Types of malocclusion — a guide to common bite problems

Key facts

• Class I, II and III describe the jaw relationship
• Overjet is horizontal; overbite is vertical overlap
• Crossbites are often linked to a narrow upper jaw
• Open bites can relate to habits and tongue posture
• Treatment depends on whether the cause is dental or skeletal

The three classes of malocclusion

Orthodontists classify bites mainly by how the upper and lower first molars and jaws relate front to back. In Class I, the jaw relationship is normal but there may be crowding, spacing, rotations or other tooth-level problems. In Class II, the lower jaw and teeth sit further back relative to the upper, often with prominent upper front teeth (Class II division 1) or retroclined upper front teeth with a deep bite (Class II division 2). In Class III, the lower jaw and teeth sit further forward, ranging from edge-to-edge incisors to a clear underbite. Each class can be dental, skeletal or a mix, which strongly affects treatment.

Overjet, overbite and deep bite

Overjet is the horizontal distance the upper front teeth sit in front of the lower ones; an increased overjet — often called “buck teeth” or loosely an overbite — makes front teeth more prone to injury and can affect lip closure. Overbite is the vertical overlap; when this overlap is excessive, it is called a deep bite, and the lower front teeth may bite into the palate or gums behind the upper teeth, or the upper teeth may cover most of the lower teeth. Deep bites can cause gum trauma and tooth wear. Both are common in Class II patterns and are treated with braces or aligners, sometimes with functional appliances in growing children or TADs in adults.

Underbite, edge-to-edge and crossbite

An underbite (anterior crossbite) is when the lower front teeth sit in front of the upper front teeth, typical of Class III; it may involve a small or set-back upper jaw, a large lower jaw, or both. An edge-to-edge bite, where front teeth meet tip to tip, is a milder form that commonly causes chipping. A posterior crossbite is when upper back teeth bite inside the lower back teeth, on one or both sides, and is often linked to a narrow upper jaw; a one-sided crossbite may cause the lower jaw to shift sideways on closing. Expansion — conventional in children or MARPE in suitable adults — is frequently part of treatment.

Open bite, crowding and spacing

In an anterior open bite, the front teeth do not meet when the back teeth are together, leaving a vertical gap; it makes biting into food difficult and can be associated with thumb-sucking, tongue posture, mouth breathing or a long lower facial pattern. Lateral open bites affect the side teeth. Crowding — not enough space for the teeth — is the most common reason people seek orthodontics and makes cleaning harder. Spacing, from small teeth, missing teeth or habits, can affect appearance and food trapping. Many patients have more than one of these problems at once, so an orthodontist assesses the whole bite rather than a single feature.

Getting the right diagnosis at Manhal

Correct treatment starts with a correct diagnosis. At Manhal Medical Center in Dubai, consultant orthodontist Dr. Moaiyad Pacha examines the teeth, bite, jaw joints and breathing pattern, takes photographs and a digital intraoral scan, and uses X-rays — with CBCT only when justified — to identify the type of malocclusion and whether it is dental or skeletal. He then explains the options, such as aligners, braces, expansion, TADs or, for marked skeletal differences, combined orthodontic and surgical care, in a written plan. Dedicated pages cover deep bite, edge-to-edge bite and other problems in more detail; contact the clinic for his Dubai dates.

It is never too late to straighten teeth. Adult orthodontics often works alongside implants, veneers or gum treatment, and discreet appliances fit professional life.

Prepared by the Manhal Medical Center editorial team · Updated: 2026-10-18 · Treating specialist: Dr. Moaiyad Pacha

This page is general information and does not replace a consultation. Suitability, risks and results vary between patients.