The Piper classification of TMJ disorders is used to fully identify the structural abnormalities in both soft tissue and bone of the TMJ. Each TMJ will have a diagnosis of disk position at the medial pole and at the lateral pole. In a normal TMJ there are tight ligaments that bind the disk to the lateral and medial poles. The earliest breakdown occurs at the lateral pole with laxity of the ligaments resulting in an intermittent click – Piper II. A chronic displacement of the lateral pole is a non-painful clicking joint – Piper IIIA, which the majority of patients with clicking joints have. The locking phase of the lateral pole is usually an a symptomatic lock with some reduced opening or locking. This Piper stage IIIB joint is usually quiet. Piper stage IVA involves disk displacement from the medial pole. The joints are likely to develop joint pain because all movements of the jaw load on retrodiskal attachment tissue. Piper IVB is locking at the medial pole, they function on the retrodiskal tissue. This stage can have limited movement and pain. Piper stage VA – perforation with acute displacement arthritis, have very inflamed painful joints, instability, progressive breakdown, and arthritis, which results in bite shifting. Piper Stage VB with chronic displacement have perforations that have adapted bone to bone – rough jaw joint noise are noticed with little pain or bite shifting.
Disk displacements that occur at the medial pole are the most problematic to TMD patients. The area anterior and medial to the mandibular condyle carries the greatest blood supply to the condylar head. This blood supply is necessary to maintain growth of the condyle in a child and structural maintenance of the condyle in the adult. The pole, the direction, the degree of displacement of the disk and the level of disk damage account for the volume of the disk into this bad zone. An MRI can only assess this.
Soft tissue injury of the disk precedes hard tissue injury of the bone- condyle in most cases. Arthritis, localized arthritis; degeneration and growth deficiencies are bone changes in the jaw joint that occur with displacement of the disk from both lateral and medial poles.
The Dawson classification of occlusion relates the posture and condition of the jaw joint to the maximum intercuspation of teeth. Centric Relation is a fully seated condyle and a fully seated disk, which is comfortable to testing. Adapted Centric Posture is a fully seated condyle but the entire disk is not fully seated, but is comfortable to testing. Transitional position is comfortable but is not a fully seated position. When seated, testing is painful. Maximum intercuspation of teeth will displace the condyle away from CR /ACR–in Dawson type 2 and 2A. Dawson type 3 has CR that cannot be confirmed, Dawson type 4 have a changing bite because of progressive arthritis.
Pain patterns in TMD patients can be divided into 3 pies of pain, which each contain 3 pieces of pie. The first pie of pain is a result of TMJ injury or breakdown. Its 3 pieces of pie include pain of masticatory muscles, the soft tissue internal joint structures and bone. Each piece of pie requires its own separate management.
The second pain pie describes pain layers that are independent of the TMJ, however these can also be injured at the same time as the TMJ. They are neurologic, odontogenic/teeth, and cervical-neck. Frequently these pain layers converge with TMJ and pain from one pie may exacerbate pain from the other pie.
The third pain pie is pain reactive to sensory afferent source (layers from the other two pies). The pains are not part of the original condition but become more prominent over time. They are fibromyalgia, migraine, and CRPS or RSD. Fibromyalgia syndrome is characterized by aching and pain in the muscles, tendons and joints throughout the body. SRPS/RSD – Reflex Sympathetic Dystrophy is painful entities of the extremities in TMD patients. The face is painful to touch. Teeth are cold sensitive which can be misdiagnosed as a root canal, which will not reduce pain.
