Orofacial Pain and Temporomandibular Disorders
Domain 2 tests mechanism-based classification and conservative management of pain arising from the masticatory system, cranial nerves, and central pain processing. The exam favors questions that separate nociceptive, neuropathic, and nociplastic pain and that apply DC/TMD criteria rather than vague labels such as TMJ.
Pain mechanisms
- Nociceptive pain is aching, localized, and provoked by movement or palpation; NSAIDs and mechanical therapy are reasonable.
- Neuropathic pain is burning, electric, lancinating, or associated with allodynia and hyperalgesia; sensory loss may be present.
- Nociplastic pain is centralized, often widespread, and associated with psychosocial distress and poor sleep.
DC/TMD axis I
- Myalgia includes local myalgia, myofascial pain, and myofascial pain with referral.
- Arthralgia is pain in the joint provoked by palpation or function.
- Disc displacement with reduction produces a reproducible click; without reduction produces limited opening and deviation to the affected side.
- Headache attributable to TMD is temporally related to jaw movement or palpation.
- Degenerative joint disease produces crepitus and imaging changes.
- Axis II records pain-related disability, depression, and anxiety because these modify treatment.
Key disorders
- Trigeminal neuralgia: paroxysmal electric pain in V2 or V3, trigger zones, normal sensory exam; carbamazepine is first-line.
- Burning mouth syndrome: bilateral burning without lesions, often postmenopausal women.
- Postherpetic neuralgia follows dermatomal herpes zoster.
- Referred pain from teeth, muscles, or cervical spine can mimic TMD.
Worked example
A 32-year-old woman has bilateral jaw ache for three months, morning clenching, and a right-sided click. Examination shows pain on masseter and temporalis palpation, opening of 42 mm, a click at 25 mm, and no crepitus. The diagnosis is myalgia plus disc displacement with reduction. Management is education, self-care, soft diet, short-term NSAIDs, an occlusal appliance, and cognitive behavioral support. Irreversible occlusal adjustment is not indicated.
Traps that cost marks
- Ordering MRI before a clinical examination and diagnosis.
- Using the single label TMJ without a DC/TMD subtype.
- Missing red flags such as unilateral sensory loss, mass, or weight loss.
- Offering surgery before conservative therapy.
- Failing to screen axis II psychosocial factors.