Overjet, overbite and types of bite
What you need to know
- Overjet: how far the upper incisors stick out in front of the lower ones, horizontally. Normal: more than 0 and up to about 3 mm. More than 3 mm is an increased overjet.
- Edge-to-edge: the incisors meet tip to tip (overjet of 0).
- Overbite: how much the upper incisors cover the lower ones, vertically. Normal: up to one third of the lower crown.
- Deep bite: the upper teeth cover the lower ones too much. The cutoff varies from study to study (for example, more than 2.5 mm or more than two thirds of the crown).
- Open bite: the front teeth don't touch or overlap vertically (negative overbite). It has been linked to sucking habits, like thumb sucking.
- Anterior crossbite: one or more upper incisors or canines sit behind the lower ones.
- Posterior crossbite: the upper molars bite on the inside (toward the tongue) of the lower ones. It can be on one side or both.
- In a worldwide review (permanent dentition): Class I ≈75%, Class II ≈20%, Class III ≈6%; deep bite ≈22%, increased overjet ≈20%, posterior crossbite ≈9% and open bite ≈5%.
Values used in studies
| Trait | How to recognize it |
|---|---|
| Normal overjet | More than 0 and up to 3 mm |
| Increased overjet | More than 3 mm |
| Edge-to-edge | 0 mm |
| Anterior crossbite | The upper teeth sit behind |
| Open bite | Negative overbite (no overlap) |
Terms in plain words
OverjetHorizontal distance between the upper and lower incisors.
OverbiteHow much the upper incisors cover the lower ones vertically.
MalocclusionWhen the teeth don't fit together the way they should when you close your mouth.
CrossbiteWhen upper teeth sit inside or behind the lower ones (the reverse of normal).
For the exam
The upper incisors stick out 6 mm in front of the lower ones. Which trait is it?
Show answerHide answer
Increased overjet (more than 3 mm).
Sources
- Yu X, et al. Prevalence of malocclusion and occlusal traits in the early mixed dentition in Shanghai, China. PeerJ. 2019;7:e6630. View source
- Alhammadi MS, et al. Global distribution of malocclusion traits: A systematic review. Dental Press J Orthod. 2018;23(6):40.e1–10. View source
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