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Dentistry used to be an ergonomic standing profession. Once practitioners took a seat, it became a pain in the neck…and back…and arms…and eyes… The general public often stereotypes a visit to the dentist as an uncomfortable experience. But patients don’t realize their dental practitioners all too often experience musculoskeletal pain that surpasses their discomfort during an oral exam. Worse yet, many professionals believe head, neck, shoulder and back pain are all part of the job.
Dentistry used to be an ergonomic standing profession. Once practitioners took a seat, it became a pain in the neck…and back…and arms…and eyes…
The general public often stereotypes a visit to the dentist as an uncomfortable experience. But patients don’t realize their dental practitioners all too often experience musculoskeletal pain that surpasses their discomfort during an oral exam. Worse yet, many professionals believe head, neck, shoulder and back pain are all part of the job.
“It’s been widely accepted among dentists that pain is an intrinsic part of dentistry, and it doesn’t have to be” said Bethany Valachi, PT, MS, CEAS, a physical therapist, lecturer and author who specializes in dental ergonomics and consults with dental professionals on all aspects of ergonomics.
An online survey conducted by DPR shows dentists want to practice ergonomically, and they are willing to make the necessary adjustments to ensure their health and that of their staff.
Three-quarters of those participating in the survey indicated that practicing dentistry in an ergonomically sound way is something they value as a dental professional, and another 20% said it is somewhat important. When asked for their reasons, many indicated they had either experienced first-hand the debilitating effects of incorrect ergonomics or have seen it in colleagues.
Obviously, dental professionals want to practice in the most comfortable working position possible, but unfortunately many resort to working in the most practical position because they have never been trained properly about tools (chairs, loupes and lights) to achieve ergonomic postures.
“There’s going to be something that you can do faster if you go into a compromised posture, and as a result, dentists teach themselves how to do damage to their health,” said Dr. David J. Ahearn, founder of Design/Ergonomics, which consults with dentists to design healthy, efficient and productive offices and operatory setups.
The key is to start in an ergonomically proper position that will be comfortable for long stretches of time. Once that is set, the other factors involved in ergonomics should relate back to the posture without altering it.
Although dentists and hygienists spend the majority of their day in a seated position as in traditional office settings, their seating requirements are quite different. Working on an office computer, the work usually is straight ahead, which warrants an upright posture and straight neck. But Alan Hedge, PhD, CPE, Director of Human Factors & Ergonomic Factors at Cornell University, said this does not translate well to dentistry because the focus of your attention-the patient’s oral cavity-is below a horizontal line-of-sight plane. Therefore sitting requires a different set of guidelines.
Have a seat
It is from an ergonomic starting position that you make your chair selection, not the other way around.
“Your operator stool is arguably your most important tool,” Dr. Ahearn said. “It should be the first thing you buy, and it’s usually the last, often an afterthought thrown in with the purchase.”
Just like dentistry presents unique requirements for sitting position, so does the seat.
“We work in a proclined position, so we need a seat with a steep waterfall or a saddle-type seat to support that,” Dr. Ahearn said.
Valachi suggests an operator stool with a tilting seat pan, but cautions operators should tilt it forward only between 5° and 10°.
“If you over-tilt it, you can cause hyperlordosis of your lumbar curve, which is too much low back curve,” she warned.
In addition, she said if the seat pan tilts too far forward, there’s a danger of sliding on the washable surface. She points out that retrofit kits or angle seat cushions are available to angle non-tilting seats for proper seating. Hedge recommends sitting on a height-adjustable split-saddle seat or on an ergonomic stool such as the swopper.
In conjunction with the seat pan, the backrest should have a forward adjustment as well.
“The lumbar support on an ergonomically designed backrest is slightly convex to naturally fit your low back curve when sitting upright,” Valachi said. “Unfortunately, most dental stools do not have this.”
The backrest does not need to be more than 8-to-10-inches tall to provide adequate lumbar support. In fact, large backrests that extend above the lower edge of the shoulder blade can inhibit movement in the operatory, she added.
Also, stools for both dentists and hygienists should have compact yet stable, multipoint caster bases for mobility and to allow a close proximity to the patient chair with easy-to-access chair adjustment controls.
Stand and deliver
Even if the majority of dental treatment calls for a seated position, variety in overall position can help prevent fatigue and stress.
“Stand up and move around whenever possible,” Dr. Hedge suggested.
Most patient chairs adjust high enough to allow dentists to perform treatment procedures while standing, if desired, Valachi pointed out.
“Dentists can stand for injections, extractions, impressions, consultations, examinations,” she said. “Alternate between sitting and standing. That’s a huge benefit right there.”
The delivery system used in the operatory is another point sometimes overlooked or treated as an afterthought.
“Certain delivery systems have pros and cons,” Valachi said. “You need to choose a delivery that best fits your body size, your operatory layout, and each team member.”
According to the survey, more than two-thirds of doctors (70%) promote proper ergonomics for themselves and their staff through specific equipment and seating purchases. Another 11% indicated they made specific purchases for their dental hygienists, and 9% for their dental assistants.
Valachi said a rear delivery system works well when true 4-handed dentistry is practiced. A side delivery setup is less effective because the assistant cannot reach instruments and handpieces.
“Over-the-patient is one of the best from an ergonomic standpoint,” she said. “But if the user has a very short torso, they’re going to be reaching repeatedly upward, and that movement biomechanically leads to shoulder pain.”
“You can’t use what you can’t reach,” Dr. Ahearn said. “Create an environment for delivery that’s efficient and ergonomic. If you’ve got the doctor in the ideal position and then you have to get out of that posture to get what you need, then we just threw it all away.”
Tim Caruso, PT, MBA, MS, Cert. MDT, CEAS, put it another way, “Sometimes, habits overrule ergonomics.” Even when dentists want to practice ergonomically, they may have trouble changing established posture and that shifting into a proper ergonomic sitting position may cause discomfort so they slide back into unhealthy sitting profiles, he added.
When designing the ideal delivery system, Dr. Ahearn worked with a NASA ergonomist as well as MIT engineers for input on working interfaces and how the patient’s sense of space fits in with the dental delivery setup. The result was an over-the-head system that allowed the doctor and assistant to access instruments without undue reach and without impeding on the patient’s personal space.
It allows for a smaller yet more spacious and efficient treatment environment,” he said. “This reduces costs and increases productivity.”
Arguably, properly selected and adjusted magnification loupes can provide numerous benefits to users in terms of reduced strain on eyes, neck, shoulders and back. However, they need to be used properly, or you will suffer the consequences.
“Many people think loupes solve ergonomic problems, but loupes can create ergonomic problems,” said B.J. Chang, PhD, President and Chief Scientist of SurgiTel/General Scientific Corp. “If they’re using the wrong kind of loupes, then they are forced to use excessive head tilt. Then they develop chronic neck pains, eventually neck surgery and early retirement. The key is to find loupes that meet their ergonomic requirements.”
“Loupes sit differently on every face, depending on the height of the nose bridge, the depth of the eyes, and other facial features,” Valachi said, emphasizing the need for loupes to be custom-fit to the individual user.
Some of the key factors to consider when selecting dental loupes include lens styles such as front-lens-mount (FLM) with flip-up option or through-the-lens (TTL) options, interpupilary distance, depth of field and working distance as well as convergence angle, viewing angle and declination angle.
Valachi said poor declination angle of loupes is the No. 1 magnification problem in dental operatories. The declination refers to the downward tilt angle of the loupe lens, which added to the neck tilt forward adds to the total viewing angle.
FLMs are almost always going to allow the best declination because the scope is not built into the glass and adjustable,” she said. “TTL models with a pantascopic tilt feature will generally provide the best declination for TTL users. The tilt feature means the bottom part of the glasses are angled back toward the cheek. The lenses of sports frames angle slightly backward as well, which allows better declination.”
The optimum declination angle will vary according to physical features of users or procedures. Too small or too large declination angles will foster poor postures. Certain FLM models feature such adjustment options as double hinges and vertical positioning mechanisms that allow users to fine-tune their declination angles to achieve the maximum comfort. Chang said the convergence angle (the inward tilt of the lenses toward the object) should be custom set and fixed to provide for the optimal working distance and depth of field, which can help offset poorer vision due to age.
He suggests a 2.5X magnification for beginning loupe users, with more powerful levels up to 3X or 3.5X for taller wearers because the longer working distance requires more magnification power to achieve the same visual acuity with the shorter working distance. Magnification powers are available up to 8X.
eight also can be a factor in loupe selection, but should not supersede affecting the vision. Valachi said FLMs, which allow the best head posture, have been less popular because they have traditionally been heavier. However, several flip-up models on the market today are ultra-lightweight with ideal declination angle to allow for optimal head posture.
A TTL model that offers good declination angle to one user may not be able to offer good declination angle to another user, Chang said.
Don't forget the patient
Now that you’ve got yourself into the proper, ergonomic posture, it’s time to add the patient into the equation.
“How you position the patient really should be balanced in favor of the doctor,” Dr. Ahearn said. “You need to be comfortable. The patient needs to be okay.”
Valachi said proper patient positioning complements doctor positioning. To get the patient’s head into this ideal position, use a chair with a double-articulating headrest that angles up into the patient’s occipital and angles downward, or add a contoured ergonomic dental cushion under the patient’s head.
“When treating the maxillary arch, the occlusal plane of the upper arch needs to be angled backward up to 25° in relation to the vertical plane,” she said. “Usually, what I see in the operatory is the upper arch more vertically angled, and then the doctor is forced to crank their head forward.”
Aggie Pennington, Senior Equipment Product Manager for DentalEZ Group, offered additional factors to consider in selecting a treatment chair for doctor and patient ergonomics.
“What you need is a very thin chair back so you can come down as low as possible onto the dentist’s legs,” she said. “The thicker that back is, the more your arms have to be up higher because the patient’s head is up higher. The more you have to raise your shoulders and arms, that’s when you start to have health issues.”
The chair back should be narrow across, and the base of the chair should be cut in to allow close access to the patient, she added.
Another feature to consider, offered in DentalEZ’s J/V-Generation J-Chair models, is an independent tilt that helps maintain proper spinal alignment to reduce stress on the discs and soft tissue around the patient’s spine. The “lounge-chair” feel allows the patient to recline farther into a supine position.
Turning for help
Ergonomics is one aspect of dentistry where dentists, dental assistants and dental hygienists often are left to find answers on their own. Hedge said he doesn’t know of any dental schools that offer training in ergonomics, and a search of dental school curricula backs his assessment.
In addition, there are no professional societies in the United States dedicated to the study and promotion of dental ergonomics, though the European Society of Dental Ergonomics does offer information for members and holds an annual meeting (June 4-5 in France).
Consultant agencies such as Valachi’s Posturedontics Inc. and Dr. Ahearn’s Design/Ergonomics provide doctors, hygienists and assistants with research-based education on establishing proper ergonomic working conditions and unbiased reviews of dental ergonomic products, as well as instruction on reversing some of the negative cumulative effects of improper ergonomics, before it’s too late.
Hedge also provides general ergonomic information online at ergo.human.cornell.edu.
“You want to pay attention before you feel pain,” he said. “You want to pay attention to discomfort. If you are getting any signs like headaches, neck aches, back aches, sore arms, sore wrists, those kinds of signs are telling you that something is not right with how you are working.”
About this survey
The February 2010 DPR Ergonomics Survey was sent via e-mail to 9,266 general practitioners in the United States. The link to the survey was also promoted on Facebook, where we currently have 4,304 followers. The survey was completed by 103 respondents.