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Healthy Hands

By improving the ergonomics of clinical practice, dental hygienists can reduce the risk of career-ending injuries.

Figure 1. When the wrist is bent downward during clinical dental hygiene care, especially greater than 45°, the risk of injury is great.

Dental hygienists’ hands are their most important asset,as they are critical for every aspect of clinical care—from prophylaxis to ultrasonic scaling. This is why maintaining healthy hand ergonomics is key to career longevity. Unfortunately, a significant number of dental hygienists experience cumulative microtrauma that prevents them from continuing in the profession. If oral health professionals integrate sound ergonomic principles and ergonomically designed products into their practice, retirement due to pain or injury can be prevented.


Dental hygienists are susceptible to musculoskeletal disorders—injuries of the muscles, tendons, and nerves that occur gradually.1 Among dental hygienists, these disorders are most commonly found in the forearm, hand, and wrist.1–3 Carpal tunnel syndrome—caused by poor neck and hand posture and a prolonged pinch grip that can compress the median nerve within the wrist—frequently affects clinicians.1–3 The median nerve can also be compressed at the elbow region, resulting in pronator syndrome.1 Additionally, the ulnar nerve passes through the wrist, and its compression results in numbness, tingling, and/or weakness in the lower arm or wrist.1 Tendinitis can result when the tendons of the wrist are inflamed due to extending the hand up or down at the wrist. Twisting the hand, grasping instruments tightly, and bending the hand back or to the left or right may cause the tendons on the side of the wrist and the base of the thumb to become inflamed, leading to tenosynovitis.1 Another painful disorder—extensor wad strain—involves injury to the extensor muscles of the thumb and fingers when the fingers are positioned independently of each other.1


Figure 2. Extending the wrist upward by more than 45° during the provision of care increases dental hygienists’ risk of developing carpal tunnel syndrome.

Dental hygiene practice involves frequent and repetitive procedures performed predominantly by the forearm, hand, and wrist. Exaggerated up-and-down or side-to-side wrist motions increase the risk of musculoskeletal disorders.4 More specifically, when the wrist is bent downward (flexion, Figure 1) or upward (extension, Figure 2) by more than 45°, the likelihood of developing carpal tunnel syndrome increases.4 Ulnar deviations greater than 30° and radial deviations exceeding 20° are just as harmful.4 Procedures, such as scaling and root planing, require a high level of pinch force and repetitive wrist motion. When calculus removal is attempted with the use of heavy instruments with small-diameter handles, a higher level of pinch force is required, increasing the risk of musculoskeletal disorders.5,6 Muscle activity and thumb pinch force also increase this risk when a finger rest is not used.7

The majority of dental hygienists use an ultrasonic scaler and rubber cup polisher on most of their patients. While these tools may reduce the pinch force required to remove plaque and calculus, the resultant vibrations can raise the risk of carpal tunnel syndrome and other hand disorders.3,7,8 Over time, the vibrations may cause injury to the sympathetic fibers, leading to poor conduction of nerve impulses. Signs and symptoms of this problem include tingling, sensitivity to heat, sweating, cold hands, vasoconstriction, red or blue skin color changes, and clotting of the ulnar artery.8

Static posture is another risk factor for musculoskeletal injury.3 Because patients are often seen back to back, the muscles, nerves, and ligaments of the hand receive little to no rest. Not only do the back and neck remain in the same position for a prolonged period, the nondominant hand does as well, which is often used to retract the cheek and tongue. This lack of movement may lead to ischemia (restriction of blood flow and oxygen) and muscle imbalance.3


Figure 3. In order to maintain musculoskeletal health, dental hygienists need to keep their wrists in a neutral position as often as possible.

The first step in addressing proper hand ergonomics is to identify specific hazards in the work environment. Instrument selection is a significant factor in ergonomic practice. Dental hygienists can minimize or avoid musculoskeletal disorders by selecting ergonomically designed handpieces and manual instruments. Choosing handpieces that are shorter or lighter than traditional models, for example, can prove ergonomically beneficial, as can selecting a unit that is designed to minimize vibration. Similarly, handpieces that include a swivel feature (to increase maneuverability) and offer a built-in light source can help clinicians maintain their hand health. Instruments equipped with lightweight (15 g or lighter), large-diameter (10 mm or greater) handles are also helpful, as are well-balanced instruments with textured, tapered grips.3,6

Decreasing force exertion and maintaining neutral wrist posture are important in reducing the risk of injury. To minimize the risk of musculoskeletal disorders, clinicians should avoid wrist flexion and extension. The wrist should be aligned with the forearm, while the thumb should be slightly higher than the opposite side of the palm (Figure 3).1 To avoid constant stress on the hand, a wrist-forearm motion should be employed rather than finger motion.1


New iProphy Air Offers Ergonomic Benefits

Brought to You by NSK Dental LLC

FIGURE 1. The new iProphy Air Prophylaxis Air Motor Handpiece incorporates ergonomic design principles

As Tabitha Tavoc, RDH, PhD, discussed, dental hygienists can support their hand health by using ergonomic products in their daily practice. NSK Dental LLC has been manufacturing dental products based on sound ergonomic principles since 1930, and the company recently launched the iProphy Air Prophylaxis Air Motor—a four-hole, fixed-back hygiene handpiece that features an ergonomic design (Figure 1). Approximately 10% lighter and 10% shorter than traditional handpieces, the iProphy Air provides excellent balance, helps minimize hand fatigue, and features a 360° swivel to increase maneuverability.

In addition, the handpiece was designed using NSK’s micro-machining technology, which minimizes both noise and vibration. The result is a whisper-quiet handpiece that enhances the comfort of both dental hygienists and their patients. Adhering to proper infection control protocol is another critical factor in the safe provision of dental hygiene care, and the iProphy Air offers a unique feature to aid clinicians in ensuring sterility. The handpiece is constructed in two parts so the nosecone can be removed from the motor (Figure 2). This allows for the nosecone to be sterilized separately—ensuring proper disinfection and compliance with infection control guidelines. Additional nosecones may be purchased at a nominal cost, which enables the handpiece to be moved easily from operatory to operatory—saving the practice from needing to purchase multiple complete handpieces. The iProphy Air is also compatible with most conventional disposable prophy angles on the market today.

FIGURE 2 The nosecone on the iProphy Air Prophylaxis Air Motor Handpiece can be separated and sterilized individually.

While using the iProphy Air, dental hygienists can feel confident they are taking the necessary steps to protect their musculoskeletal health while also benefiting from these additional features.”


(888) 675-1675 • WWW.NSKDENTAL.COM



Incorporating ergonomic principles into clinical practice and utilizing ergonomically designed products can help oral health professionals minimize dental hygiene’s inherent physical risks. Using a neutral wrist position and wrist-forearm motion can help clinicians increase productivity and minimize or avoid pain and injury, loss of income, and medical expenses stemming from musculoskeletal disorders.


  1. Nield-Gehrig JS. Fundamentals of PeriodontalInstrumentation and Advanced Root Instrumentation. 7thed. Philadelphia: Lippincott Williams and Wilkins; 2013:5–12.
  2. Hayes M, Cockrell D, Smith DR. A systematic review ofmusculoskeletal disorders among dental professionals. Int JDent Hyg. 2009;7:159–165.
  3. Yamalik N. Musculoskeletal disorders (MSDs) and dentalpractice. Part 2. Risk factors for dentistry, magnitude ofproblem, prevention, and dental ergonomics. Int Dent J.2007;57:45–54.
  4. Hawn CC, Tolle SL, Darby M, Walker M. A laboratorystudy to determine the effects of universal and rotatingultrasonic inserts on wrist movement and scaling timeefficiency of dental hygienists. Int J Dent Hyg. 2006;4:15–23.
  5. Dong H, Barr A, Loomer P, Laroche C, Young E, RempelD. The effects of periodontal instrument handle design onhand muscle load and pinch force. J Am Dent Assoc.2006;137:1123–1130.
  6. Dong H, Loomer P, Barr A, Laroche C, Young E, RempelD. The effect of tool handle shape on hand muscle loadand pinch force in a simulated dental scaling task. ApplErgon. 2007;38:525–531.
  7. Dong H, Barr A, Loomer P, Rempel D. The effects offinger rest positions on hand muscle load and pinch forcein simulated dental hygiene work. J Dent Educ.2005;69:453–460.
  8. Mann NK, Cooper MD. Hand health. Dimensions ofDental Hygiene.2011;9(4):72–75.


From Dimensions of Dental Hygiene. October 2013;11(10):45–46.


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