What is retrognathia?
Retrognathia means the lower jaw sits further back relative to the other facial structures and the upper jaw. In orthodontics it is usually called a “Class II” bite. A retruded lower jaw can result from the lower jaw being small, being positioned further back, or both.
Signs
- Upper front teeth sitting well in front of the lower front teeth (increased overjet)
- Deep bite
- A chin that looks set back in profile, a convex facial profile
- Muscle strain at the chin when closing the lips
- The lower lip resting behind the upper front teeth
- In some people, snoring and breathing difficulty during sleep
Causes
- Hereditary factors
- The direction and rate of lower jaw growth
- Habits such as lower lip sucking or thumb sucking
- Mouth breathing
Treatment during growth
During the growth spurt it is possible to support the development of the lower jaw. This period usually starts earlier in girls than in boys. Methods used:
Functional appliances
These are removable or fixed appliances that hold the lower jaw in a forward position. The aim is for the lower jaw to adapt to this new position and for the bite to improve. They are usually used for 9–18 months.
Mandibular advancement with clear aligners
Wings added to the side sections of the clear aligners hold the lower jaw forward. Tooth alignment can continue at the same time. For details, see the Invisalign mandibular advancement page.
Treatment in adults
In people who have finished growing, the growth of the lower jaw can no longer be guided. Options:
- Orthodontic camouflage: In mild and moderate cases, the bite is improved by moving the upper front teeth back and adjusting the position of the lower front teeth. Extraction may be done to gain space if needed. Clear aligners or braces can be used.
- Orthognathic surgery: In a marked skeletal retrusion, surgical advancement of the lower jaw can be planned after orthodontic preparation. For details, see the skeletal problems page.
Sleep and breathing
A marked retruded lower jaw may be linked to a narrowing of the upper airway in some people. If there are complaints such as snoring, pauses in breathing during sleep or excessive daytime sleepiness, an assessment by a sleep specialist or an ear, nose and throat specialist is also recommended.