Health Effects of Musculoskeletal Hazards
The risk factors associated with dental work that most commonly affect the wrists are chronic repetitive movements, awkward and static positions, mechanical stresses to digital nerves such as sustained grasps on instrument handles, extended use of vibratory instruments and inadequate work breaks. The wrist is in constant demand, often sustaining excessive and repeated stresses and strains. The safest position for the wrist is a straight or neutral position. Special care should be used to avoid bending the wrist downwards (flexion) or outwards (ulnar deviation).
Carpal Tunnel Syndrome (CTS)
CTS is one of the most common problems that affect the hand and wrist. CTS occurs when the median nerve, which runs from the forearm into the hand, becomes pressed or squeezed at the wrist. The median nerve controls sensations to the palm side of the thumb and fingers (although not the little finger), as well as impulses to some small muscles in the hand that allow the fingers and thumb to move. The carpal tunnel is a narrow, rigid passageway of ligament and bones at the base of the hand. It houses the median nerve and tendons. Thickening from irritated tendons or other swelling narrows the tunnel and causes the median nerve to be compressed. The result may be pain, weakness, or numbness in the hand and wrist, radiating up the arm. Repetitive wrist motions, especially while a pinch pressure is exerted by the fingers, have been linked to an increased incidence in developing CTS.
The exact amount and type of repetitive movements performed during dental work has not yet been accurately quantified by previous studies. However some researchers have highlighted that one of the predictors for the high prevalence of CTS among dental hygienists was their longer clinical period of repetitive movements when work was done on parts of the mouth that were difficult to access and required precise movement and control.
Tendonitis of the Wrist
Tendonitis is an inflammation of tendons, which are the structures that attach muscle to bone. Tendonitis of the wrist is accompanied by pain, swelling and inflammation on the thumb side of the wrist, and is made worse with grasping and twisting activities (e.g. polishing and scaling). People with this disorder have often noted an occasional “catching” or snapping when moving their thumb.
Guyon's canal is a space at the wrist between the pisiform bone and the hamate bone through which the ulnar artery and the ulnar nerve travel into the hand. Compression of ulnar nerve occurs in this space at the base of the palm. It is commonly caused by repetitive wrist flexing or excessive pressure on palm/base of hand. It is characterized by pain, weakness, numbness, tingling, burning in the little finger and part of the ring finger.
Grasping or pinching light objects becomes a problem when the item is held for long periods. The pressure can reduce blood flow and strain tendons, leading to hand symptoms. Repetitive motion, such as prolonged grasping, can lead to tendonitis (inflammation of the tendons).
This disorder is characterized by pain and swelling in the thumb and wrist area when grasping, pinching, twisting, and a decreased range of motion of thumb with pain. Possible causes include synovial sheath swelling, thickening of tendons at base of thumb, and repeated trauma or twisting hand/wrist motions.
Trigger Finger often results from sustained forceful grips and repetitive motion which irritates the tendon and tendon sheath (tenosynovium). Nodules form in tendon causing warmth, swelling, and tenderness of the tendon. Pain occurs during movement that place tendons in tension. The fingers lock in the “Trigger Position”.
The elbow should generally be held at a right angle or ninety degrees. Because blood vessels and nerves supplying the forearm and hand travel along the elbow joint, repeated or prolonged bending can cause compression, leading to forearm and hand symptoms.
Injuries at the elbow typically occur at either the inside of the elbow, referred to as Medial Epicondylitis (golfer’s elbow), or outside of the elbow, known as Lateral Epicondylitis (tennis elbow). The forearm flexors, used to make a fist, attach at the inside portion of the elbow. Whereas the forearm extensors, used to open the hand, attach at the outside of the elbow.
Cubital Tunnel Syndrome
Cubital Tunnel Syndrome is often caused by prolonged use of the elbow while flexed, resting the elbow on an armrest, or trauma from overuse can compress the ulnar nerve. It is characterized by pain, numbness, tingling and impaired sensation in the little and ring fingers, side and back of hand, loss of fine control, and reduced grip strength.
Rounding the shoulders can compress nerves, arteries, and veins that supply the arm and hand, leading to upper extremity symptoms. Poor thoracic alignment also limits oxygen intake. Slouching forward compresses the chest cavity, preventing the diaphragm muscle from completely filling the lungs with air. When oxygen is diminished, the body experiences fatigue and loss of concentration.
The term bursitis means that the part of the shoulder called the bursa is inflamed. There are many different problems that can lead to symptoms from inflammation of the bursa, one of those being impingement.
Thoracic Outlet Syndrome (TOS)
TOS is a condition resulting from compression of the nerves, arteries, and veins as they pass through from the neck to the arm (thoracic outlet). Possible causes include tight scalenes and pectoralis muscles, extra cervical rib, and prolonged durations of working with elevated elbows. This disorder is characterized by pain in the neck, shoulder, arm or hand, numbness and tingling of fingers, muscle weakness/fatigue, and cold sensation in the arm, hand or fingers.
Rotator Cuff Tear
The rotator cuff (RC) is a group of 4 muscles; supraspinatus, infraspinatus, teres minor and subscapularis. The RC assists with both gross and fine motor control of the arm. RC injury tends to occur where the muscle’s tendon attaches to the bone.
Rotator Cuff Tendonitis
This disorder is characterized with pain and stiffness in the shoulder associated with backward and upward arm movements, and weakness of rotator cuff muscles. Possible causes include swelling or tearing of rotator cuff soft tissue, shoulder joint bone spurs/abnormalities, and poor shoulder posture.
Pain and discomfort are the most common complaints reported in the neck/shoulder region amongst dental professionals. Studies have also shown that female dentists reported neck symptoms 1.4 times more often than maledentists. It is common for pain in the arm and hand to stem from problems in the neck. Neck and arm strain can be prevented by keeping the head and neck in proper alignment. The slight inward curve of the neck balances the head on the spine. Holding the head forward disturbs this balance, straining the joints and the muscles of the neck and upper back. This posture also causes compression of the nerves and blood vessels as they exit the neck, leading to symptoms in the arm and hand. Neck problems generally arise from prolonged static neck flexion and shoulder abduction or flexion, lack of upper-extremity support, and inadequate work breaks. Awkward postures are often adopted to obtain better views of the intraoral cavity, provide a more comfortable position for the patient and to coordinate their position relative to the dentist or assistant.
Myofascial Pain Disorder (MPD)
MPD is characterized by pain and tenderness in the neck, shoulder, arm muscles, and a restricted range of motion. Possible causes include overloaded neck/shoulder muscles.
This disorder is characterized by intermittent/chronic neck and shoulder pain or stiffness, headaches, hand and arm pain, numbness, tingling, and clumsiness. Possible causes include age-related spinal disc degeneration leading to nerve compression and spinal cord damage, arthritis, and time spent with the neck in sustained awkward postures.
The main risk factors associated with dental work are the sustained awkward postures and poor seating. Most individuals with low back pain do not simply injure their back in one incident but rather gradually over time. Repeated stresses from over the years begin to add up and slowly cause degeneration of various parts of the spine, resulting in low back pain.
In a seated posture the pressure in the lumbar discs increases by 50% as compared to standing. Additionally, sitting in an unsupported posture can cause twice the amount of stress as compared to standing. During bending (forward flexion) and twisting (rotation) motions of the spine, the pressure on the lumbar discs increases by 200%. This type of pressure on the disc can lead to a bulge or herniation, causingcompression on a spinal nerve.
Sciatica is characterized by pain in the lower back or hip radiating to the buttocks and legs, causing leg weakness, numbness, or tingling. It is commonly caused by bulging, prolapsed or herniated discs compressing a spinal nerve root and isworsened with prolonged sitting or excessive bending and lifting.