Dental Unit

The treatment area consists of the dental unit and chair, the dental light, and the clinician’s chair. The dental chair, a contoured chair for the client during dental care, supports the client’s head, torso, and feet. The dental chair also provides for easy maneuvering of the client via an articulating headrest and foot and side power controls (Table 9-2). The dental light transmits illumination to maximize the clinician’s view of the client’s oral cavity. The dental unit contains essential treatment equipment such as the handpiece lines, water lines, self-contained water source, air and water syringe, evacuation lines, and instrument tray(s). A cuspidor, cup filler, and liquid crystal display (LCD) monitor also may be part of the dental unit (Table 9-3).

TABLE 9-2 Dental Chair

TABLE 9-3 Dental Unit: A-dec 500 Dental Unit and Client Chair

Equipment	Description and Use
Dental chair (A)	Chair to support client during professional care
Hand piece lines (B)	Attach the motor-driven handpiece from the power source to the dental unit; lines are electrical and air compressed
Water lines (hidden in diagram)	Lines bring water to various parts of the dental unit including high-speed handpiece, three-way syringe, and cup filler
Three-way syringe (C)	Hand-held instrument attached to the dental unit provides air, water, or a combination of air and water; inserted in three-way syringe is an autoclavable or disposable tip
Evacuation lines (D)	High-speed and/or low-speed suction with autoclavable or disposable attachment tips
Pole (E)	For mounting dental light and LCD screen
Instrument tray (F)	Movable stainless steel instrument tray usually attached to the dental light post
Cuspidor (G)	Movable cup used for expectoration by the client; many are equipped with a timed water flush system and may have a disposable paper lining
Cup filler (H)	Automatic water cup filler is activated by sensors when the disposable cup is empty
Dental light (I)	Overhead light transmitting illumination into the client’s oral cavity for increased clinician visibility during dental care
Self-contained water system (J)	Minimizes biofilm growth in water lines
LCD screen (K)	For client education and case presentation

Clinician’s Chair

The chair is one of the most important pieces of equipment for the delivery of care (Figure 9-3). It should have a broad, heavy base and be readily mobile, with a minimum of five free-rolling casters to maneuver around the client’s head during care. The chair seat should allow for adequate body support and be adjusted easily for proper height so the clinician’s feet are flat on the floor with thighs parallel with the floor. New ergonomically designed chairs put the clinician in the proper position and lend total body support to reduce strain on the spine, lower back, shoulders, and arms (Figure 9-4). Too high a chair position causes the body weight to be supported by the spine, back, and shoulders. Too low a position causes the clinician to slump and sit with a curved spine (Figure 9-5).

Figure 9-3 Traditional clinician’s chair.

Figure 9-4 Neutral position of clinician. Note shoulders level and held in most relaxed position, elbows close to body, and forearms in same plane as wrists, hands, and client’s mouth.

(Courtesy Nordent Manufacturing, Inc, Elk Grove Village, Illinois.)

Figure 9-5 A, Clinician’s stool positioned too high. B, Clinician’s stool positioned too low.

(Courtesy Nordent Manufacturing, Inc, Elk Grove Village, Illinois.)

Cords on Powered Instruments²

Dental units are equipped with power-driven instruments and air and water syringes. These may be attached to the dental unit via:

Retractable cords: Retract back into the dental unit to save space and avoid tangling

Curly cords: Coiling characteristics allow cord to hang down a shortened distance and save space

Straight cords: Straight, free-hanging cord

The retractable and curly power cords are encumbering and require constant pulling by the clinician. This repetitive pulling motion increases fatigue and hand, arm, and shoulder muscle strain. A straight cord creates no tension while the clinician is using the motor-driven instrument.

Five Categories of Motion

Motions and movements can be stressful to the physical well-being of dental clinicians. Stresses caused by movement can harm the back, neck, arms, and wrists. There are five categories of motion³ based on the amount of movement and the bone and muscle support needed to carry out the movement (Table 9-4). Dental clinicians should limit their movements to categories I, II, and III.

TABLE 9-4 Five Categories of Motion

Grasp and Fulcrum

Fundamentals of grasp include holding the instrument firmly, maintaining a secure grip, and maintaining control of the instrument without causing undue strain or fatigue to the clinician’s hand, arms, and shoulders. The modified pen grasp is a three-finger grasp using the thumb, index finger, and middle finger. The pad of the thumb is placed on the instrument handle, and the joint is bent slightly. The pad of the index finger should also be placed on the instrument handle, slightly superior to the thumb. The side of the middle finger is placed adjacent to the thumb below the index finger near the junction of the instrument handle and the functional shank of the instrument (Table 9-5). A space must be maintained between the index finger and thumb to facilitate freedom of movement when rolling the instrument into interproximal spaces and around line angles of the teeth during instrumentation. Rolling the instrument between the index finger, middle finger, and thumb eliminates turning and twisting of the wrist, which will lead to an RSI such as carpal tunnel syndrome (CTS).

TABLE 9-5 Grasp, Instrument Selection, Procedure, and Pressure

Holding the instrument with all four fingers wrapped securely around the handle is the palm grasp. The thumb is placed on the handle pointed in the direction of the working end of the instrument. The modified pen grasp and palm grasp may be firm or light depending on the procedure being performed. Table 9-5 compares the procedure and instrument with the appropriate grasp. See Chapter 24 for a thorough discussion of instrument grasp.

Fulcrum and Hand Stabilization

The fulcrum is the area on which the finger rests and against which it pushes while instrumentation is performed. The fulcrum provides a basis for steadiness and control during stroke activation. Proper fulcrum and hand stabilization reduces RSIs.

The intraoral fulcrum is established by resting the pad of the ring finger (fulcrum finger) inside the mouth against a tooth surface. The fulcrum finger usually is positioned on occlusal, incisal, or facial tooth surfaces close to the working area or tooth being instrumented (Table 9-6 and see Chapter 24, Figure 24-8). The fulcrum finger must remain locked during instrument activation. A locked fulcrum allows the clinician to pivot on and gain strength from the fulcrum finger. Pivoting on the fulcrum finger helps to maintain a firm grasp, stability, and proper wrist motion. Middle and fulcrum fingers work together to add support during instrument activation. Splitting of the middle and fulcrum fingers decreases instrument control, strength, and stability. With less control, strength, and stability, the clinician will automatically tighten the grasp, contributing to RSI. Placing the fulcrum close to the working area is not always possible owing to space limitations in the mouth, teeth alignment, pocket depth, or the angle of access. A variety of intraoral fulcrums may be necessary. See Chapter 24, section on the fulcrum, for a detailed explanation.

TABLE 9-6 Fulcrum Finger Placement for Dominant Hand on the Mandibular and Maxillary Arch

The extraoral fulcrum is used when using instruments on deep periodontal pockets. It is accomplished by placing the broad side of the clinician’s palm or back of the hand against an outside structure of the client’s face such as the chin or cheek (see Chapter 24Figure 24-51Figure 24-52Figure 24-53 ). Benefits of an extraoral fulcrum are as follows:

Easier, less strenuous accessibility to deep periodontal pockets and difficult access areas

Stability and control

Less twisting of wrist during activation of maxillary posterior areas

Decreased chance of RSI to the nerves, tendons, and ligaments in the clinician’s wrist and elbow (e.g., action of the activation or pulling stroke is transmitted to the arm and shoulder and away from the wrist)

When no fulcrum is used, lateral pressure on the instrument during activation causes the instrument to slip in the hand. To stabilize and control the instrument, the clinician will automatically tighten the grasp. Tightening the grasp places stress on hand and arm muscles, tendons, and ligaments, leading to an increased occurrence of RSI.

Wrist Motion during Instrument Activation^1,2,4

Wrist motion and the fulcrum are related. Safe wrist motion is vital to the health of the clinician’s hand, wrist, and forearm muscles, tendons, and ligaments. Pivoting on the fulcrum causes the hand, wrist, and forearm to move in one unified motion, often called “wrist rock.” Failing to handle instruments using the unified motion causes the clinician to extend or flex the wrist (Figure 9-6). Continued flexion or extension of the wrist contributes to a variety of RSIs.

Figure 9-6 A, Flexion of the wrist. B, Extension of the wrist. Both movements can cause repetitive strain injuries.

Digital motion during instrument activation is also a factor contributing to RSI. Digital motion is the push-and-pull motion of the instrument using fingers only. Muscle fatigue results quickly with digital motion, and a decrease in instrument power and stability occurs.

Appointment Management²

Control of appointment procedures and time greatly reduces possible RSI. The dental hygienist should:

Alternate new clients with continued clients

Alternate root debridement and therapeutic scaling with maintenance appointments

Alternate difficult appointments with less taxing ones

Shorten continued-care intervals

Allow for “buffer time” in the daily schedule

Client-Clinician Positioning Factors^2,4

Commonly used client positions are:

Upright for interviewing and educating

Semiupright for treating persons with some cardiovascular and respiratory diseases

Supine for treating most clients

Trendelenburg for persons experiencing syncope

In the supine position the client’s mouth should be at about the height of the seated clinician’s elbow. Distance from the client’s mouth to the clinician’s eyes should be about 14 to 16 inches. The headrest can be adjusted for maxillary or mandibular arch visibility. When treating maxillary teeth, the maxilla should be perpendicular to the floor; when treating the mandibular teeth, the mandible should be parallel to the floor.

Clinician-client positioning is best explained using the face of a clock (Figure 9-7):

Client’s head is the center of the clock.

Clinician moves around face of clock, positioning between the 8 o’clock and the 4 o’clock positions.

Right-handed clinician uses the 8 o’clock to 2 o’clock range. When teeth are out of alignment, the right-handed clinician may work in the 4 o’clock position.

Left-handed clinicians work predominantly in the 10 o’clock to 4 o’clock range, with variations necessary at times to the 8 o’clock position.

Figure 9-7 Possible clinician positions around the client. Right-handed clinician: 8 to 2 o’clock. Left-handed clinician: 4 to 10 o’clock.

Table 9-7 provides a reference for accessing areas of the client’s mouth. Figure 9-8 presents a variety of client positions used during dental hygiene care.

TABLE 9-7 Accessible Areas of the Client’s Mouth

Figure 9-8 Basic client body positions used during the dental hygiene process of care. A, Basic upright position; client is seated in an 80- to 90-degree angle. B, Semiupright position; client is seated in a 45-degree angle. C, Supine position that has been modified for mandibular instrumentation. D, Supine position that has been modified for maxillary insertion.

Position of the Clinician

Clinician comfort and safety cannot be sacrificed for the client. Repetitively using incorrect clinician positioning causes stress and fatigue. Therefore client positioning should allow the operator to perform intraoral procedures without increasing RSI. Table 9-8 lists the correct positioning of the clinician’s arms, shoulders, legs, feet, back, head, and eyes during care.

TABLE 9-8 Correct Clinician Positioning

Wrist, Arm, Elbow, and Shoulder Position

Maintaining a neutral position of the wrist, arm, elbow, and shoulder reduces clinician fatigue and injury during care.⁵ Neutral positions are basic to the prevention of occupational pain and risks related to RSI.

Neutral positions include (see Figure 9-4):

Shoulders: Level and held in their lowest, most relaxed position

Elbow: Held close to the clinician’s body at a 90-degree angle

Forearm: Held in same plane as wrist and hand

Wrist: Should never be bent; it is held straight

Back and Neck Support

Adequate back and neck support reduces the occurrence of musculoskeletal injuries to the spine. Intervertebral disks in the spine resemble a jelly donut. When uneven pressure is put on an intervertebral disk, the effect is the same as if you pushed down on one side of a jelly donut: the contents of the disk (jelly donut) are pushed out. Poor posture of the clinician results in uneven support of the spine and rupture of an intervertebral disk (see Figure 9-5). Maintaining a straight back, straight neck, and erect head, with feet flat on the floor and thighs parallel to the floor, properly supports the spine.

Eye loupes (telescopes) are magnification devices worn instead of traditional eyeglasses to improve the clinician’s operative field of vision, visual accuracy, and posture during client care⁶ (Figure 9-9). Use of multilens telescopic loupes in the 2× to 2.5× magnification range offers the necessary depth of field and ensures a specific physical distance between the dental hygienist and client, keeping the dental hygienist’s back and spine straight and preventing occupational pain caused by cumulative trauma. If the clinician is too close to or too far away from the client, the visual field seen through the magnification device will be blurred. Once back into the proper position, the clinician’s field of vision will be clear.

Figure 9-9 A, Flip-up loupe on a black Rudy sport frame. B, Revolution through-the-flip loupe with insert available for prescription. C, Rudy loupe with Apollo LED light. D, Correct clinician position when using loupes.

(A to C, Courtesy Orascoptic, Middleton, Wisconsin.)

Hand Instrument Cutting Edge Sharpness²

Sharp instruments are essential to the elimination of fatigue and stress on the clinician’s hand, wrist, arm, and shoulders that cause RSI. Therefore any instrument with a cutting edge should be kept sharp during the entire procedure. Dull instruments that deviate from their original design cause the clinician to apply additional force, resulting in increased lateral pressure applied, excess stroke repetitions, and a tightened grasp. Fatigue and RSI can ensue.

Maintaining the original design of scaling instruments is accomplished by manual sharpening using a hand-held sharpening stone or powered sharpening devices that assist in maintaining the original design of the working end of the instrument as well as producing an even, sharp, cutting edge (Figures 9-10 and 9-11). New dental instrument materials have been developed that require no sharpening or reduce the need for sharpening (see Chapter 24, section on instrument sharpening).

Figure 9-10 Sidekick used to sharpen instruments.

(Courtesy Hu-Friedy, Chicago, Illinois.)

Figure 9-11 A, InstRenew Sharpening Assistant used to sharpen instruments. B, InstRenew being used to sharpen a curet. Correct cutting-edge angle is maintained.

(Courtesy Nordent Manufacturing, Inc, Elk Grove Village, Illinois.)

Ergonomic Instrument Handles²

Ergonomic instrument handles are large in diameter and light in weight. Table 9-9 and Figure 9-12, A compare instruments with standard versus ergonomic handles. Larger-diameter handles open the grasp just enough to dissipate the mechanical forces over a larger area of muscles. Instrument setups containing several styles of handles give the clinician the opportunity to rest different muscle groups while completing care, decreasing the occurrence of RSI. Another ergonomic design feature to consider is the use of instruments with padded handles (Figure 9-12, B). Padded instrument handles cushion the fingertips while the handle is grasped (see Chapter 24, section on parts and characteristics of dental instruments).

TABLE 9-9 Ergonomic and Standard Instrument Handles

Parameters	Ergonomic Design	Standard Design
Diameter (inches)	⅜-	¼
Diameter (mm)	9.53-11.11	6.35
Shape	Round or hexagonal	Round or hexagonal
Construction	Hollow	Solid
Weight	Approximately 13.2 g	Approximately 26.0 g

Figure 9-12 A, Variety of instrument handles. B, Padded handle.

(Courtesy Nordent Manufacturing, Inc, Elk Grove Village, Illinois.)

Balanced Instruments

Instruments, both single- and double-ended, should be balanced. This means that the working end is centered over the long axis of the instrument handle. When the instrument is balanced, the lateral pressure placed on the instrument handle and shank during instrument activation will be aimed toward the working end (Figure 9-13). When an instrument is not balanced, the lateral pressure placed on the instrument when activated causes the instrument to turn slightly in the clinician’s fingers. To compensate, the clinician grasps the instrument handle more tightly. Use of balanced instruments decreases occurrence of RSI.

Figure 9-13 Balanced instrument. Note that when the working end is centered over the long axis of the handle, the instrument is balanced.

Mechanized Instruments

Use of ultrasonic and sonic instruments significantly reduces repetitive hand-wrist-forearm motions (see Chapter 25). Oral debridement requires numerous repetitive strokes and significant lateral pressure when using hand-activated instrumentation techniques.

Vibrating Instruments

Instruments causing vibrations, such as the motor-driven handpiece, cause fatigue and hand, arm, and shoulder muscle strain. Application of the principles of selective polishing limits the time during which the clinician uses a vibrating instrument. A common RSI caused by vibratory instruments is Raynaud’s syndrome, which results in blanching (often painful) fingers.

Dental Mirrors

The mouth mirror is held in the nondominant hand. Practitioners focus on the hand, wrist, and arm position of the dominant hand during instrumentation with limited regard for the nondominant hand. Ergonomic adaptations in mouth mirror handles were associated with increases and decreases in muscle activity. The clinical impact of this increase or decrease in muscle activity amplifies as force is exerted.⁷ When comparing the function of the dominant and nondominant hands during dental hygiene procedures, there is a significant difference between the techniques of the scaling hand and the hand holding the mirror. The nondominant hand holding the mirror functions to increase access and visualization by retracting the tongue and cheeks. Unlike the multitasking dominant hand, the static nondominant hand often requires a forceful grip, retracting the tongue and cheek throughout care.⁸ This continuous static position of the nondominant hand decreases blood flow to the hand and fingers, increasing risk of RSI. Ergonomic adaptations to instrument handles (weight, diameter, and padding) vary muscle activity throughout the day to reduce RSIs for dental hygienists.⁷

Carpal Tunnel Syndrome^2,4,9

CTS, the most common RSI reported by dental hygienists, has the following causes:

Congenital: anatomic structure and development

Self-limiting conditions: pregnancy

Systemic conditions: edema or arthritis

Nonmedical reasons: occupational or work related

About one third of dental hygienists report symptoms of CTS, which occurs when the median nerve becomes compressed within the carpal tunnel (Figure 9-15). Function of the median nerve is sensory and motor:

It supplies sensation to the thumb, index finger, middle finger, and half of the ring finger.

It supplies a branch to the thumb (thenar) muscles.

Figure 9-15 Carpal bones. The carpal bones form a trough through which the flexor tendons and median nerve traverse into the hand. A, Transverse section of the wrist and carpal tunnel. B, Diagram of transverse section through the carpal tunnel.

(Redrawn from Agur A: Grant’s atlas of anatomy, ed 9, Baltimore, 1991, Williams and Wilkins.)

The carpal bones of the wrist and the transverse carpal ligament form the carpal tunnel. The carpal bones and transverse carpal tunnel ligament form a furrow, allowing the flexor tendons and the median nerve to pass through to the hand. Repetitive force and motion to the wrist cause tendon inflammation and swelling within the carpal tunnel. The enlarged tendons and lack of space in the carpal tunnel place undue pressure on the median nerve, causing pain. Once the nerve is compressed, CTS begins. Repeated wrist flexion and hyperextension during instrumentation aggravate tendons and cause further swelling.

Signs and Symptoms

Numbness in the areas supplied by the median nerve (earliest sign)

Pain in the hand, wrist, shoulder, neck, lower back

Nocturnal pain in hand(s) and forearm(s)

Pain in hand(s) while working

Morning and/or daytime stiffness and numbness

Loss of strength in hand(s); weakened grasp

Cold fingers

Increased fatigue in fingers, hand, wrist, forearm, shoulders

Nerve dysfunction

Chairside Preventive Measures

Maintain good operator posture: the client’s mouth should be even with clinician’s elbow; the elbow should be held in the neutral position (90-degree angle created by the upper arm and forearm).

Maintain proper position to support clinician’s body, with thighs parallel to floor and feet flat on floor.

Neutral forearm and wrist position: avoid pinching median nerve in the carpal tunnel.

Keep shoulders relaxed.

Use a unified motion (wrist, hand, forearm) during scaling and polishing; avoid flexion and extension of wrist.

Avoid extremes in temperatures.

Avoid or limit exposure to vibrating instruments.

Avoid forceful pinching and gripping of instrument handles.

Wear properly fitting gloves.

Alternate clinician positions.

Perform TGEs.

Assessing Symptoms

CTS affects the median nerve, which supplies the thumb, index finger, middle finger, and half of the ring finger. If the symptoms are felt in the little finger and right half of the ring finger, CTS may not be the problem or the operator may have CTS along with another RSI. Two simple tests can be performed to indicate symptoms of CTS:

Phalen’s test: Place the back of hands against each other. Hold flexed wrists together at a 90-degree angle for one minute. Subjective sensory changes will be felt within 1 minute. These sensory changes indicate a positive test result (Figure 9-16, A).

Tinel’s sign: Tap the median nerve at the ventral side of wrist. If nerve compression is present, sensation is felt in the fingers. The sensation could range from a tingling feeling to an electrical type shooting pain (Figure 9-16, B).

Figure 9-16 A, Phalen’s test. B, Tinel’s sign.

Thoracic Outlet Compression

Thoracic outlet compression (TOC) is an RSI resulting in compression of the brachial artery and plexus nerve trunk at the thoracic outlet. TOC affects the hand, wrist, arm, and shoulder. Compression of the neurovascular bundle (brachial plexus, subclavian artery, and subclavian vein) results in decreased blood flow to the nerve functions of the arm. The compression occurs at the neck, where the scalene muscles create an outlet or tunnel. The nerves and blood vessels run from the neck into the arm and hand.

Symptoms

Numbness and tingling along the side of arms and hands

Neck and shoulder muscle spasms

Weakness and clumsiness in hand and fingers

Cold extremities

Absence of radial pulse

Chairside Preventive Measures

Maintain proper clinician positions: head erect, back straight, shoulders in neutral position

Maintain proper height of dental chair and client positioning

Surgical Glove Injury²

Ill-fitting gloves can contribute to surgical glove injury (SGI). The glove should fit the hand and fingers snuggly but be neither too tight nor too loose from fingers to forearm (Figure 9-17).

Figure 9-17 A, Glove is too tight. B, Glove is too loose.

Symptoms

SGI is commonly mistaken for CTS and TOC because so many of the signs and symptoms, as follows, are similar:

Tingling in fingers

Cold extremities

Loss of muscle control and hand strength

Numbness or pain in fingers

Chairside Preventive Measures

Wear properly fitting gloves. Evaluate if gloves fit properly around fingertips, between fingers, between thumb and index finger, across palm of hand, and around wrist.

Do TGEs and stretch the hand and fingers (see Figure 9-14).

Guyon’s Canal Syndrome²

Guyon’s canal syndrome (GCS), caused by ulnar nerve entrapment at the wrist, differs from CTS in that the ulnar nerve does not pass through the carpal tunnel. Rather the ulnar nerve passes through a tunnel formed by the pisiform and hamate bones and the ligaments that connect them.

Symptoms

Numbness and tingling in little finger and right side of ring finger

Loss of strength in lower forearm

Loss of movement of small muscles in hand

Clumsiness of hand

Chairside Preventive Measures

Attention placed on hand and finger position during instrumentation reduces GCS and includes:

Repositioning of little finger during scaling and extrinsic stain removal

Performing periodic hand stretches

Trigger Finger Nerve Syndrome²

Trigger finger nerve syndrome (TFNS, or triggering) affects movement of the tendons as the fingers and thumb are bent (flexion) and moved. The tendons are held in place on the bones by a series of ligaments called pulleys. Friction is reduced by a slippery coating called tenosynovium, allowing the tendons to glide easily through the tendon sheaths. When the tendons and tendon sheaths are inflamed and tenosynovium thickens, a nodule forms from the constant irritation of the tendon being pulled through the pulley. As the finger is flexed, the nodule passes under the ligament and becomes stuck. The finger cannot be extended back to its original position.

Symptom

Inability to extend the fingers or thumb after flexing

Risk Factors

Repetitive use of fingers and hands causes overuse of finger and thumb tendons. Overuse often results from fingers and thumb being flexed against resistance. Digital motion during instrumentation results in overuse of finger and thumb tendons. Also, pinching the instrument handle causes fingers and thumb to flex against resistance (Figure 9-18).

Figure 9-18 Pinched fingers on the instrument handle.

Chairside Preventive Measures

Minimizing finger motion and using proper grasp, fulcrum, and unified motion of the hand, wrist, and forearm decrease risk of TFNS.

Maintain appropriate modified pen grasp for the procedure.

Grasp instrument handle using finger and thumb pads instead of pinching with tips of fingers.

De Quervain’s Syndrome²

De Quervain’s syndrome is an inflammation of the tendons and tendon sheaths at the base of the thumb (the “anatomic snuff box”). This condition occurs from repetitive motion combining hand twisting and forceful gripping along with prolonged work with the wrist held in ulnar deviation (Figure 9-19). Symptoms will occur when the pollicis longus and extensor pollicis longus tendons are unable to glide through the tunnel on the side of the wrist.

Figure 9-19 Wrist in ulnar deviation. Spine and neck out of alignment.

(Courtesy Sarah Talamantes Carter, University of California at San Francisco.)

Symptoms

Aching and weakness of thumb (along the base)

Pain migrating into forearm.

Chairside Preventive Measures

Avoid ulnar wrist deviation during instrumentation.

Eliminate twisting of wrist when reaching for dental instruments.

Maintain a neutral wrist position and unified motion during dental care.

Assessing Symptoms

Finkelstein’s test is a simple way to assess symptoms (Figure 9-20):

Bend thumb into palm of hand. Grasp thumb with the four fingers.

Place wrist in ulnar deviation position by bending wrist toward little finger.

Figure 9-20 Finkelstein’s test.

Pain over tendons and tendon sheaths at base of thumb indicates possible De Quervain’s syndrome.

Strained Pronator Muscle

The muscle involved in a strained pronator muscle (SPM) injury is an elongated, narrow pronator muscle in the forearm and flexor of the elbow joint. The pronator muscle wraps around the anterior aspect of the elbow. SPM is caused by compression of the median nerve as it passes under the pronator muscle.

Chairside Preventive Measures

Maintain neutral arm position: hold arms close to body

Maintain neutral wrist position during dental care procedures

Avoid rotation and twisting of forearm

Lateral Epicondylitis¹¹

Lateral epicondylitis (LE) is a degenerative elbow disorder. In spite of its common name (tennis elbow), the majority of cases are not from sports injuries. Rather it results from inflammation of the wrist extensor tendons on the lateral epicondyle of the elbow.

Symptoms

Aching or pain in elbow

Sharp shooting pain during elbow extension

Chairside Preventive Measures

Avoid wrist extension during dental care.

Maintain proper neutral wrist position during instrumentation.

Use proper clinician positions, allowing neutral body positions to be maintained.

Radial Tunnel Syndrome¹²

Radial tunnel syndrome (RTS) is a condition affecting the radial nerve entrapped in the radial tunnel. The radial nerve starts at the side of the neck and travels through the armpit and down the arm to the hands and fingers; the nerve passes in front of the elbow through the radial tunnel and allows the hand to turn in a clockwise direction.

Cubital Tunnel Syndrome¹²

Cubital tunnel syndrome is a condition affecting the ulnar nerve as it crosses behind the elbow. The ulnar nerve controls the muscles in the right half of the ring finger and little finger of the hand. The ulnar nerve starts at the neck and runs through the armpit and down the arm to the hand and fingers. At the elbow the nerve crosses through a tunnel of muscle, ligament, and bone (cubital tunnel). When elbow is bent, the nerve is pulled up between bones, causing compression and entrapment of the ulnar nerve. When nerve compression occurs, impulses are slowed.

Symptoms

Pain and numbness on outer side of ring and little fingers

Pain sometimes relieved when elbow is straightened

Chairside Preventive Measures

Maintain a neutral elbow position during procedures.

Alter instrument grasps; avoid prolonged use of palm grasp.

Avoid repetitive crossing of arms across the chest.

Avoid leaning on elbow when sitting at table.

Trapezius Myalgia^2,10

Trapezius myalgia (TM) is caused by static loading in the shoulder or stabilizing muscles over a long period of time. This condition is commonly found in workers in repetitive action occupations.

Chairside Preventive Measures

Manage appointment times: alternate long and short appointments.

Take stretching breaks during long procedures.

Change body positions.

Maintain proper clinician positions to ensure proper body support.

Rotator Cuff Injuries

Rotator cuff injuries (RCIs) include rotator cuff tendonitis and rotator cuff tears. Both affect the connective tissue in the shoulder and cause common shoulder pain. Most often affected is the supraspinatus tendon. RCIs are associated with repetitive motion and excessive, forceful exertion of shoulder and arm.

Symptoms

Pain when lifting the arm 60 to 90 degrees

Functional impairment

Chairside Preventive Measures

Avoid repetitive twisting and reaching.

Maintain neutral shoulder and arm positions.

Use proper clinician positions during dental care.

Adhesive Capsulitis

Adhesive capsulitis (AC), also known as frozen shoulder, results from immobility of the shoulder due to severe shoulder injury or repeated occurrences of rotator cuff tendonitis.

Symptoms

Symptoms are similar to those of RCIs:

Pain in shoulder

Limited range of shoulder motion

Chairside Preventive Measures

Avoid repetitive twisting and reaching.

Maintain proper shoulder and arm positions: neutral positions.

Use proper clinician positions and movement during instrumentation.

Lumbar Joint Dysfunction²

Lumbar joint dysfunction (LJD) occurs from repetitive and continued twisting and rotating of spine. With improper spine support during dental care delivery, the intervertebral disks experience tremendous pressure, possibly resulting in rupture or injury.

Chairside Preventive Measures

Avoid twisting back and spine.

Properly support body weight.

Modify equipment placement to avoid twisting to reach.

Tension Neck Syndrome

Also called tension myalgia, tension neck syndrome (TNS) involves the cervical muscles of the trapezius muscle.

Signs and Symptoms

Pain or stiffness around cervical spine (neck)

Pain between shoulder blades that may radiate down arms

Muscle tightness and tenderness in neck

Palpable hardness in neck

Limited neck movement

Chairside Preventive Measures

Maintain proper clinician head and neck position to support neck and spine.

Maintain proper height of dental chair and client position.

Support weight of head over entire spine, not just cervical portion of spine.

Keep back straight during dental care.

Take periodic breaks and perform stretching exercises.

Cervical Spondylolysis and Cervical Disk Disease¹

Cervical spondylolysis (CS) and cervical disk disease (CDD) lead to degeneration of the cervical spine. These RSIs affect the neck, scapula, shoulders, and arms, causing osteoarthritis of the cervical spine, disk degeneration, and herniation.

Signs and Symptoms

Stiffness and limited motion of neck

Crepitus during active or passive neck movements

Pain in upper and middle cervical region of spine

Pain in scapula of shoulder regions

Muscle spasms

Chairside Preventive Measures

Maintain proper clinician head and neck position to support neck and spine.

Position clients for easy access to the mouth.