By Anne Nugent Guignon, RDH, MPH
For years, clinicians sat on whatever kind of chair or stool the dental practice supplied. Typically, clinician chairs were -- and still are -- a part of the package anytime an office orders new patient chairs. The focus, however, is usually on matching fabrics and colors, rather than on the safety and comfort of the clinician who sits on the stool. The number of hygienists and dentists who suffer from back and shoulder pain is epidemic,1,2 but until recently, few paid much attention to the design of their seating apparatus and the ways in which the posture it requires could promote health problems.
Most of us were trained to sit with our thighs parallel to the floor, a posture that causes the pelvis to rotate backward into a non-neutral position and forces the muscles to support the torso, rather than the skeletal system. According to James Levine, PhD, from the Mayo Clinic, this type of posture leads many Americans to suffer from “sitting disease,” a condition that has ramped up the risk for obesity and other conditions associated with sedentary lifestyles.3 In addition to work-related sitting, the hours we spend sitting in cars, at desks, while watching TV and movies, and in many social settings all compound the issue.3
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Other articles by Guignon:
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According to Levine, standing is the antidote to sitting disease because it allows for deeper breathing, requires the spine to be used for supporting the body, reduces organ compression, and burns more calories. He recommends walking around while performing tasks that don't require a stationary position, such as talking on the phone.3 Still, many work settings are organized around sitting, and dentistry is no exception.
So, how can we continue to practice and optimize our personal health at the same time? Ergonomists recommend sit/stand positioning, a seating posture that keeps the spine in a standing profile. A sit/stand seating device is essentially a tool that, when properly sized and adjusted to the user, allows the user to keep their pelvis and spine in a healthy, neutral posture.4,5 Two seating options can help users accomplish this goal to varying degrees: exercise or stability balls and saddles.
Exercise or stability balls were originally used by physical therapists in Europe. Their popularity as a seating option has grown over the last decade, and balls are an economical way to begin exploring sit/stand positioning. When used on a regular basis, balls have an expected life span of about three years. Balls are made from vinyl and inflated to an individual user's preferred height and diameter. The user sits on the ball in a tripod-like position with feet flat on the floor, which favors a neutral spinal posture and facilitates deep breathing.6 Balls can be used directly on the floor or mounted in a square frame that has casters to facilitate repositioning. Small, peg-shaped wedges can be added to increase the height of the ball for those who wish to sit higher.
While there are a couple of ways to adjust balls, they lack a discrete height adjustment mechanism, which makes them less adaptable in the clinical setting than premium saddles, which can be adjusted at a moment's notice. This issue of adjustment comes into play when clinicians of various heights and weights are expected to use the same ball. Also, as patient sizes vary, there is no way to make a minor adjustment when one patient is a skinny seven-year-old but the next is a plus-sized adult.6 While sitting on a ball is a great option for one person who works at a fixed height, such as at a desk or table, it may be less functional in the clinical setting.
Shape is another limitation of balls. Balls do not allow clinicians to sit as close to the patient as saddles because balls have a round shape, while saddles have a very limited front profile. As a result of their round shape, balls also occupy more physical space than saddles do, so if treatment room space is at a premium, consider another option. The round shape of balls also complicates infection control. Since the clinician's buttocks, thighs, and calves are in contact with the surface of the ball, a much larger surface area has to be disinfected, as compared to the relatively small seat pan of the saddle. Special fabric covers are available for balls, but they need to be changed between appointments.
Saddle seating works for most women; however, not all men are comfortable with the overall design. Furthermore, saddles require for a few decisions to be made because of the different varieties. While all saddles are designed to accommodate a sit/stand posture, actual seat pan dimensions and design features vary per manufacturer, and there are four distinct seat pan designs: modified English, Western, dynamic, and the new Denver saddle, a design unique to Crown Seating. The goal is to select a saddle design that provides optimal body support and remains comfortable throughout each dental procedure:6-8
- The modified English seat pan is the most popular design. It features a relatively flat seat pan that is wider than it is deep and that has a slight rise in the middle.
- The Western saddle has a large hump in the middle and is an excellent choice for those with a narrow pelvis or tight hip muscles. The Western saddle is also rectangular in shape, but unlike the modified English seat pan, the Western seat pan is longer from front to back than it is wide.
- The dynamic saddle is made with a pivoting seat. The seat is shaped like a wedge; the front is narrower than the back, and it has a small lumbar support that allows the user to lean back during breaks.
- The Denver, unique to Crown Seating, is a more petite, square-shaped saddle that has a small cutout in the tailbone area. The Denver fits those body types that fall into the nebulous zone between the modified English design and the Western design.
In addition to looking for a saddle that provides optimum support, you'll also need to consider the saddle's cylinder height, seat pan tilt, padding, and upholstery. A premium saddle should have an adjustable cylinder and seat pan tilt. Both of these critical features allow clinicians to fully customize their seating experience. Some companies offer a range of cylinder heights. Standard cylinders work best for clinicians with an inseam length of 30 inches or less. Taller cylinders accommodate clinicians who have longer legs or who favor more narrow saddle seating designs, such as the Western or Denver. As your body adjusts to sit/stand positioning, you may want to gradually increase the saddle stool height, so it is important to purchase a saddle that has a cylinder that can be positioned higher.
Avoid purchasing a saddle that does not allow for a custom seat pan tilt. When the seat pitch is appropriate, the pelvis will be in a neutral position, and the body will feel balanced. If the seat pan tilt is incorrect, you will feel discomfort or pressure in the tailbone or pubic area. While it is normal to have a period of accommodation while learning to use sit/stand positioning, pain or discomfort after the first few weeks is a signal that the seating is putting you at risk for an injury, rather than contributing to a healthy posture.6,7
Depending on the manufacturer, a variety of padding options may be available: standard cut foam, injection-molded foam, memory foam, and injection-molded gel foam. Premium foam materials add to the overall cost but are more durable over the life of the saddle. While memory foam is quite popular, it adds bulk to the seat, which can be uncomfortable for those who are slender or who want a less bulky seating profile.
The saddle upholstery is another factor to consider. Most saddles are covered with textured vinyl, a surface that is easy to disinfect. Silvertex, a vinyl impregnated with silver ions for their natural antimicrobial properties, is available from several companies, as well. The fabric's natural antimicrobial is activated when it comes in contact with moisture, so the seat can be disinfected with either plain soap and water or a wipe. Very smooth vinyl and real leather should be avoided. Clinicians sit on saddles at an angle, so a smooth-surfaced vinyl can be too slippery. Natural leather, on the other hand, is porous and can absorb moisture from surface disinfectants, which causes the foam underneath to deteriorate.
In summary, the ideal sit/stand device allows a clinician to sit up higher and closer to the patient, maintain a healthy lumbar curve in the spine, and keep the pelvis in neutral.6-8 This is particularly important for all clinicians, but it is critical for those who are shorter in height. Wide patient chairs or chairs that won't go low enough to the ground can also compromise clinicians' abilities to access the oral cavity.
Don't be fooled by bargain-basement, nonadjustable products that are made with components that can't withstand the rigors of clinical practice. Treat your most precious tool, your body, to a seating system that supports and enhances your musculoskeletal health. Quality, custom seating is our new comfort zone.
References
1. 2007 Survey of current issues in dentistry – Physical well-being. November 2008. ADA.
2. Guignon AN, Purdy CM. Dental hygiene 2012 – workplace demographics, practice habits, injuries and disorders, academic awareness and professional attitudes. Unpublished data collected October/November 2012. https://www.surveymonkey.com/s/5K87Z25.
3. Levine JM. What are the risks of sitting too much? http://www.mayoclinic.org/healthy-living/adult-health/expert-answers/sitting/faq-20058005
4. Wang PC, Ritz BR, Janowitz I, et al. A randomized controlled trial of chair interventions on back and hip pain among sewing machine operators: the Los Angeles garment study.
5. Mandal AC. The Seated Man (Homo Sedens), Applied Ergonomics, 12.1, p. 19. Oxford 1981.
6. Tiedeman J. New concepts in seating. Accessed at content.statefundca.com/pdf/sftySeatingConcepts.pdf on June 15, 2014.
7. Mandel AC. Balanced seating posture on a forward sloping seat. Accessed at http://www.acmandal.com/ on June 15, 2014.
8. Gandavadi A, Ramsay JR, Burke FJ. Assessment of dental student posture in two seating conditions using RULA methodology – a pilot study. Br Dent J. 2007 Nov 24;203(10):601-5.
ANNE NUGENT GUIGNON, RDH, MPH, provides popular programs, including topics 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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