Table 1.

Eligibility Criteria

Inclusion criteria
1) Inclusion criteria for TMJD cases:
Participant has clinical diagnoses of masseter myofascial pain, TMJ arthralgia, as well as a MRI-depicted diagnosis of TMJ disc displacement with reduction, all of the same side. All 3 diagnoses must be on the same side.
2) Inclusion criteria for controls:
I. History
a. No lifetime history of TMD symptoms (“supercontrols”)
1. Absence of TMJ noise, locking or catching of the jaw, and
2. Absence of pain in the jaw or the temporal area, and
3. Absence of headaches affected by jaw movement, function, or parafunction.
b. Prior history of TMD symptoms (“controls”)
1. In the last 6 months, no history of TMD symptoms
2. Prior to 6 months ago:
a. No more than five isolated episodes of TMJ noise, with each episode lasting less than 1 day and not associated with jaw pain or limited mouth opening, and
b. No more than one to two isolated episodes of locking or catching of the jaw in the wide-open mouth position, and
c. No headaches in the temporal area affected by jaw movement, function, or parafunction.
II. Clinical examination
a. Any pain produced by procedures must be non-familiar, and
b. No TMJ clicking, popping, or snapping noises with more than one movement, and
c. No coarse crepitus with any movement.
III. Imaging
a. TMJ MRI for disc displacement with reduction is allowed
b. TMJ CT is negative for osteoarthrosis.
Exclusion criteria for cases and controls
I. History
a. Systemic rheumatic, neurologic/neuropathic, endocrine, or
immune/autoimmune diseases or wide spread pain.
b. Radiation treatment to head and neck.
c. TMJ surgery.
d. Trauma to jaw in the last 2 months (exclusion regardless of time: Jaw trauma from auto accident).
e. Presence of non-TMJD orofacial pain disorders.
f. Pregnancy.
g. Unable to participate due to language barrier or mental/intellectual incompetence.
h. Use of narcotic pain medication, muscle relaxants or steroid therapy unless discontinued for 1 week before examination.
i. Use of antidepressant drugs unless the participant has been on a stable dose for 60 days.
j. Use of prescription or over-the-counter nonsteroidal anti-inflammatory medications unless the medication(s) were discontinued for 7 days before the examination (use of acetaminophen was allowed as a rescue drug).
k. Drug abuse.
l. Ongoing dental treatments.
m. Wearing dentures.
n. Contraindications for imaging.
o. Ongoing TMJD treatments unless on a stable regimen for at least 2 months.
p. Unable or unwilling to give informed consent.
q. Unwilling to restrict use of OTC Vitamin C and E 3 and 7 days, respectively, before specimen collection.
II. Clinical examination
a. Presence of non-TMD orofacial pain disorders.
III. Imaging
a. MRI is positive for pathology (exception for cases and controls: TMJ disc displacement with reduction).
b. CT is positive for osseous pathology including TMJ osteoarthrosis.
c. Panoramic radiograph is positive for osseous or odontogenic lesions.