What Makes the Jaw Appear Wider? A Closer Look at the Masseter Muscle
Understanding Jaw Size, Muscle Growth, and What You Can Do About It
Many people notice their jawline looking wider, more angular, or more prominent over time especially in photos or when clenching their teeth. In many cases, this change is due to an enlarged masseter muscle. The masseter is one of the main muscles used for chewing, and like any muscle, it can grow and change based on how much it’s used.
Let’s break down the common reasons this happens, how to identify the cause, and what your options are if you want to reduce its size naturally or clinically.
What Is the Masseter Muscle?
The masseter is a thick, rectangular muscle that connects your cheekbone to your lower jaw. It’s one of the strongest muscles in your body based on weight and plays a key role in chewing and clenching.
If you’ve ever woken up with a sore jaw or noticed your teeth clenched during a stressful moment, your masseter was doing the heavy lifting.
Recent clinical reviews have confirmed that this muscle can grow significantly in size due to habitual overuse, especially in individuals who grind or clench their teeth. Not only does this lead to physical discomfort, but it can also change the visual structure of the lower face. (Gewargis, 2025).
What Causes an Enlarged Masseter Muscle?
There are several possible reasons why your masseter muscle may become noticeably larger:
1. Chronic Clenching or Grinding (Bruxism)
This is one of the most common reasons for masseter hypertrophy (muscle enlargement). If you grind your teeth at night or clench during the day (often due to stress), your masseter muscle gets stronger and larger over time just like a bicep would if you trained it regularly.
Signs of bruxism include:
Jaw tension or pain
Worn-down teeth
Headaches or ear pain
Clicking or popping in the jaw
Newer studies have highlighted how bruxism contributes to visible jawline broadening and facial tension, particularly in people who remain unaware of the habit until symptoms (like headaches or jaw pain) arise (Wu, Zeng, & Wu, 2023).
2. Chewing Habits
Constant gum chewing, chewing on pens or fingernails, or favouring one side of your mouth when eating can lead to overuse of the masseter muscle, causing asymmetry or overall growth.
Chewing-related muscle activation patterns can contribute to muscular overdevelopment, especially in younger individuals. (Nilesh, Dharamsi, Patil, & Mate, 2021).
3. Genetic and Ethnic Factors
Some people naturally have a more pronounced jawline or a larger masseter muscle. In these cases, it’s less about overuse and more about inherited structure. This type of muscle prominence tends to remain fairly consistent over time unless other factors (like grinding or clenching) add to it.
Studies also highlight that individuals of East Asian descent may be genetically predisposed to more prominent masseter muscles, often leading them to seek non-surgical contouring options like BoNT-A. (Wu, Zeng, & Wu, 2023).
4. Postural or Functional Imbalances
Issues like jaw misalignment, bite problems, or uneven dental work can create chronic overuse of one or both masseter muscles. These imbalances may also contribute to jaw discomfort or clicking.
Is It Muscle, Fat, or Bone?
Before considering any treatments or changes, it’s important to understand what exactly is making your jaw look wider. There are three main possibilities:
Muscle
More likely if the width is soft but firm to the touch when clenching
May feel sore or tense
Often changes over time (especially with stress, bruxism, or chewing habits)
Fat
Usually feels softer and doesn’t become hard when you clench
More likely to fluctuate with weight gain or loss
Typically found around the jawline and lower cheeks
Bone
Permanent and unchanging
Feels hard regardless of jaw movement
Can’t be altered without surgery
A professional assessment, often from a dentist, facial specialist, or medical provider can help determine what’s causing the change in appearance.
What Can You Do About It?
If masseter hypertrophy is contributing to a wider jawline, there are both natural and clinical solutions available:
Reducing gum chewing or nail biting
Using a nightguard to prevent grinding
Practicing relaxation techniques to reduce jaw tension
Final Thought
If your jawline has started to look wider or feel tense, it may not be due to fat or bone structure but rather your masseter muscle responding to daily habits and stress. At TT Aesthetics, our masseter contouring treatment offers a clinically supported, non-invasive way to create a more balanced facial appearance while improving jaw comfort and function.
Book a consultation to find out if this treatment is right for you.
To learn more about your masseters book a consultation with a qualified expert, book TT Aesthetics.
Citations
Wu, Y., Zeng, D., & Wu, S. (2023). Botulinum toxin type A for the treatment of masseter muscle prominence in Asian populations: Aesthetic and functional considerations. Aesthetic Surgery Journal Open Forum, 5. https://doi.org/10.1093/asjof/ojad005
MDPI. (2023). Dynamic quantitative imaging of the masseter muscles in bruxism patients: Tracking morphological changes with BoNT-A treatment. Journal of Personalized Medicine, 13(10), 1467. https://doi.org/10.3390/jpm13101467
Gewargis, J. (2025). Treating masseteric hypertrophy with botulinum toxin A: The MSFIT technique. Aesthetic Nursing, 14(2). Retrieved from https://www.aestheticnursing.co.uk/content/clinical/treating-masseteric-hypertrophy-with-botulinum-toxin
Nilesh, K., Dharamsi, R., Patil, P., & Mate, P. (2021). Management of unilateral idiopathic masseter muscle hypertrophy with botulinum toxin type A. BMJ Case Reports, 14(1), e239056. https://doi.org/10.1136/bcr-2020-239056
