Anatomy

The structures that are commonly involved in rheumatoid diseases include the joint, the joint cavity, synovial fluid, and periarticular structures. The lining membrane, known as the synovium, consists of a thin layer of macrophages (type A cells) and fibroblasts (type B cells) with a sublining of rich, vascular, loose connective tissue. Hyaline cartilage overlies the bony end plates and provides a cushion to joint motion. The cartilage has high water content and obtains its nutrition solely from the synovial fluid, which is derived from the synovium primarily as an ultrafiltrate of plasma. The synovium also secretes specialized molecules into the synovial fluid, such as hyaluronic acid. An intact bony end plate is required to support the cartilage. The joint capsule and ligaments provide further support and blend with the periosteum. Periarticular anatomy is equally important and includes the tendons, bursae, and muscles associated with each joint.¹

Pathophysiology

The cause of musculoskeletal problems is usually inflammatory, metabolic, degenerative, tumor, or some combination thereof. Synovial inflammatory disorders, such as rheumatoid arthritis, begin in the synovium and secondarily damage the cartilage, joint capsule, and bone. Inflammation at entheses, the insertion sites of tendons or ligaments on bone, is characteristic of the spondyloarthropathies, such as ankylosing spondylitis. Crystal deposition disorders, such as gout or pseudogout, may also cause articular inflammation. Infections primarily involve the joint cavity (septic arthritis) or bone (osteomyelitis). The noninflammatory, degenerative disease osteoarthritis begins in the cartilage and leads to cartilage loss, subchondral new bone formation, and marginal bony overgrowth. Cartilage loss also may occur secondarily to synovial inflammation or trauma.¹ Osteonecrosis of bone may be associated with secondary cartilage damage after collapse of the bony end plate. Inflammatory diseases of the muscle usually manifest with painless proximal weakness. Periarticular inflammation may involve tendons or bursae, and these structures are common causes of pain and stiffness, often misinterpreted as arising from the joint itself. Finally, the common clinical problem of fibromyalgia (widespread muscle pain) is characterized by soft tissue pain with local tenderness in specific points but without abnormal blood studies.¹

Although the rheumatologic diseases comprise a group of more than 100 important diseases, this chapter is limited to a discussion of eight: rheumatoid arthritis (RA), osteoarthritis (OA), psoriatic arthritis (PsA), systemic lupus erythematosus (SLE), Lyme disease, fibromyalgia (FMS), temporal arteritis, and Sjögren syndrome (SS), which are among the most common forms encountered, are more dentally related conditions, and can serve as models for the dental management of other forms. Several important items regarding the dental management of patients with rheumatologic and connective tissue disorders, including effects on the temporomandibular joint (TMJ), salivary glands, and oral mucosal tissues, organ and system involvement, and drug therapy, are discussed here.

Incidence and Prevalence

Rheumatoid arthritis (RA) is an autoimmune disease of unknown origin that is characterized by symmetric inflammation of joints, especially of the hands, feet, and knees. Severity of the disease varies widely from patient to patient and from time to time within the same patient. Prevalence is somewhat difficult to determine because of lack of well-defined markers of the disease; however, estimates range from 1% to 2% of the population. Disease onset usually occurs between ages 35 and 50 years. RA is more prevalent in women than in men by a 3 : 1 ratio.¹

Etiology

The cause of RA is unknown; however, evidence seems to implicate an interrelationship of infectious agents, genetics, and autoimmunity. One theory suggests that a viral agent alters the immune system in a genetically predisposed person, leading to destruction of synovial tissues. Although the disease can occur within families, suggesting a genetic component, one specific causative gene has not been identified.^2–4 Nevertheless, many people who develop RA have a genetic predisposition that occurs in the form of a tissue marker called HLA-DR4; however, not everyone with this tissue type develops the disease.^2–5

Signs and Symptoms

The usual onset of RA is gradual and subtle (Table 20-2), and the disorder is commonly preceded by a prodromal phase of general fatigue and weakness with joint and muscle aches. Characteristically, these symptoms come and go over varying periods. Then, painful joint swelling, especially of the hands and feet, occurs in several joints and progresses to other joints in a symmetric fashion (Figure 20-3). Joint involvement persists and gradually progresses to immobility, contractures, subluxation, deviation, and other deformities. Characteristic features include pain in the affected joints aggravated by movement, generalized joint stiffness after inactivity, and morning stiffness that lasts longer than 1 hour. The joints most commonly affected are fingers, wrists, feet, ankles, knees, and elbows. Multiple joint changes noted in the hands include a symmetric spindle-shaped swelling of the proximal interphalangeal (PIP) joints, with dorsal swelling and characteristic volar subluxation of the metacarpophalangeal (MCP) joint (see Figure 20-3). The TMJ is reported to be involved in up to 75% of patients.^2–6 Because of the variable rate of progression and pain intensity, the median period between onset of symptoms of RA and its diagnosis is 36 weeks.^1,7

TABLE 20-2 Comparison of Rheumatoid Arthritis and Osteoarthritis

FIGURE 20-3 Hands of a patient with advanced rheumatoid arthritis.

(From Damjanov I: Pathology for the health professions, ed 4, St. Louis, 2012, Saunders.)

Extraarticular manifestations include rheumatoid nodules, vasculitis, skin ulcers, Sjögren syndrome, interstitial lung disease, pericarditis, cervical spine instability, entrapment neuropathies, and ischemic neuropathies.⁸ The American Rheumatism Association has developed revised criteria for the diagnosis and classification of RA to be used in clinical trials and epidemiologic studies (Box 20-1). These criteria have high specificity (89%) and sensitivity (91% to 94%) compared with control subjects when used to classify patients with RA. For the diagnosis of RA to be made, four of seven criteria must be met.^2–5

Laboratory Findings

No laboratory tests are pathognomonic or diagnostic of RA, although they are used in conjunction with clinical findings to confirm the diagnosis. Laboratory findings most commonly seen in RA include an increased erythrocyte sedimentation rate (ESR), the presence of C-reactive protein (CRP), a positive result on rheumatoid factor assay in 85% of affected patients, and a hypochromic microcytic anemia. In patients with Felty syndrome (RA with splenomegaly), a marked neutropenia may be present.^2–5

Antibodies to cyclic citrullinated proteins (CCPs) are autoantibodies, which are important in the diagnosis of RA.⁹ Anti-CCP antibodies are highly associated with RA. They occur in 70% to 80% of patients with RA as well as in some other forms of inflammatory arthritis. These antibodies may appear before any signs or symptoms of RA and therefore may prove beneficial as early screening markers for earlier diagnosis and intervention of RA.⁹

Diagnosis

The American College of Rheumatology has established criteria for the diagnosis of RA (see Box 20-1), the classification of severity by radiography, functional classes, and the definition of remission. Although they were not designed for managing individual patients, these criteria are useful as a frame of reference and for describing clinical phenomena.^1,10

By definition, the diagnosis of RA cannot be made until the disease has been present for at least several weeks. Many extraarticular features of RA, the characteristic symmetry of inflammation, and the typical serologic findings may not be evident during the first month or two after disease onset. Therefore, the diagnosis of RA usually is presumptive early in its course.

Although extraarticular manifestations may dominate in some patients, documentation of an inflammatory synovitis is essential for a diagnosis. Inflammatory synovitis can be documented by demonstration of synovial fluid leukocytosis, defined as white blood cell (WBC) counts greater than 2000/µL, histologic evidence of synovitis, or radiographic evidence of characteristic erosions.^5–7,9,10

Combination Therapies

In people with moderate to severe disease activity, methotrexate often is used in combination with other agents.^1–7 In patients who have acute and severe disease, initial therapy often consists of a combination of DMARDs, corticosteroids, and NSAIDs. Combinations of DMARDs also are used to improve disease control; approximately 50% of people with RA who are treated by rheumatologists are prescribed combination therapies with two or three DMARDs. The combination of methotrexate, hydroxychloroquine, and sulfasalazine is among the most popular regimens, although study results are not readily duplicated among prescribing physicians.^1–7 Other successful combination therapies include methotrexate used with such agents as cyclosporine, TNF-α antagonists, leflunomide, and azathioprine.^1–7 Surgical management of severely deformed or dysfunctional joints often is necessary and may involve a variety of procedures, including arthroplasty, reconstruction, synovectomy, and total joint replacement.^1–7

Clinical tools for monitoring the patient’s well-being and the efficacy of therapy include self-assessment of the duration of morning stiffness and severity of fatigue, as well as functional, social, emotional, and pain status, as measured by a health assessment questionnaire. A patient-derived global assessment based on a visual analog scale is a simple and effective means of recording patient well-being. The number of tender and swollen joints is a useful measure of disease activity, as is the presence of anemia, thrombocytosis, and elevated ESR or CRP. Serial radiographs of target joints, including the hands, are useful in assessing disease progression.^1,7

Patient education is essential early in the disease course and on an ongoing basis. Patients are best served by a multidisciplinary approach with early referral to a rheumatologist and other specially trained medical personnel, including nurses, counselors, and occupational and physical therapists who are skilled and knowledgeable about RA. Appropriate medical care of patients with RA encompasses attention to smoking cessation, immunizations, prompt treatment of infections, and management of comorbid conditions such as diabetes, hypertension, and osteoporosis.^1,7

Medical Considerations

Because patients may have multiple joint involvement with varied degrees of pain and immobility, dental appointments should be kept as short as possible, and the patient should be allowed to make frequent position changes as needed (Box 20-2). The patient also may be more comfortable in a sitting or semisupine position, as opposed to a supine one. Physical supports, such as a pillow or a rolled towel, may be used to provide support for deformed limbs, joints, or neck.

The most significant complications associated with RA are drug-related (see Table 20-3). Aspirin and other NSAIDs can interfere with platelet function and cause prolonged bleeding; however, this effect generally is not found to be of clinical significance. A patient who is taking both aspirin and a corticosteroid may be at greater risk for bleeding. The risk is not great, however, and patients usually can be treated, so long as curettage or surgery is performed conservatively in small segments, with attention to good techniques (see Chapter 24).^14–16

Patients who are taking gold salts, penicillamine, sulfasalazine, or immunosuppressive agents are susceptible to bone marrow suppression, which can result in anemia, agranulocytosis, and thrombocytopenia. As a rule, these patients should be followed closely by their physician for detection of this problem. If a patient has not undergone recent laboratory testing, a complete blood cell count with a differential white blood cell count should be ordered. Abnormal results should be discussed with the physician. If corticosteroids are used for prolonged periods, the potential for adrenal suppression exists. Management of this problem is discussed in Chapter 15. Corticosteroids may induce a number of adverse effects, which are presented in Table 20-3.

Treatment Planning Modifications

Treatment planning modifications are dictated by the patient’s physical disabilities. A patient with marked systemic disability or limited or painful jaw function due to TMJ involvement should not be subjected to prolonged or extensive treatment, such as complicated crown and bridge procedures. If replacement of missing teeth is desired, consideration should be given to fabrication of a removable prosthesis because of the decreased chair time needed for mouth preparation and the ease of cleaning of the appliance. If a fixed prosthesis is desired, the realistic potential to keep it clean must be a significant factor in design. Unpredictable, progressive, or abrupt changes in occlusion are possible because of erosion of the condylar head. Therefore, the dentist and the patient should take these potential occlusal changes into consi/>