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5 Articles in Volume 3, Issue #4
Lidoderm Studied for New Applications
Osteoarthritis of the Temporomandibular Joint
Post-dural Puncture Headache Treatment
Preventing Post-dural Puncture Headache
Psychological Dimension of Pain Management

Osteoarthritis of the Temporomandibular Joint

Presenting as toothache, earache, headache, difficulty opening the jaw, or simply jaw pain, osteoarthiritis of the temporomandibular joint presents challenges in diagnosis and management.

Osteoarthritis (OA) of the temporomandibular joint is a unilateral, degenerative disease of the jaw joint. It is characterized by breakdown of the articular cartilage, architectural changes in bone, and degeneration of the synovial tissues causing pain and/or dysfunction in functional movements of the jaw. Figures 1 and 2 illustrate an MRI and an annotated drawing of a normal joint, while Figure 3 presents an MRI of osteoarthritis of the TMJ. Until recent years, OA of the temporomandibular joint was confusing, relatively unrecognized, and difficult to diagnose and manage. Scientific research had found neither a common cause, nor a clinically useful and differentiable diagnostic test. This resulted in a diagnostic journey full of frustration, pain, and expense. Due to its multifaceted nature, the disease has no defined or linear progression of symptoms. The symptom complex is not the same from one patient to another: it can exist in a quiet state until it is set off by an array of events or it can be painful from the start.

With osteoarthritis, the jaw joint can be the first joint to get the disease, whereas in rheumatoid arthritis it is the last joint to be affected. It can be anywhere from a 3:1 or 6:1 female-to-male ratio.1 The cost of the pathology was estimated to be $16.7 billion in 1984.2 Of the patients presenting to University Florida Parker Mahan Pain Center, 16.8 percent of the patients each year have OA of the jaw joint, of which 90 percent are female with an average age of 48.3.3 Of the patients who presented to Raleigh Facial Pain Services in the years 2000 and 2001, 11 percent had OA of the jaw joint, with 86 percent being females and an average age of 51. In another pain center study, of the 200 patients having jaw joint problems, 67 percent had disc displacement with reduction, 22 percent disc displacement without reduction, and 10 percent had OA.4 Diagnosis is complicated in that there is a lack of correlation between damage and pain with radiographic evidence.5

One of the most important events in the diagnosis of osteoarthritis was the establishment of a new specialty called orofacial pain. The orofacial pain specialist is familiar with the different presentations of osteoarthritis and can coordinate the different specialties necessary to manage the problem. However since OA of the TMJ does have several different presentations, it has taken time for the diverse specialties of rheumatology, orofacial pain, physical therapy, and psychology to coordinate the requisite patient care. With the advent of new scientific and clinical knowledge, we are entering a new era of increased awareness, improved care, and improved quality of life for people afflicted with OA.

Disease Presentation

The patients who develop OA present with a variety of symptoms including pain on opening, limited movement to the opposite side, coarse grinding noise on function, history of clicking that has now stopped, and deviation on opening to the affected side. An unusually large percentage of those diagnosed are women around the age of 35.6 In addition, 31.6 percent have had a macrotrauma usually from a maximal voluntary contraction (MVC) force or even a blow to the mandible. The clinical findings are pain on palpation of lateral pole, decreased range of motion, flattened condyle, osteophytes on condyle, heavy occlusion on second molar on the affected side, facial asymmetry, and tipped Curve of Wilson. Some other indicators include loss of condylar bone which traumatizes the posterior molar on the same side, pain referral pattern to the ear, pain on eating, talking, or function of the jaw joint, jaw locking, and pain in the front tooth of a bridge due to torque forces on two molars. In summary, a picture of pain, dysfunction, and disability is involved in osteoarthritis of jaw joint.

Figure 1. MRI of a normal temporomandi-bular joint. Figure 2. Annotated MRI drawing of a normal temporomandibular joint.
a) condyle head
b) any border disc
c) center disc
d) post border (band) disc
e) superior fibers of lateral pterygoid muscle
f) inferior fibers of lateral pterygoid muscle
g) tetrodiscal tissue
h) ear
Figure 3. Specimen section of TMJ afflicted with osteoarthritis. The arrow points to the misshaped disc.

Patient Variations

The typical patient may have years of jaw pain, joint clicking with or without pain, disc displacement, joint dysfunction, and eventually osteoarthritis. Unfortunately, most patients are not typical. Our common perception of OA is a 70-year-old man in a nursing home with osteoarthritis of knees and hips getting OA of the jaw joint also. In reality, the most common person with OA of the jaw joint is a 33-year-old female with two kids, husband, dog, and job. Even a third grader (10-year-old female) can get OA of the jaw joint. The following is a sampling of the variations in presentations that may occur to the medical and dental professionals.

Patient #1 had recurrent unilateral ear pain for years. Frequent trips to the doctor provided no evidence of ear inflammation and rounds of antibiotics provided no benefit. Eventually, an ENT specialist then referred the patient to an orofacial pain specialist.

Patient #2 went to a dentist for frequent fractured teeth, toothaches, and recurrent abscessed teeth on the posterior teeth on one side. After several root canal, crowns, or extracted teeth on the left lower posterior area, the dentist referred the patient to an endodontist. The endodontist, feeling another root canal would not be appropriate, referred the patient to an orofacial pain specialist.

Patient #3 had years of left jaw pain with the pain suddenly shifting to the right with limited opening. The panograph revealed the left joint was severely eroded but the right joint looked apparently normal.

Patient #4 having just completed 14-unit precision bridge work on the all the upper teeth, developed pain in tooth #12 on cementation. After months of fine tuning the bridge work, she was sent to an endodontist for root canal therapy on the painful tooth. The endodontist felt it was not the tooth and recommended referral to an orofacial pain specialist, but at the insistence of the patient, performed root canal therapy with no benefit. A visit to the orofacial pain specialist confirmed OA of the temporomandibular joint.

Patient #5 presented with a bite that had suddenly changed but without any pain. This patient was correctly diagnosed with OA of the temporomandibular joint when a dentist took a panograph and found a smaller deformed condylar ball on the same side as the bite change.

Disease Inception and Progression

OA of the temporomandibular joint is a disease having a great deal of variation in progression, symptoms, epidemiology, pathophysiology, and presentation. The rate of progression from a healthy joint to a severely damaged joint of OA can vary from a very short time to decades. The fourth and fifth decades of life are the most prominent age to get OA of the jaw joint.

The pattern and rate of progression relates to the set of initiators, aggravators, and perpetuators and how they interplay with each other. There are five known factors related to the onset of—or set the stage for—osteoarthritis. These contributing factors are parafunction, occlusion, psychosocial aspects, macrotraumas, and genetics.

Parafunction Impact

In recent scientific literature, an increased importance has been placed on parafunction setting the stage for OA. In a report by Makowerowa, it was reported that 55 to 83 percent of all OA patients show evidence of parafunction (clenching or grinding their teeth).7 At the Raleigh Facial Pain Center, the author has found that 93 percent of these patients show evidence of parafunction. This same statistic holds true today in most orofacial pain clinics such as UF Parker E. Mahan Pain Clinic and University of Kentucky. This destructive habit of clenching or grinding teeth degrades four different structures (teeth, bone support to teeth, muscles, and especially the joint). A recent set of studies by Dr. Nitzan in Israel8 indicates that clenching increases intra-articular pressures to exceed the perfusion pressure of blood and thereby leads to inadequate nutrition of the tissues. The study indicates that several women in the group (3 out of 20) were excessively high on the pressure. This increase in pressure is abated with an orthotic.9 The increase in intra-articular pressure causes the release of free radicals that destroy the lubricant.10 Besides reducing the friction coefficient, the lubricant carries nutrition to this avascular, aneural, and alympathetic tissue.11 This poor nutrition and lubrication creates stickiness, pulling, and tearing of the elastin and lateral ligament. The etiology of parafunction is poor sleep, certain occlusal designs, genetics, and up-regulated sympathetic systems (stress, anxiety, and depression).12

Occlusion Aspects

The aspects of occlusion that affect both parafunction and OA are lack of anterior guidance, Class II dental and skeletal relationships, lateral interferences on posterior teeth, crossbites, loss of posterior teeth, and bite discrepancy. Bite discrepancy (when the power bite and tooth bite positions are in different locations) initiates muscle recruitment to protect the jaw and teeth.13 The mixing of different etiologies creates the distinct and differential patterns of OA development.

Psychosocial Environment

A problem associated with parafunction (clenching, grinding, and bracing) has been a nonchalant attitude by both the public and, to some extent, the dental profession, despite destructive effects seen in painful enlarged chewing muscles, gum recession, bone loss around teeth, destructive tooth wear, and now disc displacement and even OA.

Macrotrauma Impact

The macrotrauma relationship to OA has been reported as low as 5 percent14 and as high as 53 percent.15 The theory is that the jaw braces on impact, allowing the muscle to oppose the force, which stretches and tears the lateral ligament and or the elastin (retrodiscal tissue). The unique characteristic of the disc interposed between the lateral pterygoid muscle and the elastin tied down by the lateral and medial ligaments sets the stage for the pathology that is observed. The lateral aspect of the elastin and the lateral ligament are the Achilles heel of the jaw joint, partially due to the anterior medial pull of the lateral pterygoid muscle.16 Even muscle tension from stress or clenching can stretch the healthy lateral ligament and retrodiscal elastin. The hypercontraction of the lateral pterygoid can fatigue the elastin and lateral ligament, especially if macrotrauma has weakened them.

Genetic Factor

A genetic factor that has been linked to this pathology is hypermobility of joints. In a study of 74 females, 41 percent of females were hypermobile and 83 percent of the hypermobile group had TMD involvement.17 The likely explanation is that hypermobility increases the potential for the macro and microtraumas to cause damage to the lateral ligament and elastin. Even though this picture of pathology explains a great deal about the pathophysiology, it does not explain the fact that some patients have OA without disc displacement.

Management

Osteoarthritis is best managed by directing care at all initiators, aggravators, and perpetuators. This is done by a team of professionals whose specialties are associated with these etiologies. While both orofacial pain specialists and oral surgeons are trained to diagnose this condition, the orofacial pain specialist has been trained to coordinate the care. One of the biggest challenges is to coordinate the requisite group of specialists who have never spoken to each other before the dawn of this research. A typical team (in order of prevalence) may be composed of an orofacial pain specialist, a physical therapist, a biofeedback specialist, a rheumatologist, a nutritionist, and—in about three percent of the cases—an oral surgeon.

The orofacial pain specialist provides therapy to reduce parafunction, improve sleep, increase the health of the cardiovascular system, improve the capillary network to ligaments and muscle, manage the orthotic, and inject trigger points in trigeminal muscles.

The physical therapist provides reduction of inflammation, reduction of pain, and improvement of function with many different modalities such TENS, ultrasound, iontophoresis, ice and stretch, neuromuscular therapy, massage, lymphatic drainage, cardiovascular conditioning, postural and ergodynamic training, etc.

The biofeedback specialist reduces the sympathetic system up-regulation, reduces muscle tension, and serves as a coach for stress management, deep breathing exercises, and other modalities. The patient is in charge of enhancing his or her biochemistry and physiology to increase the healing response of the medical and dental therapies.

The rheumatologist manages the medications in cases where systemic diseases are also present, multiple joints are affected by arthritis, and for those severe cases needing long-term management.

The nutritionist improves the diet to provide the proper nutrients and precursors for healing of the severely damaged joints.

The oral surgeon is consulted in 3 percent of cases for arthroscopic surgery to flush out joint tissue fragments and inflammatory chemicals.18

Some other honorable mentions are Pilates, craniosacral therapy, chiropractic, rolfing, trigger point therapy, and many others that may be helpful when the muscles splint or are recruited because of the pain.

Summary

Osteoarthritis of the temporomandibular joint is a disease that affects a great many people, especially females from age 10 to 90. While not always directly correlated with pain or dysfunction, it affects the important chewing machine, causes severe pain, creates disability, affects nutrition, social, and health parameters, and is under-appreciated by the public and the health professions. Many times an OA patient has seen 7 professionals before they find their way to an orofacial pain specialist to get the proper diagnosis and complete conservative care for OA. With the advent of conservative therapy, the OA patients typically need surgical treatment in only 3 percent of the cases. The conservative therapy can last up to 3 months for the different specialties to provide the symptomatic care and prophylactic care. It is amazing how well these patients respond to removing the initiators, aggravators, and perpetuators, even with the severe destructive nature of this disease. Proper treatment by a multi-faceted team most often results in virtually pain-free living and vastly improves the quality of life for these patients.

The new research has significantly improved the quality of care for osteoarthritis of the temporomandibular joint. Improved interaction and coordination among the different health professions has improved the speed and accuracy of referrals to orofacial pain specialists. The quicker the patient is referred to an orofacial pain specialist, the easier it is to manage these problems to a successful conclusion. The patient with OA of the jaw joint is the beneficiary of the pace of research, the beginning of a new profession (orofacial pain), and the improved interaction between different specialties such as physical therapy, biofeedback, rheumatology, nutrition, and oral surgery. n

Last updated on: December 20, 2011
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