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Low back pain is a daily reality for many dental professionals. In an excerpt from her new book, Bethany Valachi, PT, MS, CEAS discusses seating techniques to help safeguard your musculoskeletal health.
Chances are good that you have experienced low back pain at some point in your life. More than 75% of adults in the United States experience back pain at some point in their lives;1 in a given year, about 10 to 15% of these adults experience low back pain.2
However among US dental professionals, the one-year prevalence of low back pain hovers around 40 to 60%.3-5 In fact, low back pain is so common among dental professionals, especially general practitioners, that many have come to passively accept it as a necessary evil of their occupations.
The problem of low back pain in dentistry is a multifactorial one, and causal factors run the gamut from emotional hypertension to equipment adjustment errors.
However a primary contributing factor to low back pain among dental professionals is static, poor seated posture that directly impacts the health of the lumbar spine and musculature. Proper selection, use and adjustment of operator stools can have positive ramifications, not only for the lower back, but for your entire body.
Seated postures in dentistry
Attaining a healthy seated working posture can be surprisingly difficult for many dentists and their staff, and it can dramatically impact low back pain. It's not at all uncommon to see operators slouching, perched on the edge of their stools or in other unhealthy working postures.
Let's examine some common seated postures, how they occur in the operatory, and how they affect your low back health:
Passive sitting, which looks like slouching, is a common posture in the operatory because it expends very little energy. In this posture the pelvis rolls backward (Fig. 1A), causing the lumbar curve to flatten. Since nearly every curve of the spine affects the curve above or below it, the flattened low back curve causes a reciprocal forward movement of the head. Now the operator's spine is in a ‘C'-shape, providing little support and the body is literally hanging on the soft structures at the back of the spine.
The flattened lumbar curve significantly increases the load on muscles and spinal discs.6 It can also stretch and permanently elongate the iliolumbar ligaments (aka ‘creep'), decreasing spinal stability.7,8
Over time, ligaments, muscles and soft tissue may stretch or shorten to adapt to a slouched working posture and hold the spine in unbalanced posture. Muscle strains, headaches and trigger points result from this posturing as well as the possibility of disc degeneration or herniation.9
Active sitting. Remember your mother always telling you to sit up straight? You may have also heard a version of this in dental or hygiene school, or even an ergonomics seminar. While it is obvious that good posture is key to injury prevention in dentistry, this advice is often given without context or specific instructions. Commanding operators to "sit up straight" encourages most of them to assume active sitting (Fig. 1B).
This type of sitting actively forces your pelvis into a more neutral position through constant contraction of the back extensor muscles which help maintain your lumbar curve.10 Unfortunately, this posture places greater loads on the spine than does standing, uses up significant energy, and cannot be maintained for very long.11,12 When your muscles fatigue, you simply slump into passive sitting. A backrest can help reduce muscle fatigue, but during procedures you are rarely resting against the backrest.
Learning how to properly "sit up straight" involves correct biomechanics, proper chair adjustment, seat selection, specific endurance training of certain back muscles: the erector spinae (large muscles on either side of your spine) and multifidus muscles (small muscles located close to your spine, deep in your low back) and proper working distance and declination angle of your scopes.
This is a lot of information to absorb. Try to think of each part of your body as a tool with a specific function (which it is). You wouldn't use a hammer to install a screw, so why would you force the structures of your back to assume postures it wasn't meant to hold? This is why it's crucial to find a seating option that places the pelvis in its most neutral position so it balances the spine, reduces muscle strain and decreases disc pressure.13
Improving operator posture
Maintaining neutral low back posture in dentistry is essential in the prevention of low back pain and your career longevity. This means maintaining a slight curve in the low back when seated or standing.
In dental school, you were probably taught to sit with your thighs parallel to the floor, or your hips at a 90-degree angle on a flat seat pan. This seating encourages the pelvis to roll backward and flatten the low back curve (Fig. 1A).2,6,14 Your only options to maintain your lumbar curve on a flat seat pan are to either 1) sit actively, which requires constant contraction of the back muscles and can usually only be maintained for short periods of time, or 2) maintain constant contact with a well-designed lumbar support.
