THE SCIENTIFIC JOURNAL
Overbite: What Is Normal and When a Deep Bite Matters
By Dr. Khalid Aletaibi8 min readQUICK ANSWER
An overbite is the vertical overlap of the upper front teeth over the lower front teeth when you bite together, and roughly 2 to 4 mm of overlap is considered the normal range [1]. An overlap covering more than half the height of the lower front teeth is a deep overbite, or deep bite [2]. It becomes a health matter when the lower teeth bite into the gum behind the upper teeth, the front teeth wear, or protruding upper teeth make chipping more likely.
What is an overbite?
An overbite is how far the upper front teeth cover the lower ones vertically, measured with the back teeth closed. Some overlap is healthy, because the front teeth help guide the jaw as it moves. The word describes a measurement rather than a disease: the overlap is called deep when excessive, and an open bite when a vertical gap replaces it.
What is the difference between an overbite and an overjet?
Overbite is the vertical overlap of the front teeth, while overjet is the horizontal distance by which the upper front teeth sit ahead of the lower ones. The two are correlated [1], and people who say "overbite" about buck teeth usually mean a large overjet; prominent upper front teeth affect about a quarter of 12-year-olds in the UK [11].
| Feature | Deep bite (deep overbite) | Large overjet ("buck teeth") |
|---|---|---|
| Direction | Vertical overlap | Horizontal protrusion |
| What you notice | Lower front teeth hidden behind the upper | Upper front teeth that stick out |
| Main health concern | Gum injury and tooth wear [2] | Chipped or knocked front teeth [12] |
How much of an overbite is normal?
An overlap of roughly 2 to 4 mm is regarded as normal, though there is no single agreed definition [1]. Populations differ: English samples tended towards larger overbites and Iraqi samples towards smaller ones [1]. Thresholds for a deep bite vary too, from more than half the height of the lower front teeth [2] to more than 3.5 mm [3] or 4 mm [4]. Across 53 studies worldwide, about 22% of the people examined had a deep overbite [8], so the number alone rarely decides anything; its effect on the teeth and gums does.
What causes a deep overbite?
A deep overbite can come from the teeth, the jaws or both, and the teeth tend to play the larger part [4]. In 252 patients aged 16 to 41, how far the lower front teeth had erupted and how the front teeth were angled explained more of the overlap than jaw shape did [4]. In 124 patients, an exaggerated curve in the line of the lower teeth (the curve of Spee) was present in 78%, against 37.1% for a squarer angle at the back of the lower jaw, the main jaw-related finding [5].
One person can show several features, so the figures do not add up to 100%.
Genes contribute too: in young twins, about half the variation in overbite was attributed to genetic factors (heritability 0.53) [6]. Upper front teeth that tilt back towards the palate are characteristically paired with a deep overbite [10], and in children, airway factors such as mouth breathing can influence how the jaws grow.
Can a deep overbite damage your teeth and gums?
Yes, a deep overbite can injure the gums and wear the teeth, and these signs make it a health matter rather than a cosmetic one:
- Gum contact. The lower front teeth can bite into the gum behind the upper teeth, or the upper teeth into the gum in front of the lower ones. Case reports link this to unusual gum and bone lesions, especially with poor oral hygiene [15].
- Wear and lack of space. Deep overbites are associated with tooth wear and too little room for restorations [2].
- Chipping when the overjet is large. School-age children with an overjet over 5 mm had 2.43 times the odds of a dental injury [12], and among children in Arab countries an overjet above 3.5 mm was linked with 1.78 times the odds of a dental injury [13].
Can an overbite cause jaw pain or headaches?
An overbite can play a part, since a deep bite may contribute to functional disturbances [4], but it is rarely the sole cause of jaw pain or headaches, which usually have several contributing factors. With jaw symptoms, the bite is examined alongside the muscles and joints, as in occlusal therapy, rather than assumed to be the cause.
What does an overbite assessment look at?
An overbite assessment measures the overlap and the overjet, then checks the gums, the teeth and the underlying cause.
- 1
Measure the bite
The overlap and the overjet are measured with the back teeth together.
- 2
Check the gums
The gum behind the upper front teeth and in front of the lower ones is examined for marks or recession.
- 3
Look for wear and room
Biting edges, chips, existing restorations and the space between the teeth are checked.
- 4
Find the cause
Scans, photographs and, where needed, X-rays show whether the teeth, the jaws or both are responsible.
How is an overbite corrected?
An overbite is treated according to its cause and symptoms, with options ranging from a simple removable appliance and gum care to combined orthodontic, surgical and restorative treatment [2]. Tooth movement is team care: Dr. Khalid assesses the whole mouth and plans the movement jointly with the orthodontist he works with, from a restorative end result agreed first, and he stays on the case throughout; see orthodontics.
Can Invisalign fix an overbite? Invisalign and other clear aligners can correct some tooth-based deep bites; whether they or braces suit yours depends on the movement needed. See clear aligners, where clear aligners are compared with traditional braces.
Can veneers fix an overbite? Not on their own. Veneers change the shape and colour of the front teeth, not how the jaws meet, and a tight deep bite may leave little room for them [2]; see braces or veneers.
Can rebuilding worn teeth open the bite? Where wear has shortened the teeth, restorations can sometimes rebuild them and raise the bite at the same time [2], within a planned full mouth rehabilitation for a worn-down smile.
How I decide whether an overbite needs treatment
I decide by looking first at the tissue around the overlap: the gum behind the upper front teeth and in front of the lower ones, the biting edges for wear and chips, and whether a tooth that may need a restoration would have room for it. A deep bite with healthy gums, no wear and a patient happy with their smile is a measurement, not a problem, and there I advise monitoring rather than treatment.
My advice changes when the bite is injuring the gum, wear is progressing, a large overjet leaves the upper teeth more prone to injury [12], or there is no space for work a tooth genuinely needs. Where teeth need to move, I plan the case jointly with the orthodontist I work alongside, from the same scans and records. We agree the restorative end result first, so the tooth movement is planned to that brief, and I stay on the case until we review the result together, carrying out any restorative work myself. When the jaws are the main cause, I explain why a combined plan may be worth discussing, bringing in the surgeons and orthodontists I work with as the case needs.
I would rather move a healthy tooth than reshape it to disguise the bite, because moving it keeps the enamel that reshaping would remove, and I go through each option on the patient's own scans before anything is decided.
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