Masseter hypertrophy, morning headaches and neck tension - when they follow from clenching the teeth

How much of this is actually bruxism

• Whether bruxism changes the face is not settled in front of a mirror. Masseter thickness measured by ultrasound in 80 dental students did not differ between people with bruxism and the comparison group - even though the shape of the face is often the first thing the patient notices.
• The figures that circulate about bruxism are sometimes inflated by study design: masseter hypertrophy was found in 32 of 35 people with bruxism, but an enlarged muscle was one of the four criteria on which patients were assigned to that group.
• In one study, morning pain in the temples was reported by 21 of 35 people with diagnosed bruxism. Where sleep was measured instrumentally, however, no association between sleep bruxism and primary headache was demonstrated, and the sample was far too small to detect such an association. A systematic review links tension-type headache rather with daytime tooth clenching.
• The neck cannot be left out of this conversation: sensitivity of the neck muscles and of the masticatory muscles goes hand in hand, and in patients with the myogenous form of temporomandibular disorders (complaints of the joint and of the masticatory muscles) treating the cervical spine alone reduced facial pain.
• Tinnitus is sometimes linked with temporomandibular disorders, but tinnitus in one ear, worsened hearing and dizziness belong first to an ENT specialist, and sudden and severe dizziness requires urgent assessment.
• Morning headache together with snoring and daytime sleepiness calls for breathing during sleep to be checked before anyone proposes a night guard.

Bruxism, the face and headache converge in some patients into a single question, and the stake is a measurable one: the order of appointments.

A woman past the age of forty has been treated for tension-type headaches for a year. The medication works for a few hours. She comes to the dental surgery about something else entirely and only in passing mentions that her jaw is heavy in the morning and that her neck has been hurting for months.

An error in the direction of dentistry means months of a night guard and exercises for a problem that lies elsewhere. An error the other way means further painkillers for an overloaded muscle that nobody has examined. This article concerns only symptoms outside the mouth: the face, the head, the neck and the ear. What is visible in the teeth themselves is covered separately by the article on the signs of bruxism a dentist spots.

Masseter hypertrophy and the face: what is actually visible

The masseter - a thick muscle running from the zygomatic arch to the angle of the mandible - can be felt under your fingers when you clench your teeth. Patients usually say that with bruxism their jaw hurts. Anatomically this most often concerns the mandible and the muscles attached to it. A muscle that works excessively grows, and the lower part of the face then becomes wider. That is textbook bruxism.

Masseter hypertrophy was found in 32 of 35 people with bruxism and in nobody in the comparison group. The figure comes from a Turkish case-control study. An enlarged masseter was there one of the four signs on which a patient was assigned to the bruxism group at all. In other words: the researchers assigned to the group, among others, people with a thick masseter, and then counted how many people in that group had a thick masseter. Such a figure looks impressive and says very little.

When the same muscle was measured, the picture came apart. Masseter thickness on ultrasound did not differ between people with bruxism and the comparison group, either at rest or at maximum clenching. Eighty people aged 20 to 25 were measured, dental students at a single university. The diagnosis was made in 38 of them, on the basis of a questionnaire and clinical examination, without instrumental measurement during sleep. The result therefore describes young adults, and only them.

The shape of the face alone is a poor witness. A wider lower third is sometimes an inherited feature or simply a male build, and about whether bruxism has really changed the face more is said by tenderness of the muscle under pressure and by signs of wear on the teeth.

You can check this yourself. Place your fingers on the cheek two centimetres in front of the ear, clench your teeth and feel whether the muscle tightens, then press it with your thumb while it is relaxed: an overloaded muscle is tender under pressure, a muscle that is simply large is not. The check on its own settles nothing, but it says more than a mirror does. Wear and cracks that have already developed are a separate task for prosthetic restoration with crowns and veneers. What weakening the muscle itself changes, what it does not change and what remains unknown in this matter is covered separately by the text on botulinum toxin in the masseter muscle.

Where does morning headache in the temples come from?

Most often from the muscle, not from the teeth themselves. Teeth grinding at night in adults usually goes on without a witness: the patient does not remember it. The temporalis muscle raises the mandible. It lies exactly where the patient points to the pain: above the ear and at the sides of the forehead. Overloaded, it produces a complaint described as pressure or as a band. The morning pattern comes from the muscle working at night, with the effect of that work perceived by the patient on waking.

In the same Turkish study, with 35 people in each group, morning headache was reported by 23 people with bruxism and 3 people without it. Pain in the temples on waking was reported by 21 people against one, and tiredness after the night by 27 against 10. The diagnosis rested on a questionnaire and a clinical examination.

Where sleep was measured, the association disappeared. A Brazilian study covered 42 adults referred for polysomnography, that is an overnight sleep study with a recording of muscle activity. Sleep bruxism was confirmed instrumentally in 32 of them, and primary headache was diagnosed by an independent neurologist in 24. People with bruxism had headache roughly as often as the rest. This result, however, settles nothing in the other direction: the authors themselves state that the power of the study was very low, and that with forty-two participants the chance of detecting an association that does exist was negligible. This is an absence of evidence of an association, not evidence that there is no association.

What is associated with tension-type headache is rather awake tooth clenching than teeth grinding at night. That is how a systematic review of five observational studies came out. Before the figure is given, a reservation is needed: the authors rated the certainty of this evidence as low to very low, and the studies themselves differed from one another enough that they could not be pooled.

With that reservation, the authors summarise the difference as odds of tension-type headache five to seventeen times higher in people who clench their teeth during the day. Both ends of that range, 5.23 and 17.29, are odds ratios from a single study. An odds ratio does not say how many times more often the headache occurs; a seventeen-fold frequency cannot be read out of that number. For sleep bruxism no association with tension-type headache was demonstrated. Two studies on migraine came out inconclusive: both pointed to higher odds, but in only one was the difference statistically significant, that is unlikely had there been no association. A shared mechanism has not so far been identified by any review of the literature.

The two forms of bruxism are distinguished by the text on sleep bruxism and awake clenching.

Why does the neck hurt too when you clench your teeth?

Not because the jaw pulls on the neck. The mechanism has not so far been established. What is known is that sensitivity of the neck and sensitivity of the masticatory muscles go hand in hand, and that only this can be measured.

The most frequently repeated explanation, forward head posture, does not hold up in the research. In 145 patients with temporomandibular disorders, head posture and the pain threshold under pressure on the muscles were measured; people with a forward head position and people without that feature had similar sensitivity of the masseter and of the temporalis muscle. The relationship appeared elsewhere: the lower the pain threshold in the neck muscles, the lower it was in the masticatory muscles as well. That study did not measure bruxism.

Treating the neck alone reduced pain in the facial muscles in adults with the myogenous form of temporomandibular disorders; that research did not include people with bruxism. The result was pooled from seven trials with random allocation to groups: cervical rehabilitation reduced the intensity of pain in five studies covering 223 participants in total, and raised the pain threshold in the masseter in six studies covering 395 participants. The effect was described as large on the scale used in meta-analyses. The difference between the treated group and the comparison group was clear, but that measure does not tell you by how many points of pain the average patient improved. The results of the individual studies differed considerably, and the conclusions apply only to the short term after treatment. Whether the improvement lasts is not known.

Whether correcting posture on its own helps was not tested in these studies. Clicking and locking of the jaw are a different matter. They are diagnosed separately and treated separately, and what they mean is explained by the symptoms from the temporomandibular joint.

Can tinnitus and a sense of a blocked ear come from the jaw?

Sometimes they can. That is not, however, where the reasoning starts.

A form of tinnitus called somatosensory has been distinguished. It intensifies or eases with movements of the jaw, clenching of the teeth, pressure on the masticatory muscles or movements of the neck. Among 47 patients with tinnitus diagnosed in this way, examined at a hospital in Milan, temporomandibular disorders were found in 46. The relationship in the other direction turned out to be considerably weaker: among 50 patients presenting because of those disorders, somatosensory tinnitus was diagnosed in 12.

These two figures are read in opposite directions. The first comes from an audiology clinic. The people who reach it are those in whom other causes of tinnitus have already been excluded, so the figure describes a selected patient. The second comes from a dental clinic and concerns people with a diagnosed temporomandibular disorder: somatosensory tinnitus was present there in roughly one in four. If an ENT specialist finds no cause and the tinnitus changes with movements of the jaw, examination of the masticatory muscles by a dentist makes sense only then.

That boundary must not be crossed on a guess. To an ENT specialist, and not to a dentist, belong:

• tinnitus in one ear only;
• worsening of hearing on one side, and where it has come on suddenly - urgent medical assessment, not a scheduled appointment;
• sudden and severe dizziness, and sudden worsening of hearing, require urgent medical assessment; you do not wait for a scheduled appointment with them;
• discharge from the ear, or ear pain with fever.

Putting off such a consultation has a real cost, because nothing on this list is explained by bruxism. The face and the ear are anatomical neighbours, and that neighbourhood can mislead.

Face, neck and ear: a map of symptoms

With bruxism the face, the neck and the ear hurt much as they do with several other causes: what decides the direction is not the site of the pain but what makes it worse. The table below organises the typical situations and does not replace a medical examination.

Symptom you come in with	Points towards the masticatory system	Suggests another lead (and to whom)
Pain in the temples and the forehead	pressure, worse on chewing and after the night, muscles tender to touch	throbbing, nausea, photophobia, brief visual disturbance resolving before the pain - neurologist
A wider lower part of the face	muscle hard and tender under pressure, signs of wear on the teeth	change on one side only, a palpable lump, increasing swelling - family doctor or maxillofacial surgeon
Tension in the neck and shoulders	tenderness of the neck and of the masseter occurring together, pain varying through the day	numbness of the arm, pain running below the elbow, loss of strength - neurologist
Ear pain and blockage	complaints changing with movement of the jaw, normal hearing	tinnitus in one ear, worse hearing, dizziness, discharge - ENT specialist
Morning headache	usually resolves within an hour, jaw heavy and stiff on waking	snoring, breathing pauses noticed by someone close, daytime sleepiness - sleep investigation

A complaint arising from the masticatory muscles can be provoked again - by chewing, by clenching the teeth or by pressure on the muscle in the surgery. This feature separates the situations above more reliably than the site of the pain does. The International Classification of Headache Disorders (ICHD-3) treats provocation of the pain on examination as one of three indications of a causal link, and requires at least two of them to be met. Failure to reproduce the pain therefore does not settle the question in favour of another source.

When the first appointment does not belong to a dentist

With some symptoms there is no room for observation, and the urgency is not the same in every case.

Emergency number or hospital emergency department, without waiting for an appointment:

• a headache building to its maximum in less than a minute;
• a headache with fever, neck stiffness, disturbance of speech or vision, or weakness of a limb.

A neurological consultation within days, not weeks:

• a first-ever severe headache after the age of 50, or a clear change in the previous pattern of pain;
• pain waking you from sleep and building from week to week;
• paroxysmal, stabbing pain in one half of the face triggered by touching the skin.

Separately and urgently: tenderness of the temple combined with pain in the jaw on eating, in a person over the age of 50. That combination raises the suspicion of giant cell arteritis (temporal arteritis), which left untreated threatens loss of vision, so medical assessment cannot wait.

Breathing during sleep is a different matter, because the symptoms can be deceptively similar to those of bruxism. Snoring, breathing pauses noticed by someone close and daytime sleepiness together with morning headache call for sleep to be checked by polysomnography - before anyone proposes a night guard. The referral for it comes from a family doctor, an ENT specialist or a pulmonologist, not from a dentist. Among 105 patients with obstructive sleep apnoea, probable sleep bruxism was diagnosed in 39. Morning pain in the jaw muscles was reported by more than half of them, but morning complaints were one of the criteria for assignment to that group. In treating patients at our surgery in the Wola district of Warsaw, we pay particular attention to this combination of symptoms, because it leads to an investigation entirely different from a dental one.

A night guard is not a diagnostic test, although it is sometimes taken for one. Resolution of pain after it has been fitted does not prove that bruxism was the cause. The face, the neck and the head respond to many things at once, and a lack of improvement excludes nothing.

Frequently asked questions

Does bruxism make the face wider?

It can, but the shape of the face on its own is not proof. A masseter working excessively grows as any muscle does, except that on ultrasound measurement in 80 dental students the thickness did not differ between people with bruxism and the comparison group, either at rest or at maximum clenching. Sex differentiated this muscle more clearly. What speaks for clenching, then, is tenderness of the muscle under pressure and signs of wear on the teeth.

Does masseter hypertrophy regress after treatment?

A muscle that stops working with excessive force usually shrinks over time. The pace of that change after conservative treatment alone was not measured in the studies cited here. It depends on whether the force of clenching has actually fallen; a night guard alone is not enough, because it does not remove the habit.

Do headaches resolve once a night guard is fitted?

In some patients the complaints ease, although this is not the rule and it does not confirm the diagnosis. A night guard protects the teeth and changes the distribution of forces, but it does not remove the cause of the clenching. If a headache persists despite a correctly fitted night guard, what is needed is a neurological consultation rather than another adjustment of the device.

Could this be migraine rather than bruxism?

The face and the temples hurt in both cases, and the two conditions are sometimes present at the same time. What speaks for migraine is pain that is throbbing and one-sided, with nausea and sensitivity to light, sometimes preceded by visual disturbance. What speaks for a muscular cause is pain described as pressure, which can be provoked by chewing or by pressure on the muscle.

Why is the jaw stiff and heavy in the morning?

Because the muscles that raise the lower jaw worked during the night, and the effect of that work is felt on waking. Muscular stiffness usually resolves within an hour and is not accompanied by clicking or locking of the jaw. If in the morning the mouth cannot be opened to the width of three fingers, or the movement jumps, this requires examination of the masticatory muscles and of the temporomandibular joint.

Which doctor should you go to first?

With a headache building to its maximum in less than a minute, and with a headache accompanied by fever, neck stiffness, disturbance of speech or vision or weakness of a limb, the hospital emergency department comes first. With the remaining red-flag symptoms - a neurologist or an ENT specialist, depending on the complaint. Without them it is more sensible to start with a dentist, who will examine the masticatory muscles, the temporomandibular joint and the teeth. If the examination does not explain the complaints, the next step is a neurological consultation, and where a sleep disorder is suspected, investigation of breathing during sleep.

Is tinnitus connected with bruxism?

Tinnitus is sometimes described together with temporomandibular disorders, particularly when it changes with movements of the jaw or with pressure on the muscles. This does not mean that clenching the teeth is its cause. Tinnitus on one side, worsening of hearing and dizziness always require an ENT examination first, regardless of the state of the dentition. Sudden and severe dizziness requires urgent medical assessment; you do not wait for a scheduled appointment with it.

How long before improvement shows?

That depends on the symptom. Muscle tenderness usually responds fastest, within a few weeks of work on the habit and of wearing a night guard. Morning headaches resolve more slowly and unevenly. If bruxism has changed the face, its outline responds last. These timescales were not measured by the studies cited here. A lack of improvement after two or three months is an indication to reassess the diagnosis.

Where to start when the face, head and neck hurt

With the red-flag symptoms. Those go to a doctor at once, and everything else starts with an examination of the muscles, the joint and the teeth.

The evidence linking bruxism, the face and headache is weaker than conversations in the surgery would suggest. The face, the neck and the temples may hurt for several reasons at once.

Two weeks of notes shorten that path, and four things a day are enough for them: the hour at which the pain appeared, its character (pressure or throbbing), the state of the jaw on waking, and whether the pain changed with chewing.

Read more:

• Modern Dental Prosthetics in Warsaw
• Bruxism - symptoms: eight signs your dentist spots before you do
• Teeth grinding at night or clenching during the day — two different problems, two different treatments

Content and liability disclaimer

This article is informational and educational in nature and does not constitute medical advice, a diagnosis or a therapeutic recommendation — it does not replace a consultation with a specialist. If you are experiencing symptoms, have doubts or are facing a decision about treatment, consult a dentist. The methods described and the data cited are general in nature. The results of scientific studies relate to populations, not to an individual patient. The course and outcome of therapy depend on the individual clinical situation and may vary between patients. No information contained in this article constitutes a guarantee of result. The content has been prepared with due care, based on publicly available medical knowledge and the scientific publications indicated in the Sources section. We do not advise taking or refraining from any health-related action solely on the basis of the content of this article, without prior consultation with a doctor.

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