When the teeth in a normal mouth are brought firmly together, the upper incisors slightly overlap the lower incisors. The rest of the teeth bite together, each upper tooth against its mate in the lower jaw and also against the lower tooth back of it. The bite is called occlusion. If the teeth do not bite together properly, the condition is called malocclusion. This may interfere with chewing as well as with the symmetry of the face.
Orthodontists are dentists trained to correct malocclusion by moving the teeth into proper position.