Quality Resource Guide

Temporomandibular Disorders 3rd Edition

www.metdental.com

between a number of cranial and cervical nerves,

including the trigeminal system, complicating the

evaluation of the patient with orofacial pain. This

shared neurologic circuitry makes the etiology

of orofacial pain difficult to diagnose.

Confusion

regarding diagnostic and clinical decision-making

is compounded by the fact that signs associated

with TMD occur quite commonly in the general

population. Therefore, decisions regarding who

should, and who should not, be treated may

be challenging. Seventy-five percent of those

evaluated in a non-patient study exhibited at least

1 sign (joint noise or palpation tenderness) and

33% exhibited at least one symptom

, while only

3.6% to 7% of individuals with TMD are in need of

treatment.

7,8

Pain in other regions of the body, and more

specifically

the

head

and

neck,

commonalities or are comorbid with TMD.

Headache and ear-related symptoms are frequent

complaints among TMD patients.

9-14

Pain in other

regions of the body including other joints have

been associated with TMD.

15,16

A study of a TMD

patient population indicated that 75% also reported

concomitant neck pain. Seventy-two percent of the

study group was experiencing pain in areas of the

head other than the masticatory region, and 72%

reported back pain.

It has also been reported

that high pain intensity and long pain duration

increase the probability of having co-existing pain

and comorbidities in this patient population.

Who is at Risk?

The most common age group found to be affected

is between 15 and 45 years of age (mean: 33.9

years).

Demographic data from clinically based

studies indicate that TMD symptoms are least

prevalent in the young and seem to decrease

after the age of 45. A significant sex bias exists

among patient populations of 6:1 to 9:1, with

females more represented than males.

20,21

The

literature on experimentally-induced pain indicates

sex differences, with females displaying greater

sensitivity.

Sex differences are also noted in

epidemiological studies with females reporting

more severe pain, more frequent pain, and pain of

longer duration.

23,24

Introduction

In a general population survey involving 805

individuals having a persistent pain disorder, it

was revealed that more than four out of 10 people

had not found adequate relief, saying their pain is

out of control— despite having the pain for more

than 5 years and switching doctors at least once.

Therefore, it should not be a surprise the most

common reason patients seek medical or dental

care in the United States is due to pain. Lipton and

others, in a study of 45,711 households, revealed

that 22% of the U.S. population experienced

orofacial pain on more than one occasion in a 6

month period. Odontogenic pain was the most

frequently reported condition.

Non-odontogenic

pain involving the orofacial region such as

temporomandibular joint (TMJ) pain, face pain,

and neuropathic conditions were also commonly

reported. Since each pain disorder is unique,

establishing an accurate and complete differential

diagnosis is fundamental. It is mandatory that dental

practitioners develop the necessary scientific and

clinical expertise on which he/she may base

diagnostic and management approaches.

Temporomandibular disorder (TMD) is currently

viewed as a group of musculoskeletal and

neuromuscular conditions that involve the TMJs,

the masticatory muscles, and all associated

tissues.

TMD has been identified as one of the

most common non-odontogenic pain complaints

and is the second most frequent cause of

musculoskeletal pain and limitation, only preceded

by low back pain.

Population-based studies

indicate the prevalence of TMD-related pain is

12%.

The National Institutes of Health reported

that 10 million Americans suffer from TMD related

complaints each year.

TMD Signs and Symptoms

The cardinal signs (objective indicators) and

symptoms (subjective experiences) of TMD are:

pain in the temporomandibular region; limitation

or disturbance in mandibular movement and/or

masticatory functional ability; and, TMJ sounds.

However, this description is far too simplistic.

The complexity of neural pathways in the head

and neck region provides dynamic interactions

Arthrogenous (joint related) TMD

The most common sign of TMD has been identified

as TMJ clicking, due to displacement of the

articular disc. General population based studies

have reported clicking, popping or crepitus to

occur in about 50% of those studied.

A magnetic

resonance image (MRI) study identified that 86%

of a TMD patient population demonstrated disc

displacement. However, 33% of the non-patient

controls also had disc displacement.

Although

the concept of natural progression of TMD has

been purported in the past, there is a lack of

evidence supporting the concept that TMJ joint

clicking progresses to locking and degeneration,

or that arthritic changes develop in joints that lock.

It has been reported that most degenerating joints

tend to become non-painful with time; although, as

many as 16% of these individuals may experience

pain long-term.

Myogenous (muscle related) TMD

Muscle-related signs and symptoms are very

common in the general population and account

for the most common subgroup of patients with

TMD.

27,28

Definitive theories do not presently

exist that totally explain why masticatory muscles

become painful, their associated symptomatology,

or the cause(s) leading to chronicity. Furthermore,

there is no single identifiable etiologic factor;

therefore myogenous pain is considered complex

and multifactorial, making it more challenging to

identify risk factors and their unique contributions

to the process.

It is important to recognize there

exists a dynamic relationship between the function

of the masticatory and cervical muscles. Due to

this relationship, these regions must be thoroughly

assessed during routine TMD patient evaluations.

In fact, cervical tenderness scores have been

shown to differentiate between TMD patients and

controls and between different TMD diagnoses.

The putative mechanisms behind masticatory

myalgia typically include overuse of a normally

perfused muscle or ischemia of a normally working

muscle, sympathetic reflexes produciing changes

in vascular supply and muscle tone, or changes

in psychological and emotional states.

Individual

variations in muscle anatomy, biomechanics, and