Precision dental Instrumentation

UNDERSTANDING MAGINIFICATION

Magnification is the increase in size of an image, produced by an optical system, compared to its true size. For years, many dental practitioners have benefited from the use of vision-enhancement devices, such as loupes, surgical telescopes, and head-mounted surgical fiber-optic lamps . It is generally accepted that the better the visual access to the operating field, the higher the quality of treatment that can be accomplished.

WITHOUT AUGMENTED MAGNIFICATION

Dentistry is a profession that demands fine and accurate skill. Practice of fine dentistry is highly dependant on excellent hand-eye coordination and the utmost perfection of manual dexterity. Years of committed practice of dentistry burdens the operator with many an occupational hazard and the most common among them is eyestrain. Studies have shown that87 % of dentists suffer from some form of eyestrain, and 90 % of dentists will require visual assistance at some point in their practice. In addition to eyestrain, recent studies have also demonstrated that dentists also suffer from various musculoskeletal disorders, commonly chronic lower back pain. In a landmark survey conducted in 2006, amongst dentists of Queensland,indicated 87 % of dentists report symptoms from musculoskeletal disorder! It is a very well documented fact that permanent cure or relief from chronic lower back pain is slim. Carpel Tunnel Syndrome(CTS) is another scourge that haunts both dentists and dental hygienists. CTS results from poor posture at work, particularly arising from slouching shoulders and excessive neck strain.

Evidence suggests that using magnification loupes will improve the posture of dental clinicians, thus decreasing work-related musculoskeletal disorders. According to extensive studies carried out by - James T& Gilmour AS at Cardiff University School of Dentistry, magnification loupes clearly enhances visualization of fine detail, compensates for the loss of near vision (presbyopia) & ensures maintenance of correct posture. The wearing of loupes is becoming an accepted norm amongst qualified practitioners and increasingly in the undergraduate population.

VIEWING UNDER PROPER MAGNIFICATION AND LIGHTING

In order to understand the need and advantage that magnification offers, one should appreciate the limitations of the human eye in viewing fine objects. The human eye is really ill equipped when it comes to viewing fine objects placed away from the eye. This is because the total refractive power, measured in diopters, of the internal lens of the eye, is only 20 diopters ! But the internal lens , in response to nervous signals from the brain, can increase its curvature markedly to provide “accommodation” . Which means, the lens could gain a higher refractive power to bring in more magnification. The more a lens bends light rays, the greater is its “refractive power.” However, this greater refractive power is possible only through contractions of two sets of ciliary muscle fibers. It is thus with this increased refractive power, obtained through straining the ciliary muscles, that the eye focuses on objects nearer than when the eye has less refractive power. [ See Presbyopia ]

In the dental operatory the clinician spends the bulk of his/her time focusing on objects [ eg: margins of preparations, orifices of root canals etc] that are extremely small in size and considerably away from the eye. When the operators is unable to focus clearly, two events take place – [1] The ciliary muscles of the eyes strain to achieve the refractive power; [ 2 ] the operator tries to move his eyes closer to the object [ eg: margins of preparations, orifices of root canals etc]by slouching , bending the lower back , bending the neck or even elevating the patient’s head! These compensatory actions, taxes the muscles of the eyes, lower back and the neck. When these muscles are strained in such manner, multiple times in a day, over several years, irreversible degenerative changes set in.

By bringing in an external magnifying lens [ a pair of surgical loupes ] with a higher refractive power than the internal lens of the human eye,and positioning it between the fine object and the human eye, a higher magnification of the object is achieved. The size or enormity of the magnification achieved is purely dependant on the power of the external lens and can be controlled. The object maybe magnified 2.5 times the original size, 3.5 times or higher. Magnification provided by the external lens, helps relax the ciliary muscles of the eyes by reducing the strain upon it. The external lens do not have the feature of accommodation that the human eye possesses, hence can be in sharp focus only at a set distance. Which means the operator is forced to maintain an upright posture to be able to see clearly, thus the muscles of the lower back and the neck are spared from compromising stresses.

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