Excessive grinding and clenching of teeth, otherwise known as bruxism, can lead to tooth wear, jaw disorders,headaches and hypertrophy of the muscles of mastication. Professor Bob Khanna discusses his preferred treatment approach, using a combination of botulinum toxin and occlusal therapy


For at least 10 years, medical professionals from dermatological, surgical and dental backgrounds have been injecting various masticatory muscles to treat bruxism, so it’s imperative that we look at the underlying aetiological factors so as to fully understand this complex condition prior to treatment. The medical background of the treating practitioner is essentially irrelevant as the patient presents with the same features and hence we need to understand what these are.

Its estimated that at least 40% of us will suffer with bruxism at some point in our life. It involves over zealous clenching and grinding of the teeth ie.a parafunctional activity which is so outside of the norm.

It’s a complex situation and often poorly understood. It has been related to certain personality types, such as high-achieving go-getters and, of course, stress.
This is not a condition that only occurs later on in life—it can happen in children and can progress firmly into adulthood. We’re all aware of masseteric hypertrophy and how it’s particularly discernible in women, as we often deem this to be more masculine characteristic.

However, research on masseteric hypertrophy is quite thin on the ground, particularly pertaining to the involvement of botulinum toxin. There has been a distinct lack of  dose-related response studies and hence a  “one size fits all” approach to date.In my opinion we need to have a dose-related type of response strategy  and  methodology to be able to treat different types of presentations and variations within bruxism cases.

The masseters are an important part of the masticatory system, but we can’t ignore the temporalis or the medial and lateral pterygoids. We could also look at the sternocleidomastoid, trapezius and splenius capitis, which are often involved, and even the platysma in excessive bruxism.

Injection complications

Back in 2003, I looked at trying to achieve a dose-related protocol for the injection of masseters. I looked at a number of ways of achieving this in a systematic way, being mindful of the complications that can ensue, notably inadvertent injection into adjacent superficial muscles such as the risorius.

This is superficial to the masseter but extends quite far laterally overlying the muscle, so if your injections aren’t deep enough and posterior enough this can lead to smile asymmetry. This is one of the most cited complications following injections of masseters.

Over-exuberant treatment to the masseter can result in ‘jowling’ in patients with excessive and slack skin at the mandibular border.

In such cases  we can treat over two or three sessions over an 8 week period and achieve very good results—dramatic results in many cases without exacerbating any pre-existing jowls. In addition we can improve the definition of  the cheekbones without physically treating those areas, just by changing the balance of the facial parameters.

If necessary as part of the diagnosis,treatment of the medial and lateral pterygoids can be done extra-orally, if we consider the anatomy.

Underlying cause

In 2003, I looked at my referral patients and every single one—as is the case today—had to complete a comprehensive occlusal assessment. I investigated the underlying aetiology and it was clear to me that the majority of these patients had discernible signs of occlusal disease, and TMJ degeneration or derangement.
This is of course a problem—the danger is that if we adopt the approach of merely ‘putting a plaster on the wound’,then we’re not getting to the underlying cause and diagnosing the problem as a medical practitioner ought to.

This issue is not a new discovery; it was highlighted back in 1901 by Karolyi looking at the role of occlusion and TMJ function. There has since been a disconnect between Dentistry and Medicine and therein lies the problem.

In 1961, Ramford noted that malocclusions and dental inferences are a large etiological factor to bruxism and the pathophysiology of pain. That seems to be the accepted norm now for most teaching within the dental fraternities across the world. This is a serious problem and the key is early intervention.

Bruxism itself is a very complex disorder and seems to be related to genetic susceptibility and autonomic dysfunction with faulty descending inhibitory pain controls.
If we consider this male patient with unilateral masseter hypertrophy, after carrying out a differential diagnosis to ensure the problem is indeed a muscular one, we need to understand why he has this unilateral masseter hypertrophy.

Examining the occlusion it was found that the patient had a unilateral dental interference in the molar teeth -this is not uncommon. These are what we call non-working side or working side posterial occlusal interferences .

On lateral excursion, when the mandible is moved to either the right or left, certain teeth are clashing when they ought not to be. In an idealised occlusion, the canines should be the only teeth that actually guide this excursion.

The relevance to muscle hypertrophy is that the occlusal interferences in the posterior teeth lead to excessive and differential contractions of the masticatory muscles—in particular the masseters, therefore inducing hyperactivity and hypertrophy which will eventually lead to oro-facial pain and the continued destruction of teeth and the TMJs.

Therefore if we only treat the muscles with botulinum toxin, we’re not going to solve the underlying problem and aetiology.


The solution starts with a comprehensive diagnosis and dental assessment, looking at occlusional interferences and temporomandibular joint issues with x-rays, MRIs and CTs.

We need to conduct a comprehensive muscle examination with or without EMJ tracing, looking at all the muscles of mastication and then take a comprehensive history. Most people who clench and grind are aware that they do it or if not their partners certainly do!.It’s not something that goes on without being noticed.

In excessive situations it’s audible, so partners will often say they hear their partner crunching and grinding their teeth in their sleep because it’s often nocturnal.
Failure to carry out a comprehensive assessment will lead to an incomplete diagnosis and therefore complete ignorance and neglect of the underlying aetiology.
We have to avoid continued TMJ and dental degeneration and the potential for exacerbating these pathophysiologies by just using botulinum toxin.

We wouldn’t treat a diabetic ulcer without treating the underlying cause; the diabetes. We wouldn’t treat a retrosternal chest pain with a little ointment or analgesics without looking deeper at the cause of that particular condition, so why are we doing this with bruxism?

Therefore treatment in my opinion should involve botulinum toxin as an adjunct to occlusal therapy.

Occlusal therapy can range from very specific designs of removable or fixed splints followed by occlusal equilibration treatment (adjustement of tooth surfaces)
I’ve developed specific protocols for the treatment to strategically administer btx to the masticatory muscles that are in spasm or hypertrophic,so as to deal with all types of presenting cases.

Professor Bob Khanna is a cosmetic and reconstructive dental surgeon, with clinics in Ascot and Reading. He also runs the Dr Bob Khanna Training institute for Facial aesthetic training

Author: bodylanguage

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