he ability to understand and investigate the pathophysiologic
processes underlying a disorder depends on a valid, reliable
classication system and common terminology to facilitate
communication among clinicians, researchers, academics, and pa-
tients. Without a universal system of organization in place, discus-
sion, investigation, and ultimately understanding of the disorder are
difcult to achieve.
Classication begins by grouping disorders according to common
signs and symptoms and then dividing further by common patho-
physiology and treatment approaches. In this manner, the diagnos-
tic classication can assist clinicians in treatment selection. From a
clinical perspective, it is not important to further divide subgroups
when all of the disorders within a given subgroup are managed by
the same therapy; therefore, from a therapeutic standpoint, subcat-
egories are only useful when therapy demands it.
◊ Diagnostic systems are needed to assist with manage-
ment of orofacial pain.
◊ There are many widely varying diagnostic schemes, which
reects the complexity of pain as a eld.
◊ No diagnostic classication is without shortcomings and
criticism, and there is still an urgent need for validation of
◊ The diagnostic classication presented in this chapter is in
accord with internationally accepted standards and should
be useful for clinicians attempting to manage patients
who are suffering from orofacial pain.
Another purpose of a common diagnostic
classication system is to assist researchers
in gaining insight into the prevalence, etiol-
ogy, and natural course of a specic disorder.
Knowledge can only be advanced when there
is agreement on specic disorders so that
research efforts can be compared between
patients and various research groups. At this
time, it is uncertain whether diagnostic crite-
ria for research purposes are compatible with
diagnostic criteria for determining therapy.
For example, it is quite reasonable to sepa-
rate muscle disorders from intracapsular joint
disorders for the purpose of studying the
natural course of these disorders. However,
merely identifying that a patient is suffering
from one of these types of disorders may not
be adequate to effectively manage the con-
dition. The most useful classication system
would provide both research and diagnostic
The process of developing a classication
system begins by identifying a group of com-
mon signs and symptoms. Once these signs
and symptoms have been identied, the disor-
der is named. The disorder, with its common
signs and symptoms, is then investigated to
learn more about its etiology so that effec-
tive treatment may be developed. It is very
important that the signs and symptoms used
to identify the disorder be unique to the dis-
order so that other unrelated disorders are
not misidentied. It is therefore necessary to
develop specic inclusion and exclusion crite-
ria that will permit accurate grouping of simi-
lar disorders. To eliminate as much variability
in diagnosis as possible, it is very important
to be specic, avoiding words such as “usu-
ally,” “typically,” or “sometimes.” Testing is
then necessary to determine if the diagnostic
criteria are valid and reliable for determining
the disorder. Once they are proven reliable, re-
search efforts can be directed toward gaining
better insight into etiology, eventually leading
to more effective treatment.
In this chapter, past and present terminol-
ogy and diagnostic classication systems for
temporomandibular disorders (TMDs) and oro-
facial pain disorders are discussed, and a clas-
sication system for orofacial pain disorders is
presented. To assist the reader, the codes from
The International Classication of Diseases,
Tenth Edition (ICD-10) will be provided for each
diagnosis throughout the next chapters.
Over the years, functional disturbances of the
masticatory system have been identied by
a variety of terms, which likely led to confu-
sion in this area. In 1934, Dr James Costen
described a group of symptoms that centered
around the ears and temporomandibular joints
(TMJs), which became known as Costen syn-
drome. In 1959, Shore
used the term tempo-
romandibular joint dysfunction syndrome for
those symptoms. Later, the term functional
temporomandibular joint disturbances was in-
troduced by Ramfjord and Ash.
terms, such as occlusomandibular disturbance
and myoarthropathy of the temporomandibu-
lar joint, were based on possible etiologic
Other terminology stressed the
featured pain symptom, such as temporoman-
dibular pain-dysfunction syndrome and myo-
fascial pain-dysfunction syndrome.
Because the symptoms are not always iso-
lated to the TMJs, some authors believe that
the previously mentioned terms were too lim-
ited and a broader, more collective term should
be used, such as craniomandibular disorders.
suggested the term temporomandibular
disorders, which has gained wide acceptance
and popularity. As described in this text, this
term includes not only problems related to the
TMJ but all functional disturbances of the mas-
ticatory system. Any musculoskeletal disorder
of the masticatory system can be considered
Was this article helpful?
The ability to understand and investigate the pathophysiologic processes underlying a disorder depends on a valid, reliable classication system and common terminology to facilitate communication among clinicians, researchers, academics, and pa-tients. Without a universal system of organization in place, discus-sion, investigation, and ultimately understanding of the disorder are difcult to achieve.Classication begins by grouping disorders according to common signs and symptoms and then dividing further by common patho-physiology and treatment approaches. In this manner, the diagnos-tic classication can assist clinicians in treatment selection. From a clinical perspective, it is not important to further divide subgroups when all of the disorders within a given subgroup are managed by the same therapy; therefore, from a therapeutic standpoint, subcat-egories are only useful when therapy demands it.Key Points◊ Diagnostic systems are needed to assist with manage-ment of orofacial pain. ◊ There are many widely varying diagnostic schemes, which reects the complexity of pain as a eld.◊ No diagnostic classication is without shortcomings and criticism, and there is still an urgent need for validation of classication schemes. ◊ The diagnostic classication presented in this chapter is in accord with internationally accepted standards and should be useful for clinicians attempting to manage patients who are suffering from orofacial pain.Diagnostic Classiﬁcation of Orofacial Pain3 51TerminologyAnother purpose of a common diagnostic classication system is to assist researchers in gaining insight into the prevalence, etiol-ogy, and natural course of a specic disorder. Knowledge can only be advanced when there is agreement on specic disorders so that research efforts can be compared between patients and various research groups. At this time, it is uncertain whether diagnostic crite-ria for research purposes are compatible with diagnostic criteria for determining therapy. For example, it is quite reasonable to sepa-rate muscle disorders from intracapsular joint disorders for the purpose of studying the natural course of these disorders. However, merely identifying that a patient is suffering from one of these types of disorders may not be adequate to effectively manage the con-dition. The most useful classication system would provide both research and diagnostic advantages.The process of developing a classication system begins by identifying a group of com-mon signs and symptoms. Once these signs and symptoms have been identied, the disor-der is named. The disorder, with its common signs and symptoms, is then investigated to learn more about its etiology so that effec-tive treatment may be developed. It is very important that the signs and symptoms used to identify the disorder be unique to the dis-order so that other unrelated disorders are not misidentied. It is therefore necessary to develop specic inclusion and exclusion crite-ria that will permit accurate grouping of simi-lar disorders. To eliminate as much variability in diagnosis as possible, it is very important to be specic, avoiding words such as “usu-ally,” “typically,” or “sometimes.” Testing is then necessary to determine if the diagnostic criteria are valid and reliable for determining the disorder. Once they are proven reliable, re-search efforts can be directed toward gaining better insight into etiology, eventually leading to more effective treatment.In this chapter, past and present terminol-ogy and diagnostic classication systems for temporomandibular disorders (TMDs) and oro-facial pain disorders are discussed, and a clas-sication system for orofacial pain disorders is presented. To assist the reader, the codes from The International Classication of Diseases, Tenth Edition (ICD-10) will be provided for each diagnosis throughout the next chapters.TerminologyOver the years, functional disturbances of the masticatory system have been identied by a variety of terms, which likely led to confu-sion in this area. In 1934, Dr James Costen1 described a group of symptoms that centered around the ears and temporomandibular joints (TMJs), which became known as Costen syn-drome. In 1959, Shore2 used the term tempo-romandibular joint dysfunction syndrome for those symptoms. Later, the term functional temporomandibular joint disturbances was in-troduced by Ramfjord and Ash.3 Some earlier terms, such as occlusomandibular disturbance and myoarthropathy of the temporomandibu-lar joint, were based on possible etiologic factors.4,5 Other terminology stressed the featured pain symptom, such as temporoman-dibular pain-dysfunction syndrome and myo-fascial pain-dysfunction syndrome.6,7 Because the symptoms are not always iso-lated to the TMJs, some authors believe that the previously mentioned terms were too lim-ited and a broader, more collective term should be used, such as craniomandibular disorders.8 Bell9 suggested the term temporomandibular disorders, which has gained wide acceptance and popularity. As described in this text, this term includes not only problems related to the TMJ but all functional disturbances of the mas-ticatory system. Any musculoskeletal disorder of the masticatory system can be considered a TMD. 52Diagnostic Classiﬁcation of Orofacial Pain3Diagnostic Classication SystemsHistory of classication systemsA review of the literature regarding the clas-sication of orofacial pain reveals little consen-sus on the most favorable diagnostic classi-cation system. Many classication systems with varying advantages and disadvantages have been offered. Categories of division in-cluded etiologic factors, common signs and symptoms, tissue origin or functional region of the body, or combinations thereof. Perhaps the rst classication system for TMJ prob-lems was offered by Weinmann and Sicher.10 In 1951, they classied TMJ problems into (1) vitamin deciencies, (2) endocrine disorders, and (3) arthritis. Five years later, Schwartz11 introduced the term temporomandibular joint pain-dysfunction syndrome to distinguish or-ganic disturbances of the joint proper from masticatory muscle disorders. In 1960, Bell12 developed a classication composed of six groups, recognizing both intracapsular and muscle (ie, extracapsular) disorders. Acknowl-edging the need for a suitable classication for functional disorders of the masticatory sys-tem, the American Academy of Orofacial Pain (AAOP) published a position paper with a sug-gested classication system.8 Soon after, the American Dental Association (ADA) organized a national conference in which Bell suggested the term temporomandibular disorders, and a revised classication of TMDs consisting of ve categories was introduced. Both the term and the classication were accepted by the ADA, but unfortunately, no diagnostic criteria were offered at that time.13In 1989, Stegenga et al14 proposed a sys-tem of classication emphasizing TMJ articular disorders. They divided their classication into inammatory and noninammatory articular disorders and nonarticular disorders. The sub-categories of osteoarthrosis and internal de-rangements were further divided according to staging over time. Although this classication provided insight to intracapsular disorders, it placed little emphasis on masticatory muscle disorders. No diagnostic criteria were offered with this classication. As the dental profes-sion began to appreciate the similarity between many TMDs and other medical conditions, a need grew to include TMDs in a more inclu-sive medical classication for pain disorders. In 1986, the International Association for the Study of Pain (IASP)15 published a classication of pain conditions. Of the 32 categories of pain disorders, category III was designated as “cra-niofacial pain of musculoskeletal origin.” Within this category were two subcategories: (1) temporomandibular pain and dysfunction syn-drome; and (2) osteoarthritis of the TMJ. This classication failed to recognize any pain dis-orders arising from the masticatory muscles.In 1990, the American Academy of Head, Neck, Facial Pain and TMJ Orthopedics16 pro-posed a classication with ve TMD categories and two non-TMD categories. The subcatego-ries represented a mixture of both traditional and nontraditional disorders. Brief explana-tions were offered for most subcategories but not for all. There were 19 subcategories under the main category of “myofascial disorders,” some of which were separated by the specic muscle or tendon involved. Some diagnostic categories, such as “bruxism,” might better represent a precipitating or contributing factor of muscle pain and not necessarily a muscle pain disorder itself. No diagnostic criteria were offered to assist in classifying these disorders. Another classication suggested a much broader approach. Woda and Pionchon17 pro-posed the adoption of a unifying classica-tion for “idiopathic orofacial pain disorders.” Most clinicians who treat orofacial pain disor-ders recognize that there are certain patients who present with clinical symptoms that do not easily t into the known and generally well-accepted classications of orofacial pain disorders. The authors suggest that many of these unclassied conditions present with some common clinical symptoms. Because 53Diagnostic Classiﬁcation Systemsour understanding of these disorders is not complete, the profession has assigned such terms as atypical facial pain and atypical od-ontalgia. These atypical cases may present with common clinical symptoms associated with common pathophysiologic mechanisms. If common mechanisms do in fact exist, then it may be useful to group these conditions to-gether. Yet until these mechanisms are better understood, grouping them into a large classi-cation will not likely improve treatment selec-tion. In fact, it would appear that placing TMDs with relatively known etiologies and treatment strategies into a group of idiopathic orofacial pain disorders would be taking a step in the wrong direction.In 2012, a group of researchers and clini-cians attempted a new approach to the clas-sication of orofacial pain, which was based on ontology.18 Ontology is the study of the nature of being, such as whether an entity exists or not, how entities are similar and different as well as how they relate to each other within a hierarchy, and how these differ-ences or similarities dene their subgroup.19 Identifying a disorder or disease is dependent on several levels of evidence, such as reality, observations, interpretations, and/or beliefs. This new endeavor to classify orofacial pain has only attempted to examine a few orofacial pain conditions, and therefore a full classica-tion is not available. This approach to nosol-ogy is unique, and its usefulness has yet to be demonstrated.In 2014, the Analgesic, Anesthetic, and Ad-diction Clinical Trial Translations Innovations Opportunities and Networks (ACTTION) and the American Pain Society (APS) developed a mechanistic chronic pain classication sys-tem called the ACTTION-APS Pain Taxonomy (AAPT), which describes pain in ve dimen-sions: (1) core diagnostic criteria; (2) common features; (3) common medical and psychiatric comorbidities; (4) neurobiologic, psychosocial, and functional consequences; and (5) puta-tive neurobiologic and psychosocial mecha-nisms, risk factors, and protective factors. In the AAPT, “temporomandibular disorders” and “other orofacial pain” are organized in the “orofacial and head pain system.”20,21The ICHDIn 1988, the International Headache Society (IHS) proposed their rst classication for headache composed of 13 broad categories, called the International Classication of Head-ache Disorders (ICHD).22 The 11th category was designated as “headache or facial pain attributed to disorder of cranium, neck, eyes, ears, nose, sinuses, teeth, mouth, or other fa-cial or cranial structures.” There were no spe-cic subcategories related to TMDs, despite recommendations by the AAOP.23 In 2004, the IHS published their second version of the classication, outlining more than 230 types of headaches. TMDs were still minimally ad-dressed in this version under category 11.24 The AAOP provided diagnostic criteria and subcategories from the third and fourth edi-tions of this book in 1996 and 2008, respec-tively.25,26 In 2013, the IHS published a beta version of the third edition of the ICHD, which is the classication system used in this text for headaches and neuropathic pain.27 Over the past few years, many clinicians have embraced this classication because of its inclusive con-siderations for all head pains. This classica-tion offers more than 300 types of headaches and thus requires the clinician to possess a very high level of appreciation for all head pain disorders before a diagnosis can be properly established. In this version, only “Headache attributed to temporomandibular disorder (TMD)” is addressed under category 11. The RDC/TMD and DC/TMDIn 1992, Truelove et al28 proposed a classica-tion system for TMD that allowed for multiple diagnoses within the same subject group. Re-quired operational criteria were listed for each 54Diagnostic Classiﬁcation of Orofacial Pain3diagnostic group, allowing the researcher to in-vestigate a sample population and determine the types and severity of disorders present. This concept was further elaborated through the research diagnostic criteria (RDC) offered by Dworkin and LeResche.29 This classication not only provided very specic diagnostic cri-teria for eight TMD subgroups—it also recog-nized another level or axis that must be consid-ered when evaluating and managing TMD pain: the psychosocial component. For the rst time in any classication system, a dual diagnosis was established that recognized the physical conditions (Axis I) and psychologic conditions (Axis II) that contribute to the suffering, pain behavior, and disability associated with the patient’s pain experience. (This Axis II should not be confused with the designated axis sys-tem endorsed by the Diagnostic and Statisti-cal Manual of Mental Disorders, Fifth Edition [DSM-5] of the American Psychiatric Associa-tion.) This dual-axis classication approach has been incorporated in Bell’s classication for all orofacial pain disorders.30The RDC offered what appeared to be rea-sonable diagnostic criteria, specically for re-search purposes.29 Although some questioned whether these criteria were specic enough to accurately distinguish subgroups of TMD patients, the use of Research Diagnostic Cri-teria for Temporomandibular Disorders (RDC/TMD) for the most common TMDs has accept-able reliability.31–34 The International RDC-TMD Consortium from the International Association for Dental Research and the Special Interest Group on Orofacial Pain from the IASP joined forces to revise the RDC/TMD diagnostic al-gorithms to produce the dual-axis Diagnos-tic Criteria (DC/TMD) for the most common pain-related TMDs. These are evidence-based, have improved diagnostic accuracy, and are easy to use by both clinicians and research-ers.35 The validation project established high sensitivity and specicity for the painful mus-culoskeletal TMDs and high specicity for disc derangements in the DC/TMD.36,37 Peck et al38 expanded on the DC/TMD taxonomy in 2014 to include less common—but still clinically relevant—disorders such as adhesions, ankylosis, idiopathic condylar re-sorption, synovial chondromatosis, tendonitis, masticatory muscle spasm, movement disor-ders, and coronoid hyperplasia. This list of 37 disorders all featured plausible diagnostic cri-teria that could be operationalized and further studied.38 An executive summary of the DC/TMD published in the Journal of the Ameri-can Dental Association in 2016 promoted this evidence-based, biopsychosocial approach to TMD classication with the wider dental au-dience.39 Future directions for the DC/TMD may include (1) incorporating synovial uid biomarkers for TMJ arthritis; (2) developing longitudinal trials to evaluate the predictive role of demographics, function, and structure in the progression of disc-condyle disorders; (3) validating whether myofascial pain and myofascial pain with referral are the same or separate entities; (4) clarifying the etiologic, diagnostic, and management overlap of sleep and awake bruxism, orofacial dyskinesia, and oromandibular dystonia; (5) reconciling the ICHD and DC/TMD denitions of headache attributed to TMD; and (6) establishing the most efcient and effective Axis II biobehav-ioral screening instruments for use in the clini-cal setting.40Future directions The upcoming ICD-11 will make considerable advances in the classication of chronic pain, spearheaded by the IASP Task Force for the Classication of Chronic Pain on behalf of the World Health Organization (WHO). Slated for release in 2018, the ICD-11 (which can be ac-cessed as a beta draft on the WHO website) al-lows for cross-referenced categories. Chronic pain disorders are divided into seven groups: primary pain, cancer pain, posttraumatic and postsurgical pain, neuropathic pain, headache and orofacial pain, visceral pain, and muscu- 55Dierential Diagnosis of Orofacial Painloskeletal pain. For example: “chronic head-ache and orofacial pain” would encompass TMDs and posttraumatic trigeminal neuropa-thy (PTTN), with the PTTN cross-referenced to chronic neuropathic pain. The ICD-11 organizes chronic pain entities rst according to their eti-ology, then the pathophysiologic mechanism underlying the pain, and then the location of pain in the body.41Although it would be desirable, there is no current single all-encompassing chronic pain classication system to unify and streamline patient care worldwide.42 However, signicant strides have been made in the last 25 years, and future efforts could streamline chronic orofacial pain classication by focusing on hypothesis-driven descriptions and interrela-tions of disease entities, incorporating physi-ologic and psychosocial domains, beta-testing the classications for sensitivity and specic-ity, and designing the classications for clinical implementation.43 Incorporating genetic mark-ers, neurobiologic pain processing changes over time, and ontologic principles could gen-erate an even more comprehensive and unify-ing classication system.44Dierential Diagnosis of Orofacial PainThe diagnostic process is a clinical skill that joins science and art. The goals of the pro-cess are to determine the existence of any primary and/or secondary physical (Axis I) or psychologic (Axis II) diagnoses, the contrib-uting factors, and the level of complexity of the patient’s problem(s), including the prog-nosis. Listing conditions that may be respon-sible for each of the presenting complaints of the patient, as well as other factors that may contribute to the complexity of the tentative diagnosis, usually facilitates the process. The diagnostic process involves dening the inclu-sion criteria that are specic to a disorder and ruling out specic disorders that can cause similar symptoms. This should be done from a diagnostic classication that includes all pos-sible disorders. It is important to rule out seri-ous, life-threatening intracranial or extracranial disorders or diseases early in the diagnostic process because these conditions may require immediate care. Pain sources should be pur-sued until all correct diagnoses are established using inclusive diagnostic criteria. The process of differential diagnosis is critical because an incorrect or omitted diagnosis is one of the most frequent causes of inappropriate and misdirected treatment or treatment failure.Establishing the correct diagnosis in pa-tients with orofacial pain is particularly difcult because of the complex interrelationship of physical and psychologic factors in the etiology of biopsychosocial chronic pain syndromes. Many disorders have similar signs and symp-toms. If the source of painful symptoms is uncertain, the appropriate diagnosis is “pain, cause unknown or undetermined.” Although individual clinicians can be successful in diag-nosing the simpler orofacial problems, a mul-tidisciplinary team approach is often required for diagnosing and managing complex chronic orofacial problems, especially when Axis II factors are present or signicant other comor-bidities exist, including central sensitization, irritable bowel syndrome, pelvic pain, chronic headache, and chronic low-back pain.45–51The guidelines in this text incorporate the classication structures proposed by the Taxon-omy Committee of the International RDC-TMD Consortium Network and the Special Interest Group on Orofacial Pain, as presented in the expanded DC/TMD36 (see Box 8-1) for TMDs, as well as the ICHD for headaches and neuro-pathic pain. The broad categories included in these guidelines are as follows: • Vascular and nonvascular intracranial pain disorders• Primary headache disorders• Neuropathic pain disorders• Intraoral pain disorders 56Diagnostic Classiﬁcation of Orofacial Pain3• Temporomandibular disorders• Cervical pain disorders• Extracranial and systemic causes of oro-facial painEach of these categories represents a group of Axis I physical orofacial pain condi-tions. Another category will be included to re-view the Axis II psychologic factors that are commonly associated with orofacial pain dis-orders. The seven broad categories of orofa-cial pain (Axis I) are briey introduced in this chapter along with the Axis II considerations. An additional section includes how sleep dis-orders may inuence these conditions. A more complete description of each is presented in separate chapters.Vascular and nonvascular intracranial pain disordersDisorders of the intracranial structures (eg, neoplasm, aneurysm, abscess, hemorrhage or hematoma, and edema) should be consid-ered rst in the differential diagnosis because they can be life-threatening and may require immediate attention. The characteristics of serious intracranial disorders include new or abrupt onset of pain or progressively more severe pain, interruption of sleep by pain, and pain precipitated by exertion or positional change (ie, coughing, sneezing). Other charac-teristics of intracranial disorders are signs or symptoms of weight loss, ataxia, weakness, fever with pain, neurologic signs or symptoms (eg, seizure, paralysis, vertigo), and neurologic decits.28,44Primary headache disordersPrimary headache disorders are a group of pain disorders that have their origin in both neuro-logic and vascular pathology. Because some of these headaches appear to have a neurologic mechanism that triggers a vascular response, they are frequently referred to as neurovas-cular. Headaches that comprise this category include migraine, tension-type headache, and trigeminal autonomic cephalalgias. The charac-teristics of these headaches vary. Migraine for example is described as throbbing, pulsating, and disabling, whereas tension-type headache is characterized as a dull, steady aching pain. The dental profession has become increas-ingly active in managing some of these pain disorders; however, the major burden of man-aging most of these disorders still lies within the medical community.Neuropathic pain disordersNeuropathic pain is dened as pain caused by a lesion or disease of the somatosensory nervous system.52 These pain conditions arise from functional abnormalities of the nervous system.53–55 Because the somatic structures are not affected, the examination fails to re-veal any obvious cause or pathology. An ideal classication for neuropathic pain would be based on the mechanisms that are respon-sible for producing the pain condition.56–58 Unfortunately, our current understanding of these conditions is not sophisticated enough to achieve this. Complicating the development of a classication system for neuropathic pain is the understanding that both the periph-eral and central nervous systems contribute to these pain conditions, often at the same time. Terms such as persistent dentoalveolar pain disorders and peripheral painful traumatic trigeminal neuropathies have been proposed to describe neuropathic pain conditions with peripheral etiologies in the facial region.22,59,60 Classic trigeminal neuralgia appears to be caused by a central mechanism initiated by peripheral stimulation. These examples reect the difculty in developing an encompassing classication for neuropathic pains. Several episodic as well as a variety of continuous neuropathic pains are described. 57Dierential Diagnosis of Orofacial PainIntraoral pain disordersIntraoral pain is the most common source of orofacial pain. The dentist plays an important role in the diagnosis of intraoral pain because many of these disorders are solely managed by those in the dental profession. The dentist must be extremely thorough in ruling out intraoral pain disorders involving the dental pulp, peri-odontium, mucogingival tissues, and tongue.Temporomandibular disordersTMDs include disorders involving the mastica-tory muscles and/or the TMJ. TMDs have been identied as a major cause of nonodontogenic pain in the orofacial region and are consid-ered a subclassication of musculoskeletal disorders.61Cervical pain disordersCervical pain disorders represent a very com-mon group of musculoskeletal conditions that can greatly inuence the orofacial structures. These disorders are subdivided into those that predominantly originate in the muscles and those that predominantly originate in the cer-vical spine. These structures very commonly refer pain to the face and therefore deserve a signicant diagnostic consideration.62Extracranial and systemic causes of orofacial painThere are a variety of associated structures that can cause orofacial pain, such as the ears, eyes, nose, paranasal sinuses, throat, lymph nodes, and salivary glands. Many of these structures produce heterotopic (ie, referred) pain felt in the orofacial region, which is often misinterpreted as dental or TMD pain. Al-though pain from these structures may not be primarily managed by the dentist, a thorough understanding of their characteristics is nec-essary to establish an accurate diagnosis and avoid inappropriate interventions. Once the di-agnosis has been established, proper referral should be considered.Sleep disordersThe presence of pain, especially chronic pain, greatly interferes with the duration and quality of sleep. As will be discussed in chapter 11, the quality of sleep is vital for maintaining physical and psychologic health, and poor-quality sleep can actually initiate pain experiences in some individuals. It is very apparent that pain and sleep are often closely associated conditions for many chronic pain patients. The orofacial pain clinician needs to appreciate this relation-ship, and a chapter on sleep disorders has therefore been included in this text.Axis II: Psychologic factorsThere are many psychologic factors that con-tribute to the patient’s pain experience. In fact, rarely does pain exist without some inuence of these Axis II factors, especially as pain be-comes more chronic. Even common stressful life events, such as conicts in home or work relationships, nancial problems, and cultural readjustment, may contribute to illness and chronic pain.63–66 These stressors may heighten tensions, insecurities, and dysphoric affects, which may in turn lead to increased strains on the masticatory system by way of unusual parafunctional behaviors. Once established, these adjustment reactions (often with mixed disturbance of emotions and conduct) lead to an upregulation of the autonomic nervous sys-tem, which can further exacerbate the physical condition.67,68Depression, anxiety, and prolonged nega-tive feelings are common among chronic pain patients and may make the persistent pain more difcult to tolerate or manage. Negative cognitive factors, such as counterproductive thoughts or attitudes, can make resolution of the illness more difcult. Confusion and mis- 58Diagnostic Classiﬁcation of Orofacial Pain3understanding are commonly seen in chronic pain patients because they have often received many opposing and varied opinions, diagnoses, and treatment suggestions. This confusion re-duces motivation and increases anger or non-compliance. Also, patients with persistent pain often have unrealistic expectations and may expect complete or immediate pain relief.It should be emphasized that mental disor-ders and orofacial pain disorders are not mu-tually exclusive conditions. When psychologic factors are prominent in the patient’s presen-tation, collaboration with a mental health care professional should be an integral dimension of assessment and management.References1. Costen JB. Syndrome of ear and sinus symptoms de-pendent upon functions of the temporomandibular joint. Ann Otol Rhinol Laryngol 1934; 3: 1–4.2. Shore NA. Occlusal Equilibration and Temporomandibu-lar Joint Dysfunction. Philadelphia: JB Lippincott, 1959.3. Ramfjord SP, Ash MM. Occlusion. Philadelphia: WB Saunders, 1971.4. Gerber A. Kiefergelenk und Zahnokklusion. Dtsch Zahn-ärztl 1971; 26: 119–141.5. Graber G. Neurologische und psychosomatische Aspe-kte der Myoarthropathien des Kauorgans. ZWR 1971; 80: 997–1000.6. Schwartz L. Disorders of the temporomandibular joint. Philadelphia: WB Saunders, 1959.7. Laskin DM. Etiology of the pain-dysfunction syndrome. J Am Dent Assoc 1969; 79: 147–153.8. McNeill C, Danzig D, Farrar W, et al. Craniomandibular (TMJ) disorders—State of the art. J Prosthet Dent 1980; 44: 434–437.9. Bell WE. Clinical Management of Temporomandibular Disorders. Chicago: Year Book Medical Publishers, 1982.10. Weinmann JP, Sicher H. Pathology of the temporoman-dibular joint. In: Sarnat BG (ed). The Temporomandibular Joint. Springeld, IL: Charles C Thomas, 1951: 65–81.11. Schwartz LL. A temporomandibular joint pain- dysfunction syndrome. J Chron Dis 1956; 3: 284.12. Bell WE. Temporomandibular Joint Disease. Dallas: Egan, 1960.13. Grifths RH. Report of the President’s Conference on Examination, Diagnosis and Management of Temporo-mandibular Disorders. J Am Dent Assoc 1983; 106: 75–77.14. Stegenga B, de Bont L, Boering G. A proposed classi-cation of temporomandibular disorders based on syno-vial joint pathology. Cranio 1989; 7: 107–118.15. Merskey H. Classication of chronic pain: Descriptions of chronic pain syndromes and denitions of pain terms. Pain 1986; (suppl 3): S1–S226.16. Talley RL, Murphy GJ, Smith SD, Baylin MA, Haden JL. Standards for the history, examination, diagnosis, and treatment of temporomandibular disorders (TMD): A position paper. Cranio 1990; 8: 60–77.17. Woda A, Pionchon P. A unied concept of idiopathic orofacial pain: Pathophysiologic features. J Orofac Pain 2000; 14: 196–212.18. Nixdorf DR, Drangsholt MT, Ettlin DA, et al. Classifying orofacial pains: A new proposal of taxonomy based on ontology. J Oral Rehabil 2012; 39: 161–169.19. Smith B, Ceusters W. Ontology as the core discipline of biomedical informatics: Legacies of the past and rec-ommendations for the future direction of research. In: Crnkovic GD, Stuart S (eds). Computing, Philosophy, and Cognitive Science: The Nexus and the Liminal. Cambridge, UK: Scholars Press, 2007: 104–122.20. Fillingim RB, Bruehl S, Dworkin RH, et al. The ACTTION-American Pain Society Pain Taxonomy (AAPT): An evidence-based and multidimensional ap-proach to classifying chronic pain conditions. J Pain 2014; 15: 241–249.21. Dworkin RH, Bruehl S, Fillingim RB, Loeser JD, Terman GW, Turk DC. Multidimensional diagnostic criteria for chronic pain: Introduction to the ACTTION–American Pain Society Pain Taxonomy (AAPT). J Pain 2016; 17(suppl 2): T1–T9.22. Oleson J. Classication and diagnostic criteria for head-ache disorders, cranial neuralgias and facial pain. Ceph-alalgia 1988; 8(suppl 7): 1–97.23. McNeill C. Temporomandibular Disorders: Guidelines for Classication, Assessment, and Management, ed 2. Chicago: Quintessence, 1993.24. Oleson J. The International Classication of Headache Disorders. Cephalagia 2004;24(suppl):1–160.25. Okeson JP. Orofacial Pain: Guidelines for Classication, Assessment, and Management, ed 3. Chicago: Quin-tessence, 1996.26. de Leeuw R. Orofacial Pain: Guidelines for Assessment, Diagnosis, and Management, ed 4. Chicago: Quintes-sence, 2008.27. Headache Classication Subcommittee of the Interna-tional Headache Society. The international classication of headache disorders, 3rd edition (beta version). Ceph-alalgia 2013; 33: 629–808. 28. Truelove EL, Sommers EE, LeResche L, Dworkin SF, Von Korff M. Clinical diagnostic criteria for TMD. New classication permits multiple diagnoses [see com-ments]. J Am Dent Assoc 1992; 123: 47–54.29. Dworkin SF, LeResche L. Research Diagnostic Criteria for Temporomandibular Disorders: Review, criteria, ex-aminations and specications, critique. J Craniomandib Disord 1992; 6: 301–355. 5959References30. Okeson JP. Bell’s Oral and Facial Pain, ed 7. Chicago: Quintessence, 2014. 31. Naeije M, Kalaykova S, Visscher CM, Lobbezoo F. Evalu-ation of the Research Diagnostic Criteria for Temporo-mandibular Disorders for the recognition of an anterior disc displacement with reduction. J Orofac Pain 2009; 23: 303–311.32. Okeson JP. Critical commentary 1: Evaluation of the Research Diagnostic Criteria for Temporomandibular Disorders for the recognition of an anterior disc dis-placement with reduction. J Orofac Pain 2009; 23: 312–315.33. Steenks MH, de Wijer A. Validity of the Research Diag-nostic Criteria for Temporomandibular Disorders Axis I in clinical and research settings. J Orofac Pain 2009; 23: 9–16.34. John MT, Dworkin SF, Mancl LA. Reliability of clinical temporomandibular disorder diagnoses. Pain 2005; 118: 61–69.35. Schiffman EL, Ohrbach R, Truelove E, et al. Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) for clinical and research applications: Recommendations of the International RDC/TMD Consortium Network and Orofacial Pain Special Interest Group. J Orofac Pain Headache 2014; 28: 6–27.36. Ohrbach R, Dworkin SF. The Evolution of TMD Diagnosis: Past, Present, Future. J Dent Res 2016; 85: 1093–1101.37. Schiffman EL, Ohrbach R, Truelove EL, et al. The re-search diagnostic criteria for temporomandibular disor-ders. V: Methods used to establish and validate revised axis I diagnostic algorithms. J Orofac Pain 2010; 24: 63–78.38. Peck CC, Goulet JP, Lobbezoo F, et al. Expanding the taxonomy of the diagnostic criteria for temporoman-dibular disorders. J Oral Rehabil 2014; 41: 2–23.39. Schiffman E, Ohrbach R. Executive summary of the Di-agnostic Criteria for Temporomandibular Disorders for clinical and research applications. J Am Dent Assoc 2016; 147: 438–445.40. Michelotti A, Alstergren P, Goulet JP. Next steps in de-velopment of the diagnostic criteria for temporoman-dibular disorders (DC/TMD): Recommendations from the International RDC/TMD Consortium Network work-shop. J Oral Rehab 2016; 43: 453–467.41. Treede RD, Rief W, Barke A, et al. A classication of chronic pain for ICD-11. Pain 2015; 156: 1003–1007.42. Renton T, Durham J, Aggarwal VR. The classication and differential diagnosis of orofacial pain. Expert Rev Neu-rother 2012; 12: 569–576.43. Ceusters W, Michelotti A, Raphael KG. Review: Per-spectives on next steps in classication of oro-facial pain – part 1: Role of ontology. J Oral Rehab 2015; 42: 926–941.44. Klasser GD, Goulet J-P, De Laat A, Manfredini D. Clas-sication of orofacial pain. In: Contemporary Oral Medi-cine. Philadelphia: Springer International Publishing, 2 01 7.45. Bertoli E, de Leeuw R. Prevalence of suicidal ideation, depression, and anxiety in chronic temporomandibular disorder patients. J Oral Facial Pain Headache 2016; 30: 296–301.46. Fricton JR, Kroening RF, Hathaway KW. TMJ and Cranio-facial Pain: Diagnosis and Management. St Louis: Ishi-yaku EuroAmerica, 1988.47. Lorduy KM, Liegey-Dougall A, Haggard R, Sanders CN, Gatchel RJ. The prevalence of comorbid symptoms of central sensitization syndrome among three different groups of temporomandibular disorder patients. Pain Practice 2013; 13: 604–613.48. Bonato LL, Quinelato V, de Felipe Cordeiro PC, de Sousa EB, Tesch R, Casado PL. Association between temporomandibular disorders and pain in other regions of the body. J Oral Rehabil 2017; 44: 9–15.49. Bair E, Gaynord S, Slade GD, et al. Identication of clus-ters of individuals relevant to temporomandibular disor-ders and other chronic pain conditions: The OPPERA study. Pain 2016; 157: 1266–1278.50. Velly A, Ahmed A, Lenton P, Fricton J. Comorbidities in chronic temporomandibular disorder patients: The links between painful and non-painful conditions. J Pain 2013; 14: S12.51. Velly A, Fricton J. The impact of comorbid conditions on treatment of temporomandibular disorders. J Am Dent Assoc 2011; 14: 170–172.52. The IASP Taxonomy website. https: //www.iasp-pain.org/Taxonomy?navItemNumber=576#Neuropathicpain. Accessed 14 July 2017.53. Fields H. Pain. New York: McGraw-Hill, 1987.54. Wall P, Melzack R. Textbook of Pain, ed 6. Edinburgh: Churchill Livingstone, 2013.55. Okeson JP. Principles of pain diagnosis. In: Bell’s Oral and Facial Pain, ed 7. Chicago: Quintessence, 2014: 135–180.56. Woolf CJ, Reynolds ML, Chong MS, et al. Denervation of the motor endplate results in the rapid expression by terminal Schwann cells of the growth-associated pro-tein GAP-43. J Neurosci 1992; 12: 3999–4010.57. Woolf CJ, Mannion RJ. Neuropathic pain: Aetiology, symptoms, mechanisms, and management. Lancet 1999; 353: 1959–1964.58. Finnerup NB, Jensen TS. Mechanisms of disease: Mechanism-based classication of neuropathic pain—A critical analysis. Nat Clin Pract Neurol 2006; 2: 107–115.59. Benoliel R, Kahn J, Eliav E. Peripheral painful traumatic trigeminal neuropathies. Oral Dis 2012; 18: 317–332.60. Benoliel R, Zadik Y, Eliav E, Sharav Y. Peripheral painful traumatic trigeminal neuropathy: Clinical features in 91 cases and proposal of novel diagnostic criteria. J Orofac Pain 2012; 26: 49–58.61. Okeson JP. Pains of muscle origin. In: Bell’s Oral and Facial Pain, ed 7. Chicago: Quintessence, 2014:287–326. 603603Diagnostic Classiﬁcation of Orofacial Pain62. Piovesan EJ, Kowacs PA, Tatsui CE, et al. Referred pain after painful stimulation of the greater occipital nerve in humans: Evidence of convergence of cervical affer-ences on trigeminal nuclei. Cephalalgia 2001; 21: 107–109.63. Bertolotti G, Vidotto G, Sanavio E, Frediani F. Psychologi-cal and emotional aspects and pain. Neurol Sci 2003; 24(suppl 2): S71–S75.64. Rollman GB, Gillespie JM. The role of psychosocial fac-tors in temporomandibular disorders. Curr Rev Pain 2000; 4: 71–81.65. Korszun A, Papadopoulos E, Demitrack M, Engleberg C, Crofford L. The relationship between temporomandibu-lar disorders and stress-associated syndromes. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1998; 86: 416–420.66. Dworkin SF. Behavioral, emotional, and social aspects of orofacial pain. In: Stohler CS, Carlson DS (eds). Bio-logical and Psychological Aspects of Orofacial Pain. Ann Arbor: University of Michigan, 1994.67. Carlson C, Bertrand P, Ehrlich A, Maxwell A, Burton RG. Physical self-regulation training for the management of temporomandibular disorders. J Orofac Pain 2001; 15: 47–55.68. Curran SL, Carlson CR, Okeson JP. Emotional and physi-ologic responses to laboratory challenges: Patients with temporomandibular disorders versus matched control subjects. J Orofac Pain 1996; 10: 141–150.