Studies have noted that internal derangements in the temporomandibular joints result in posterior displacements of the condyles at full occlusion resulting in compression and injury to retrodiscal tissues.
Retrodiscal tissue is referring to the tissue located just posterior of the condyle and anterior of the auditory meatus – the ear hole. Retrodiscal tissue is known to be highly vacular and neurally innervated. The called this area the bilaminer zone. Anytime the condyles are compressed up and posterior within the joint space (glenoid fossa) due to insufficient vertical support of the bite (occlusion), these most posterior tissues are compressed and cause injury to the retrodiscal tissues.
Continued compression of this delicate region of vascularity and nerves can contribute to ear congestion feelings in the ears, stuffy feelings, ringing (tinnitus) and swishing sounds in and around the jaw joints.
Anterior disc displacement-early to non reducing late – disc deformed
Moderate to marked disc thickening
4. Intermediate Late
Restricted motion – chronic pain, headaches
Abnormal bone contours
Anterior disc displacement – non reducing, marked disc thickening
Degenerative remodeling of boney surface – adhesions, deformed disc without perforation
Painful function – variable pain, joint crepitus
Degenerative osseous changes
Anterior disc displacement – non reducing with perforation
Gross degenerative changes of disc and hard tissues – multiple adhesions
**According to the American Society of Temporomandibular Joint Surgeons – Guidelines for Diagnosis and Management of Disorders Involving the Temporomandibular Joint and Related Musculoskeletal Structures
It is not uncommon for individuals who have deficient occlusal vertical support in the posterior regions to have degenerative joint disease or internal derangement problems in and around their temporomandibular joints. Deviations of the lower jaw during mouth opening (to the left or right side) can occur either unilaterally (one side) or bilaterally (both sides) because the condyles are positioned posteriorly and superiorly with the glenoid fossa. When the condyles are postured back and upward within the joint space it increases the likelihood for the articular disc to also be displaced anteriorly (forward) and medially during opening and closing of the mouth.
As time evolves the pressures on these boney condyles begin to change and alter their shape and form causing further boney (osseos) surface changes and break down. This is what is known as “condylar degeneration” or degenerative joint disease (DJD).
The temporomandibular (TM) joints are not load bearing joints. If they were designed so, joint disease would not be as prevalent as studies have shown. Some in the dental community believe it is a load bearing joint, but this author and many others do not believe it is since the temporomandibular joint is a synovial joint meaning that it has both an upper joint space above and a lower joint space below the disc both filled with synovial fluid. The TM joint is very different than other arthrodial joints like the hip joint or elbow joint or knee joint which do not have an articulating disc that has two compartments. Arthrodial joints also do not have teeth attached to the same both that also must occlude and articular with another as is the two temporomandibular joints which are connected by the same mandibular bone with two condyle at the opposite end of the same bone and must accurately related and occlude with the maxillary bone of the skull.
It is the teeth that should be taking the load, not the temporomandibular joints.
Clinical dysfunction and symptoms occur when the need for structural and physiologic accommodation exceeds the ability of the organ system to accommodate.
Compression of anatomic structures is a generic medical model of patho-physiology, pain and dysfunction.
Decompression of impinged anatomic structures is the medical therapeutic model.
General laws of homeostasis support the desirability of analysis of maxillo-mandibular posture from optimal muscle relaxation. Relaxation is good in the postural state. Muscle tension is bad in the postural state.
Repeat: Abnormal forces placed on the condyles will contribute to deterioration and boney break down. Lack of vertical occlusal support in the bite will contribute to joint degenerative changes and further masticatory dysfunction.
Use of Splints and Intra Oral Appliances When DJD Exists
Splints and or any interocclusal appliance that do not support the good laws of homeostasis and physiologic closure along an isotonic path of closure (myo-trajectory) will only contribute to pathology and further break down.
It is the belief of this author based on clinical case studies, experience, training and knowledge that extensive understanding of using K7 instrumentation that aids in the objective measurement of mandibular positioning of his cases that the proper use of an anatomical orthotic can assist in removing abnormal condylar forces on the joints which have been diagnosed with DJD.
Cooper and Kleinberg, April 2008.
Haskin CL, Milam SB and Cameron IL: Pathogenesis of Degenerative Joint Disease in the Human Temporomandibular Joint. Critical Rev Bio Med, 1995.
Emshoff R., et al.: Magnetic resonance imaging predictors of temporomandibular joint pain. J Am Dent Assoc 2003, Vol 134, No 6, 705-714.
Tasaki MM, Westesson PL, Isberg AM, Ren YF, Tallents RH. Classification and prevalence of temporomandibular joint disk displacement in patients and symptom-free volunteers. Am J Orthod Dentofacial Orthop 1996;109:249–62.
Katzberg RW, Westesson PL, Tallents RH, Drake CM. Anatomic disorders of the temporomandibular joint disc in asymptomatic subjects. J Oral Maxillofac Surg 1996;54:147–53.