Part one of this 2-part series focused on the resolving power of the human eye and how magnification could improve that resolving power. In addition, the amount of visual information across various powers of magnification was shown graphically. The concept of how many clinicians progress from entry-level loupes through midlevels of magnification and, at times, end up using operating microscopes was broached with the “Magnification Continuum.” Part 2 will look at the advantages of using telescopic loupes in dentistry, and conclude with the 4 advantages of using the operating microscope in dentistry.
Benefits in Using Loupes
Two of the most common benefits that clinicians find for using loupes in dentistry are the purported improvements in ergonomics, and in precision of treatment rendered. The perception is that when loupes are properly fitted, they will encourage improvements in posture, and in doing so reduce stress on the neck and back. It is a common refrain from many of the loupes companies that properly adjusted loupes lead to improvements in ergonomics, which in turn will decrease the risk of debilitating injury to the clinician.1-10 The concept is that when a clinician has a forward head position of 20° or more for greater than 70% of the time, he or she will have a higher risk of neck pain.11 In dentistry, most dentists are working with a forward head position of 30° or more for 85% of the time in the operatory, and this leads to neck pain in 70% of dentists and dental hygienists.12-14 The need and desire to more clearly see the operating field causes the clinician to lean forward, and the neck vertebrae cannot support the spine in this forward position. This then leads to rapid fatigue of the shoulder muscles that are stabilizers, and inclusion of other muscles to compensate for a job they are not designed to do. These compensations can lead, amongst other things, to tension neck syndrome with pain in the neck, shoulders, and intercapsular muscles. Long-term disc degeneration has been noted from a prolonged forward position of the head. It is important to know that improper adjustment or use of magnification aids can in fact either increase the risk of injury or worsen existing pain.15-17
While none of the telescopic loupes systems mentioned previously (single lens, Galilean, or Prismatic) can lead to a complete neutral and balanced posture, the use of well-designed loupes can enable a working posture of 25° forward.18 It is important to choose loupes with a good declination angle that will allow for as minimal forward head position as possible, as the more forward the loupes push the head, the more likely that strain on the neck muscles and discs will occur.19-20
Another issue of concern that must be properly fitted with telescopic loupes is the working distance to the surgical site. If the chosen working distance is too short, then the operator will likely be forced to either hunch over or use excessive neck flexion in order to obtain a sharp image of the operating field.21 It is important to realize that the working distance is related to operator height, and is measured from the corner of the eye to the working surface. Working distances can vary from 14 inches to more than 20 inches, and this needs to be tailored to the operator. In addition, intraoral mirrors are used frequently in dentistry and can be important in selection of the correct working distance for any individual and should be used when figuring out the correct distance for any clinician.
Finally, the larger the frame selected for any set of loupes, the lower these glasses will sit on the cheek of the operator. Lower positions are better, as they allow for an improvement in declination angle of the through-the-lens (TTL) telescopes, as they can be placed with a steeper declination angle at the bottom of the frame.
As the level of magnification increases through the Magnification Continuum, the need for accessory illumination also becomes more important. Today, many powerful LED lights offer tremendous illumination with reduced weight and extended battery life. Some new cordless varieties of diodes are beginning to enter into the dental market, and this not only reduces cabling but weight of the illumination module. The cost for loupes typically ranges between $700 and $2,200, depending on the company, magnification chosen, and type of loupe chosen. A properly adjusted set of loupes, when adjusted for declination angle, working distance, and frame size can significantly reduce the risk of debilitating occupationally induced neck and back discomfort (Figures 1 and 2).
|Figure 1. A dental hygienist with improved posture, using 2.5x through-the-lens (TTL) loupes for hygiene.|
|Figure 2. Key ergonomic factors to consider when considering ergonomic principles with surgical loupes.|
Another advantage found with using loupes, cited by many clinicians, is an improvement in precision due to the increased amount of visual information that magnification and illumination provide to the operator. Unfortunately, there are very few well-designed, peer-reviewed scientific studies that have been published showing a correlation between enhanced visual acuity leading to an improvement in quality of care.4,22 In fact, although some studies have shown that dental students make fewer errors with loupes,23-25 other research is not so definitive in its conclusion of a positive impact in quality with magnification.26,27Although the literature, at this point, does not support the fact that quality of treatment, longevity of treatment, or overall prognosis of treatment is affected by magnification, the general consensus amongst many clinicians is that their work was improved upon beginning with surgical magnification, when compared to before. In addition, subsequent increases in the amount of magnification used also commonly seem to yield improvements in the precision of one’s work. The list below is meant as an introduction to some of the manufacturers in North America, and this should not be seen as an exhaustive list, but a starting point for those with an interest in purchasing loupes or headlights.
- Designs for Vision (designsforvision.com)
- Orascoptic Loupes (orascoptic.com)
- Surgitel Loupes (surgitel.com)
- Zeiss Loupes (meditec.zeiss.com)
- Sheervision Loupes (sheervision.com)
- Seiler Loupes (seilermicro.com)
Advantages of Using Operating Microscopes
As the clinician enters into the higher levels of magnification (4x to 6x power and above), the choices are limited to heavier and more expensive TTL loupes with headlamps, the dental operating microscope, and a few heads-up display systems. Mamoun28 has cited the benefits of higher magnifications for all areas of dental practice.
The Dental Operating Microscope (DOM) is different than loupes in that it offers true stereoscopic vision (as compared to the loupes with its convergent vision). The DOM can be mounted on a ceiling, wall, or floor stand, but may also have a mobile base that allows some mobility from room to room. The microscope has coaxial (light pathway coincident with the visual pathway) illumination and this provides intense shadow-free lighting. The microscope has multiple levels of magnification, typically ranging from low magnification (2.1x, 3.2 x) to medium magnification (5x to 8x) and high levels of magnifications (13x to 19x), making it easy to access with the turn of a turret. All ranges of the magnification spectrum are used, depending on the procedural needs (Figures 3a to 4).
|Figure 3a. At 2.1x magnification.||Figure 3b. At 8x magnification.|
|Figure 4. At 19x magnification.|
The DOM will provide clinicians with 4 main advantages. These include improvements in precision of treatment, improvements in ergonomics, better communication with patients (through live video, and an increased ease in documentation.
The application of the operating microscope in clinical dentistry can be traced back to Drs. Apotheker and Jako in 1981.29 He converted a medical operating microscope for use in endodontics. Although the scope itself was a rudimentary one level of magnification and required the operator to stand upright, it was the introduction of a concept that would revolutionize the discipline of endodontics. Pioneering endodontists including Drs. Carr, Arens, Buchanan, Kim, and Ruddle, led to the routine use of the therapy.30-37 The usage of the operating microscope in endodontics has been shown to improve the ability to uncover more pulpal anatomy as compared to the use of little magnification or low power loupes38-45 (Figures 5 and 6).
After the introduction of the microscope to endodontics, there was a spike of interest in the DOM for periodontics, and it was found by Drs. Shanelec, Belcher, Nordland, McGregor, and others that routine usage of the DOM could provide for more delicate surgical procedures, utilizing microsurgical armamentarium, including smaller blades and 7-0 to 10-0 sutures. These delicate surgical procedures allowed for improvements in postoperative pain and quicker healing.36,46-53
|Figure 5. The MB1 and MB2 canals, 3x magnification.||Figure 6. Pulp chamber, lower molar.|
|Figure 7. Early occlusal caries, 13x magnification.||Figure 8. Crack entering MB canal at 13x magnification.|
|Figure 9. Veneer preps at 5x magnification.||Figure 10. Evaluating impressions, 13x magnification.|
|Figure 11. Crown prep at 13x magnification.||Figure 12. Veneer cement removal at 19x.|
During the 1990s, a small group of restorative dentists, many with an active interest in endodontics, started to incorporate the microscope as an important part of the armamentarium in general practice. For these restorative dentists, the microscope became an integral part of all dental procedures, as they discovered that the dramatic improvement in visual information provided by the DOM allowed for a level of precision in both diagnosis and treatment outcomes that were not previously possible54-68 (Figures 7 to 12).
In addition, and perhaps most importantly, the operating microscope provides tremendous ergonomic benefits. The clinician sits in a comfortable upright position, relying upon directed patient movements or movements of a mirror to visualize the surgical site (Figure 13). The head has the ability to look straight ahead, with little forward head rotation if the microscope is properly adjusted. If the operator uses a microsurgeon’s chair to support the gross motor joints (shoulders and forearms), then precise micromotor movements can be completed. The balanced position of the clinician when using the microscope may help reduce musculoskeletal injuries that are common among members of the dental profession.2,3 Future work needs to be completed to see whether the ergonomic benefits in using a microscope will be superior to that of well adjusted loupes, but the author is familiar with several clinicians who have had severe neck pain, degenerative discs, or in one instance (Figure 14) spinal injury, who were able to resume their practice with the introduction of the operating microscope to their practice.
As well as the ergonomic benefits, dentists using the operating microscope have discovered that either a medical grade cube video camera, or a slightly heavier HD digital camcorder (Sony HDR SR12 or similar) (Figure 15) (when attached to the microscope) can be useful in providing both patients and the auxiliary staff with the ability to observe treatment in real time. In fact, today’s single-lens reflex cameras have the ability to capture short clips of video on the same camera card that digital photographs are captured.
One advantage of running the video from the microscope to the monitors in the operatory is that you can now involve the assistant in the “micro” world. This helps aid in instrument passages, and in addition helps alleviate the assistant from being inadvertently “blinded” from reflections of the microscope light off an intraoral mirror.
Patients can benefit from being able to watch the video overhead via connection to a LCD monitor or television in that they are able to follow along live during treatment. A consequence of this is that patients tend to hold still, and are educated to the complexity of the procedure by being given an opportunity to observe treatment as it progresses. There are a multitude of benefits to the integration of video to the microscope.69
|Figure 13. Improved ergonomics are evident with microscope use; note less head forward position, and less declination angle, resulting in less neck and back pain. The operator practices in a neutral “comfortably slumped” posture, resulting in less tension for both the shoulders and spine.|
|Figure 14. Dr. Rex Hawthorne (general dentist, Vernon, British Columbia) was paralyzed from the waist down in a mountain bike accident, but was able to return to work with a specially designed wheelchair. An operating microscope and a tremendous desire helped him accomplish a full return to private practice.|
Mehrabian70 has shown that as much as 55% of the understanding that occurs in verbal communication is through visual cues, and that only 7% of the comprehension in communication comes from the words we use. Stated differently, patients remember more of what they see than what they hear, leading to the familiar phrase, “A picture is worth a thousand words.” Many microscope enthusiasts ask then, “How much is a magnified, real-time video image worth?” Clinicians have found that the images from the operating microscope are a benefit in educating patients about their treatment needs. The ability to easily document a procedure using digital microphotography and micro-videography with cameras attached to the operating microscope opens up new possibilities for patient education, documentation for articles, professional presentations, and medical/legal documentation.71 Microscopes costs vary between $5,000 to $50,000, depending on the manufacturer, number of magnification steps, options and accessories chosen. Some manufacturers include:
- Global microscopes (globalsurgical.com)
- Zeiss microscopes (meditec.zeiss.com)
- Seiler microscopes (seilerinst.com)
- Leica microscopes (leica-microsystems.com).
A newer technology in the arena of magnification is the heads-up display, which involves a camera that is placed over the patient, projecting the image to a monitor. The projection of the image can be 2-dimensional (Magna Vu) or 3-dimensional (3-D) (MoraVision [moramicro.com]) and may help reduce the learning curve that has been associated with the operating microscope. The ergonomic benefits of these heads-up displays have also been discussed as perhaps having the possible improvements in treatment outcome and communication through documentation with video and captured stills.72 These systems are, in many cases, more expensive than the operating microscope, ranging in price from $25,000 to $50,000 (with the 3-D system being more expensive) (Figure 16).
|Figure 15. Attachment of a Sony digital camcorder (Sony HDR HC7) to document procedures in video format and transfer it to monitors in the operatory.|
|Figure 16. The author tries out the 3-dimensional (3-D) heads-up display (Moravision 3D) where the operator works in 3-D with glasses while looking at a monitor. There are 4 HD cameras that supply the image to the monitors for both clinician and dental assistants.|
Challenges of Incorporating Magnification Into Daily Practice
Any time that a practitioner is interested in incorporating new technology into a practice, there will be challenges, and integrating higher levels of magnification is no different. Initially, there is a cost to purchase any form of magnification. Typically, loupes are less expensive than an operating microscope or heads-up display system. The price of magnification can be sizable if one is equipping multiple operatories or purchasing more than one set of loupes. Most clinicians agree that the first set of loupes will likely not be your last, and those clinicians who fully integrate microscopes into their office often discover that one microscope is not enough if multiple operatories are used on a daily basis.
The learning curve varies with the degree of magnification, and for that reason, many clinicians would be wise to purchase their initial loupes in the 2x to 3x magnification range. This will make the learning curve from days to weeks, but of course this can vary with many factors such as the age of the practitioner, the speed of the office pace, the ability of the practitioner to handle the slowdown that is necessary initially as more visual information is seen. There is also the issue of magnification scotoma (blind zone) that makes peripheral vision difficult with loupes. This blind zone increases with the power of magnification, and with loupes, the magnification scotoma can be best overcome by subtle repositioning of the head one way or another laterally. In the case of the microscope, the operator must learn to move less, relying more upon moving the head or position of the patient or by moving the intraoral mirrors more. This process will increase the learning curve in microscope integration to months before proficiency is met with all magnifications being able to be used in all areas of the mouth.
Many clinicians are concerned with the perception that patients, including children, will find the magnification systems to be peculiar. However, even microscopes and heads-up displays have been integrated into pediatric practices.72,73
Finally, there is a concern that dependency will occur with the full integration of magnification in one’s practice. There is no evidence in either the dental literature or the medical literature to suggest that consistent usage of loupes will create a weakness or early deterioration of natural eyesight, and as mentioned, clinicians in their 40s will naturally encounter difficulty with presbyopia, which necessitates the usage of reading glasses for close up viewing.
Dentistry is both physically and mentally challenging on a daily basis, and the rapid influx of new equipment, techniques, and materials have made our profession even more demanding. The incorporation, proper setup, and regular use of magnification into regular daily practice can alleviate neck and back pain, aid in treatment outcomes, and assist in documenting and communicating with patients. You cannot treat what you cannot see. So, do not hesitate to begin your journey along the Magnification Continuum, or to continue to a higher level of magnification should you already have some form of magnifiers. It’s a win-win for you and your patient!
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Disclosure: Dr. van As has received honoraria from Global Surgical Corporation.