How to Profit From...handpieces — Handpiece ergonomics: weight, balance, and sound

Oct. 1, 2001
My childhood dentist was old and crotchety.

by Anne Nugent Guignon, RDH, MPH

My childhood dentist was old and crotchety. He worked without an assistant and used a belt-driven, slow-speed handpiece for all treatment. In 1968, the University of Missouri-Kansas City Dental School built a new building with state-of-the art, air-driven handpieces for all dental and dental hygiene students. We were proud to be the first class trained to do sit-down dentistry with such elegant equipment. More than 30 years later, dentists and hygienists are still looking for ways to provide quality patient care without sacrificing their physical and mental well-being in the process.

Since most dental procedures involve using a handpiece, it is important to consider the ergonomic impact of these tools when picking the perfect handpiece.

First, evaluate the weight of the handpiece. Typically, high-speed handpieces weigh about three ounces. In contrast, most slow-speed handpieces weigh at least twice as much. Some of the older slow-speed handpieces weigh more than half a pound! Many of these heavier models are still used for the polishing portion in a hygiene appointment.

Clinicians with small hands have a higher risk for significant fatigue if they have to support this type of unbalanced load. Fortunately, there are handpieces, generally marketed for the dental hygienist, that are specifically designed for polishing. These new polishing handpieces have their weight evenly distributed and weigh a mere three ounces, just like the high-speed models.

Handpiece balance is another important variable. It is impossible to evaluate the true balance of a handpiece if, for example, you go to an exhibit booth at a meeting and just pick one up.

Attaching the proper tubing to the handpiece will allow you to completely assess the weight and "feel" of a handpiece. The most accurate appraisal, however, is when you use the product in your own treatment room. Make sure the manufacturer will honor a return on the merchandise if it does not feel correct in your hands.

Another factor affecting handpiece balance is the hand size. A handpiece that fits a petite woman would not be optimal for a man with hands that can stretch two octaves on a keyboard. Also, most older, slow-speed handpieces are designed with very heavy motors at one end. The clinician is forced to leverage this additional weight during the dental procedure to keep the handpiece balanced. While this additional weight may not sound like much, repetitive stress injuries can occur within the muscles and nerves; the hands and forearms are particularly vulnerable. The angle of the handpiece head is also an important consideration. In the belt-driven days, handpieces were straight; a variety of attachments allowed clinicians to use these devices in many different ways. Some attachments were straight and others were contra-angled, allowing clinicians to maintain a neutral wrist position.

These contra-angled latch handpieces accepted everything from a bur to a mandrel to a prophy cup. Hygienists who upgraded from the hand-activated porte polisher thought they had really achieved something when they were allowed to use the belt-driven devices.

It is interesting to note that all of today's high-speed handpieces have contra-angled heads. The angulations range from 10 to 21 degrees; however, today's slow-speed handpieces typically are straight. Contra-angled attachments are available for slow-speed handpieces; however, straight attachments are the biggest sellers. If maintaining a neutral wrist position is important, then the contra-angled design is critical. Even though all of today's polishing handpieces are straight, there is one disposable contra-angled prophy angle available that allows clinicians to take advantage of this superior ergonomic design. Since every gram counts, also consider that disposable prophy angles weigh much less than the all-metal varieties.

For more than a decade, the diameter of most dental instruments has steadily increased. A larger shaft on any instrument decreases pinch/grip. In other words, you can lighten your grasp. A lighter grasp not only improves tactile sensitivity, but also keeps the body's muscles from working so hard to control these devices. A few years ago, a manufacturer developed a polishing handpiece with a much wider diameter grip in the posterior, allowing a more relaxed hand position. This larger grip has now been incorporated into the design of a new high-speed handpiece. Most likely, the handpieces of the future will incorporate these design innovations.

The texture on the instrument shaft also affects a clinician's pinch/grip. Texture equals traction; therefore, some type of texture or ribbing improves the clinician's ability to grasp the handpiece lightly while still maintaining control.

High-speed handpiece heads are available in a variety of sizes, from standard to a mini-configuration that is approximately 10 percent shorter from the back cap to the bur insertion point. Short-shanked burs also can reduce the overall size of the handpiece. High-torque heads are a bit wider than mini or standard heads. Selecting the appropriate head size enhances operator and patient comfort. Head size is also pertinent when polishing with slow-speed handpieces. Imagine trying to cram a long prophy cup into the mouth of a three-year-old just to polish the buccal of the upper right second deciduous molar. Petite cups are available either on disposable angles or for use on autoclavable angles.For many years, handpiece swivel was taken for granted, yet it is an important feature in overall operator comfort. If the handpiece cannot swivel, your wrist does all of the moving. This can become very fatiguing within a short period of time. Both high-speed and low-speed handpieces have swivel devices built-in at the hose end; however, several of the newest polishing handpieces have a 360-degree swivel control at the fingertips. Polishing with a handpiece controlled at the fingertips provides maximum clinician comfort.Handpiece hoses are an important part of the puzzle. Hoses should be supple, straight, and lightweight. Over time, hose material ages and loses elasticity. Chemical disinfection can discolor the hose materials, but it is oil that attacks the plastic in the tubing and causes rigidity. Inflexible hoses reduce the ability to manipulate the handpiece freely.

Replacing worn or dated hoses makes providing dental care a more comfortable experience. For example, a new ergonomic handpiece cannot perform at its ultimate potential if hooked up to short, inflexible tubing. Coiled hoses constantly tug on the hands and wrist and are as outdated as transistor radios. Heavy hoses, short hoses, and coiled tubing place unnecessary stress on the clinician's hands, wrists, and forearms. New hoses are easy to replace and are relatively inexpensive.

Cordless handpieces have been designed for specific clinical applications. Clinicians using cordless handpieces can maintain a neutral wrist position, because they are never forced to accommodate a handpiece hose. Several companies offer an endodontic model, which operates at one-quarter the speed of the cordless polishing handpiece. This endodontic model is designed with a gear reduction that allows the operator to use files at 130-400 rpms. The polishing handpiece gives the user control over the speed of the cup rotation. Both the cordless endodontic and polishing handpieces are contra-angled, adding to their ergonomic benefits.

Finally, have you considered the possibility that your handpiece might affect your hearing? Audiologists have established specific guidelines regarding noise and its potential to cause long-term damage. For example, the noise level in most libraries is 30 dB, while normal speech registers 60 dB. Intrusive noise, including background music, a noisy office, or a city street, starts at 60 dB. A noisy restaurant or a highway 30 feet away can register 70 dB. Noise levels above 90 dB are proven to cause permanent hearing loss, but what is the long-term effect of exposure to an 80-90 decibel range year after year? High-speed handpieces normally register from 65 to 75 dB; the additive effect of high-volume suction on hearing should concern all dental professionals..

Air turbine high-speed handpieces with metal bearings create more noise than the newer ceramic bearings, which reduce the overall noise of the handpiece by 10 to 15 percent. As metal bearings begin to wear, the overall noise output from a high-speed handpiece increases. Slow-speed and polishing handpieces have motors rather than bearings and do not generate the same noise levels as high-speed devices.

The issue of noise gets even more complicated when one considers that hard surfaces do not absorb sounds. Infection-control protocols demand easy-to-clean surfaces like tile on the floors of dental offices, rather than sound-absorbing materials like carpet. Consequently, sounds bounce around and become more amplified. If three clinicians are using high-speed handpieces in open cubicles full of hard surfaces, everyone's eardrums are at risk. What is the effect day in and day out?

One common patient complaint is the noise of the dental drill; the high-pitched whine can make the most compliant person completely uncooperative. You know the signs — patients who have their chins buried in their chests and whose facial muscles are so tense that you can barely slip a No. 4 mirror between the buccal mucosa and facial of tooth No. 14. Any clinician required to work in such a confined space certainly will be worn out by the ordeal. Clinician tension adds fuel to the ergonomic bonfire.

Since we're not going to trade in our modern handpieces for the old belt-driven models, what are some other options? Audiologists can fabricate custom-made earplugs; musicians' earplugs are another choice. These earplugs come with a tiny hole so that the wearer can hear a small amount of sound.

You may not be experiencing discomfort or hearing impairment at this point, but what are the long-term implications of using noisy, heavy handpieces? Do you know if your hygienists are having problems? Since many hygienists are reluctant to bring up these subjects, an employer who initiates an open dialogue about these these issues will be greatly respected. Unfortunately, many dental professionals accept pain as a normal part of practice. This is unacceptable, and we must be responsible for making the changes that will create a safer workplace.

Handpieces are built to be durable and provide consistent outcomes with each appointment. So why are we so content to use the same old handpiece, year after year, despite the advancements in technology? Why do we never consider upgrading one of the key instruments in generating practice revenues, yet rarely hesitate to upgrade the machines that collect the revenue?

Where is the economy in this type of thinking? When handpieces become obsolete, they can be replaced. Our physical well-being may be much more difficult, if not impossible, to restore. What if ergonomically designed handpieces reduced clinician physical stress and resulted in fewer repetitive stress injuries? What is the value to our spouses, children, and friends if we finish our day at the dental office feeling calmer and less fatigued?

It makes good economic sense for both dentists and hygienists to consider today's handpieces that can offer superb performance, in addition to helping us protect our careers from the ravages of cumulative trauma disorders.

Oh, yes, I must tell you: As a practicing clinician, I do not miss getting my hair caught in the spinning handpiece belt any more than I miss having my teeth rattled out of my head by a slow-speed, belt-driven handpiece. Thank goodness for technology!

The author wishes to thank Dr. Roger Kaestner for his invaluable assistance with this article.

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