Introduction : Temporomandibular
disorders (TMD) is a collective term embracing a
number of clinical problems that involve the
masticatory musculature, the temporomandibular
joint or both. TMD have been identified as a
major cause of non-dental pain in the oro-facial
region and have been considered to be a
subclassification of musculoskeletal disorders.
Cross-sectional epidemiological studies in
specific populations have shown that about 75%
have at least one sign of joint dysfunction
(joint sound, joint tenderness, etc.) and about
33% have at least one symptom (face pain, joint
pain, etc.). Although once viewed as a single
syndrome, current research supports the view
that TMD are a group of related disorders that
may have many common feature. The most
frequent presenting symptom is pain, usually
localized in the muscles of mastication, the
pre-auricular area and/or the temporomandibular
joint, which is aggravated by jaw functions like
chewing and yawning.
The precise aetiology and mechanism of TMD
is still poorly understood and remains the
centre of much debate and controversy. This
controversy has been fuelled in part by the lack
of standardized diagnostic criteria for defining
clinical TMD subtypes and uniformity in research
protocols/designs. A project to create research
diagnostic criteria for TMD was undertaken at
the University of Washington to redress this
lack. The efforts of this project yielded a set
of research diagnostic criteria (RDC), labelled
'RDC/TMD' that allows for standardization and
replication of research into the most common
forms of muscle and joint related TMD. Research
diagnostic criteria/temperomandinular disorders
(RDC/TMD) is divided into two axes. Axis 1
involves the clinical TMD conditions and Axis 2
the pain-related disability and psychological
status. This two-axis approach enables physical
diagnosis to be co-ordinated with
operationalized assessment of psychological
distress and psychosocial dysfunction associated
with chronic TMD and oro-facial disability.
Currently, the RDC/TiMD is administered via
pen-and-paper. The data collected is then
entered manually and batch processed by a
mainframe statistical package to obtain Axis 1
diagnosis and Axis 2 profiles. A time lag
between patient history taking/clinical
examination and the generation of diagnoses is
thus inevitable. As knowledge of the patient's
psychological status is important for the
initial management of TMD, the time lag required
for the generation of the Axis 2 profile is not
beneficial.
The current project investigated the
clinical TMD, pain-related disability and
psychological status of TMD patients using a
computer-aided TMD diagnostic systern (NUS TMD
vl-1) developed by the National University of
Singapore. This diagnostic system aimed to
address the current deficit of the RDC/TMD and
provided on-line real-time Axis 1 and 2
diagnosis/ profiles and database construction
for research on TMD. The relationship between
limitations related to mandibular functioning
(LRMF) scores and graded chronic pain
severity/depression status and the association
between clinical TMD and Axis II non-specific
pain items were also
investigated.[...]
Discussion : The RDC/TMD is offered
for research purposes and is, of necessity,
based more on a description of observable
findings that appear to cluster together than on
underlying àetiological mechanisms. It
deals with only the most common forms of TMD as
they manifest themselves in adults and
encompasses TMD conditions for which there is
information of sufficient reliability and
validity to develop working case definitions
using physical examination and interview
procedures. Some of the less common conditions
excluded from RDC/ TMD include ankylosis,
aplasia or hyperplasia, contracture or
hypertrophy and neoplasms.
About 13,1% of patients experienced
myofascial pain and 7,5% experienced myofascial
pain with limited opening. Patients with
myofascial pain were significantly more
distressed by headaches than patients with no
muscle disorders. Headaches are a very common
finding, especially in patients with TMD.
Several studies have found that subjects
suffering from headaches have a higher frequency
of tenderness in the TMJ and muscles of
masticatio. In the present study, patients with
TMJ pain were not significantly distressed by
headaches compared with those without TMJ pain.
Difference in patient types and the low
incidence of arthralgia and osteoarthritis in
the present may account for the difference
observed.
The results of the present study lend some
support to the view that recurrent headaches
should be considered as part of the symptom
panorama in patients with TMD. Conversely,
examination of the masticatory system should be
included in the medical diagnosis of all
headache sufferers. The association of headache
and TMD has been further strengthened by the
positive results of headache from different
types of prosthetic and orthotic treatment aimed
at correcting TMD. More cross -disciplinary
research is warranted in this area. It was also
observed that patients suffering from myofascial
pain with limited opening were significantly
less distressed by soreness of muscles than
those with myofascial pain without limited
opening. This may be explained in part by the
fact that those with limited opening were
inclined to restrict their mandibular movements
and functions compared with those who were not
limited. The majority of patients (> 80%) did
not suffer from disc displacements and joint
conditions. The low incidence of
osteoarthritis/osteoarthrosis may be accounted
for by RDC/TMD's use of only coarse crepitus in
making these diagnoses and the lack of
correlation to tomograms. Findings concur with
several epidemiological studies which showed the
higher incidence of muscle disorders compared
with disc displacements and joint tenderness. No
significant difference in distress levels from
the various non-specific pain items was observed
between the patients with the different Group2
(disc displacements) and 3 (otherjoint
conditions) diagnosis.
Depression and anxiety related to major life
events might alter patient's perception of and
tolerance for physical symptoms causing them to
seek treatment. There is evidence that some TMD
patients experience more anxiety than do healthy
control groups. The plethora of emotional and
interpersonal connotations associated with the
functions of the jaw and mouth makes these
anatomical sites the ideal focus for symbolic
portrayal of psychological conflicts. For some
TMD patients, these symptoms are somatic
metaphors that express and resolve pre-existing
or concurrent psychological conflicts.
Psychological factors had been implicated in
several aspects of TMD. Firstly, stress-related
muscle hyperactivity and oral habits had been
suggested as aetiological factors. Secondly,
psychological factors have been suggested to
explain why some patients seem to be more
bothered by symptoms and why a small percentage
of patients with symptoms actually seek
treatment. Finally, psychological conditions
such as depression and secondary gain have been
used to explain why some patients do net respond
to conventional therapy. About 38% of the
population examined in the present study was
moderately to severely depressed. Patients with
mild depression was not determined as the
current SCL-90-R Depression Scale does not
provide for it and no raw mean scale scores for
mild depression are currently availabre. Results
lend support to the clinician's view that TMD
patients are 'psychologically different'. It is
therefore essential that psychological factors,
if present, be identified early in the initial
management of TMD as failure to do so may result
in treatment non-success and worsening of the
patient's condition. On-line reporting of
pain-related disability and psychological status
is the greatest advantage of this computer-aided
diagnostic system as this information, which is
usually not available to TMD clinicians, is
crucial in the management of TMD patients.
Patients who were moderately or severely
depressed were significantly more distressed by
headaches, nausea or upset stomach and general
soreness of muscles compared with normal
patients. In addition, severely depressed
patients were also more distressed by heart or
chest and lower back pain than normal and
moderately depressed patients. Dworkin et al.
(1990) assessed multiple pain conditions and
their association with affective disturbance,
somatization and psychological distress based on
the questionnaire data from 1016 members of a
large health maintenance organization.
Respondents were asked about the presence of the
same five pain conditions investigated in this
study and were classified empirically in terms
of dysfunctional chronic pain status based on
pain severity, pain persistence and pain-related
disability. They concluded that the number of
pain conditions reported was a better predictor
of major depression than were measures of pain
experience, including pain severity and
persistence. The results of the present study
support their hypothesis.
The majority of patients (78-5%) had low
disability with almost equal distribution
between low (Grade I) and high (Grade Il)
intensity. The results from an earlier pilot
study of a different patient pool were similar
(78,3% with low disability). As only 4,7% of
patients had high disability that was moderately
limiting (Grade III) and none had high
disability that was severely limiting (Grade
IV), it can be concluded that disability
associated with TMD is generally low. There was
no significant difference in graded chronic pain
severity between normal and depressed
patients.
The jaw disability checklist was used to
assess the extent to which TMD interferes with
the activities specifically related to
mandibular function. The three most frequent jaw
disabilities were: eating hard foods (77,6%),
yawning (75,7%) and chewing (64,5%).
These disabilities were all classical symptoms
used for the screening of TMD. Limitations
related to mandibular functioning scores were
computed by calculating the number of positive
responses and dividing this by the number of
items answered. The mean LRMF scores
corresponded to the graded chronic pain
severity. Ranking of LRMF scores were as
follows: grade IV > grade III > grade Il
> grade I > Grade 0. Patients who were
moderately and severely depressed also had
higher LRMF scores than normal patients. No
statistically significant difference in LRMF
scores was, however, observed between
normal/depressed patients and between patients
with the different graded chronic pain severity
classification. An extension of the present
study, involving more TMD patients, is currently
being undertaken. This is necessary before any
conclusive results pertaining to clinical TMD,
pain-related disability and psychological status
of TMD patients can be drawn.
Conclusions : The clinical TMD,
pain-related disability and psychological status
of 107 TMD patients were investigated using a
computer-aided diagnostic system (NUS TMD vl-1).
About 20,6% of the patients had myofascial pain
but only 7,5% experienced limited mandibular
opening associated with myofascial pain. The
majority of patients (>80%) did not suffer
from disc displacements (right and left joints).
The frequency of arthralgia was also low (right
joint 8,4%; left joint 7,5%) and only one
patient had osteoarthosis of the TMJ. About
78,5% of the patients had low disability with
almost equal distribution between low and high
intensity pain. About 27,1% of the patients were
moderately depressed and 11,2% had severe
depression. No significant difference in LRMF
scores was observed between normal/depressed
patients and between patients with the different
graded chronic pain severity classification. The
three most frequent jaw disabilities are: eating
hard foods (77,6%), yawning (75,7%) and chewing
(64,5%). NUS TMD vl-1 is an extremely useful
tool in the diagnosis/research of clinical
TMD.
