The right angle for avoiding pain

June 1, 2010
Cumulative trauma disorders are the result of multiple episodes of stress over time.

by Anne Nugent Guignon, RDH, MPH
[email protected]

Cumulative trauma disorders are the result of multiple episodes of stress over time. While individual activities may seem inconsequential, the net effect over time can be painful, long-lasting injuries that are difficult if not impossible to resolve.

Clinicians often don’t give much thought to how a device such as a prophy angle can contribute to the development of a musculoskeletal disorder. Every activity, though, has the potential to either protect our health or create unnecessary stress.1-4 This discussion focuses on the design features of a prophy angle that limit musculoskeletal strain, not the issue of whether or not to polish.

Weight is the first consideration. While all metal angles are autoclavable and therefore more friendly to the planet, an all-metal angle weighs over a half ounce as compared to a disposable prophy angle that weighs a mere 0.15 ounce. The angle is only a small part of the polishing device. But the excess weight — combined with a handpiece that may be heavy or nonswiveling or one that is attached to a heavy or coiled hose — means the potential for a future disaster lurks in the background.5-6

Prophy angles are available in two different body styles: right angle and contra-angle. While the majority of all prophy angles are right angle configurations, a growing number of clinicians have converted to contra-angle devices.

A right-angled body design requires more wrist flexion and extension, especially when adapting the cup to posterior tooth surfaces.2-4 Contra-angled configurations mimic the profile of a high-speed handpiece head, which helps keep the wrist in a neutral position. Three contra-angled disposable angles are available today. Two have fixed bodies and one has an adjustable rotating contra head that improves access for those who use a polishing handpiece that does not swivel.5-7

Years ago, few options were available with respect to the size, shape, or design of prophy angle cups or brushes. A wide variety of choices now address specific clinical applications. Cup or brush length is a matter of personal preference, but many find a shorter, more squatty profile provides better access when polishing posterior buccal surfaces or when trying to access lower lingual surfaces on a patient with a large muscular tongue, a lingual tilt, or a bad gag reflex. Petite prophy cups are designed to accommodate pediatric dentition.

Prophy cups and brushes either snap on or screw into the body of the angle. While most snap-on cups and brushes remain stable throughout the polishing procedure, there is a greater tendency to wobble, requiring more frequent wrist positioning.3-6 Screw cups and brushes deliver consistent concentric rotation.

It is also important to evaluate the smoothness of a prophy angle. There are definite differences between various products. Some provide a smooth polishing experience, while others produce significant vibration, another risk factor for developing an injury.5,8

Traditional prophy cups feature smooth exteriors and have ribbed, webbed, or a fluted inner surfaces, configurations that enhance stain removal. Cups with oblique inner ribs capture and hold excess prophy paste, reducing unwanted splatter. One unique angle has a small brush embedded inside the cup, combining the features of both polishing modalities. Two brands of prophy angles feature cups with small ridges set at an angle on the outside of the cup. This design facilitates interproximal stain removal but its best feature is the fact that excess paste and saliva collect around the spinning cup, giving clinicians time to activate a suction device and avoid being covered with unwanted, contaminated splatter.

Cup flexibility affects not only patient comfort but clinician health as well. Soft, flexible cups that readily adapt to complex tooth surfaces require less pressure, which reduces unnecessary force, a factor considered by ergonomists in evaluating work stress and subsequent fatigue.3,5-7,9 And the lighter the touch, the more pleasant the experience from the patient end of the equation.

If you’re experiencing any kind of hand, arm, elbow or shoulder discomfort, maybe it’s time to take a look at your prophy angle and consider trying one of the newer designs. Many companies are happy to send complimentary samples, creating a risk-free trial in your own clinical setting. You’ll be amazed with the difference between brands and designs. A change of angles may be all that you need to update your comfort zone. Stay tuned for a breakthrough technology in the polishing world coming later this year.


  1. Lindfors P, von Thiele U, Lundberg U. Work characteristics and upper extremity disorders in female dental health workers. J Occup Health. 2006 May;48(3):192-7.
  2. Szymanska J. Disorders of the musculoskeletal system among dentists from the aspect of ergonomics and prophylaxis. Ann Agric Environ Med. 2002;9(2):169-73.
  3. Yamalik N. Musculoskeletal disorders (MSDs) and dental practice Part 2. Risk factors for dentistry, magnitude of the problem, prevention, and dental ergonomics. Int Dent J. 2007 Feb;57(1):45-54.
  4. Novak CB. Upper extremity work-related musculoskeletal disorders: a treatment perspective. J Orthop Sports Phys Ther. 2004 Oct;34(10):628-37.
  5. Pheasant S, Haslegrave CM. Bodyspace: anthropometry, ergonomics, and the design of work. Bocca Raton: Taylor and Francis. 2006
  6. Helander M. A guide to human factors and ergonomics – 2nd ed. Boca Raton: Taylor & Francis, 2006.
  7. Mani L, Gerr F. Work-related upper extremity musculoskeletal disorders. Prim Care. 2000 Dec;27(4):845-64.
  8. Sartorio F, et al. Work-related musculoskeletal diseases in dental professionals. 1. Prevalence and risk factors. G Ital Med Lav Ergon. 2005 Apr-Jun;27(2):165-9.
  9. Bao S, Spielholz P, et al. Quantifying repetitive hand activity for epidemiological research on musculoskeletal disorders--part I: individual exposure assessment. Ergonomics. 2006 Mar 15;49(4):361-80.

Anne Nugent Guignon, RDH, MPH, provides popular programs, including on biofilms, power driven scaling, ergonomics, hypersensitivity, and remineralization. Recipient of the 2004 Mentor of the Year Award and the 2009 ADHA Irene Newman Award, Anne has practiced clinical dental hygiene in Houston since 1971.

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