Results Showing efficacy of Nighttime Biofeedback as a Tool for the Reduction
of Habitual Bruxism Activity and Related TMJ/TMD Symptoms.
by Lee Weinstein,
January 1, 2013
The National Institutes of Health estimates that 10.8
million people suffer from TMJ disorder (TMD, aka TMJD) in the United States,
and 90 percent of those sufferers are women in child-bearing years. In a
recent study done at Tufts involving 504 TMD patients, about 70% of patients
self-reported that they attributed their TMD symptoms to bruxism 1.
It has long been known that Bruxism is one of the main causes of TMD, but until
the recent advent of wearable, quantitative EMG measurement equipment, it had
been difficult to measure the correlation between various TMD symptoms and the
quantity of bruxism that a patient exhibits. The advent of the first EMG
measurement headband in 2001 made quantitative assessment of bruxism much
easier and more economical.
Fig. 1 The EMG measurement and biofeedback headband
used in this study uses conductive rubber pads that rest on the temples to pick
up EMG signals from the temporalis muscles during sleep, and logs the number of
clenching incidents, and the accumulated clenching time.
One of the most challenging things about bruxism to both
patients and clinicians is that in many cases even if the initial cause of
bruxism can be identified and eliminated, the bruxism behavior may have become
habitual and thus the behavior may not be eliminated by the elimination of the
cause. The habitual nature of bruxism is one of the reasons that all treatment
modalities available prior to nighttime biofeedback (including splints, drugs,
Botox, chiropractic techniques, acupuncture, etc.) have met with only limited
success. In a survey of 300 habitual bruxers conducted through Google 2,
no more than 15% of the patients that had used any one of these prior treatment
modalities rated the modality highly effective.
There has been a large body of research to support the use
of biofeedback to aid in treatment of TMD pain 3, with dental
co-treatment 4-10, for temporomandibular joint (TMJ) muscle
tension 11-15, and bruxism 16, 17. These
studies were all done using tabletop biofeedback units that connect to the
patient with wired adhesive electrodes.
In this study we examine the efficacy of nighttime
biofeedback in the reduction or elimination of habitual bruxism. Efficacy was
measured through quantitative EMG measurements made during sleep, using the EMG
measurement and biofeedback headband shown in figure 1. Although the majority
of patients who participated in the study self-reported reduction or
elimination of symptoms, the basis of this report is quantitative EMG
The SleepGuard biofeedback headband (shown in figure 1) is an
EMG measurement and biofeedback devise worn on the head. It measures
electromyographic signals (EMG) from the temporalis muscles. The headband may be
used while awake or during sleep. In this study, patients wore the headband
while sleeping. The headband can be worn either in silent mode (to measure
baseline bruxism) or in biofeedback mode. In both modes it measures two things
over the course of a night: a count of bruxism events, and the total
accumulated clenching time of those bruxism events. The headband includes a
piezoelectric tone generator which contacts the forehead and can produce an
acoustic biofeedback tone which is heard through bone conduction in both ears.
When the headband is used in biofeedback mode, the tone
starts at a low volume when clenching starts, and ramps up in volume after
about one second if clenching continues. As soon as clenching stops, the tone
stops. The intent is to provide a signal that patients can respond to (by
relaxing their jaw muscles) in sleep, without waking up, thus cutting clenching
incidents short and thus reducing the damage caused by clenching. In this
study, the headband was worn by each patient for 30 nights. During the first
three nights, the headband was used at night in silent mode to gather baseline
data, and patients did a few minutes of wakeful practice responding to the
tone, to increase their likely ability to respond in sleep. During the
remaining 27 nights, the headband was used in biofeedback mode.
Clinical Trial Results
The first round of clinical trials to test the efficacy of using a
biofeedback headband to reduce bruxism involved 92 patients. The total clenching time recorded by the
biofeedback headband each night was logged on a daily basis. The first
three days of data for each participant were baseline data. The remaining
27 days of data were data taken with the biofeedback turned on. Running the
data through a statistical analysis package yielded a p value for the data of 10-16.
One illuminating way to view the data is to divide the
clinical trial patients into four groups (quartiles), ranked by overall end
reduction in nightly bruxism at the end of the trial versus the beginning. The
four graphs below represent efficacy quartiles (23 patients each, with each
graph representing the average of the normalized data from the 23 patients in
the quartile). The most responsive quartile is shown first and the least
responsive quartile is shown last. Average nightly reduction in bruxism time
was measured as the difference between the normalized average nightly clenching
time during the three days of initial baseline measurement (this average was
normalized to 1 for all patients), and the normalized average nightly clenching
time during the last three days of the trial.
The best performing quartile (23 patients) results are shown
in figure 2 below.
Fig. 2 Clenching time reduction of most efficacious
30-day clinical trial.
These patients showed an average initial reduction in
bruxism time of 80% in one day after turning on the biofeedback, and by the end
of the month they had a nightly bruxism time reduction of 90%. Since clenching
force typically ramps up during a clench, cutting the clench short cuts out the
most damaging part of the clench.
Since the body’s nervous system senses mostly differences
and rates of change rather than absolutes, a clencher’s brain gets more of the
clenching sensation it is addicted to by increasing bite force throughout each
clench, and this is indeed what happens during a typical clench. The force-vs.-time
diagram of a typical clench whose force linearly increases through the clench
is shown in figure 3. The peak clenching force varies from person to person,
as does the length of the clench, but the numbers shown in figure 3 are not
Fig.3 Typical variation of clenching force during a
Clench of a bad bruxer
Assuming increasing clench force throughout a typical
clench, and taking into account the probable average reduction of peak clenching
force of 50% to 90%, gives a probable 95% to 99% reduction in nightly damage.
Most patients in this quartile report substantial reduction or complete
elimination of pain such as jaw pain, migraines, TMJ pain, etc..
The next best performing quartile (23 patients) is shown in figure 4 below.
Fig. 4 Clenching time reduction of second most
efficacious quartile during
30-day clinical trial.
The "remaining bruxism" of these patients is about twice the most
efficacious group (in terms of remaining clenching time), but still very low.
Again, because the damaging, higher-force later part of each clench is not
happening, the reduction in ongoing damage and pain may be reduced far more than
one might think from the percentage reduction in clenching time indicated above.
As can be seen in both of the upper quartiles above, nightly
clenching time was trending down steadily toward the end of the month, perhaps
indicating that these patients are on the average training themselves out of
their bruxism habit. This theory is supported by anecdotal evidence in
follow-up interviews several months later, where a number of patients said that
after using the biofeedback for between two and four months, they were able to
go for long periods (over a month) without using the headband before any daily
Most patients in this second quartile, like the first
quartile, report substantial reduction or complete elimination of pain such as
jaw pain, migraines, TMJ pain, etc..
The average of the data from the lower mid quartile (23 patients) is shown in
figure 5 below.
Fig. 5 Clenching time reduction of third most
efficacious quartile during
30-day clinical trial.
These patients experience approximately a 60% initial reduction in nightly
clenching time when the biofeedback is turned on, and their nightly clenching
times remain at roughly this level for the rest of the month. In addition to
the reduction in clenching time, it is estimated that this group experiences a
reduction in clenching force of about 50%.
There is no obvious trending downward toward the end of the
month for this group, so there is no evidence that they are training themselves
out of their bruxism habit, but continued use of the biofeedback appears to be
a viable tool in ongoing mitigation of bruxism damage and pain. Some patients
in this quartile reported a complete elimination of pain symptoms, including
TMJ pain and migraines.
The data from the worst-performing quartile (excluding one outlier, whose data
is included in the whole group average, but whose data warps the average of the
quartile significantly) is shown in figure 6 below.
Fig. 6 Clenching time reduction of lest efficacious
30-day clinical trial.
These patients respond well to the biofeedback at first, and then over time,
their nightly bruxism times came back to a level close to their baseline
One way to interpret why this may happen is that each person
may be thought of as being of "two minds". One part of the mind
wants to learn to relax and get out of the bruxism habit. This part of the
mind hears the biofeedback tone as a caring reminder about something important.
The other part of the mind wants to learn to ignore any
sound heard during sleep, and continue with any addictive behavior. For this
group, this second part of the mind appears to win out, and patients return to
near-baseline levels of clenching (though there is some reduction in clenching
time and some reduction in clenching force, so they still benefit). This is
discussed further in the later section titled “Efficacy Factors”.
Averaging the data from all 92 patients in the clinical
trial, the overall average clenching time graph is shown in figure 7 below.
Fig. 7 Average clenching time reduction of all 92
patients in clinical trial .
As can be seen by comparing the "overall average"
graph above to the four quartile graphs, the overall average is only
representative of a small percentage of people in the trial.
To place the results of this study in proper context it is
important to understand the neurological nature of habit formation and habit
modification and their relationship to biofeedback and bruxism. Below we will
first present a modern neurological model of habit formation and modification,
which form the basis for the design of this study. After that premise is
shared, we will discuss other treatments and how they fit within this
neurological model of habit formation and modification. We will then present
key differences between nighttime biofeedback and daytime biofeedback in the
treatment of nighttime bruxism.
The Habitual Nature of Bruxism
How nighttime clenching becomes a habit
Lets take a look at how we human beings build habits. One
of the key functions of the neocortex (the part of the brain that makes humans
different from animals) is the formation and execution of habits. Habits
enable us to do many things subconsciously and simultaneously, while our
conscious attention can only handle doing one or two things. Recent brain
research 18 has shown that the basic function of the
neocortex is to memorize, recognize, predict, and replay patterns. Habit
formation and the triggering of habitual actions (such as stepping on the brake
when the brake lights of a car in front of you go on) are subsets of these
basic cortex functions of memorizing, recognizing, predicting, and replaying
We survive by building thousands of such "good"
habits, all of which are triggered by associated feelings or situations. Once
a recognition sequence (of a feeling or situation) and the appropriate response
action sequence have been learned, that recognition and those responses can
(and do) become subconscious, in that the recognition of circumstances and the
acting out of the response both happen without us thinking about it. There are
many such recognition and action sequences involved in being able to do
something like play a sport, or drive a car. Once a given recognition neuron
has been wired up to trigger an action sequence neuron, it takes substantial
re-training to prevent that triggering from happening, or to mitigate the
action once it has been initiated. The perception patterns we learn to
recognize to trigger a motor sequence (habit) can include all our senses, plus
emotional states, plus imagined situations and emotions.
When we learn a habit such as bruxism, both an action
sequence (clenching), and the resulting sensation sequence are stored in our
brains through repetition, in the form of strengthened neural connections, and
later either imagining the sensation sequence or something associated with it
(or experiencing an associated emotion) can trigger the action subconsciously.
As we first develop a habit
where there is no initial tendency, the (non-conscious) neural pathway from
sensation sequence to desired action sequence could be thought of as a
meandering pathway (sequence of neurons that fire) through an un-cut jungle to
a destination (an action).
For habits where there is an
initial tendency, a jungle with a path through it may be a better initial
Each time a particular neural
pathway gets used, it gets strengthened. This happens physically at the synapses
between neurons. So as the habit gets more entrenched, that path through the
jungle may begin to look more like a road (which is easier to go down than a
When the habit becomes still
more entrenched, it may look more like a highway.
The structure of breaking a habit
If we have a habit (a neural highway toward a particular
action sequence such as bruxism) and we want to stop using that highway for a
while so it can become “overgrown with trees and look more like a jungle.” How
might this be accomplished?
With habits like fingernail biting or thumb-sucking, the
answer may seem obvious. A way to change the habit is to develop awareness of
the onset of the behavior, and then substitute a different behavior. Repeated
conscious intervention is the key to modifying any habit. But how can a habit
be modified if it occurs during sleep?
The key to modifying a habit that occurs during sleep is to
provide some level of conscious awareness of the onset of the habitual action,
so the sleeping person can substitute a different action sequence. Nighttime
biofeedback can provide a signal at the onset of an action but the challenge
remains as to how to recognize and respond to such a signal when sleeping.
Most parents will realize through their own experience that if they hear a
sound in the house that could indicate his or her child is in danger, the
parent will usually suddenly wake. This sudden waking happens when a
subconscious process in the cortex recognizes (for instance) a sound sequence
that could indicate a child is in danger. If a signal is recognized during
sleep this signal could be effectively used to change a habit particularly if
it can occur without awakening the patient.
Bruxism Habit Formation
Let's take a look at the stages of habit formation as they
relate to bruxism:
Intense Thought/Emotion --------------->
instance stress, traumatic memory of
accident, allergic reaction to a food,
reaction to a drug)
(Clenching and/or grinding of teeth)
Sequence (in presence of thought/emotion) ------>
Clench with force ramping up,
Nerve Sensation Sequence from teeth
-> Predictive memory of sequence -> Habitual Muscle/Sensation sequence
While in the beginning it may be an exceptional
circumstance, such as a traumatic event, or a very stressful period of time, or
a drug or nutritional situation that throws the patient's system into
imbalance, and results in bruxism, once Bruxism becomes a habit, it only takes
a subconscious memory to trigger the previously memorized bruxism action
sequence in sleep. As the bruxism happens, neural associations are built
between emotions, physical sensations, and muscle actions. Additionally,
memories are formed of those emotional states and physical sensations, and
later recalling of those memories can trigger the associated muscle action
Detecting and Interrupting Bruxism
The muscles involved in typical
bruxism are the temporalis and masseter muscle groups. Typically these two
muscle groups fire together during normal chewing and bruxism. There are
exceptions to this, but those exceptions are relatively uncommon.
What is much more common is for bruxism to occur in a way
which is imbalanced between the right and left sides of the head. During
normal chewing, food is shifted between the left and right sides of the mouth,
and the brain automatically actuates jaw muscles on opposite sides of the head
in a ratio that shifts with the shifting of the food being chewed. Most people
are able to consciously selectively actuate the jaw muscles on either side of
their head if so instructed. The biofeedback headband is designed to detect
muscle groups on both sides of the head, in order not to offer the brain the opportunity
to subconsciously addictively seek to produce the feeling of clenching on only
one side of the head to avoid detection.
Daytime Response Conditioning
Prior to this clinical trial, interviews were conducted with
100 patients who had used the headband for bruxism reduction for at least two months.
Anecdotal reports from those interviews indicated that patients who spent
wakeful time training themselves to relax when they heard the biofeedback tone
did better than patients who did not.
Within the clinical trial presented herein, written
instructions directed all participants to spend at least a few minutes per day
in the first few days doing “response training” to train themselves to relax
cooperatively and immediately when the tone was heard. The instructions
explained that the intent was for this training to carry over into sleep, and
increase the patient's ability to respond (by relaxing his or her jaw) in sleep
without waking when the biofeedback tone is heard. No verification was done to
confirm that patients understood the importance of the daytime conditioning,
and no patient interviews were conducted to determine to what extent each
patient followed the instructions concerning daytime conditioning.
In the year following the clinical trial, experiments were
conducted with numerous patients whose results were analogous to those in the
least efficacious quartile of the clinical trial, and more effective daytime
conditioning practices were developed.
Mental Alignment With the Process
Mental alignment with the process has been found to be one
of the key factors influencing efficacy. Patients who describe themselves as
feeling grateful for the audio reminder to relax their jaw muscles tend to decrease
their nighttime clenching faster and by a higher percentage than patients who
do not describe themselves as feeling grateful for the reminder. Thus the
suggestion of practicing feeling grateful has also been added to the suggested
Louder Biofeedback Sound Helps Some Deep Sleepers
Subsequent to the clinical trial, some patients who
considered themselves heavy sleepers and whose results were analogous to those
in the least efficacious quartile of the clinical trial were given biofeedback
headbands modified to supply the biofeedback sound through and earphone rather
than the standard piezoelectric transducer which contacts the forehead. About
50% of those patients were able to get bruxism reduction analogous to that of
the more efficacious quartiles using a louder biofeedback sound through the
This clinical trial showed that about 75 percent of patients
are able to reduce their nightly clenching substantially through ongoing use of
the biofeedback headband in its standard configuration. On the average, the
bulk of the benefit in nightly clenching time reduction is realized from the
day the biofeedback is turned on. Reduction in pain or elimination of pain
usually follows within several days. About 25% of patients appear to remain at
the initially-reduced level ongoingly, and there are indications that about 50%
of patients are able to continue to steadily reduce their nightly clenching
times beyond the initial reduction. Future
research will include a follow up trial that is 60 days long
instead of 30 days long, and includes 3-day baseline measurements after 27 days
and after 57 days, as well as at the beginning of the trial. Another clinical
trial is being designed specifically as a migraine reduction study. Holistic Technologies
is interested in partnering with researchers interested in doing related
Next Steps - Partners Wanted
Holistic Technologies is interested to partner with professionals, including Doctors, Dentists, Chiropractors, and Physical Therapists to learn even more from this clinical trial (through patient interviews), and publish journal articles based on this trial and future work. Please contact us if such a partnership would be of interest to you.
1. van der Meulen MJ, Ohrbach R, Aartman IH,
Naeije M, Lobbezoo F (2010). Temporomandibular disorder patients' illness
beliefs and self-efficacy related to bruxism. J Orofacial Pain 24
Technologies LLC - On-line bruxism survey (2010) through Google
AdWords re people searching on
terms including the word bruxism.
SG, Gale EN. Biofeedback in the treatment of long-term temporomandibular
joint pain: an outcome study. Biofeedback Self Regul. 1977
JJ, Barwell DR. Biofeedback training and relaxation exercises for treatment
of temporomandibular joint dysfunction. Otolaryngology. 1978 Sep-Oct;86(5):ORL-766-9.
L, Carlsson SG. Treatment of mandibular dysfunction: the clinical usefulness
of biofeedback in relation to splint therapy. J Oral Rehabil. 1984 May;11(3):277-84.
6. Crider AB, Glaros AG. A meta-analysis of EMG biofeedback
treatment of temporomandibular disorders. J Orofac Pain. 1999
7. Müller F. [Biofeedback as a part of the treatment of
mandibular dysfunctions]. [Article in German] Dtsch Zahnarztl Z.
8. Medlicott MS, Harris SR. A systematic review of the
effectiveness of exercise, manual therapy, electrotherapy, relaxation training,
and biofeedback in the management of temporomandibular disorder. Phys
Ther. 2006 Jul;86(7):955-73.
A, Glaros AG, Gevirtz RN. Efficacy of biofeedback-based treatments for
temporomandibular disorders. Appl Psychophysiol Biofeedback. 2005 Dec;30(4):333-45.
DC, Zaki HS, Rudy TE. Effects of intraoral appliance and biofeedback/stress
management alone and in combination in treating pain and depression in patients
with temporomandibular disorders. J Prosthet Dent. 1993
F. Castrillon E, Svensson P. Effect of conditioning electrical stimuli on
temporalis electromyographic activity during sleep. Journal of Oral
CL, Kraft GH. Electromyographic biofeedback for pain related to muscle
tension. A study of tension headache, back, and jaw pain. Arch Surg. 1977
RA, Wedding D, Sanders SH. The comparative efficacy of relaxation training
and masseter EMG feedback in the treatment of TMJ dysfunction. J Oral
Rehabil. 1983 Jan;10(1):9-17.
RA. Relationships between jaw pain and jaw muscle contraction level:
underlying factors and treatment effectiveness. J Prosthet Dent.
JJ, Barwell DR. Biofeedback training and relaxation exercises for treatment
of temporomandibular joint dysfunction. Otolaryngology. 1978
16. Pierce CJ, Gale EN. A Comparison of Different Treatments for
Nocturnal Bruxism. J Dent Res 67(3):597-601, March, 1988.
PS. Use of the Calmset 3 biofeedback/relaxation system in the assessment and
treatment of chronic nocturnal bruxism. Appl Psychophysiol Biofeedback.
18. Hawkins J, Blakeslee S. On Intelligence. First Edition.
Henry Holt and Company: New York, NY. 2004: 106-76.