This proposal will investigate pain modulatory mechanisms and brain functional and structural characteristics using multiple MRI modalities in persistent dentoalveolar pain disorder (PDAP) patients with and without temporomandibular disorders (TMD). All measures from patients will be compared to painfree controls.

Chronic orofacial pain disorders may present localized in the mouth such as with persistent dentoalveolar pain disorder (PDAP) or widespread in the head/face/jaw such as with temporomandibular disorders (TMD). PDAP pain manifests in a tooth that usually underwent root canal treatment or in the site formally occupied by such tooth, while TMD pain is usually reported over the preauricular area, jaws and temples. These commonly comorbid disorders have a significant impact on the individual and society. Their mechanisms are poorly understood with evidence suggesting deficient pain modulation and abnormal brain features. PDAP and TMD patients, when compared to controls, have abnormal sensory/pain processing as well as brain structural and functional differences.

This proposal will investigate pain modulatory mechanisms and brain functional and structural characteristics using multiple MRI modalities in PDAP patients with and without TMD. All measures from patients will be compared to painfree controls. This knowledge will support better understanding of mechanisms involved in PDAP and will support development of mechanistic-based clinical treatments for the patients the investigators serve. Findings from these investigations will likely contribute to our understanding of other chronic pain conditions.

Inclusion Criteria:

1. Age- and handedness-matched painfree controls using frequency matching to maintain similar group averages:

   • No self-report of persistent pain conditions for the last 6 months;
   • No diagnosis of PDAP or TMD;

2. PDAP only:

   • Fulfilling diagnostic criteria per Nixdorf et al., 20122
   • Characteristic dentoalveolar PDAP pain cannot be increased by pressure provocation from jaw muscle trigger points (referred pain)

3. PDAP with TMD:

   • Fulfilling diagnostic criteria for PDAP2 and chronic TMD myalgia per Schiffman et al. 20143

Exclusion Criteria:

Self-report:

1. Chronic widespread pain
2. Current use of opioids or other pain medications (e.g., ibuprofen/acetaminophen) that cannot be stopped <3 days prior to testing
3. Conditions/diseases associated with altered pain perception: neurological (e.g., multiple sclerosis, trigeminal neuralgia) psychiatric disorders, diabetes, neoplasm and cardiovascular disorders
4. Injury to hands
5. Substance abuse
6. MRI contraindications including pregnancy

Females with age range 18-65 years