232 Theories and techniques of oral implantology

vidual. The degenerative process destroys the binding material that holds the cartilage's fibers together. The fibers may then wear away, leaving fissures and pits. Eventually the joint space disappears, leaving the hones in direct contact with one another. Then outgrowths of the bone   called lipping, osteophytes,

or exostoses   occur at the joint margins.

The cause of degenerative arthritis is unknown, as is why degeneration occurs faster in some individuals than in others. Wear and tear on the joints and trauma, such as fractures, torn ligaments, and poor posture, and other forms of stress appear to play some role, but heredity seems to be the major predisposing factor.

The principal symptoms of early degenerative arthritis are stiffness and pain, which occurs during motion and abates with rest. The patient has no fever, weight loss, anemia, inflammation of the joints, or generalized or extreme stiffening or deformity of the joints. In the early stages x-ray diagnosis is almost impossible, since the changes are so minor and occur gradually. The major clinically observable sign, particularly in women, is the appearance of knobs at the ends of the joints of the first and second fingers. Men are more affected in the lower spine. The knees, hips, ribs, lumbar and lower cervical vertebrae, sacroiliac, and shoulders are other common sites of degenerative changes. Rarely are the wrists, knuckles, elbows, or feet involved. Involved sites eventually may become painful and stiffen as the cartilage wears away and the bony outgrowths occur. Local nerves may be affected, particularly when the spine is involved. If thoracic nerves are affected, the resulting pain may be confused with the pain of heart disease. In the lumbar region, the nerves will give rise to the pain commonly called sciatica.

Unlike rheumatoid arthritis, there is no inflammation, deformity, or crippling. The symptoms of degenerative arthritis may be mildly troublesome or quite painful, depending upon the stage of the disease and its location. Degenerative arthritis is rarely a contraindication for implants unless there is a severe involvement of the temporomandibular joint.

Rheumatoid arthritis. Rheumatoid arthritis, sometimes called rheumatism, is a progressive systemic disease that increasingly impairs and limits motion. Unless checked, crippling deformities result. Although the cause is unknown, infection is suspected of initiating the process. Disease-causing microorganisms or toxins produced in remote infections may be circulated to the joints, or the joints

may become sensitized to the organism, with the allergic reaction taking place in the form of arthritis. The adrenal glands may have some effect on the condition, and certain persons appear to be hereditarily predisposed to the condition.

Unlike degenerative arthritis, rheumatoid arthritis occurs at a fairly early age, usually between the twentieth and fortieth year. Precipitating factors may be acute or chronic respiratory infections, over-exposure to cold and damp, overfatigue, and emotional stress. The onset is usually characterized by fever, pain, and swelling in one or more joints. Any joint may be affected, and the temporomandibular joint is not an unusual site   a fact to be noted by the implantologist.

The disease is progressive. The synovial membrane, which lines the joint, is affected first. Extensions of this membrane eat into the underlying cartilage, and at the same time the bone under the cartilage loses its mineral components and becomes fibrous. The cartilage thus attacked by the diseased synovial membrane and the diseased bone converts into a thick, bloodless, fibrous tissue. The result is an ankylosis, or stiffening, of the joint. As the ankylosis becomes bony, the joint becomes immovable. The pain ends but the patient is permanently crippled. To compound the difficulties, changes are also occurring in the joint's supporting structures. Because motion causes pain, the muscles go into spasm. The flexor muscles, being stronger than the extensors, hold the joint in the flexed position and the extensors wither from disuse. Eventually the flexors wither too. These changes, plus those occurring simultaneously within the joint, give rise to the deformities typical of rheumatoid arthritis.

Because rheumatoid arthritis can attack any joint and because the temporomandibular joint is not an uncommon site, the implantologist must base his decision on the local condition of the temporomandibular joint. If it is not yet affected, it may well be eventually as the disease progresses. In the meantime, the patient may enjoy the freedom and comfort permitted by an implant-supported dental restoration.

Currently there is no cure for rheumatoid arthritis, although some patients are relieved or their symptoms retarded by chemotherapy. Some of the drugs used are counterirritants, gold compounds, chloroquine phosphate, indomethacine, adrenocortical steroids, and intraarticular hormonal treatments. However, the patient must be carefully observed for any adverse reactions.