Overjet: horizontal overbite
The overjet describes the horizontal distance between the upper and lower incisors. In a horizontal overbite, the upper jaw is too large compared to the lower jaw and protrudes significantly. Accordingly, the upper incisors protrude too far forward, creating a large gap between them and the lower teeth.
Ideally, this distance should be only 1–2 mm. When we talk about “overbite”, most people imagine a positive overjet – a malocclusion where the upper teeth protrude forward. This can have skeletal or dental causes and can be either a jaw or a tooth misalignment. In a negative overjet, the lower teeth protrude and the upper teeth are further back, creating a so-called prognathism.
Overbite: vertical misalignment
Contrary to the overjet, the overbite describes the vertical position of the teeth in relation to each other. Normally, the protrusion is 2–3 mm and the upper teeth are in front of the lower teeth. However, if the upper front teeth completely cover the lower teeth, this is referred to as deep bite. If, on the other hand, the upper teeth are covered by the lower teeth, it is called prognathism.