Adapting the diagnostic definitions of the RDC/TMDto routine clinical practice: A feasibility study

Fatin Hasanain a, Justin Durhamb, Adel Moufti a, Ian Nick Steen c, Robert W. Wassell d,*aDepartment of Restorative Dentistry, United KingdombDepartment of Oral and Maxillofacial Surgery, United Kingdomc Institute of Health & Society, United KingdomdDepartment of Restorative Dentistry, The School of Dental Sciences, Framlington Place, Newcastle upon Tyne, NE2 4BW, United Kingdom

j o u r n a l o f d e n t i s t r y 3 7 ( 2 0 0 9 ) 9 5 5 – 9 6 2

a r t i c l e i n f o

Article history:

Received 12 December 2008

Received in revised form

3 August 2009

Accepted 5 August 2009

Keywords:

RDC/TMD

Reliability

CEP-TMD

Physical TMD diagnosis

Clinical tool

a b s t r a c t

The Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) is a well-

known diagnostic tool for clinical trials on TMD.

Objectives: This study aims to assess the reliability, validity and feasibility of a new method

of physically diagnosing temporomandibular disorders (TMD), designed for routine clinical

use. This version, known as Clinical Examination Protocol-TMD (CEP-TMD), was compared

to the gold standard original RDC/TMD.

Methods: A total of 49 subjects (41 referred TMD patients and 8 symptom free subjects) were

examined using both RDC/TMD and CEP-TMD versions. Three examiners, with varying

levels of experience in diagnosing TMD, worked in pairs. Each member of a pair saw the

same patient twice, once for the RDC/TMD and once for the CEP-TMD examination. The

examination order was randomized. Each patient’s examinations alternated between

examiners to reduce the memory effect. Examinations could yield single, multiple or no

diagnosis. Kappa statistics were calculated to estimate reliability.

Results: There was substantial overall agreement between the CEP-TMD and the RDC/TMD

(kappa = 0.70). Intra-examination agreements were substantial in both RDC/TMD

(kappa = 0.70) and CEP-TMD (kappa = 0.90). For examination and diagnosis, the CEP-TMD

was almost 3 min faster than the RDC/TMD ( p < 0.05).

Conclusions: It was concluded that the CEP-TMD’s diagnosis is comparable to the RDC/TMD

thus providing a convenient and intuitive approach for dentists to physically diagnose TMD

in clinical practice. The well-established RDC/TMD remains the gold standard for research

diagnosis of TMD.

# 2009 Elsevier Ltd. All rights reserved.

avai lab le at www.sc iencedi rect .com

journal homepage: www.intl.elsevierhealth.com/journals/jden

1. Introduction

Diagnosing temporomandibular disorders (TMD) has been a

subject of much research for the past three decades. Since its

introduction in 1992, the Research Diagnostic Criteria for TMD

(RDC/TMD) has gained wide acceptance as a diagnostic

classification tool and its validity has been tested several

* Corresponding author. Tel.: +44 0191 2226000; fax: +44 0191 2226137.E-mail address: R.W.Wassell@ncl.ac.uk (R.W. Wassell).

0300-5712/$ – see front matter # 2009 Elsevier Ltd. All rights reserveddoi:10.1016/j.jdent.2009.08.001

times,1–4 so much so that it is now considered a gold standard

by much of the dental research community. It has truly

operationalized TMD examination and diagnoses by providing

detailed instructions as well as diagnostic algorithms.

Despite the existence of these diagnostic criteria, many

general dental practitioners tend to look upon TMD diagnosis

and management with a large degree of confusion and

.

Fig. 1 – Diagnostic criteria for the CEP-TMD derived from the RDC/TMD.

j o u r n a l o f d e n t i s t r y 3 7 ( 2 0 0 9 ) 9 5 5 – 9 6 2956

ambiguity. Tegelberg et al.5 found that many dentists lacked

routines for making diagnoses and only 25–50% of dentists

reported positive experiences in relation to TMD diagnosis and

management. Another study found that general dental practi-

tioners expressed a fear of misdiagnosing TMD and often

referred these patients to specialist centres or hospital settings.6

The systematic approach of the RDC/TMD has the potential

to help dentists overcome these problems, but so far the RDC/

TMD appears to be used rarely in routine clinical practice.

A team of researchers at Newcastle created a new

diagnostic protocol for TMD7 which has been in clinical use

for over 5 years; this is referred to as the clinical examination

protocol-TMD (CEP-TMD). To simplify diagnosis of TMD in the

routine clinical setting, the CEP-TMD provides a list of the

main criteria for each diagnostic group and subgroup derived

from the RDC/TMD1 (Fig. 1). As the examination proceeds and

the criteria are met, a diagnosis can be made, which has the

potential to reduce the time needed with the RDC/TMD

algorithms after the examination.1

Both examinations can be seen as online videos at http://

www.rdc-tmdinternational.org/ and http://www.ncl.ac.uk/

dental/AppliedOcclusion/ (both last accessed 31.07.09). These

sites also provide history and examination forms.

The purpose of this study is to examine the feasibility of

using the CEP-TMD as a valid and reliable means of diagnosing

TMD in the routine clinical setting. The two aims are to:

j o u r n a l o f d e n t i s t r y 3 7 ( 2 0 0 9 ) 9 5 5 – 9 6 2 957

(1) compare the diagnoses obtained by using the CEP-TMD to

those made using RDC/TMD.

(2) determine the average time required to complete the

diagnosis for each system.

2. Materials and methods

2.1. Subjects

Two groups of subjects were used in this study; TMD patients

and symptom free subjects. Putative TMD patients were

identified from their general dental practitioner’s letter of

referral to Newcastle Dental Hospital. The term ‘‘TMD patient’’

was used for this group even though a hospital TMD diagnosis

had yet to be made. To be included they needed to be 18 years

of age or over and the letter needed to describe a TMD related

complaint or a provisional diagnosis of TMD. They were

excluded if at any point it was found that: their pain did not

originate from TMD; they were in acute pain; they were

undergoing orthodontic treatment as this can produce

transient TMD symptoms; they had one or two edentulous

arches; or they had been previously treated for TMD.

A member of the team contacted potential patients by

telephone after they had been sent a letter explaining the

nature of the trial and invited them to be included in the study.

Those who agreed to be involved were offered an appointment

solely to have their TMD diagnosis made. They were then seen

2–4 weeks later for routine management on a consultant

clinic.

Symptom free subjects were volunteers selected by the

nurse working with the research team to avoid biasing the

clinicians. The inclusion criteria were that the subjects were

over 18 years of age and did had not have a facial ache or pain

in the jaw muscles, the joint in front of the ear, or inside the ear

(other than infection) for the past 6 months.8 The same

exclusion criteria applied for them as for the symptomatic

subjects.

The RDC/TMD website recommends 24 subjects for a

reliability study (18–20 TMD patients and 4–6 asymptomatic

subjects). As this study compared two types of examinations,

the recommended sample size was doubled and then checked

to see that it would enable the estimation of sensitivity and

specificity with a reasonable amount of precision. It was

determined that with 48 patients, the standard of error would

be 4.33% assuming 90% confidence. Accordingly, 60 subjects

were booked for the research clinics, but due to 8 subject

withdrawals and 3 exclusions (one complete denture wearer

and two patients in severe pain at time of presentation) this

reduced to 49; 41 of which were putative TMD patients and 8

were non-symptomatic subjects.

This project gained ethical approval in October, 2006 from

the Newcastle and North Tyneside Local Research Ethics

Committee (ref: 06/Q0905/120).

2.2. Procedure

The research team consisted of 3 clinicians:

� a restorative consultant with extensive experience diagnos-

ing and treating TMD (Examiner 1)

� a clinical fellow/honorary specialist registrar with seven

years of experience of diagnosis of TMD and its conserva-

tive, holistic and surgical management (Examiner 2)

� a clinician who had 5 years of experience as a general dental

practitioner (Examiner 3).

The three clinicians’ training began with the RDC/TMD

online teaching video (produced by the Dept of Oral Medicine

of the University of Washington at http://www.RDC/TMD-

tmdinternational.org/). Electronic scales were used to train the

team in applying appropriate palpation force (1 Kg extra orally

and 500 g intra orally). The team was then calibrated in using

the RDC/TMD examination form. Following the examination

of three TMD patients by all three clinicians the results were

discussed and any minor differences ratified.

After calibration, the examiners were divided into three

pairs for the clinical study. Pair A (examiners 1 and 2), pair B

(examiners 2 and 3), and pair C examiners (1 and 3). Each pair

of examiners examined subjects using both the CEP-TMD and

RDC/TMD Axis I examination forms.1 That meant each subject

would receive a total of 4 examinations, two by each examiner.

The order of examination was randomly assigned.

Subjects were seen in two groups of three per research

session to allow each clinician to be the first to see a patient,

thus balancing the order effect. For the RDC/TMD examination

the multi page examination form was used. For the CEP-TMD a

single page examination form was used based on that of the

Temporomandibular Index TMI.9 The TMJ and muscle palpa-

tion sites were the same as for the RDC/TMD but with minor

modifications made to the protocol. These are:

(1) The TMJs and extra-oral muscles are palpated bilaterally

rather than unilaterally.

(2) The neck muscles are included, although they are not

directly involved in the TMD diagnosis.

(3) The order of examination (Table 1) was changed to make it

more intuitive for clinicians.

Each patient was examined in private by one examiner at a

time using the examination sequence outlined in Table 1 (for

further details please access the online video mentioned in

Section 1). This prevented any influence on the outcome of

the next examination, which was carried out by the second

member of the pair while the first member examined another

patient. In this way, the memory of the first examination was

reduced. Examiners made the CEP-TMD diagnosis as the

examination proceeded by matching the criteria to the

clinical findings in respect of the TMJs, muscles of mastica-

tion and jaw movement. Examiner 3 made all the RDC/TMD

diagnoses using the appropriate algorithms1 after the clinic

had finished.

After the last exam, a dental examination was performed

to ensure there was no dental cause for a subject’s symptoms.

In addition, the history was then reviewed. This information

had been gathered using a Performa in the waiting room and

had been kept away from examiners by the nurse leading the

clinic until that point. A diagnosis was given to the patient

based on this information plus the CEP-TMD diagnosis.

Patients then received initial counselling using the host

institute’s TMD counselling sheet which details exacerbating

Table 1 – Summary of RDC/TMD and CEP-TMD showing differences in examination order and palpation.

RDC/TMD CEP-TMD

Order of examination 1.Deviation and pattern of opening 1. Joint examination

2.Vertical range of motion Pain evoked by digital palpation of TMJa and wide opening

3.Digital palpation of: Joint sounds on opening, closing and excursionsa

a. Joint sounds on opening and closinga 2. Muscle examination: digital palpation of

b. Muscle and joint pain on excursive movementsa a. Neck and shoulder musclesc

c. Joint sounds on excursive movementsa b.Extra-oral muscles of masticationa

d. Extra-oral musclesb c. Intraoral musclesb

e. Joint painb 3. Functional examination:

f. Intra oral musclesb Deviation and pattern of opening

Vertical range of motion

a Bilateral palpation.b Unilateral palpation.c The results of the bilateral neck muscle palpation do not influence the TMD diagnosis.

j o u r n a l o f d e n t i s t r y 3 7 ( 2 0 0 9 ) 9 5 5 – 9 6 2958

factors as well as self management techniques including

habit modification, exercises, diet modification and analge-

sia. The diagnosis and any other relevant observations were

forwarded with their referral letter to the consultant clinics in

the Dental Hospital. At follow-up their conditions were then

re-assessed and management continued on a case-by-case

basis.

2.3. Statistical analysis

This study evaluated a new diagnostic tool (CEP-TMD) against

a gold standard (RDC/TMD). With both tools, each subject was

assigned to zero, one or multiple diagnostic categories. These

were treated as independent observations and individually

coded to allow statistical analysis. The gold standard was

then used to determine the proportion of asymptomatic

subjects and patients correctly identified using the CEP-TMD

system. With 49 subjects the standard error of the estimate

was 3.5%.

Comparisons between the CEP-TMD and the RDC/TMD

were made using Cohen’s kappa10 for each individual

examiner and between examiners in each of the 3 pairings.

To provide an overall comparison (Cohen’s kappa) between

CEP-TMD and RDC/TMD all the examiners’ results were

combined. This process also allowed overall comparisons

between the diagnoses resulting from repeated examina-

tions with each diagnostic system. Clearly, the greatest

statistical power would be with the overall comparison

between CEP-TMD and RDC/TMD as this would have twice

the number of observations as the RDC/TMD cf. RDC/TMD

and CEP-TMD cf. CEP-TMD comparisons. The kappa values

and confidence intervals were calculated by using a web

based application http://faculty.vassar.edu/lowry/kap-

pa.html (last accessed 31.07.09). This application was

advised by our statistician as, unlike many proprietary

packages, it allowed multiple kappa comparisons between

groups of unequal size.

The value of kappa varies between 0 and 1; the higher the

kappa the better the agreement. It is generally agreed that a k

value of 0.2–0.4 signifies fair agreement, 0.41–0.60 is moderate,

0.61–0.80 is substantial, and 0.81–1 is almost perfect.11

The examination times were analyzed using Student’s t

test with the level of significance for a type 1 error set at

0.05.

3. Results

The 41 TMD patients had a mean age of 44.2 years (SD = 13.8)

and a male: female ratio of 8:33. The 8 control subjects had a

mean age of 35.9 years (SD = 15.3) and a male: female ratio of

1:7. Neither of the examinations diagnosed any of the controls

as having a TMD. Therefore, all the results in Tables 2–7 relate

to the referred TMD patients.

For the 41 TMD patients examined in this study, 48

independent diagnoses were made using the RDC/TMD

examination and 50 were made using the CEP-TMD exam.

Table 2 shows their breakdown into the main RDC/TMD

diagnostic groups. In each pair, the more experienced

member’s diagnoses were used as the final diagnoses in cases

of a lack of agreement.

Table 3 illustrates the number of referred patients securing

zero, one or more diagnoses with either RDC/TMD or CEP-

TMD. Clearly, some patients did not obtain a TMD diagnosis; 8

for RDC/TMD and 6 for CEP-TMD.

Intra-examiner agreement for RDC/TMD versus CEP-TMD

was calculated for each of the 3 examiners. The kappa values

and percent agreements are shown in Table 4. Interexaminer

kappa agreements for each of the three examiner pairs ranged

from 0.6 to 0.67 for the RDC/TMD and from 0.82 to 0.85 for the

CEP-TMD.

3.1. Overall agreement within and between diagnosticsystems

Table 5 provides kappa values and confidence intervals for the

comparison within diagnostic systems (RDC/TMD cf. RDC/

TMD, CEP-TMD cf. CEP-TMD) and between diagnostic systems

(RDC/TMD cf. CEP-TMD) for the TMD patients. Overall, the

RDC/TMD showed substantial agreement (kappa = 0.70, CI

0.56–0.84), while the CEP-TMD showed almost perfect agree-

ment (kappa = 0.90, CI 0.81–0.99). The comparison between

CEP-TMD and RDC/TMD showed substantial agreement

(kappa = 0.70 CI 0.60–0.79). In addition, Table 5 provides kappa

values for the three main RDC/TMD diagnostic groups.

Agreements generally ranged between substantial and almost

perfect. However, fair to moderate agreements were seen with

Group I diagnoses when comparing the CEP-TMD with the

RDC/TMD and also with Group II diagnoses from the RDC/TMD

examination.

Table 3 – Frequency table of number of diagnoses perpatient in RDC/TMD and CEP-TMD.

RDC/TMD CEP-TMD

No diagnosis 8 7

One diagnosis 21 22

Two diagnoses 8 9

Three diagnoses 4 3

Table 4 – Intra-examiner testing comparing RDC/TMDand CEP-TMD.

Examiner Kappa Percent agreement

Examiner 1 0.71 76%

Examiner 2 0.69 73%

Examiner 3 0.69 74%

Table 2 – Breakdown of main RDC/TMD diagnostic groups in both RDC/TMD and CEP-TMD Exams.

RDC/TMD CEP-TMD

No. of diagnoses % of total No. of diagnoses % of total

Group I (muscle disorders)

I a 14 29 15 31

I b 5 10 8 17

Total 19 39 23 48

Group II (disc displacement)

II a rt 5 10 4 8

II a left 13 27 11 23

II b rt 3 6 2 4

II b left 2 4 1 2

II c rt 0 0 0 0

II c left 1 2 1 2

Total 24 49 19 39

Group III (Arthralgia, osteoarthrosis and osteoarthritis)

III a rt 3 6 3 6

III a left 0 0 0 0

III b rt 0 0 0 0

III b left 0 0 0 0

III c rt 1 2 1 2

III c left 2 4 2 4

Total 6 12 6 12

j o u r n a l o f d e n t i s t r y 3 7 ( 2 0 0 9 ) 9 5 5 – 9 6 2 959

3.2. Examination times

Table 6 shows the difference between the time for examining

and diagnosing TMD in referred TMD patients using the CEP-

TMD and the RDC/TMD. The CEP-TMD was significantly faster

to perform than the RDC/TMD ( p < 0.05).

4. Discussion

This study was undertaken to compare the reproducibility of a

more ‘‘user friendly’’ version of the RDC/TMD, i.e. the CEP-

TMD, within itself and against the RDC/TMD. The study was

principally designed to allow intra-examiner comparisons

between RDC/TMD and CEP-TMD, but as two examiners

examined each patient, it was also possible to provide inter-

examiner comparisons for each diagnostic system. Agree-

ments within and between the individual examiners were

substantial, despite differing experience in managing TMD.

These findings justified the decision to make overall compar-

isons by amalgamating the examiners’ data.

The overall agreements within and between examination

systems ranged between substantial to near perfect and had

relatively narrow confidence intervals (see Table 5). The

overall agreement was substantial with a kappa of 0.70 in

both RDC/TMD versus RDC/TMD, and RDC/TMD versus CEP-

TMD. It is worth emphasizing that these agreements would

have been even better if the asymptomatic controls were

included because both examination systems correctly identi-

fied every subject as not having TMD. Interestingly, the intra-

examiner agreement was higher for the CEP-TMD than that for

the RDC/TMD (0.9 c.f. 0.7). This could be because the

examiners were generally more familiar with the CEP-TMD,

with examiners 1 and 3 using it routinely in clinical hospital

practice.

When comparing the overall agreements for each of the

three main RDC/TMD diagnostic groups (Table 5), it is

important to bear in mind the wide confidence intervals for

the kappa values, which reflect the relatively small number of

observations for individual diagnoses. Nevertheless, the point

estimates of kappa showed agreement to be generally

substantial to near perfect, but with two exceptions where

agreement was less good: Group I diagnoses comparing CEP-

TMD with RDC/TMD, and Group II diagnoses using the RDC/

TMD examination.

The agreement for Group I diagnoses was substantial

within each diagnostic system, but became only fair to

moderate when comparing the CEP-TMD to the RDC/TMD.

Table 5 – Agreement within and between diagnostic systems (cf. compared with).

RDC/TMDdiagnosis

RDC/TMD cf. RDC/TMD CEP-TMD cf. CEP-TMD RDC/TMD cf. CEP-TMD

Kappa 95% confidence interval Kappa 95% confidence interval Kappa 95% confidence interval

Lower limit Upper limit Lower limit Upper limit Lower limit Upper limit

Group I 0.6 0.27 0.93 0.75 0.50 1 0.43 0.22 0.64

Group II 0.37 0.12 0.63 0.71 0.48 0.95 0.60 0.42 0.77

Group III 0.71 0.20 1 0.71 0.20 1 0.86 0.60 1

Overall 0.70 0.56 0.84 0.90 0.81 0.99 0.70 0.60 0.79

Table 6 – Time taken to examine and diagnose TMD patients using RDC/TMD and CEP-TMD.

Examiner RDC/TMDmean time

CEP-TMDmean time

p value 95% Confidence interval ofthe difference

Lower Upper

1 12.9 9.2 0.010 2.8 4.8

2 8.5 5.9 0.000 1.6 3.5

3 9.6 7.4 0.016 1.3 3.0

1 + 2 + 3 10.3 7.5 0.000 2.1 3.5

j o u r n a l o f d e n t i s t r y 3 7 ( 2 0 0 9 ) 9 5 5 – 9 6 2960

Other studies have reported Group I diagnoses to have

relatively low kappa scores in some clinical studies12–14 but

good agreement in others2,15 suggesting muscle palpation

responses vary from day to day as well as from one exam to

another.13,16 In the same way, our findings may suggest

problems generally with the reliability of muscle palpation. It

may simply be, however, that each diagnostic system is

effective in diagnosing myofascial pain but one system

diagnoses more patients than the other. The number of Group

I diagnoses will ultimately depend on the number of muscle

palpation sites that are tender, which may in turn depend on

the mode of palpation. In this respect, Table 2 shows that the

CEP-TMD provided 4 more patients with Group I diagnoses

than did the RDC/TMD. Clearly, this difference in number of

diagnoses is likely to have been a major factor in reducing the

overall agreement when comparing diagnostic systems.

Further work is needed to determine whether any systematic

differences underlie the greater number of CEP-TMD Group I

diagnoses. Surprisingly, there are no previously published

comparisons of unilateral versus bilateral palpation of jaw

musculature. It should be remembered that the RDC/TMD

system specifies unilateral palpation, although bilateral

muscle palpation is the usual textbook teaching.

In relation to Group II diagnoses, the reliability of

diagnosing disc displacements with the RDC/TMD appears

generally somewhat variable. John and Zwijnenburg3 reported

agreements for Group IIa (disc displacement with reduction) to

vary between 0.33 and 0.71 and in another study reported a

median ICC of 0.61.17 On the other hand, Wahlund et al.2 noted

excellent reliability in Group II (kappa > 0.78). Such variability

reflects inconsistencies in the presentation of clicking and

locking. It also reflects the ability of the examiner to detect

them reliably which, as with other aspects of the examination,

may improve with training.16 Interestingly, the examiners in

the current study did rather better with the CEP-TMD

examination than with the RDC/TMD examination

(kappa = 0.71 c.f. 0.37). As with muscle palpation, however,

the method of palpation may influence results. The CEP-TMD

requires bimanual palpation from directly behind the patient,

whereas the RDC/TMD requires the examiner to sit to one side

in front of the patient. Such a posture results in asymmetrical

palpation, making it more difficult to standardize digital

location and pressure when assessing TMJ clicking. Again,

further work is needed to determine systematic differences

between palpation techniques. Such work would require

larger numbers of examiners and patients, no doubt benefiting

from a multicentre approach.

With the time taken for examination and diagnosis, overall

the CEP-TMD was almost 3 min faster than the RDC/TMD

(p < 0.05). This difference was significant for each of the three

examiners. With a simpler and shorter form to complete and

immediately available diagnoses this may make the CEP-TMD

more appropriate and attractive for day-to-day busy clinical

practice or for those who may have a limited knowledge of TMD

and need clear and concise direction in their diagnostic process.

Furthermore, the same form is a useful means for recording

clinical data at follow-up and the single sheet format makes it

simple to assess treatment outcome in terms of changes in joint

sounds, tenderness to palpation and jaw mobility.

The broad range of patients seen in this study was typical of

those referred to a dental hospital for management of TMD.

The TMD patients who did secure a diagnosis were distributed

between every RDC/TMD diagnostic group with the exception

of Group III b. The majority of the diagnoses were either RDC/

TMD Group I (39% using the RDC/TMD examination, 48% using

the CEP-TMD) or Group II (49% using the RDC/TMD examina-

tion and 39% using the CEP-TMD) making them the most

prevalent conditions in this study. The remaining 12% in both

examinations fell into RDC/TMD Group III, thus making it the

least prevalent set of conditions. John et al.17 found similar

prevalence.

Paradoxically, several patients failed to secure a diagnosis (8

using the RDC/TMD examination and 6 using the CEP-TMD with

5 of them not diagnosed by either examination) even though

j o u r n a l o f d e n t i s t r y 3 7 ( 2 0 0 9 ) 9 5 5 – 9 6 2 961

they had a complaint in or around the TMJ and muscles of

mastication. The 5 patients not diagnosed by either examina-

tion had been referred for the following jaw problems:

� Loud, non painful click

� History of a click which disappeared, leaving mild dis-

comfort

� History of dislocating jaw

� Transient pain in the jaw and neck area

� Bruxism during stress and jaw ‘‘aches’’ during those periods

of life.

The remaining patients scored a diagnosis with one exam

but not with the other. Two of them had 1–2 painful muscles

on palpation during the first two exams which increased to 4–5

by the time the second two exams were carried out. Both these

patients had the RDC/TMD carried out first. The other two

patients had a variable click during the first two examinations

that became more reproducible in the second two. One of the

patients had the RDC/TMD examination first but scored a

diagnosis in the CEP-TMD, while on the other had the CEP-

TMD carried out first and secured a diagnosis in the RDC/TMD.

These findings illustrate the potential difficulty of using a

research tool to make a working clinical diagnosis where the

signs and symptoms (e.g. those of dislocation) may not fit the

strict definitions of the RDC/TMD criteria or the CEP-TMD

definitions derived from them. Alternatively, an RDC/TMD

diagnosis may not be possible because symptoms are not

reproducible or transient.

4.1. Strengths and limitations

To determine whether a high degree of expertise is needed to

carry out the RDC/TMD and CEP-TMD examinations this study

used three examiners with different backgrounds and

experience in diagnosing TMD. Each one of them had

examined sufficient patients in line with the RDC/TMD

recommendations. Fortunately, the each of the three exam-

iners showed similar agreement between RDC/TMD and CEP-

TMD diagnoses, but had there been differences these could

have skewed the results. In view of the good inter-examiner

agreement all the examiners’ diagnoses were amalgamated,

allowing overall comparisons to be made within and between

RDC/TMD and CEP-TMD.

The number of examinations per patient was necessarily

limited. The ideal way of comparing the two examinations

would have been to examine each patient 8 times with each

examiner in a pair using both the RDC/TMD and CEP-TMD

twice. Even though that would ensure that intra- and inter-

examiner reliability could be calculated on the same patient, it

would have been ethically unacceptable as well as intolerable

to the patients. The statistical solution was to examine each

patient only 4 times and then amalgamate the diagnoses of all

three examiners which the authors acknowledge causes a

decrease in the sensitivity of the results.

A minor limitation of multiple examinations is that they

are inappropriate for patients in severe pain. Only two patients

were excluded for that reason.

The memory effect could have skewed the results had

examiners simply recalled aspects of their initial examination.

However, the imperfect intra-examiner agreement for detect-

ing muscle tenderness and disc displacements showed this to

be unlikely.

It must be acknowledged that with two of the examiners

substantially more familiar with the CEP-TMD than the RDC/

TMD there is a potential for bias in favour of the CEP-TMD. It is

therefore recommended that the study is repeated in other

centres where neither the CEP-TMD nor preferably the RDC-

TMD is in general use.

4.2. Clinical implications

Being able to diagnose TMD patients’ physical problems

effectively is helpful for dentists in deciding whether to treat

or to refer; it also helps standardize communication during

referral. More importantly, it would allow GDPs to allay

patients’ fears immediately rather than waiting for a

specialist or hospital based consultant to do so which

sometimes, due to waiting lists, takes some months.6,18,19 If

the dentist decides to treat the patient, the examination form

has the potential to provide a useful means of monitoring

changes at follow-up.

Should dentists use either the RDC/TMD or CEP-TMD

systems in clinical practice they need to recognize that the

RDC/TMD is principally designed to provide a physical

research diagnosis with a high level of sensitivity and

specificity. Clearly there will be those patients with genuine

sub-diagnostic level TMD symptoms not securing an RDC/

TMD diagnosis which in this study comprised 20%. Until

research proves the contrary it should not be assumed that

they have lesser associated problems, e.g. impact on quality of

life,17,19 than those that do secure such a diagnosis. Further-

more, a lack of an RDC/TMD diagnosis does not imply that

treatment be withheld. Finally, it should also be emphasized

that any diagnostic system used for TMD relies on clinicians

also making an appropriate evaluation of other causes of facial

and dental pain as well as confirming the presence or absence

of TMD. In particular, the use of static and dynamic tests may

sometimes be helpful to supplement muscle and TMJ

palpation in reaching an accurate diagnosis of TMD related

pain.20 Such tests have the capacity to provoke the patient’s

underlying pain if TMD related.

5. Conclusion

In conclusion, the CEP-TMD’s diagnosis is comparable to that

of the RDC/TMD. It is quicker and less sophisticated than the

RDC/TMD and provides an instant physical diagnosis, which

may make it more intuitive and attractive for general dental

practitioners to use in routine clinical practice. The RDC/TMD

remains the gold standard for use in research.

Acknowledgements

The authors would like to thank Mrs. Angela Fenwick for her

expertise in running the research clinics. The authors would

also like to thank the Saudi Cultural Office in London for

sponsoring and supporting the work.

j o u r n a l o f d e n t i s t r y 3 7 ( 2 0 0 9 ) 9 5 5 – 9 6 2962

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