There have been several attempts to classify CMD in the past. Often, the classifications proved to be too imprecise, such as the Helmiko index (1974).
Today, craniomandibular dysfunction is divided into three groups according to the causes of the symptoms.
- Primary dento-/occlusogenic cause – tooth-related/occlusion-related (any contact of the teeth of the maxilla with those of the mandible) causes.
- Primary myogenic cause – muscle-related causes.
- Primary arthrogenic cause – joint-related causes.
The Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) represents another accepted classification. The system, which was developed by clinicians, epidemiologists and basic researchers, takes into account both physical and pain-associated psychological parameters.Three diagnostic groups are distinguished:
- Pain in the region of the jaw musculature
- Myofascial (affecting muscle (= myo) and its connective tissue sheath (= fascial)) pain.
- Myofascial pain with restricted jaw opening.
- Displacement of the articular disc (fibrocartilaginous articular disc; is attached to the joint capsule and divides the joint cavity into two chambers)
- Dislocation of the discus articularis (displacement of the cartilaginous disc forward from its normal position) with reduction (return to a (near) normal or normal position) during jaw opening
- Disc displacement without reduction with restricted jaw opening.
- Disc displacement without reduction without restricted jaw opening
- Arthralgia, arthritis, osteoarthritis
- Arthralgia (joint pain)
- Arthritis (inflammation of the joint) of the temporomandibular joint.
- Osteoarthritis (degenerative change; joint wear) of the temporomandibular joint.
The RDC/TMD are recommended by the German Society for the Study of Pain (DGSS) for the standardized recording of orofacial pain.
