An ‘Underbite’ occurs when the lower teeth are in front of the upper front teeth. This is a reverse bite, compared to normal. The accurate way to describe this is a reverse overjet/ negative overjet or Class III incisor malocclusion.
When this happens, you can not really see the upper front teeth from the front view and maybe associated with a long jaw face and a large, strong chin. This unnatural way of biting leads to uneven wearing out and damages teeth. An underbite not only affects facial appearance, but also eating efficiency and sometimes speech too, as the air escapes in an akward way during talking.
Patients with a severe underbite and a big gap between the upper and lower teeth sometimes adapt to eating and drinking by performing a tongue thrust.
Underbite in young children should be investigated at 7 years old. It is possible to intercept a developing underbite in some cases. The best window of opportunity is between the age of 7-9 years old.