Short answer: A retruded lower jaw is a condition in which the lower jaw sits farther back relative to the upper jaw and is classified as a Class II bite. It is mostly hereditary; habits such as thumb sucking and mouth breathing can also contribute. In growing children it is treated with functional appliances, and in adults with orthodontic camouflage or jaw surgery. The appropriate method is determined through an examination and measurements.
A retruded lower jaw is a condition in which the lower jaw sits farther back than it should relative to the upper jaw, and in orthodontics it is usually assessed under the heading of Class II bite. In profile, it can make the chin look set back and the upper teeth look as if they stick out. A retruded lower jaw is not just an aesthetic matter; it can also affect biting, lip closure, the jaw joint and, in some people, breathing. The treatment approach varies considerably depending on the person's age and whether the source of the problem is the skeleton or the teeth.
What is a retruded lower jaw?
A retruded lower jaw is a jaw relationship in which the lower jawbone (mandible) does not match the upper jaw in size or position and sits too far back. Orthodontists generally classify it as a Class II bite. In this classification, the lower molars close farther back than they should relative to the upper molars.
There is an important distinction here. In some people, the problem is truly skeletal; that is, the lower jawbone is small or positioned too far back. In others, the jawbones are relatively balanced, but the tilt and alignment of the teeth create the impression of a set-back lower jaw. Telling these two apart is the first and most critical step in choosing the right treatment. To make the distinction, a lateral skull X-ray called a cephalometric X-ray and measurements are used in addition to the examination.
Subtypes of Class II bite
- Class II, division 1: The upper incisors tilt forward and there is a noticeable horizontal distance between the upper and lower front teeth. Strained lip closure is common.
- Class II, division 2: The upper incisors tilt backward and a deep bite is usually present; the lower front teeth largely disappear behind the upper teeth.
Causes: genetics and habits
The most common cause of a retruded lower jaw is heredity; facial and jaw structure is largely passed down in families. Children whose mother or father has a similar profile are more likely to have this condition. However, some environmental factors that act during growth can also contribute.
- Long-term thumb sucking or pacifier use: Can affect the bite by pushing the upper incisors forward and holding the lower jaw back.
- Mouth breathing: Breathing through the mouth for a long time because of enlarged adenoids or allergic nasal congestion can change tongue and jaw position and affect facial development.
- Tongue thrusting and an incorrect swallowing pattern: Can negatively affect the position of the front teeth and the bite.
- Early loss of baby teeth: Baby molars extracted without a space maintainer can cause teeth to shift and disrupt the bite relationship.
Noticing and addressing these habits early can help keep the problem from getting worse, especially while growth is still ongoing.
What are the signs of a retruded lower jaw, and what does the profile look like?
The most typical sign of a retruded lower jaw is a convex profile, in which the chin appears set back when viewed from the side. There may also be other signs noticeable inside the mouth and in daily life:
- The upper front teeth sitting noticeably ahead of the lower teeth
- A deep bite in which the lower front teeth disappear behind the upper teeth
- Lips that do not close comfortably, with muscle strain at the chin when closing
- A less defined angle between the chin and the neck
- Difficulty biting with the front teeth
- In some people, snoring or irregular breathing during sleep
- Noises, pain or muscle fatigue in the jaw joint
Having some of these signs alone does not establish a diagnosis; a similar appearance can have different causes. A detailed examination and measurements reveal the true source of the problem. If you are curious about what a deep bite means, we cover the topic in detail in our deep bite and clear aligners article.
How is a retruded lower jaw treated in children?
In growing children, a retruded lower jaw is usually treated with functional appliances that guide the jaw's natural growth potential. These appliances position the lower jaw forward and help the jaws develop in a more balanced way during the growth spurt.
Timing is decisive for the success of this approach. Treatment is generally planned to coincide with the growth spurt before and during puberty; this period starts earlier in girls than in boys. The child's skeletal maturity can be assessed from a hand-wrist X-ray or from the appearance of the neck vertebrae on a lateral skull X-ray.
The appliances used fall roughly into two groups:
- Removable functional appliances: Appliances the child can put in and take out, which hold the lower jaw in a forward position. Success depends on wearing them consistently for the prescribed hours.
- Fixed functional appliances: Systems fixed to the teeth that depend less on the patient's cooperation.
For some growing patients, options in which the lower jaw is held forward by wings added to clear aligners may also be considered. Which appliance is chosen is decided by the dentist according to the child's age, cooperation and the severity of the problem. After functional treatment, a second orthodontic phase is often needed to fine-tune the teeth.
When are orthodontic camouflage and surgery needed in adults?
In adults who have finished growing, the size of the lower jawbone cannot be changed with orthodontic appliances; therefore treatment is done either with orthodontic camouflage, which balances the bite by adjusting the position of the teeth, or with orthognathic surgery, which surgically moves the jaw forward.
Orthodontic camouflage
In mild to moderate skeletal discrepancies, the teeth are repositioned to compensate for the difference between the jawbones. For this purpose, the upper front teeth can be moved back, planned extractions can be done if needed, or elastics between the jaws can be used. Camouflage corrects the bite and the alignment of the teeth; however, it produces limited change in the facial profile.
Orthognathic surgery
When the skeletal difference is marked and both function and facial balance are affected, jaw surgery planned jointly by an oral and maxillofacial surgeon and an orthodontist is considered. The process usually consists of pre-surgical orthodontics, the operation and post-surgical orthodontics. When considered necessary, chin reshaping (genioplasty) can also be added to the plan. The decision for surgery is made after a joint assessment that takes into account the examination, imaging and the patient's expectations.
Do clear aligners work for a retruded lower jaw?
Clear aligners can be an effective option for correcting the bite in mild to moderate forms of a retruded lower jaw that come from the teeth; however, in adults they do not change the size or position of the jawbone. Aligners move teeth, not the size of the bone.
In suitable cases, aligners can:
- Correct the tilt of the upper incisors and reduce the distance between the front teeth
- Open a deep bite
- Improve the molar relationship with elastics between the jaws
- Align the teeth before and after surgery in cases where surgery is planned
For growing children and teenagers, special aligner designs that guide the lower jaw forward may be considered in certain cases. In marked skeletal differences, aligners alone are not enough, and expectations need to be set accordingly. We look at the topic more broadly in our can clear aligners correct jaw structure article.
When should you see a dentist about a retruded lower jaw?
If you notice that your child's chin looks set back in profile, their upper teeth stick out noticeably or they have difficulty closing their mouth, it is a good idea to have a first orthodontic assessment around age 7 so as not to miss the advantage of the growth period. For adults, difficulty biting, jaw joint complaints or aesthetic concerns are reason enough for an examination. At our clinic in Oran, Çankaya, our orthodontist assesses the source of the problem with measurements and discusses camouflage, functional treatment or surgical collaboration options with you.
Frequently asked questions
Does a retruded lower jaw correct itself?
A retruded lower jaw of skeletal origin usually does not correct itself with growth. An assessment during the growth period offers the chance to guide the development of the jaw. That is why an early orthodontic examination is recommended.
What is the most suitable age to treat a retruded lower jaw?
Treatment with functional appliances is generally planned to coincide with the pubertal growth spurt. This period starts earlier in girls than in boys. The exact timing is determined by assessing the child's skeletal development.
Is treatment without surgery possible for adults?
In mild and moderate cases, the bite can be balanced by adjusting the position of the teeth; this is called orthodontic camouflage. This approach does not change the size of the jawbone and produces limited change in the profile. In marked skeletal differences, the surgical option is also considered.
Can a retruded lower jaw cause snoring?
A lower jaw positioned too far back can, in some people, contribute to the base of the tongue moving backward and the airway narrowing. However, snoring has many different causes. If there are signs such as pauses in breathing during sleep, an assessment by the relevant specialist is also needed.
