Night guard or botulinum toxin: what to do about clenching your teeth at night

You wake up with a tense jaw, your temple aches as if after a workout, and when you yawn widely something clicks in the joint. Or no one hears anything at night because you clench silently, and the first signal comes from the dentist: the biting edges are flattened, vertical cracks can be seen in the enamel, fillings are chipping. Two proposals then come up: a night guard from the dentist, and botulinum toxin in the masseters from an aesthetic medicine doctor. These are not competing solutions. Each works on a different end of the same problem.

What happens at night

Bruxism is not a disease of the tooth but a repetitive muscle activity: clenching and grinding outside conscious control. The masseter is short and thick, built to work under heavy load. During the day it works in short bursts when eating; at night it can hold tension for much longer. That is where the morning order of symptoms comes from: first the muscle and joint speak up, and only then the tooth.

• Jaw and temple pain right after waking, easing during the day
• Fatigue when biting hard things, sometimes a click in the temporomandibular joint
• Worn biting edges and flat, polished surfaces on the back teeth
• Chipped fillings and hairline vertical cracks in the enamel
• Sensitivity to cold in places where there is no decay
• A lower face contour that over the years can become wider and squarer

Not all wear comes from clenching. An acidic diet, reflux and brushing too hard give a similar picture, and they are treated differently. That is why we establish the cause at an examination, not from a list of symptoms.

A night guard: it protects the tooth but does not switch off the muscle

A relaxation splint, or night guard, is a custom-made appliance, most often worn at night. It separates the arches, sets the lower jaw in a repeatable position and takes the contact that would otherwise wear down the enamel. The guard wears, not the tooth, and that is its role. The starting point is an examination and a record of the arches; an iTero or 3Shape intraoral scan saves their shape digitally, so we have something to compare the condition with after a few months.

What a night guard does not do: it does not reduce the force with which you clench. The muscle keeps working, only it meets a layer of plastic instead of the opposing tooth. In some people the tension eases over time, because the distribution of contacts in the bite changes. In others the teeth are protected but the morning pain remains, and that is exactly the moment when the conversation turns to the masseters. A night guard also requires consistency: one that sits in a drawer or fits badly protects nothing.

Botulinum toxin in the masseters: it works on force

Botulinum toxin temporarily limits the transmission of the signal from nerve to muscle. Injected into the masseter, it does not switch it off but weakens it. The muscle contracts with less force, so night-time activity still happens, only the load it produces is smaller. The night guard and the toxin approach the same problem from two sides: the first protects the surface of the tooth, the second reduces the force acting on it.

A visit with a medical history, an assessment of how the muscle works and marking the points fits into 20–30 minutes; the injections themselves with a fine needle take a few minutes. The first effect appears after 3–7 days, and the full effect is assessed after two weeks; we set the follow-up date straight after the injection, and then, if needed, top up the dose. At the first injection we plan more cautiously, because it is easier to add to a dose than to take away. The effect usually lasts 3–6 months, and in the masseters it can last longer than in expression areas, after which the muscle returns to its previous activity.

Choosing criteria

The question is not “which is more effective” but “what is being damaged fastest in your case”. The answer comes from the examination, not from preference.

• Worn edges, enamel cracks and chipped fillings are in the foreground: we start by protecting the hard tissues, that is, with a night guard
• Muscle and temple pain are in the foreground, the masseter hurts when pressed, and the teeth are still in good condition: it makes more sense to reduce the force
• The night guard has been worn for months, the teeth are protected, but the morning tension does not ease: toxin can then be a complement, not a replacement
• You cannot tolerate the night guard and wake up without it: say so plainly, because it changes the order of the plan
• A cosmetic restoration is in the plan, whether bonding, flow injection or veneers: we assess the biting loads before the work, not after it
• Symptoms get worse in periods of mental strain: part of the plan lies outside the practice, and we say so openly

What toxin in the masseters will not do

It is a prescription medicine, not a cosmetic. A doctor assesses you for it and injects it, after a medical history covering general conditions and medicines you take. We do not inject during pregnancy or breastfeeding, with neuromuscular diseases such as myasthenia gravis, with an infection or inflammation at the injection site, or with hypersensitivity to the product. After the treatment there may be bruising, swelling and headache, and depending on the injection area, a temporary asymmetry of expression or a drooping eyelid. We discuss this before the injection, not after.

The limits of the treatment are worth remembering separately. The toxin does not remove the cause of grinding, does not rebuild worn enamel and does not replace treatment of the temporomandibular joint. For the first few weeks, biting hard food may tire you faster than usual; this is a consequence of the weakened muscle, not a complication. And one more thing: with longer use the masseter shrinks in volume, and the lower face can become narrower. For some people this is an argument for, for others a reason to lower the dose. Say before the injection which side you are on.

Why we ask about clenching before a restoration

Composite wears, ceramics crack: each of these materials has a limit of strength, and with bruxism you reach it sooner. That is why, when assessing for bonding, flow injection and veneers, we evaluate the biting loads before setting the treatment date. If clenching goes unrecognised, the new biting edges will take the same force as the old ones and the story will repeat itself, only on fresh work.

This is one of the few topics on which a dentist and an aesthetic medicine doctor have to agree the plan between themselves: one assesses wear and bite, the other assesses for an injection into the muscle. With us both skills are in one practice, so decisions are made in one place, not in two separate referrals.

Where we start

With an examination. A dental check-up takes 30–45 minutes and covers the teeth, gums, soft tissues and the contact of the teeth in the bite. Whatever raises doubts we show on intraoral photos, because wear is easier to assess from an image than from a description. When the examination alone does not settle the diagnosis, we add imaging: we have a CT scanner on site.

1. Examination and medical history: morning symptoms, medicines, general conditions, past orthodontic treatment.
2. Recording the starting point: intraoral photos and, if needed, an iTero or 3Shape scan.
3. Sorting findings into urgent, planned and to monitor.
4. Deciding the order: a night guard, injection into the masseters, both, or something else first.
5. Follow-up: two weeks after the toxin injection, and for a night guard a fit check after it is delivered, then at check-ups.

If for years you have been waking up with a tense jaw and hearing at the dentist that your teeth are worn, you have one question to settle: is it more urgent to protect what is left, or to reduce the force that damaged it? Usually the answer is not “either-or”.

Find out what works at night

Start with an examination: an assessment of wear, bite and masseter tension, and then a decision: a night guard, an injection into the muscle, or both.

See the treatment