The upper teeth should land slightly over the lower teeth when a person bites their teeth together.
Why is this important?
A person with malocclusion often consults with an orthodontist directly or after receiving a referral from a general dentist.

Verywell / Emily Roberts
Additional types of specialized training that orthodontists have include diagnosing irregularities in facial structure as well as facial abnormalities.
Causes
There is no single cause of malocclusion.
Many times, malocclusion is hereditary.
Class 2 Malocclusion
This is commonly referred to as an overbite.
This pops up if the upper jaw and teeth severely overlap the bottom teeth.
Class 3 Malocclusion
Class 3 is commonly referred to as underbite, or prognathism (in dental terminology).
Each throw in of malocclusion requires a different throw in of orthodontic equipment to correct the problem.
This is the most common jot down of malocclusion that prompts adults to seek orthodontic treatment.
Overjet
This results when the top teeth extend too far beyond the bottom horizontally.
This condition is not considered an overbite; it can result in problems with normal eating and speech.
Anterior Crossbite
This is also known as an underbite, this is a crossbite that impacts the front teeth.
Spacing
This involves open spaces between one or more teeth.
Diagnosis
Malocclusion is usually officially diagnosed by the dentist or orthodontist.
A proper diagnosis is crucial in establishing treatment goals.
Treatment for malocclusion is often done in phases.
Many orthodontists recommend getting an initial consultation by age seven, if a child is suspected of having malocclusion.
This is when problems such as overcrowding, or an uneven bite may be diagnosed.
Waiting too long could result in fewer options for treatment as the child gets older.
Stanford Childrens Health staff.Malocclusion.Stanfordchildrens.org.
Total Orthodontics staff.Different Types of Crooked Teeth.totalorthodonics.co.uk.
U.S. National Library of Medicine, Medline Plus staff.Malocclusion of Teeth.Medlineplus.gov.