Orthognathic surgery, receding chins and mandibular retrognathia: what does it all mean?

A receding chin, or mandibular retrognathia as it's medically known, is something you might have thought was just down to poor eating habits, genetics or simply bad luck.

In this article, we'll talk about the link between mandibular retrognathia and class 2 malocclusion, or overbite as it's more commonly known.

What is a receding chin?

Having a weak or unpronounced chin is a genetic disposition and in some cases, congenital as part of a condition. In some cases, a weak chin is outgrown. In this article, you'll find us touch on the difference between aesthetic fixes, such as dermal fillers and medical treatment options, like orthognathic surgery, to fix facial structure and jawlines.

What is mandibular retrognathia or a recessed jaw?

Mandibular retrognathia, or recessed jaw, is a dentofacial bone deformity in which the upper jaw is located in front of the lower jaw because the mandibular bone has not developed properly.

In cases of moderate or severe recessed chin, we can see how the teeth of the upper arch completely cover those of the lower arch, causing problems with diction, swallowing or bite, as well as aesthetically, in the form of a weak chin.

Link between a weak chin and overbite

A weak chin and an overbite are two concepts that are often used interchangeably, but it is important to clarify the difference between the two, because although they are related, they are not the same.

The difference between a receding chin and an overbite lies mainly in the origin: the former originates in the bones, whereas the latter in the teeth. The relationship between the two, therefore, is one of cause and effect: an overbite is usually the result of a receding chin problem.

Receding chin or retrognathic mandible causes

In most cases, the main cause of a receding chin is genetic inheritance and is due to insufficient growth of the lower jaw, increased growth of the upper jaw or a combination of the two. During the diagnostic phase, it’s important to know the patient’s family dental history, to see if genetics is the triggering factor.

A receding chin can also be caused by habits acquired during childhood, such as finger sucking in infancy, chronic mouth breathing, allergies, poor respiratory function or atypical swallowing.

Receding chin or retrognathic mandible causes

In most cases, the main cause of a receding chin is genetic inheritance and is due to insufficient growth of the lower jaw, increased growth of the upper jaw or a combination of the two. During the diagnostic phase, it’s important to know the patient’s family dental history, to see if genetics is the triggering factor.

A receding chin can also be caused by habits acquired during childhood, such as finger sucking in infancy, chronic mouth breathing, allergies, poor respiratory function or atypical swallowing.

Retrognathic mandible consequences

The consequences of a retrognathic mandible are varied, but the most visible is the alteration in facial aesthetics. A recessed jaw can be identified as having the appearance of a weak chin, when the lower third of the face looks more sunken and is of a higher proportion to the rest of the face, which can trigger self-esteem problems.

The aesthetic consequence of a weak jawline, although the most visible, is not necessarily that which can most alter the patient's daily life. Amongst the most notable problems that people with a receding chin may suffer are the following:

• Sleep apnea due to airway obstruction
• Speech problems
  
• Problems with swallowing, which may trigger dysphagia
  
• Temporomandibular Joint (TMJ) disorder
  
• Bruxism
  
• Teeth problems, such as crowding, diastema, high canines or uneven wear on the teeth
  
• Class 2 malocclusion, or overbite, which we will discuss in the next section.
  

What is an overbite?

There are different types of malocclusion, but the one most associated with a receding chin is an overbite, or class 2 malocclusion.

You may be wondering what an overbite is. It is a dental alteration in which the upper first molars are positioned in front of the lower first molars. The main consequence of a class 2 malocclusion is, thus, that the upper teeth bite in front of the lower teeth, causing various problems depending on the type of overbite.

Types of overbite

There are two types of overbite according to the position of the incisors: class 2 division 1 and class 2 division 2.

Class 2 division 1 occlusion

People with a class 2 division 1 occlusion have upper central incisors that are inclined toward the outside of the mouth, completely covering the teeth in the lower arch.

Typically, those with a class 2 division 1 occlusion may suffer from dental crowding and excessive wear of the incisors.

Class 2 division 2 occlusion

In cases of class 2 division 2 occlusion, the central incisors are inclined towards the inside of the mouth, presenting a deep bite and respiratory problems in most cases.

How to fix a receding chin

How to fix a receding chin varies depending on the degree of the condition and the age of the patient.

The orthodontist and maxillofacial surgeon should perform an assessment, including x-rays, to determine the most appropriate treatment for the recessed jaw.

Recessed jaw treatment for adults

A recessed jaw in adults is more difficult to treat than in children. In most adult cases, the solution involves surgery, as we will see below.

Weak chin surgery

In adults, the only treatment for a weak chin is surgery, since bone development is complete and, therefore, cannot be altered with orthodontics.

In the following section we will explore which receding chin surgeries exist to treat this condition in adults.

Orthognathic surgery

Class 2 orthognathic surgery corrects the size and position of the upper and lower jaw in order to restore facial harmony and recover bone functionality. Depending on the bones to be operated on, there are 2 classes:

• Bimaxillary orthognathic surgery: the surgeon operates on the lower and upper jaw.

• Monomaxillary orthognathic surgery: the surgeon only operates on the upper or lower jaw to advance it. In cases of a retrognathic mandible, class 2 monomaxillary orthognathic surgery advances the lower jaw.

In many cases, class 2 orthognathic surgery must be accompanied by orthodontic treatment to complete the process and resolve the problem correctly.

Mentoplasty or chin augmentation

Mentoplasty improves chin projection and lower lip aesthetics by modifying the chin bone and facial features.

Chin augmentation is used in cases with good occlusion but with a recessed chin. Chin augmentation is usually complementary to orthognathic surgery to achieve greater facial balance.

How to fix a receding chin without surgery

Although in adults it’s not possible to fix a receding chin without surgery, there are cases of overbite that can be treated with orthodontics.

It’s important to highlight that non-surgical treatments in adults are complementary to orthognathic surgery to solve a retrognathic mandible and class 2 malocclusion.

Facial fillers in receding chins

One of the purely aesthetic treatments for a receding chin is to inject hyaluronic acid into the soft tissue of the chin area to add volume to the area, though this does not solve facial bone abnormalities.

Orthodontics: can braces fix a weak chin in adults?

Braces cannot fix a weak chin as the condition is a problem of the bones and is, therefore, not able to be resolved with orthodontics. It’s only effective to use orthodontic treatment in cases of adults with overbite, since the origin of the issue is in the teeth. It’s important to emphasise that this can correct the occlusion, although braces cannot treat the receding chin, since it’s not possible to modify the bone position with orthodontics in adults.

Orthodontics can also be used as a continuation of orthognathic surgery to correct dental irregularities caused by a receding chin.

In addition, there are also mandibular advancement splints, which advance the position of the patient’s jaw by a few millimetres while the patient sleeps. These splints facilitate the passage of air and solve problems of snoring or mild to moderate sleep apnea. However, mandibular advancement splints are only a temporary solution in certain cases, not a correction method.

Fixing receding chins for children

The best and most effective time to treat mandibular retrognathia is from the age of 6, after the eruption of the first molars and while the child is still growing. At this stage, interceptive or functional orthodontic treatments can be used. Here are two commonly known orthodontic devices used in some scenarios. In certain cases, extraoral anchorage may be used, meaning the device is fitted using headgear and face masks.

Herbst appliance

The Herbst appliance, or fixed functional appliance, is another type of extraoral interceptive orthodontic treatment that shortens the distance between the upper and lower jaw. The Herbst appliance propels the growth of the jaw forward, making the bite optimal and thus correcting the receding chin.

Bionator appliance

The Bionator is a functional mandibular advancement appliance. It’s another removable interceptive orthodontic treatment, in this case intraoral, ideal for correcting mandibular retrognathia in children. The Bionator appliance stimulates the movement of the mandible forward, blocking the movement of the teeth, with the aim of reducing the deep bite and improving physiological problems.

Impress treatments for cases of receding chin in patients of all ages

In adult cases of a recessed chin, as already mentioned, the only solution is surgery. However, when a receding chin causes class 2 malocclusion problems, we, at Impress, can help solve the dental issue with different treatments. Although we will be able to treat the bite, the bone problem will still be present.

At Impress, we can also treat adult cases in which a recessed jaw has caused crowding, separation of teeth or other dental problems.

These dental procedures may be performed after undergoing surgery for a receding chin.

Impress also treats adolescent cases of receding jaw where growth is still ongoing and all the permanent teeth have come through. With Impress Teens, we can treat cases requiring mandibular advancement with invisible aligners.

We have expert staff and tools adapted to perform the most appropriate treatments for the future of your dental health or that of your family’s.

Check which Impress centres offer Impress Teens services: contact us by making an appointment through our website, by phone or WhatsApp on +44 20 3808 1072.