How Magnification and Ergonomics Matter in Dentistry
One of the major challenges in dentistry is viewing the oral cavity. Since the early days of fiber optic lights to today’s highly-refined procedure scopes, visualizing the oral cavity has come a long way. With the advancements in magnification, dentists are now more productive and confident in the treatment that is provided to patients. Additionally, magnification comes with many ergonomic benefits. Today, magnification aids, such as surgical loupes or telescopes, are becoming a worthy investment in the field of dentistry.
It has been shown in many studies that students who use magnification loupes work in much better ergonomic positions than those who only use safety glasses. But why should good posture matter? Neck pain is associated with working conditions in which a person holds a forward head position of 20 degrees or more for 70 percent of the working time. Dentists and hygienists routinely work with a forward head position of 30 degrees for up to 85 percent of their working time. This leads to the staggering statistic that 70 percent of dental professionals experience neck pain.
What happens when the head is held in an awkward, unbalanced working position is that the vertebrae cannot support the spine, which causes the shoulders’ stabilizing muscles to quickly fatigue. When other muscles, such as the levator and trapezius, try to compensate to hold the neck and shoulders stabile, they too fatigue because they are performing tasks for which they are not designed. These factors lead to what is known in the field of dentistry as “tension neck syndrome,” or TNS. The symptoms of TNS include chronic neck pain, headaches, shoulder pain and pain radiated into the arms. In more severe conditions, excessive forward head positions can lead to cervical disc degeneration and spondylosis.
With quality surgical and dental loupes (or telescopes), a proper head position of 0 to 25 degrees can be easily achieved. This is because loupes, microscopes and procedure scopes maintain a set focal range, or working distance while keeping an image in focus, allowing the user to maintain a correct working position.
On the market today, the three basic types of magnification systems: loupes (TTL or flip-up), surgical microscopes and the procedure scope. Similarly to other technical device, all of these systems require proper selection, accommodation time and adjustments. The learning curve with microscopes and procedure scopes is a few months, whereas, most users feel comfortable with the loupes after one to two weeks. Numerous surveys show that the loupes users notice immediate improvement with the forward head position and lessening of TNS symptoms.
Well made loupes need to be light, have good declination angle and high quality optics. They are much preferred over the older styles of loupes that are heavy and bulky. Today, more and more dental professionals are “discovering” the value that the surgical and dental loupe systems have to offer. Loupes also stand today as the most popular magnification system in the field.
Loupes are also known as telescopes. And while they do not provide a neutral head position (ear-over-shoulder), they do enable a working head position of less than 25 degrees forward. The magnification strength available in loupes range from 2X to 8X. Two distinct styles are available: flip-up loupes and through-the-lens (TTL) loupes.
Flip-up loupes are the most popular type of system. It features magnification loupes that are mounted on a hinge mechanism in front of an eyeglasses lens. As the name implies, the scopes can be flipped up when magnification is not needed. Flip-up loupes offer the steepest declination angle for correct head posture. This angle is adjustable and, therefore, can be customized to any working style. Dental flip-up loupes allow for easy changes to eyeglass prescriptions without expensive changes to the lenses.
Most advanced surgical flip-up loupes are being offered by Precision SCOPE, a US company based in Maine. The system was developed by a dentist and distinguishable by a barely noticeable 1mm bar that is located under the magnification loupe. Such unique bar position makes looking over the loupes easer with less weight.
TTL loupes feature a magnification scope mounted directly onto the eyeglasses lens and have a fixed declination angle. TTL loupes have a wide field of vision since the scope is closer to the dentist’s eye. There are a few downsides to TTL loupes. If the dentist changes the eyeglasses prescription, the loupes must be modified by the manufacturer increasing the cost. In addition, not all procedures require magnification at all times, whereas safety eyeglasses might be necessary. Some doctors find that since the magnification loupes are positioned very close to the eyes, the user has to bend forward too much to see over the loupes. Such repetitive movement is not ergonomic and increases chances of neck disorders.
Understanding Procedure Scopes.
Procedure scopes enable a neutral head position and reduce eye fatigue. It features an extra oral camera positioned above a patient’s mouth from which an image is projected onto a flat LCD video screen. The screen is at the dentist’s eye level and allows the provider to move around freely while still viewing the LCD screen. Equipment is sanitized similarly to microscopes.
The procedure scope’s depth of field is four inches, so the entire oral cavity can be in focus at the same time. It takes a few months for most providers to feel comfortable using a procedure scope. The scope offers a great deal of flexibility and does not require additional prescription lenses except safety glasses.
Microscopes enable a near-neutral head position and indirect viewing of the oral cavity. An upright posture is maintained because a microscope can bend the path of an image 90 degrees or greater (via inclinable binoculars).
Some degree of customization to achieve an optimal working position is possible by adding vertical spacers to the microscope or by replacing the objective lens to increase working distance. Microscopes can achieve the magnification power of up to 40x. Due to their size and small field of view, microscopes are primarily limited to the field of endodontics.
Finding the Right Loupes
As the most popular and cost-effective magnification means, the surgical and dental loupes had become the standard of practice. Loupes can range from $700-$2,200 for either flip-up or TTL styles; whereas microscopes range from $14,000 to $45,000 and procedure scopes can cost in excess of $30,000.
It is important to cover the main criteria, such as quality, for selecting the right pair. Poorly made loupes and lenses can actually worsen symptoms of TNS, muscle strain and headaches. It is important to select a reputable company with high quality standards since you will use the loupes daily for many years. The three criteria to consider for proper loupe selection are working distance, declination angle and frame shape/size.
The working distance is the essentially the distance from the dentist’s eyes to the work area. If the working distance is too short, a dentist will hunch and experience excessive neck flexion. A proper working distance is dependent on the size of the operator, but generally it is between 14 and 20 inches when measured sitting in a neutral position with the patient’s mouth at or slightly above the elbow.
The declination angle is the angle at which an operator’s eyes are inclined downward toward the working area. It is important that this angle is steep enough to attain a comfortable working position without too much forward head tilt.
Generally, flip-up loupes allow for the steepest declination angle and a more neutral head position over TTL loupes. Flip-up loupes are preferred by many dentists, because the scopes can be flipped up when the magnification is not used. For example, during treatment the doctor can talk to the patient, apply additional anesthetic or trim temporaries while seeing the entire working field. All can be achieved without removing the loupes and gloves. When possible, request the steepest declination angle available from the manufacturer of the surgical loupes.
Proper frame shape and size is built around the simple concept that larger frames sit lower on an operator’s face, thereby allowing a steeper declination angle (even on TTL loupes). Still, always request the lowest placement of the scopes on the eyeglasses lenses as the manufacturer allows. Ideal frames should wrap around the face with minimal fogging of the lenses while wearing the mask.
Magnification Strength and Illumination.
Selecting the right magnification strength depends on the type of work being performed. In general, hygienists and general dentists prefer 2.5X to 3.0X magnification; and endodontists/periodontists prefer a power between 3.5X and 4.5X, or higher. It is often best to choose the lowest magnification. This way one can both view and control the surgical field. Remember that the higher the power of magnification, the shorter the depth of field, the more difficult the hand eye coordination.
Illumination is also important for efficient working postures, as shadows in the oral cavity can encourage the provider to lean or hunch. It is recommended that operatory light be placed parallel to or within 15 degrees of the operator’s line of sight. Surgical headlamps can significantly reduce shadowing by aligning the light’s direction with the operator’s line of sight. Loupe manufacturers often carry a wide selection of surgical headlamps or portable LED headlights.