Review Article
Dental anxiety and expectation of pain: cognitive modulation
of the pain experience of dental patients
CHIA-SHU LIN
SHYH-YUAN LEE
Faculty of Dentistry, Yang-Ming University, Taipei, Taiwan, ROC.
Pain is a multidimensional concept composed of sensory and cognitive components. Modulation of
cognitive factors (e.g., attention, memory, and emotion) plays a key role in our perceived pain experience
during dental treatment. Among these factors, dental anxiety is the most common emotional disturbance
in dental patients. Clinical research has shown that patients with high dental anxiety expect a bad pain
experience during treatment. Cognitive theory suggests that an increase in the uncertainty of a
stimulus-outcome association may contribute to one’s anxiety level. Based on clinical data and a
theoretical framework, we suggest that techniques for modulating pain expectations, such as graduated
exposure to a stimulus or correcting patients’ faulty dental beliefs, are effective ways of managing pain
and anxiety in dental practice. （J Dent Sci, 2(3)：129-135, 2007）
Key words: anxiety, dental anxiety, pain, pain expectation, cognitive modulation.
Pain: an integrated view
The very first complaint of most dental patients
is always pain. It is not uncommon for dentists to meet
patients with clear and typical pathological findings
(e.g., the size of an apical radiolucency), but rather
inconsistent or atypical pain experiences and
behaviors (e.g., emotional expressions and subjective
descriptions). This clinical perspective is largely
consistent with the definition of pain offered by the
International Associate of Study of Pain (IASP), that
pain is “an unpleasant sensory and emotional
experience associated with actual or potential tissue
damage, or described in terms of such damage”1.
This definition explicitly conceptualizes pain as an
entity with great multidimensional variety, rather than
a one-dimensional symptom, such as the level of
gingival recession or the size of a radiolucency.
All too often, dentists treat pain as a symptom
simply derived from certain biological damage;
Received: March 8, 2007
Accepted: July 10, 2007
Reprint requests to: Dr. Shyh-Yuan Lee, Faculty of Dentistry, Yang-Ming
University, No. 155, Linong Street, Section 2, Peitou
District, Taipei, Taiwan 11221, ROC.
J Dent Sci 2007‧Vol 2‧No 3
however, they eventually may find that patients’ pain
experiences are far more complicated than just a result
of any actual damage. This confusion partly arises
from the traditional view of ‘sensory pain’, i.e., pain
as a result (sensation) of tissue damage (stimulus) and
nothing more, which is a misleading concept. Unlike
other somatosensory modalities such as tactile and
temperature sensations, pain is not the direct product
of primary noxious stimuli, but a kind of collective
experience modulated by higher cortical function,
such as one’s emotional status2,3, expectations of
pain4,5, or contextual information6. Therefore, the
IASP definition of pain suggests that pain is a
multidimensional construct consisting of sensory (e.g.,
the intensity and duration of a stimulus) and cognitive components (e.g., attentional modulation and
memory). This concept is supported by recent
neuroscience research7,8, which has demonstrated the
activation of several brain cortical regions related to
emotion and attention processing when subjects
receive pain stimulation in experimental settings. This
‘top-down’ modulation of pain perception is also
predicted by physiological models, such as the gate
theory of pain9, which emphasizes the role of the
central nervous system (CNS) in modulating
peripheral noxious inputs.
In general, pain experiences differ from ‘pain
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C.S. Lin and S.Y. Lee.
stimulation’. Taking pulpal pain as an example:
stimulating the A-delta nerve ending within the
pulp-dentin junction evokes an action potential relay
to the CNS. This electrophysiological ‘pain signal’ is
finally perceived after cortical processing in the brain
and being brought to the conscious level. It is through
brain processing that pain emerges as a vivid
experience. Such an integrative concept of pain is
consistent with one’s dental experience. Clinical
research on dental behavior has shown that certain
cognitive factors participate in the cortical processing
of pain signals, such as attention10, anxiety levels11,
information provided12,13, negative cognition14, and
memory of pain15. Many of these factors can modify
both the pain intensity and the negative feelings
(unpleasantness) perceived by patients. In this article,
we focus on dental anxiety (DA), and related
cognitive theories which may help us manage the pain
experience of highly anxious patients.
Dental anxiety and the pain experience
The multidimensional view of pain predicts that
a subjective pain experience can be modulated by
cognitive factors, especially one’s emotional status.
Decades of clinical research in dental-related fields
have indicated that patients’ anxiety level is critical to
their pain experiences, including judging pain
intensity and feeling unpleasant. DA, defined as ‘a
conditioned response to negative stimuli in dentistry
or as a cognitively learned anxiety influenced by
relatives, close friends or the mass media’16, is
currently the most well-known emotional disturbance
of dental patients worldwide17. Past surveys in North
American18, Asian19,20, and European populations21,22
indicate that approximately 10% of dental patients
suffer from a moderate to high degree of DA. These
high-DA patients are usually reluctant to receive
regular dental treatment, and this avoidance leads to
even poorer oral hygiene18,23,24. DA may even lead to a
misdiagnosis on some clinical examinations, such as
the vitality test for endodontic therapy25.
Both North American and western and northern
European studies have noted that increases in DA are
highly correlated to patients’ negative experiences
during dental treatment (Table 1). One should note
that the pain experience during treatment significantly
differs between high- and low-DA groups, indicating
that DA can be a predisposing factor but not the direct
results of pain itself. Compared to patients with low
DA, patients with higher DA may feel more
unpleasantness during treatment26 and be more
reluctant to receive regular treatment18,23,24.
The problem of DA is also associated with other
psychological issues. DA is positively correlated with
the level of fear of pain, and most high-DA patients
have negative beliefs toward dental treatment, and
they expect to experience more pain than do low-DA
patients27. Such evidence reveals that DA does not
simply result from a psychiatric origin (e.g., general
anxiety or depression), but from the collective
modulation of several cognitive factors. For example,
high-DA patients usually exaggerate their memory of
pain28; they recall worse pain experiences (especially
on the affective dimension) during previous treatments
than do low-DA patients. High-DA patients tend to
focus on the emotional but not the sensory feeling of
Table 1. Selected landmark research about the effects of dental anxiety (DA) on pain
Topic
Anxiety and pain memory
Major findings
28
High-DA patients recalled more unpleasantness about previous treatment; they also expected a
worse pain experience before treatment.
Anxiety of expected pain 26
Situation (dental treatment)-specific anxiety, but not general dental anxiety, is strongly associated
with the pain experience.
Theoretical framework of dental anxiety 11
Situational factors (e.g., appraisal of situation) and dispositional factors (e.g., past experiences)
interact and affect the pain experience of dental patients.
Dental anxiety in relation to mental health
and personality factors 16
The chronicity of DA is associated with higher neuroticism, lower extraversion, and more
psychiatric impairment at the baseline. Remission of DA is associated with higher extraversion at
the baseline.
DA affects dental patients’ expectation and
perceived pain 27
During stressful dental procedures, high-DA patients are more likely to exaggerate pain
expectations and unpleasantness.
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Pain and anxiety of dental patients
treatment10, and this leads to an overemphasis on
negative emotions during treatment. In addition,
high-DA patients usually have biased attitudes toward
dental practice14,29; these patients have more-negative
dental beliefs, such as ‘dentists do not care about my
feelings’ or ‘I feel embarrassed to talk to the dentist’.
Therefore, high-DA patients are not simply
losing their mind, spoiled, or weird. In fact, they are
just thinking incorrectly. From this point, traditional
managing strategies such as reassurance (‘You won’t
get hurt! I promise to you!’), threatening (‘Let’s do
it, otherwise you will lost all your teeth!’), or showing
tenderness (‘Don’t be afraid, I’ll be by your side’)
may be futile with high-DA patients, especially when
they are in a stressful pain-causing situation. In order
to understand their way of thinking, we delve into
some recent theoretical work in the following section,
to see how anxious patients think during stressful
dental treatment.
Cognitive theory of anxiety and
expectations
Since the 1980s, the development of neuroimaging techniques and advancements in cognitive neuroscience have contributed to building up
more-elaborate frameworks of human thinking,
emotions, and behaviors. Those studies, together with
clinical observations, have provided more insights into
the cognitive processing of anxiety. Herein, we look
into the effect of patient expectations on their pain
experiences, and the possible relationship between
pain expectations and DA.
Relation between pain expectations
and uncertainty
Expectations of an outcome (e.g., pain intensity)
of a noxious stimulus are highly related to the
probabilistic structure of the cue-outcome association30. The concept of expected uncertainty is a
continuous spectrum of the association from
‘deterministic’ to ‘random’. This spectrum can be
presented as a percentage scale: from 100%
probability that an outcome will follow a cue
(deterministic), to a 50% probability that an outcome
will appear (unpredictable). In modern psychological
research, perceived cue-outcome associations can be
J Dent Sci 2007‧Vol 2‧No 3
established by visual cues that signal an incoming
stimulus31 or by explicit instructions given by
experimenters32. In the former paradigms, a subject
gradually learns the type or the intensity of an
incoming stimulation that follows a cue display; in the
latter paradigms, the cue-outcome association is given
verbally, such as ‘It may or may not be painful’.
For the deterministic or highly predictable (HP)
association, the cue is followed each time by the
corresponding stimulus without exception. On the
contrary, a probabilistic or poorly predictable (LP)
association is formed by instruction with some degree
of uncertainty (e.g., ‘It hurts sometimes’) or
ambiguous signalling, such as a 60% chance of
experiencing pain following a cue.
Such an operational definition of uncertainty can
be a decent tool for investigating patient behavior. In
clinical settings, most patients predict what they will
feel by evaluating cues they perceive during treatment.
In dental practice, the cacophony caused by the
high-speed handpiece may be a good example of the
effect of some cue-outcome associations. Many
patients regard the cacophony as a strong cue which
signals incoming painful feelings (e.g., ‘It must be so
painful when the terrible sound begins’); on the other
hand, they might not be so sure about the outcome of
treatment in other contexts, such as with drilling on
a tooth that has never been painful. In the latter
condition, patients feel greater uncertainty (or less
predictability) by the feeling brought on by the
incoming stimuli, and hence a kind of LP cue-outcome
association. This association between the cacophony
and perceived uncertainty is frequently observed by
dentists in clinical settings; however, one may note
that patients may refer to a combination of multiple
cues (e.g., site of the tooth, tenderness of the dentist,
and perceived illness) rather than just a single one.
Therefore, the cue-outcome association may be more
complicated in dental chairs than those in controlled
psychological experiments.
This perceived uncertainty between a stimulation and outcome also plays a key role in one’s
emotional status33. For example, Rhudy and Meagher
(2000) demonstrated that subjects report enhanced
levels of fear under inevitable pain stimulation, and
enhanced levels of anxiety when expecting pain
stimulation, compared to a neutral condition (in which
they were promised that no pain stimulation would
take place). Compared to the neutral condition,
subjects expecting pain (i.e., being told that a stimulus
131
C.S. Lin and S.Y. Lee.
may or may not be painful; however, no painful
stimulus is given) reported a higher level of anxiety
and a decrease in the pain threshold; on the other hand,
for those who expected pain and inevitably received it,
an enhanced level of fear was reported. From this view,
fear and anxiety differ but are both related to the
emotional status. A fearful dental patient might highly
associate the painful feeling with drilling (hence
‘drilling’ is the major fearful event); on the other hand,
some patients might feel less certain of the stimulus-outcome association (it may or may not hurt),
and hence are worried and anxious toward the dental
treatment itself (but not specific procedures or things).
Clinical research on dental patient behavior also
indicates that the expectation of pain of dental patients
is highly correlated with their DA level. Rachman and
Arntz suggested that DA predicts the expected pain
experience of dental patients38. This is supported by
further evidence that high DA of patients will predict
more-negative pain experience in both affective and
sensory dimensions27. These results indicate a possible neuropsychological mechanism underlying the
association between pain and anxiety (Figure 1) :
compared with high-DA patients who expect more
pain in coming treatment, low-DA patients do not
exaggerate their pain expectancy and perceive lower
pain levels in either the sensory or affective dimension
of the pain experience. Thus, for high-DA patients,
controlling their expectation of pain is a critical step in
their pain experience.
The theoretical framework postulated above
suggests that modulating one’s expectation of pain is
crucial to pain perception, especially in patients with
high DA levels. Nevertheless, one should note that
there is evidence indicating that a decrease in pain
expectation leads to a decrease in perceived pain;
while conclusion for the other way round (i.e.,
increased expectation leads an increase in perceived
pain) is still unconfirmed. For high-DA dental patients,
we cannot simply attribute their pain experience to the
Dental anxiety and altering expectations
In a recent study using functional magnetic
resonance imaging (fMRI), Koyama et al. demonstrated that expectations of decreased pain
significantly reduce the subjective pain experience34.
This finding is supported by past clinical study on
irritable bowel syndrome35 and experimental results36.
Further study also demonstrated that a distinct brain
modulatory network is in charge of the convergent
processing of noxious stimuli and expectancy of pain
intensity37.
Cognitive theory
of expectation
Anxiety / Fear
A
C
B
Pain experience: sensory
(intensity) and emotional
(unpleasantness)
dimension
Correlated
Dental anxiety
(other cognitive
factors? )
Figure 1. Schema of the association among pain, emotions, and expectations. (A)
Neuroimaging studies support the relation between expectations and emotions of cognitive
theory. (B) Altering one's pain expectations modulates one’s perceived pain. (C) Cognitive
theory predicts the effectiveness of pain and anxiety management for dental patients.
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Pain and anxiety of dental patients
effect of expectations, because there may be many
other cognitive factors involved. Therefore, lowering
anxiety (by altering expectations) is one, but not the
only, strategy for pain management.
Cognitive modulation: an important
component for effective pain management
Pharmacological intervention (e.g., local anesthesia) has been proven effective for most pain in
clinical dentistry. However, one should note that
the injection itself may induce more-intense
unpleasantness, i.e., worse pain experience in the
affective dimension. This negative experience
increases one’s DA level and eventually leads to
avoidance of dental treatment. As stated above,
although the local anaesthesia procedure successfully
blocks neural transmission of pain signals, it does not
necessarily alter one’s perception of pain, which is
mainly modified by other cognitive factors.
Recently researchers have concluded that
cognitive-oriented approaches, which aim to alter the
way one thinks about pain, can be effective in
reducing DA and the pain experience, especially for
negative emotions toward stressful treatment (e.g.,
injections). These methods include distraction,
preparation (providing information), modeling, and
rehearsal (Table 2). Here we examine the application
of ‘altering expectations’ for 3 reasons: (a) the relation
between pain and expectancy has generally been
supported by previous cognitive studies (for a review
see ref. 30), (b) dental patients show differences in
expecting pain (i.e., they either over- or underestimate
the incoming pain experience38, and (c) to alter
patients’ expectation is feasible and time-saving in
clinical settings, compared to other methods (e.g.,
hypnotic induction). Dentists can alter or redefine a
patient’s way of thinking about pain by gradually
eliminating their negative experiences with pain
(technically termed ‘graduated exposure’39), as well as
correcting some faulty beliefs which affect patients'
expectations.
Graduated exposure
Graduated exposure has been proven effective for
DA patient management. In this case, a patient
receives successive procedures little by little, with
negative experiences being tolerated in each trial39.
Graduated exposure is technically the major component of desensitization procedures, a common
strategy used by clinicians for highly anxious patients40. Desensitization is sometimes misunderstood as
‘habituation’ -- the same stimulus is given to the
patient repeatedly until he or she ‘gets used to it’.
Desensitization is not habituation, and success with
this technique requires graduated exposure to a
stimulus (e.g., drilling) as well as cognitive modulation.
We suggest that in each trial during desensitization, when the patient expects more-intensive
stimulation (e.g., a more-prolonged duration of
drilling), it is appropriate for the dentist to notify the
patient that more-intensive drilling ‘does not
correspond to more pain’. Unlike the traditional way
to reassure ‘no pain will take place’, the verbal
instructions should focus on the relation between the
dentist’s practice (drilling) and the patient’s general
experience, rather than only on the outcome (painful
Table 2. Methods to alter one’s cognition about dental treatment for reducing anxiety and pain40
Strategy
Distraction
Distraction can be taken as a combined behavioral and cognitive intervention, such as singing, visual
distractions, or shaking the lip during administration of a local dental anesthetic. Distraction is more
effective in infants and young children than older children.
Preparation (providing information)
Preparation provides children with procedural and sensory information about the next procedure.
Procedural information describes each step of the procedure. Sensory information includes descriptions
of sensations that a child will experience.
Modeling and rehearsal
In modeling and rehearsal, the dentist has an adult or other child demonstrate positive coping behaviors.
For small children, for example, a doll can model holding still during a procedure.
Altering expectations
See the text.
Desensitization
See the text.
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C.S. Lin and S.Y. Lee.
or not painful). Such a modification highlighting the
reduction of patients’ expectations of pain is based on
the cognitive theory stated above. Further evidence
specific to dental conditions is needed.
Correcting faulty dental beliefs
Another important application of cognitive
theory in pain and emotion management is the
correction of faulty dental beliefs. Here ‘dental
beliefs’ are defined as a set of background knowledge
and attitudes toward dental treatment29. Because of
the probabilistic nature of expectations, the way
one defines the stimulus-outcome association will
ultimately affect his / her expectancy. Background
knowledge and beliefs about dental procedures may
play a key role in shaping the association. If a patient
lacks of critical information on a treatment or
misunderstands the dentist’s instructions, he / she
usually develops biased expectations of the subsequent procedures, hence increasing anxiety. It is not
surprising that dentist-patient communication is key to
correcting faulty dental beliefs. In clinical settings,
dentists are supposed to carefully attend to their
patients’ concerns through listening, and give
adequate healthcare education on relevant issues41.
CONCLUSIONS
In this article, we reviewed the importance of
pain expectations toward dental patients’ pain
experiences and dental anxiety (DA). The cognitive
theory of expectation and emotion based on
neuroimaging studies support results from clinical
observations of dental patients. These convergent
results indicate that pain expectations may underlie
the complicated pain experiences of dental patients,
especially those with high DA. We summarize our
argument as follows.
1. Pain is a multidimensional concept. Modulation of
cognitive factors plays a key role in our perceived
pain experiences.
2. As the major emotional disturbance for dental
patients, DA is the result of collective modulation
by several cognitive factors.
3. Research in cognitive neuroscience supports a
framework of pain expectations and emotions.
The cognitive theory states that an increase in
uncertainty about the stimulus-outcome association
134
contributes to one’s anxiety.
4. High-DA patients expect more pain during
treatment. Altering pain expectations (e.g., graduated exposure) and redefining expectations (e.g.,
faulty dental beliefs) contribute to pain and anxiety
management of dental patients, especially for
high-DA ones.
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