Why magnification can be the ergonomic breaking point for endodontists
Do you see it clearly?
Endodontists have one thing in common: they work on a millimeter scale. Without magnification, precise, reliable root canal treatment is unthinkable. Yet, magnification is a double-edged sword: it can be a blessing for your vision, but a pitfall for your body. The choice between working without magnification, with loupes, or with a microscope determines not only the quality of your treatment but also the longevity of your career. As Dr. Gary Carr, pioneer in endodontic ergonomics and microscopy, once said: “If you can’t see it, you can’t treat it.” I would like to add: “If you can’t sit in a relaxed way, you won’t last in your profession.”Thus, the right magnification method is not only an optical decision but, just as importantly, an ergonomic one.
Loupes under the microscope
In dentistry, roughly two types of loupes are used: Galilean loupes and prismatic loupes (also called refractive or Keplerian loupes). Both magnify the view, but their impact on working posture differs drastically.
The Galilean loupe is still by far the most common model in dental practice. Through the combination of two lenses, an objective and an eyepiece, this loupe offers a clear and magnified image. Manufacturers often present it as “the better lens,” but optical quality doesn't tell the whole story.
With the Galilean loupe, the lenses are set at a fixed, downward angle in the frame. This requires the practitioner to tilt their head slightly forward to maintain the correct line of sight. At the same time, the eyes must remain directed diagonally downwards, which eventually leads to overuse of the neck muscles and fatigue of the extraocular eye muscles.1, 2 In other words: optically functional, but ergonomically a pitfall, especially with prolonged use.
The prismatic loupe, on the other hand, currently represents the top segment among loupes. Thanks to its built-in prism, light rays are deflected, allowing you to look down with a straight neck. The declination angle, the angle at which you look down without bending your head, is significantly increased. The result: a relaxed, upright sitting posture and a drastic reduction in the strain on neck and back muscles.1
1. Dentist with Galilean loupes. The Galilean loupe magnifies the view, but only partially improves working posture. (Note: This dentist is not wearing a face mask because the photo was taken during a simulated treatment as part of an individual ergonomics training session).
2. Dentist with prismatic loupes. The prismatic loupes not only magnify but also ensure a much better working posture. Note: the loupes are only effective if the practitioner has completed proper ergonomics training. Failing to do so is one of the 7 most common ergonomic mistakes (see the article in Dentista 3, 2025, pp. 6063). (Note: This dentist is not wearing a face mask because the photo was taken during a simulated treatment as part of an individual ergonomics training session).
"For dentists who do not (yet) work with a microscope, the prismatic loupe is, in my opinion, the only responsible choice."
Why a maximum of 3x magnification?
It sounds tempting: the more magnification, the better you see. But precisely here lies the greatest ergonomic pitfall. With magnifications above 5x, the depth of field becomes so small that even minimal head movements can blur the image. This leads to an unconscious tendency to move the head or torso to maintain a clear view. And that's precisely what you want to avoid. A magnification of 3-4x offers a good balance: sufficient detail, while the depth of field remains large enough to work upright in a relaxed manner. Anything above that is fantastic for the first five minutes, but disastrous for your neck, shoulders, and upper back after five years.3. Do you need greater magnification from a dental (visual) perspective? That's what a microscope is for.
The microscope: the gold standard
For endodontists, the microscope is the gold standard. Not only because of its optical quality, but certainly also because of its ergonomic benefits. A properly adjusted microscope offers four essential advantages:
1. Magnification as desired – stepless or adjustable in six steps, without having to adjust your posture.
2. Stereoscopic vision – through both eyes, the brain receives two slightly different images, enabling true depth perception.4
3. Working at a distance – the magnification allows for a generous working distance, so you can remain seated upright.
3. Practitioner behind the microscope with their eyes aligned with the binoculars (without the tube extender). The dentist has their head in anteposition because the tube is too short. This leads to neck complaints/a painful, tired feeling between the shoulder blades.
4. The dentist behind the microscope with their eyes not aligned with the binoculars. In this image, they are sitting relaxed and upright, making good use of the lumbar support. The distance between their eyes and the binoculars shows how much their head was previously brought into anteposition.
4. Integrated illumination – optimal illumination of the working field, without extra weight on the bridge of the nose. However, the microscope is not automatically ergonomic. In practice, I often see endodontists bringing their head into anteposition while working. This is a forward position of the head relative to the torso. This is often due to incorrect adjustment of the binoculars or a tube that is too short. The result is a slight but prolonged static muscle tension in the neck, which almost always leads to complaints in the long run.5
Therefore, correct adjustment of the microscope is crucial. It must be adapted to the user's height and sitting posture. When working, always keep your back against the lumbar support and let the microscope move towards you, not the other way around.
If the tube + binocular combination is 'too short', an extension ring (tube extender) can be placed in consultation with the manufacturer. This increases the working distance, allowing the practitioner to remain seated upright in a relaxed manner. (Image 5: The tube extender is placed under the black arrow).
Dr. Carr describes doing "everything" under the microscope, even placing the rubber dam. A prerequisite is that the microscope has six magnification levels. Or, in the case of stepless adjustment, that the area between the nose and chin remains clearly visible at the smallest magnification.1
Six ergonomic factors when purchasing loupes
When purchasing loupes, it's not just about magnification, but about balancing optics and ergonomics. Six factors are decisive:
1. Working distance. The distance between your eyes and the working field determines your sitting posture. If the distance is too short, you lean forward; too long, and you unnaturally stretch your neck. Therefore, always have this distance professionally measured and custom-set.
2. Depth of field zone. The larger the zone in which the image remains sharp, the less you have to move. Above 3–4x magnification, the depth of field decreases sharply.2
3. Declination angle. How far can you look down without tilting your head? Prismatic loupes score best here; Galilean loupes do not deflect the image, causing the head to tilt forward more quickly.
4. Convergence angle. The angle at which the two optical axes converge. With correct adjustment, the axes intersect precisely in the working field, so the image remains comfortably sharp. Incorrect convergence causes double vision and fatigue.
5. Magnification factor. A magnification of 3-4x is ideal. Less provides too little detail; more leads to unnecessary muscle tension.
6. Lighting needs. Loupes with integrated LED lighting are convenient but add weight to the bridge of the nose. The microscope has illumination integrated into the optical axis, which is both ergonomically and visually superior.
5. Practitioner behind the microscope with a tube extender. Below the black arrow, you can see the tube extender we installed. Now the practitioner is sitting completely relaxed, supported upright, with the binoculars fitting nicely.
Microscope versus prismatic loupe: stereoscopic vision
A key difference between the microscope and the prismatic loupe is the method of depth perception. The microscope offers true stereoscopic vision: the brain receives two slightly different images through both eyes, creating a realistic experience of depth.4 The prismatic loupe works with convergent vision: light rays are artificially brought together, creating the illusion of depth. It appears as if there is depth, but the perception is less true to life.
Is stereoscopy really an advantage then? Yes, especially in endodontics. Depth perception is essential for recognizing subtle structures such as fissures, foramina, and calcifications. A well-adjusted microscope provides a clear, three-dimensional image, making these microstructures more visible and allowing treatments to be performed more accurately.9-11 Nevertheless: a poorly adjusted or rarely used microscope is less valuable than a well-adjusted and correctly used prismatic loupe.
The chair: with armrests
A common mistake is working without armrests. Without support, the arms remain in static elevation for prolonged periods, leading to increased muscle tension in the shoulders and neck.6 Research shows that using arm and backrests significantly reduces muscle strain and improves the precision of hand movements.7 Dr. Gary Carr and Juan Carlos Ortiz Hugues consistently emphasize this in their ergonomic literature: a chair with armrests is not a luxury for endodontists, but a necessity.
The correct inclination angle
In dental microscopy, the inclination angle refers to the slight downward tilt of the binocular tube relative to the horizontal line. This fixed angle ensures that the image from the working field is optically guided to the practitioner's eyes. The goal is simple: the microscope allows you to look straight ahead, while the optical system bends the image upwards.
When the binoculars are correctly adjusted, the practitioner's gaze is in a neutral, relaxed position. The tube then tilts only slightly downwards, about ten to fifteen degrees, so that the eyes remain in their natural, slightly downward position without the eye muscles constantly having to correct. This allows the endodontist to work sharply and comfortably, with a straight neck and a stable posture.
It is important that the practitioner does not adapt to the microscope, but the microscope adapts to the practitioner. A correct inclination angle makes it possible to work with sustained concentration without visual or cervical overload. Recent research also confirms that using a microscope significantly reduces the strain on the neck and shoulder muscles compared to working with loupes or without magnification. This is precisely due to this ergonomic viewing direction.8 It is therefore one of the most underestimated, but also most decisive settings for sustainable microscopic working comfort.
The author
Matthijs Luitjes is a physiotherapist and ergonomist, specializing in oral care professionals. With his company Ergonomic Solutions (www.ergonomicsolutions.nl) and via LinkedIn, he helps professionals in the Netherlands and abroad with alleviating and preventing work-related pain.
info@ergonomicsolutions.nl.
References
The literature list can be requested from the editorial office and viewed online with the article at
Conclusion
Endodontics is a high-performance sport. Like an athlete, an endodontist needs precision, stability, and endurance, and that starts with an ergonomic working posture. Magnification is not only a visual aid but a prerequisite for sustainable work.
Galilean loupes offer reasonable optics but are ergonomically inadvisable. Prismatic loupes are an excellent choice for those not (yet) using a microscope. The microscope remains the gold standard, provided it is properly adjusted and combined with a chair that offers arm and back support.
Error! Filename not specified.Because seeing well is one thing. Staying pain-free at work, that's the real gain.