Medical-led masseter assessment and non-surgical jawline slimming
At Skin and Scar Care Clinic, we offer personalised assessment and treatment for prominent jaw muscles, square face shape, jaw clenching, teeth grinding and lower-face widening.
A wide or square lower face can be caused by several factors, including a strong masseter muscle, natural jawbone structure, dental bite, facial fat, previous filler, or lower-face skin laxity. Jaw grinding and clenching can also enlarge the masseter muscle over time, making the jawline appear wider or heavier.
Our treatment options may include:
- Masseter anti-wrinkle injections for muscle relaxation and lower-face slimming
- Detailed masseter muscle assessment
- Assessment of clenching, grinding and jaw tension
- Dental review for tooth wear and mouth guard/splint where appropriate
- TMD and jaw pain assessment
- Lifestyle and stress-related bruxism support
- Lower-face contour assessment
- Skin tightening or facial balancing where needed
- Referral to a dentist, GP, orthodontist, oral surgeon or maxillofacial specialist where appropriate
Our aim is to soften jaw muscle prominence while preserving natural facial balance, smile movement and cheek support.
What is the masseter muscle?
The masseter is one of the main chewing muscles. It sits at the side of the jaw and becomes firm when you clench your teeth.
A strong or enlarged masseter can make the lower face look:
- Square
- Wide
- Heavy
- Masculine in shape
- Bulky at the jaw angle
- Asymmetric
- Tense or clenched
Masseter enlargement can be natural, genetic or related to repeated clenching and grinding.
square face /prominent jaw muscle
1. Masseter muscle hypertrophy
Masseter hypertrophy means the jaw muscle has become enlarged or overdeveloped. This may happen gradually due to repeated muscle activity.
Common triggers include:
- Teeth grinding
- Jaw clenching
- Stress-related tension
- Night-time bruxism
- Chewing gum frequently
- Chewing hard foods
- TMD (Temporomandibular dysfunction) jaw dysfunction
- Habitual one-sided chewing
- Genetic muscle strength
2. Jaw grinding
Bruxism means grinding or clenching the teeth. It can happen during the day or while asleep.
It may cause:
- Jaw ache
- Facial tension
- Headaches
- Tooth wear
- Cracked teeth
- Sensitive teeth
- Enlarged masseter muscles
- Tired jaw on waking
- Clicking or discomfort around the jaw joint
If there is tooth wear, pain or jaw-joint symptoms, we may advise dental assessment before or alongside aesthetic treatment.
3. Natural jawbone shape
Some people have a naturally broad lower jaw due to bone structure rather than muscle enlargement. In these cases, anti-wrinkle injections may not significantly slim the face.
4. Facial fat or lower-face fullness
A square or heavy lower face may also be caused by facial fat, jowls, skin laxity or previous filler rather than masseter muscle.
5. Previous aesthetic treatment
Overfilling the jawline, chin or cheeks can make the lower face appear wider or heavier. Previous filler history is important during assessment.
6. Ageing and skin laxity
As skin and soft tissues descend with age, the lower face may look heavier even if the masseter muscle is not enlarged.
Why masseter assessment is essential
Masseter treatment should not be performed without careful assessment.
At Skin and Scar Care Clinic, we assess:
- The size of the masseter at rest
- The masseter during clenching
- Whether the bulk is muscle, fat, filler, bone or skin laxity
- Jawline shape from the front, side and three-quarter view
- Facial symmetry
- Smile movement
- Cheek hollowing risk
- Existing jowls or skin laxity
- Bite and dental history
- Bruxism symptoms
- TMD symptoms
- Previous toxin or filler treatment
- Medical history and medication
The aim is to treat the correct structure and avoid creating unwanted changes such as a hollow cheek, over-slimmed lower face, smile asymmetry or worsening jowls.
Masseter anatomy and safe treatment planning
The masseter is a layered muscle with superficial and deeper fibres. It is also close to important structures, including facial expression muscles, salivary gland tissue, facial nerves and blood vessels.
One of the key muscles to protect is the risorius muscle. The risorius helps pull the corner of the mouth sideways during smiling. If anti-wrinkle product spreads too far forward or superficially, it may affect the risorius and cause a temporary crooked or asymmetric smile.
For this reason, masseter treatment requires careful anatomical planning.
Our safety-focused approach includes:
- Palpating the masseter while you clench
- Marking the strongest part of the muscle
- Avoiding treatment too close to the mouth corner
- Avoiding unnecessary anterior spread
- Avoiding superficial placement where the risorius may be affected
- Considering deeper muscle placement for bulk reduction
- Considering superficial and deep muscle layers only where clinically appropriate
- Using conservative treatment where cheek hollowing risk exists
- Avoiding excessive slimming in naturally thin faces
- Reviewing before adding further product
This helps protect the smile and maintain natural facial support.
Deep and superficial masseter treatment
Some clients have masseter bulk mainly in the deeper part of the muscle. Others may have more superficial lower-face muscle thickness.
Treatment planning may involve:
Deeper masseter targeting
This is often used when the masseter is thick, strong and clearly enlarged during clenching.
The aim is to reduce muscle strength and bulk while limiting spread to nearby expression muscles.
Superficial masseter targeting
In selected cases, careful superficial treatment may be considered when superficial muscle fibres contribute to visible lower-face width.
This must be performed cautiously because superficial spread can increase the risk of affecting the risorius muscle and smile movement.
Why careful balance matters
Over-treatment can make the face look too slim, tired or hollow. It can also make existing cheek hollowing, jowls or skin laxity more noticeable.
At Skin and Scar Care Clinic, we prefer a conservative and staged approach.
Anti-wrinkle injections for masseter reduction
Anti-wrinkle injections can be used to relax the masseter muscle. Over time, reduced muscle activity may lead to a softer, slimmer lower-face appearance.
This treatment may help with:
- Prominent masseter muscles
- Square lower face
- Jawline bulk caused by muscle
- Jaw clenching
- Teeth grinding
- Facial tension
- TMD-related muscle overactivity in selected cases
- Lower-face asymmetry caused by uneven masseter size
What to expect
The treatment involves small injections into the masseter muscle on each side of the jaw.
The treatment is usually quick, with minimal downtime.
You may notice reduced clenching first, followed by gradual slimming of the lower face.
Treatment timeline
- First 1–2 weeks: muscle relaxation begins
- 4–6 weeks: clenching and jaw tension may feel reduced
- 6–12 weeks: slimming effect becomes more noticeable
- 3–4 months: result usually continues to stabilise
- 3–6 months: maintenance may be needed depending on response
For aesthetic jaw slimming, visible changes are gradual and depend on muscle size, dose, anatomy and lifestyle.
Jaw grinding treatment
Masseter injections may help reduce the force of clenching and grinding in suitable clients. However, bruxism can have several causes and may need more than one approach.
Other evidence-based bruxism treatments may include:
- Dental assessment
- Custom night guard or mouth splint
- Tooth-wear assessment
- Stress management
- Sleep assessment
- Reduction of caffeine or alcohol triggers
- Avoiding chewing gum and very hard foods
- Jaw physiotherapy
- TMD management
- Bite or orthodontic assessment where appropriate
- GP review if medication, sleep apnoea or anxiety may contribute
Masseter injections do not protect teeth in the same way as a dental splint. If you grind at night, dental input is still important.
Square face: muscle, bone, fat or filler?
A square face is not always caused by masseter muscle.
Muscle-related square face
The jaw looks wider when clenching. The masseter feels strong and bulky.
Treatment may include masseter anti-wrinkle injections.
Bone-related square face
The jaw angle is naturally broad due to skeletal structure. Anti-wrinkle injections may have limited effect.
Surgical or maxillofacial assessment may be more appropriate if major reshaping is desired.
Fat-related lower-face fullness
The face may look wide due to buccal fat, lower cheek fat or general facial fullness.
Treatment may include weight management, Endolift® in selected cases, or surgical assessment.
Filler-related heaviness
Previous jawline or cheek filler may make the face appear wider or heavier.
Treatment may include filler assessment, ultrasound where appropriate and dissolving if hyaluronic acid filler is contributing.
Laxity-related lower-face heaviness
Loose skin or jowls can create lower-face heaviness.
Treatment may include Endolift®, CO₂ laser, Erbium Glass laser, biostimulation or surgical referral depending on severity.
Avoiding hollow cheeks and an over-slimmed face
One of the most important parts of masseter treatment is avoiding over-slimming.
Masseter reduction may not be suitable, or may need to be very conservative, if you already have:
- Hollow cheeks
- Thin face
- Significant weight loss
- Ozempic or Mounjaro face changes
- Loose lower-face skin
- Jowls
- Poor cheek support
- Previous cheek hollowing after toxin
- Advanced facial ageing
- Low facial fat
In these cases, aggressive masseter slimming can make the face look more gaunt or aged.
If you have both a prominent masseter and cheek hollowing, we may recommend a balanced plan that considers cheek support, skin tightening and lower-face structure.
Combination treatments
Some clients need a combination approach rather than masseter injections alone.
Prominent masseter with jaw grinding
Possible plan:
- Masseter anti-wrinkle injections
- Dental splint or mouth guard
- Stress and sleep review
- Jaw physiotherapy if needed
Square face with lower-face heaviness
Possible plan:
- Masseter assessment
- Endolift® if fat/laxity contributes
- Skin tightening
- Jawline contour review
Square face with previous filler
Possible plan:
- Filler history review
- Filler dissolving if appropriate
- Conservative rebuilding only if needed
Masseter bulk with hollow cheeks
Possible plan:
- Conservative masseter treatment
- Bio Remodelling / Bio Stimulator Structura, PRF, PLLA, CaHA or HA filler where cheek support is needed
- Avoid over-slimming
- Review before further toxin
TMD symptoms or significant pain
Possible plan:
- Dental or maxillofacial review
- Mouth guard/splint
- Physiotherapy
- Masseter treatment only if suitable
Suitable candidates
You may be suitable for masseter treatment if you have:
- Prominent jaw muscles
- Square lower-face shape caused by muscle
- Jawline bulk that increases on clenching
- Teeth grinding or jaw clenching
- Jaw tension
- Mild TMD-related muscle overactivity
- Facial asymmetry caused by uneven masseter size
- Good general health
- Realistic expectations
- No significant hollow-cheek risk
- Willingness to have staged treatment and review
Who may not be suitable?
You may not be suitable for masseter treatment if you have:
- A naturally broad jawbone rather than enlarged muscle
- Very thin face or existing hollow cheeks
- Significant cheek hollowing after weight loss
- Severe jowls or lower-face laxity
- Previous poor response to masseter toxin
- Active dental infection
- Untreated severe TMD
- Significant jaw-joint locking or restricted opening
- Neuromuscular disease
- Pregnancy or breastfeeding
- Known allergy to botulinum toxin ingredients
- Active infection at the injection site
- High bruising risk without assessment
- Unrealistic expectations
- Desire for dramatic surgical-level jaw reshaping
- Difficulty chewing or swallowing at baseline
- Facial nerve weakness or significant smile asymmetry
If your concern is mainly dental, skeletal or surgical, we will advise referral rather than cosmetic treatment.
Possible side effects
Masseter anti-wrinkle treatment is generally well tolerated, but side effects can occur.
Possible side effects include:
- Bruising
- Swelling
- Tenderness
- Headache
- Jaw tiredness
- Temporary chewing weakness
- Asymmetry
- Uneven slimming
- Smile asymmetry
- Crooked smile
- Difficulty with wide smile
- Over-slimming
- Hollow cheeks
- Worsening appearance of jowls
- Dry mouth in rare cases
- Incomplete improvement
- Need for maintenance treatment
More serious side effects are rare but can include unintended spread of toxin causing muscle weakness, swallowing difficulty, speech difficulty or breathing symptoms. Urgent medical advice should be sought if these occur.
How many sessions are needed?
Most clients start with one treatment session and review the result after several weeks.
A staged approach is often safest because it allows us to assess:
- Muscle response
- Facial slimming
- Smile movement
- Chewing comfort
- Hollow-cheek risk
- Whether further treatment is needed
Maintenance is usually required because anti-wrinkle injections are temporary.
What to expect during consultation
Your consultation will include:
- Facial assessment at rest
- Assessment while clenching
- Palpation of the masseter muscle
- Smile and expression assessment
- Jawline and cheek support assessment
- Medical and dental history review
- Bruxism and clenching symptom review
- Previous toxin/filler history
- Discussion of risks, expectations and alternatives
We will explain whether your square face is likely due to muscle, bone, fat, filler or skin laxity.
Aftercare advice
After treatment, you will receive personalised aftercare.
General advice may include:
- Avoid rubbing or massaging the treated area
- Avoid strenuous exercise for 24 hours
- Avoid alcohol for 24 hours
- Avoid sauna, steam rooms and excessive heat for 24 hours
- Avoid dental treatment immediately after where possible
- Do not lie face down or apply pressure to the treated area for several hours
- Avoid chewing gum or very hard foods if the jaw feels tired
Contact the clinic if you notice significant asymmetry, chewing difficulty, smile change or any concerning symptoms
Frequently Asked Questions
A square face may be caused by enlarged masseter muscles, jawbone structure, facial fat, previous filler, skin laxity or a combination of factors.
The masseter becomes firm when you clench your teeth. During consultation, we palpate the muscle and assess whether your jaw width is mainly muscle-related.
Yes, in suitable clients with true masseter hypertrophy, anti-wrinkle injections can gradually reduce muscle activity and soften the lower-face width.
It may help reduce clenching force in suitable clients, but it does not replace dental assessment or a mouth guard where tooth protection is needed.
Smile asymmetry can occur if product spreads to nearby smile muscles such as the risorius. This is why careful anatomy, correct placement and conservative treatment are important.
The risorius helps pull the corner of the mouth sideways during smiling. If affected, the smile may look temporarily uneven or restricted.
Yes, over-treatment or treatment in a naturally thin face can make the cheeks look more hollow or the lower face look aged. We assess cheek support before treatment.
Jaw tension may improve within a few weeks. Facial slimming usually becomes more noticeable around 6–12 weeks.
Results commonly last around 3–6 months, depending on muscle strength, dose, metabolism and grinding habits.
Most clients tolerate treatment well. The injections are quick and usually involve minimal downtime.
Why choose Skin and Scar Care Clinic?
At Skin and Scar Care Clinic, we provide medical-grade aesthetic treatments with a personalised and safety-led approach.
We focus on:
- Detailed masseter assessment
- Understanding jaw muscle anatomy
- Protecting smile movement and the risorius muscle
- Avoiding over-slimming and hollow cheeks
- Natural-looking lower-face contouring
- Bruxism and jaw-grinding assessment
- Dental referral where appropriate
- Honest advice about muscle, bone, fat, filler and skin laxity
- Conservative staged treatment planning
- Aftercare and review
We will always advise if masseter treatment is not the safest or most suitable option.
Book a Masseter and Jawline Consultation in Altrincham
If you are concerned about prominent jaw muscles, square face shape, jaw clenching, teeth grinding or lower-face heaviness, book a consultation at Skin and Scar Care Clinic.
We will assess whether your concern is caused by the masseter muscle, jawbone, facial fat, previous filler, skin laxity or a combination of factors.
Skin and Scar Care Clinic
25 Barrington Road
Altrincham
WA14 1HP
WhatsApp / Tel: 07376 311884
Website: www.skinscarcare.com
Disclaimer
Masseter and jawline treatments are medical aesthetic treatments and results vary between individuals. Treatment outcomes cannot be guaranteed.
Prominent jaw muscles, square face shape and jaw grinding may be caused by masseter hypertrophy, bruxism, stress, TMD, bite problems, natural bone structure, facial fat, previous filler, skin laxity or medical/dental conditions. A consultation is required to assess the true cause.
Masseter anti-wrinkle injections may improve selected cases of masseter enlargement, jaw clenching and lower-face widening, but they are not suitable for all square-face concerns and do not replace dental treatment, mouth guards, orthodontic care, TMD management, surgery or medical assessment where these are required.
Treatment must be planned carefully to protect nearby facial expression muscles, particularly the risorius muscle. Possible side effects include bruising, swelling, tenderness, headache, jaw tiredness, chewing weakness, smile asymmetry, crooked smile, uneven results, over-slimming, hollow cheeks, worsening appearance of jowls, dry mouth, incomplete improvement and the need for further treatment.
Rare but serious complications can include unintended toxin spread causing excessive muscle weakness, swallowing difficulty, speech difficulty, breathing difficulty or allergic reaction. Seek urgent medical advice if any of these symptoms occur.
Results are temporary and maintenance may be required. Over-treatment may create an aged, gaunt or hollow appearance, especially in clients with low facial fat, cheek hollowing, significant weight loss or loose skin.
We always aim to provide 100% effort, but final results depend on anatomy, muscle size, clenching habits, bone structure, facial fat, skin laxity, previous treatments, metabolism, lifestyle factors and adherence to aftercare.