Facial asymmetry: how much can be corrected?

How common is facial asymmetry?

In most people, the left and right sides of the face are not exactly the same. A 2011 literature review also described facial asymmetry as common, and considered that when the asymmetry is pronounced, it can cause both functional and aesthetic problems ^[1].

A 2020 literature review on dental care said that facial skeletal development that departs from the average is relatively normal in the majority of patients ^[2]. It therefore summarized that correction is usually considered only when there is a related condition, a functional problem, or psychosocial difficulty ^[2]. A small difference alone does not necessarily mean that treatment is needed.

Causes of asymmetry

Causes of facial asymmetry include congenital conditions, acquired conditions, trauma, and variations in development ^[1]. However, the cause of asymmetry that arises during development is often unclear ^[1]. Most abnormalities of the jaws and teeth also arise during development, and they range widely from barely noticeable to pronounced ^[2].

When a patient is concerned about asymmetry, the underlying cause should be identified first ^[1]. Some asymmetry is caused by muscle movement, as in facial nerve palsy, so the approach differs depending on whether the problem lies in the bone or in the soft tissue or muscles.

• Congenital conditions
• Acquired conditions
• Trauma
• Variations in development
• Problems with muscle movement, such as facial nerve palsy

How is it assessed?

Facial asymmetry is assessed through a medical history, a physical examination, and imaging tests ^[1]. Imaging helps diagnose and measure the asymmetry objectively and plan treatment ^[1]. The assessment separates out which components, the soft tissue, the teeth, or the skeleton, are involved in the asymmetry ^[1].

When asymmetry is present, a misaligned bite (malocclusion), a tilted biting surface (occlusal plane), and a shifted facial midline are often found as well ^[1]. That is why chewing function needs to be examined along with the visible shape.

Treatment methods

Treatment of facial asymmetry first aims to correct the underlying condition ^[1]. For asymmetry with a bite problem, orthognathic surgery is performed with the aim of achieving a symmetrical facial midline, a harmonious profile, and a proper bite ^[1]. Additional surgery to increase or reduce the volume of the skeleton and soft tissue on either side may be needed to achieve better symmetry ^[1].

Orthognathic treatment is a process that combines orthodontic treatment with oral and maxillofacial surgery, and it is used for problems that are hard to solve with ordinary orthodontics, such as severe misalignment of the upper and lower jaws, front teeth that do not meet, and facial asymmetry ^[4]. People with these problems can face a range of difficulties, from functional problems such as trouble biting and chewing to feeling self-conscious in daily and social life ^[4]. Treatment carries risks as well as benefits, so you should make your decision after receiving a full explanation ^[4].

Asymmetry caused by facial nerve palsy

When facial nerve palsy lasts a long time, its aftereffects cause functional, aesthetic, and psychological problems ^[5]. A 2017 systematic review considered facial asymmetry to be strongly related to difficulties in social interaction and to how people perceive their own appearance ^[3]. It described botulinum toxin injection as a minimally invasive method that helps restore symmetry at rest and during movement in chronic facial nerve palsy, and said it may be especially helpful when combined with physical therapy ^[3].

However, this systematic review was able to include only 3 of the 47 papers it found, and the optimal dose and interval between injections have not yet been established ^[3]. A 2024 literature review also stressed that there are no standardized recommendations yet, and that injections should be planned based on what bothers the patient ^[5].

What you can expect, and what to check during your consultation

The goal of treatment is not to make the two sides identical but to improve function and balance. The literature also describes the purpose of additional surgery as achieving better symmetry ^[1]. What is possible differs from person to person depending on the cause, the degree of asymmetry, and the condition of the bone and soft tissue, so a plan should be made after confirming these through an examination and imaging.

• Whether the cause of the asymmetry lies in the bone, teeth, soft tissue, or muscles
• Whether there is also a functional problem, such as with chewing
• Whether orthodontic treatment is also needed
• The benefits and risks of each treatment method
• The range of change you can expect after treatment