Audio-Visual Entrainment: II. Dental Studies
by Siegfried Othmer | May 26th, 2004DF Attached at bottom Audio-Visual Entrainment: II. Dental Studies
David Siever¹, Edmonton, Alberta, Canada
Abstract: A great deal of temporo-mandibular joint dysfunction and myofascial pain dysfunction
is activated in relation to anxiety and fear responses to challenging tasks, self-criticism and daily
hassles. AVE, like passive meditation, appears to effectively alleviate these symptoms.
Historical Background
The first few studies of visual entrainment (VE) involved a device called the Brain Wave
Synchronizer. The seminal hypnosis study by Kroger and Schneider in 1959 prompted more
research along hypnosis lines. Shortly thereafter VE was used as an analgesic for gastrointestinal
surgery, where it was found that over 90% of patients entered useable levels of trance
induction prior to surgery (Sadove, 1961). The Sadove study caught the interest of the dental
profession, which was awakening to the role of anxiety in temporo-mandibular joint (TMJ) and
myofascial pain dysfunction and during dental procedures.
Dental Studies
VE was shown to reliably “drive” dental patients into a hypnotic induction during dental work in
a short period of time, if the VE frequency was set near the dominant natural alpha frequency of
the patient (Margolis, 1966). Margolis placed the “synchronizer” near the patient during a dental
procedure. He noted several positive effects.
1) VE reduced the amount of anesthetic used.
2) In some cases, hypno-anesthesia could be used exclusively.
3) Anesthesia could be terminated immediately following surgery.
4) VE produced no depressing physiologic side-effects.
5) VE made post-hypnotic anesthesia possible.
6) VE controlled gagging.
7) VE reduced fear and anxiety in the dental situation.
TMJ dysfunction is an affliction that affects many people. In order to understand the scope of the
VE studies with TMJ, it is important to have a deeper understanding of TMJ dysfunction and
myofascial pain dysfunction.
Theories of TMJ Dysfunction
Two theories exist as to explain the origins of bruxism, TMJ dysfunction and myofascial pain
dysfunction (MPD), a condition involving severe pain in facial regions. The tooth-muscle theory
ascertains that disharmony in occlusion produces altered proprioceptive information that
activates the occlusal pattern generator which activates the masticatory (jaw-closing) muscles,
which in turn grind down the dentition until a satisfactory occlusion is reached (Manns, et.al.,
1981, Moulton, 1966, Laskin, 1969). Certainly, many people can recall a time when a poorly
made dental filling or orthotic has activated this response, quickly resulting in jaw tension and
pain.
The psychophysiologic theory implies that emotional factors such as stress and anxiety manifest
in increased muscle tension (Manns, et.al., 1981, Laskin, 1969, & Moulton 1966) and increased
perception of pain (Christensen, 1981). It has also been shown that all people show high levels of
masseter tension during initial exposures to a stimulus-response task (Yemm, 1971). Further, it
has been shown that masseter muscle activity increases during challenging tasks, primarily when
the subjects made errors (Yemm, 1969). The Yemm study implies a direct relationship between
self-critical thoughts and tension. Controls show a trend towards relaxation with repeated
exposures to the task, whereas those suffering with TMJ dysfunction show an initial relaxation
phase during the first few exposures followed by a marked increase in masseter muscle tension
with repeated exposures to stimulus-response tasks. This performance anxiety was termed TMJ
personality by Yemm. Anxiety and stress, and the consequent impact on trait arousal are a major
part of a variety of dental disorders. (Spielberger, et.al.1970, Rugh & Solberg, 1975, Yemm,
1971, Weinstein, et. al., 1971). Some additional disorders relating to stress are gingivitis,
osteoporosis of the alveolar bone in animals, alterations in the chemical composition of saliva,
and ulcerative oral legions in dogs (Giddon, 1966). A further investigation of those with
gingivitis, revealed reduced salivary output, increased gingival arterial dilation and increased
sublingual temperature in response to stress.
Rugh and Solberg devised a study where the participants used a small data-logging EMG on the
masseter to measure nighttime or nocturnal bruxism. Hard clenches activated the recorder. This
device could log several days worth of data, which was displayed as the amount of time of
bruxing, in brux seconds/hour. Figure 1 shows a typical example of the relationship between life
stressors and jaw tension, in this case, in a young lady.
Figure 1 Stressful Life Events and Nocturnal Bruxism
When experienced Transcendental Meditators were exposed to photic stimulation near natural
alpha frequencies, they reported subjective experiences similar to their usual experience during
meditation (Williams & West, 1975). A comparison of various strategies aimed at reducing trait
anxiety have shown that passive meditation techniques such as TM are considerably more
effective than other strategies such as progressive relaxation or concentration meditation (Eppley
& Abrams, 1989). This connection between the ability to entrain a brain wave pattern similar to
that of meditators, combined with the subjective meditative experience of AVE, and the fact that
meditation produces a pronounced reduction in trait anxiety, may explain why AVE produces
such striking reductions in anxiety as measured in AVE studies. The next study demonstrates this
point.
Audio entrainment (AE) has shown promise as a singular therapeutic modality for treating
tension and pain (Manns, Miralles, & Adrian, 1981). In this study, people suffering with
myofascial pain and TMJ dysfunction were split into two groups — group A, those with
symptoms for less than one year (n=14), and group B, those with symptoms for longer than one
year (n=19). They received 15 minute sessions of auditory entrainment (AE) consisting of
isochronic, pure (evenly pulsed sine wave) tones, followed by 15 minutes of EMG feedback and
concluding with 15 minutes of AE and EMG feedback combined, for an average of 14 sessions.
The study clearly shows greater reductions in EMG activity during AE. Table 1 shows the
reduction in MPD/TMJ symptoms following treatment.
Table 1 TMJ Symptoms Following Audio Entrainment and EMG Feedback
Symptom Group A (n=14) Group B (n= 19)
Participants with symptoms (%) Participants with symptoms (%)
Pre Tx Post Tx Pre Tx Post Tx
Bruxism 100 7 100 32
Emotional tension 100 14 100 21
Muscle fatigue 93 0 74 21
Insomnia 57 0 53 0
Dizziness 21 0 53 0
Headache 93 0 74 0
TMJ Pain 64 0 47 0
Masticatory muscle pain 71 0 58 9
Neck muscle pain 79 9 79 26
Otalgia 79 9 32 17
Mastoid process pain 43 0 16 0
Articular clicking 50 29 68 54
Mandibular deviation 79 36 84 56
Restricted opening 43 0 16 0
A study involving 10 people (Figure 2) with long histories of TMJ dysfunction was conducted to
see whether they would relax to a guided imagery exercise. Just prior to the guided imagery, they
were given the suggestion of entering deep relaxation by the end of the guided imagery (Thomas
& Siever, 1988). With this expectation in mind, all of the subjects showed bracing or dysponesis
as indicated by a drop in hand temperature and a short fall in masseter muscle (EMG) tension
followed by a considerable increase in tension until the “relaxing” gui ded imagery ended (at
which time they did begin to relax moderately). Interestingly, all members subjectively reported
feeling very relaxed, even though they all had tensed up somewhat. The group then underwent
10 minutes of 10 Hz AVE from a DAVID1 system. Within five minutes masseter muscle tension
became very relaxed and hand temperature increased, signs of sympathetic deactivation and
parasympathetic activation — the meditation response.
Figure 2. Masseter Muscle Tension and Hand Temperature during a Guided Imagery
and AVE
Dental patients often suffer anxiety before and during dental appointments (Lazarus, 1966,
Dewitt, 1966, Corah & Pantera, 1968). Of all the dental procedures, root canal (endodontic)
therapy is the most feared (Morse 1993). Audio-analgesia using white noise and/or music (as
produced by a commercially marketed unit) has been shown to effectively increase pain
threshold and pain tolerance during a dental procedure (Gardner & Licklider, 1959; Gardner,
Licklider, & Weisz, 1960; Schermer, 1960; Monsey, 1960; Sidney, 1962; Morosko & Simmons,
1966).
A study implementing AVE to reduce anxiety during a root-canal procedure has also shown
promising results (Morse 1993). This study involved three groups of 10 subjects. The groups
consisted of a group receiving 10 Hz AVE, a group receiving 10 Hz AVE plus an alpha
relaxation tape (developed by Shealy) simultaneously, and a control group (Figure 3). The study
confirmed that the part of a root-canal procedure that produces the greatest anxiety is the
Novocaineâ„¢ injection, pushing average heart rate up to 107 bpm. The group using AVE had an
average heart rate of 93 bpm, while the group that was further dissociated (AVE and music), had
an average heart rate of 84 bpm.
Figure 3. Heart Rate during a “Root-Canal” Procedure
AVE may settle down jaw tension through muscle spindle de-activation (Siever, 1992). Muscle
spindles regulate body tone and posture as well as facilitate the myotatic reflex (McClintic,
1978). They are fibers that are directly attached to either the muscle fibers (extrafusal fibers) or
to the filaments of tendons. As shown in Figure 4, the spindle consists of two parts, the nuclear
chain fiber and the nuclear-bag fiber. Spiral sensory endings called afferent neurons wrap around
the central portion of both fibers. The fibers receive gamma efferent neurons. These serve to set
the “tone” or sensitivity of the spindle.
Figure 4. Muscle Spindle
The spindle responds when it is stretched, by sending off a stream of pulses. As shown in Figure
5, the primary endings alert the nervous system that a stretch is occurring, whereas the secondary
endings indicate a fair approximation of actual amount or objective measure of stretch of the
muscle (Bradley, 1981).
Figure 5. Muscle Spindle Output
This has important implications in dentistry. When the mouth is opened wide for dental work,
the spindles within the masticatory or jaw-closing muscles stretch, sending output down the
afferent fibers, which synapse with the alpha motor neuron of the muscle. Thus the muscle
tightens up and attempts to return to its original length (Bradley, 1981). Therefore, the jaw
muscles become very tight on wide openings. This in turns loads the temporo-mandibular joint
and can damage the cartilage, or inter-articular disc in the joint and cause TMJ dysfunction. To
make matters worse from a dental perspective, the gamma efferent fibers receive input from the
basal ganglia. The basal ganglia are a set of structures that surround the limbic system. They are
involved with integrating feelings, thoughts and movement and help to smooth motor behavior.
The basal ganglia regulate the body’s “idle speed”, affecting anxiety level (Amen, 1998, p. 43).
So how does this all tie together? When we are relaxed we have a small space of 1 — 3 mm
between our teeth when we are sitting or standing. When we get anxious or scared, the basal
ganglia sends output to the gamma efferent neurons, which in turn make the spindle “hyper –
sensitive.” A hyper -sensitive spindle behaves as if the spindle is stretched, and before we realize
it, we are clenching our teeth (watch the coaches and general managers during sporting events.
Not only are they often clenching, but they have large, well developed masseter muscles seen as
large lumps on the sides of their face). The basal ganglia / spindle mechanism causes severe jaw
tension in patients who are scared when visiting a dentist, which in turn can damage the
temporo-mandibular joint, leading to a lifetime of jaw and facial pain.
Now here’s the critical study. In this simple jaw-open study, six participants were asked to open
their mouth near maximal openings to activate muscle spindles within the masseter muscle. The
participants indicated that they had no reasons to be anxious during this study, so activation of
the basal ganglia should not have been a confounding factor. The participants served as their own
controls. EMG activity involving primarily fast-twitch muscle (100-300 Hz), and TMJ symptoms
such as muscle soreness, stiffness of jaw and TMJ clicking sounds, was collected on the left
masseter muscle during wide opening on both trials. The following day, the exercise was
repeated during 10 Hz AVE from a DAVID Paradise. The results show a marked reduction in
muscle tension and symptoms of TMJ dysfunction in the AVE trial. Figure 6 shows the EMG
results of the study.
Figure 6. Masseter Muscle Tension during Wide Mandibular Opening
Conclusion
A great deal of TMJ and MPD symptoms are directly related to stress, fear and anxiety. Both
meditation and AVE have been shown to effectively reduce these symptoms. Furthermore, AVE
may also de-activate muscle spindle tone and the resulting muscle tension through two
processes: 1) calming related basal ganglia activity, and 2) de-activating the reflex loop that
controls muscle tone in relation to muscle stretch.
Footnote:
1. For more information, address all correspondence to:
David Siever, Mind Alive / Comptronic, 9008-51 Avenue, Edmonton, Alberta, Canada T6E
5X4. Toll Free: 800-661-6463, Phone: 780-461-9551, Web: http://www.mindalive.ca, Email:
info@mindalive.ca
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