recession. Jaw strain arrives alongside, since a bite that prevents the back teeth from meeting evenly makes the jaw muscles work harder to find a stable position. Children who grind at night compound all of it, and worn edges alongside morning jaw soreness often point toward teeth grinding happening together with the bite problem.
Function is the part families notice at home. Children with deep bites struggle to bite into sandwiches and apples, compensate by chewing on one side, and sometimes develop a lisp because the tongue cannot reach its normal contact point behind the upper front teeth.
What Does an Overbite Do to Your Face?
A deep overbite can make the lower third of the face look slightly shorter and the chin look set back when the bite closes. The effect is usually subtle, and it comes from where the jaw rests rather than from the shape of the bone itself. Descriptions that treat an overbite as disfiguring overstate what a bite does to appearance.
Lip posture accounts for most of the visible difference. Upper front teeth that sit forward push the upper lip out and can make closing the lips at rest take conscious effort. A deep vertical overlap allows the lower jaw to close further than it should, which shortens the lower face fractionally.
This is worth stating plainly for parents of children who have been looking at social media comparisons. Correcting a bite improves how the lips rest and how the profile balances, and in a growing child guided jaw development can change the profile more noticeably. It does not reshape a finished face, and any content promising that is selling something.
Do Overbites Get Worse With Age?
Yes, overbites get worse with age when they go untreated. A deep bite tends to deepen as the lower front teeth keep erupting into the space available, the upper front edges wear down, and neighboring teeth drift. Bites do not correct themselves once the permanent teeth are established.
Mild cases in young children are the exception. Some overlap present in baby teeth improves as the permanent teeth arrive and the arch changes shape, which is why a finding at four does not automatically become a diagnosis at eight. Significant overlap rarely self-corrects and usually holds steady or deepens.
Tracking the difference is what monitoring is for. We compare measurements across visits rather than relying on a single reading, and most of that tracking happens alongside routine checkups so families are not adding appointments to watch a bite develop.
Is It Possible to Live With an Overbite?
Yes, it is possible to live with an overbite, and most people do. A normal overlap of 2 to 4 millimeters needs no treatment at all, and a modestly deep bite causing no wear, no tissue contact, and no jaw symptoms can reasonably be monitored rather than treated. Treatment becomes the recommendation when the bite starts costing something.
The threshold is functional rather than cosmetic. Worn or chipped front edges, lower teeth contacting tissue, jaw soreness after chewing, difficulty biting into food, and speech sounds that have not improved with time all move a bite from acceptable to worth correcting. None of those present means watching is a legitimate plan, and a good orthodontist will say so rather than finding a reason to treat.
Before deciding whether to seek an evaluation, here is what to check at home:
- Have your child bite together normally and pull the lips back. Note roughly how much of the lower front teeth you can still see.
- Look at the edges of the upper front teeth. Flattening or chipping at a young age signals abnormal contact.
- Check a side-profile photograph. Note whether the chin looks set back or the lips take effort to close.
- Watch a meal. Notice whether your child bites with the front teeth or tears with the back ones, and whether they favor one side.
- Listen for s and z sounds. A persistent lisp can reflect where the teeth sit rather than a speech habit alone.
- Ask about soreness. Jaw fatigue after eating, clicking, or morning headaches are worth mentioning at the next visit.
None of this replaces a measurement, and it is not meant to. It tells you whether to raise the subject. Families across Yorktown Heights bring exactly this kind of observation to a first visit, and it gives us a useful starting point.
Do I Need Braces If I Have an Overbite?
You need braces for an overbite only when the overlap causes functional problems or when the appearance genuinely bothers you. A normal overbite needs nothing, a moderate one may be monitored, and a deep bite causing wear or tissue damage is the case where treatment is recommended. Severity and cause decide, not the presence of the word overbite.
When treatment is warranted, several paths exist. Fixed braces handle the full range from mild to severe and give the most precise control over the vertical movement a deep bite requires, which is why they remain the most common approach for children and teens.
Removable options suit narrower cases. Clear aligners correct mild to moderate dental overbites in patients who wear them consistently, while growing children with a jaw-based overbite often do better with an appliance that guides jaw development during growth.
What Types of Braces Correct an Overbite?
Metal braces, ceramic braces, and clear aligners all correct overbites, with metal braces handling the widest range of severity. Ceramic brackets work the same way as metal ones with tooth-colored hardware, and aligners trade some control for removability. The appliance matters less than whether the case is dental or skeletal.
Whichever route a case takes, elastics usually play a part, since rubber bands stretched between the arches are what change the jaw relationship while the brackets or trays handle the teeth. We go through the full options at the consultation rather than online, because bite correction depends on measurements a photograph cannot provide.
Frequently Asked Questions
Is an Overbite the Same as a Deep Bite?
An overbite and a deep bite are not quite the same thing. Overbite describes the vertical overlap generally, including the normal amount everyone has, while deep bite is the term for an overbite that exceeds the healthy range. Every deep bite is an overbite, but most overbites are not deep bites.
Can a Retainer Fix an Overbite?
A retainer cannot fix an overbite, though it is essential for holding one that has been corrected. Retainers are designed to maintain tooth position rather than to move teeth, and the force needed to reduce a vertical overlap is well beyond what a retainer applies. A retainer worn after treatment is what keeps a corrected bite from drifting back.
Will My Overbite Come Back After Braces?
An overbite can come back after braces if retainers are not worn as directed. Deep bites are among the corrections most likely to relapse, because the muscle patterns and eruption tendencies that created the overlap remain after the teeth have moved. Consistent retainer wear on the prescribed schedule is what holds the result long term.
Is an Overbite Genetic?
Yes, an overbite is largely genetic, since jaw size, jaw position, and tooth size are all inherited traits. A child with a parent who had a deep bite is more likely to develop one. Childhood habits and early tooth loss can deepen an overlap that genetics started, which means most cases have more than one contributing factor.
At What Age Should an Overbite Be Checked?
An overbite should be checked by age 7, which is when the American Association of Orthodontists recommends every child have a first orthodontic evaluation. At that age enough permanent teeth have erupted to read the bite reliably. A child showing signs earlier should be seen when the sign appears rather than waiting for the milestone.
Can an Overbite Cause a Lisp?
Yes, an overbite can cause a lisp when the overlap moves the tongue’s contact point out of reach. Sounds like s and z require the tongue to approach a specific spot behind the upper front teeth, and a deep bite or large overjet can block that position. Correcting the bite removes the obstacle, though a habit formed over years may need separate speech practice to resolve.
The Bottom Line
An overbite is the vertical overlap of the upper front teeth over the lower front teeth, and nearly everyone has one. A healthy overlap runs 2 to 4 millimeters and covers roughly a quarter to a third of the lower front teeth. Past about 50 percent coverage the bite is called deep, and at 90 to 100 percent the lower teeth disappear and may strike tissue. Getting the word right matters because overbite, overjet, underbite, crossbite, and open bite describe different problems with different causes and different timing.
The practical question for a parent is never whether a child has an overbite but whether theirs is doing any harm. Worn front edges, tissue contact, jaw soreness, and trouble biting into food are the signs that move a bite from ordinary to worth measuring. Every child should be evaluated by age 7, and here in Yorktown Heights most of the children we see at that age leave with a monitoring schedule rather than an appliance. If something about your child’s bite has been on your mind, we would be glad to measure it and tell you plainly where it falls at Cohen Family Smiles, and you can contact us whenever it suits you.
