Overbite commonly refers to a lower jaw being too far behind the upper jaw (retrognathia) or a misalignment of the teeth. Medically, the term refers to the extent of vertical (superior-inferior) overlap of the maxillary central incisors over the mandibular central incisors, measured relative to the incisal ridges.
The term overbite does not refer to a specific condition, nor is it a form of malocclusion. Rather an absent or excess overbite would be a malocclusion. Normal overbite is between 3–5 mm (or approximately 20–30% of the height of the mandibular incisors) and is commonly expressed as a percentage. Young children commonly have a deep bite (excessive overbite), however it is resolved due to the growth of the maxilla and the mandible. If it is not corrected it may lead to trauma.