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MAGNIFICATIONSeminar by Dr. SAPNA RANJANI You can only treat what you can see Prof. Syngcuk KimHuman vision Human eye is the unaided tool in vision and to a little extent in magnification Although clinicians have routinely tried to create bacteria-free seals, the resolving power of the unaided human eye is less

Limitations of human visionAn object can be focused generally no closer than 250 mm from the eye (depending upon how old you are!)

Young people may be able to focus as close as 125 mm so they can magnify as much as 2x because the image covers a larger part of the retina - that is, it is magnified at the place where the image is formedWhy enhanced vision in dentistry? Beneficial in producing precision dentistry

They routinely perform procedures requiring resolution well beyond 0.2 mm limit of human sight.Caries removal, root canal location, postplacement or removal, crown margins, scaling, incisions, grafting are some of the procedures that demand tolerance well beyond the 0.2 mm limit5The various development that aids in enhancing the vision Microscopes Magnifying Loupes

The Microscope according to American English dictionary defines it as an optical instrument that uses a lens or a combination of lenses to produce magnified images of small objects, especially of objects too small to be seen by the unaided eyes."

7HISTORY

1590 - Hans Janssen - the first compound microscope

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1665 - Robert Hooke History 1962 Jako

Baumanns microscope 1978Apotheker

Brought the concept of extreme magnification in the form of an operating microscope 1980sNoah chivianMicroscopes in dentistry 1981Chayes Dentiscope first commercially available DOM 1992Gary CarrErgonomically Operating microscopes ( Endo )OPERATING MICROSCOPES

How does Operating Microscope works?MagnificationIlluminationDocumentationAccessories

? ? MagnificationFour factors

Power of the eyepiece Focal length of the binoculars Magnification change factors Focal length of the objective lens

Power of eye piece Availabale in sizes 6.3x, 10x, 12.5x, 16x, and 20x.

Have adjustable diopter settings (adjust for accommodation i.e. the ability to focus the lens of the eyes)

Ranges from -5 to +5

BinocularsThey hold the eyepieces.

Adjusting the distance between two binocular tubes, sets the IPD.

Comes in different focal lengths. ( longer FL greater Magnification)

Available with straight, inclined or inclinable tubes.

Abilit decreases with age.14Straight tube binoculars preferred.

Chair positioned below for maxillary and above for mandibular arch

Disadvantage with Inclinable tube binoculars - its cost and difficulty to engineer .Magnification Changer

Available as either three or five-step manual changers or power zoom changers.

A power zoom changer is merely a series of lenses that move back and forth on a focusing ring to give a wide range of magnification factors.

Avoids momentary visual disruption or jumps

Controlled by either a foot control or manual Located on the head of the microscope

Focal length of the Objective Lens

Determines distance between the lens and the surgical field

Available with focal length ranging from 100 to 400mm

A 175 lens focuses at 7 inches, a 200mm at 8 inches and a 400mm at 16 inches

A 200mm objective lens recommended

Calculating total magnification:

The equation for calculating total magnification is:

MT = ft / fo x Me x McWhere:MT = Total magnification Ft = Focal length of the binocular tube fo = Focal length of the objective lensMe = Magnification of the eye pieceMc = Magnification factor / factor of the magnification changer

The Lower Magnifications 2.5x to 8x allow wide field of view and orientation to the surgical field

Midrange Magnifications 10x to 16x used for Operating procedures

Higher-range Magnifications 20x to 30x used for Observing fine details MAGNIFICATIONMagnification 2.5x to 30x recommended

Increasing the magnification, decreases the depth of field and vice-versa.

A typical microscope package could be one with 12.5X eyepieces, 125mm straight or inclinable tube binoculars, a power zoom magnification changer, and objective lens of 200mm.Short summaryIlluminationImportant to understand the path the light takes when it travels through the microscope.Light source is a 100-watts xenon halogen bulb.Intensity controlled by rheostat, cooled by a fan.Light field width of 45mm.Path of light Light Reflected - Condensing Lens - Series of Prisms - Objective Lens - The Surgical Field reflected back.

The separation of light beams is what produces the stereoscopic effect that allows the clinician to see depth of field.Two light source advised: Fan cooled xenon halogen bulb Quartz halogen bulb used in fiberoptic light system

Recommended lightingA fan cooled xenon halogen bulb(XHB) recommended

Fiberoptic absorbs light, tendency to be light deficient

XHB brighter & warmer, projects same against bone & soft tissue

Illumination with microscope is coaxial - Possible as it uses Galilean Optics

Galilean Optics focus at infinity & send parallel beam of light

Advantage being lengthy operation performed without eye fatigueDocumentationDocumentation is useful for

Patient Education, Medicolegal Documentation, Reports to Referring Dentist & Insurance Companies

Ability to produce quality videos & slides is proportional to the quality of Magnification & Illumination systems.

Beam splitter can be connected to photo & cine adaptersBeam splitter :

A beam splitter can be inserted in the path of light as it returns to the operator's eyes.

The function of a beam splitter is to supply light to an accessory such as a camera or an auxiliary observation tube.

Because the beam splitter divides each path of light separately, up to two accessories can be added.

Half of the light is always available for the operatorPhoto adapters attach 35mm camera & video camera to beam splitter which gets only half the light.

Hence , it is necessary to augment lighting system by adding strobe

Several strobes commercially available

AccessoriesMany accessories are made for the operating microscope

Pistol grip & Bicycle-style handles can be attached

An Eyepiece with reticule field can be substituted which helps in alignment.

Observation Ports added to beam splitter for teaching.

Auxiliary monocular or articulating binocular - for assistant

Assistants viewing is enhanced with LCD

Advantage of LCD being cost effective, sees what surgeon sees without taking eyes away from field.

Operating PositionsEach Division of medicine has developed operating positions from the uniqueness of its own speciality

Endodontists regarded as master of indirect vision

An approach that uses direct vision, is practical & comfortable.Most appropriate operating position is a combination of

Patient Head PositionDental Chair PositionMicroscope PositionSurgeon PositionAssistant PositionAssistant observation DevicesPatient Head PositionEnsuring Patient comfort - utmost important

No straining/torquing of head & neck muscles

Occlusal plane be parallel to floor for mandibular arch perpendicular for maxillary arch.

Head be comfortably centered or slightly turnedDental Chair PositionCan be maneuvered in variety of positions

Chair positioned slightly below the operator position for maxillary arch while slightly above for mandibular arch.

Microscope PositionCeiling mounted operating microscope most preferred.

Suspension arms supports in horizontal & vertical positions.

Friction Couplings allows movement of the arms & flexible joints.

Inserting 135 inclined coupler allows additional movements and more versatility

Surgeon PositionUse Adjustable stool

Thighs parallel to floor

Arms relaxed, comfortable at side

Facing side of patient ( may be the affected side).

Mandibular rightMandibular left

Mandibular anteriorMaxillary anterior

Maxillary rightMaxillary left Assistant PositionA well designed may use three dental assistants First assistant responsible for suctioning and is seated

Second assistant passes instruments & stands. Positioned to surgeons dominant side

Third assistant functions as change nurse. Also, in-charge of video and photographic features

Assistant Observation DevicesThree Observation Devices:

Articulating Assistant Binoculars,

LCD Screens &

High Resolution Monitors

Pre requisites For The Use Of The Microscope In Non-Surgical EndodonticsRubber Dam Placement

Indirect View and Patient head Position

Mouth Mirror Placement

Some Key Instruments

Advantages of DOMIncreased visualisationImproved quality and precision of treatmentImproved and ideal treatment ergonomicsEase of proper digital documentation capabilitiesIncreased ability to communicate through integrated videoDisadvantagesNeed for specific training as DOM has a restricted working field , 11-55mm.

Learning curve 9 months

High costAPPLICATIONS..Diagnosis untreated canalsLocating hidden canalsCalcified canalsPerforation repairBroken instrument retrievalFinal examinationSurgical endodonticsPatient educationIN ENDODONTICSIN RESTORATIVE DENTISTRYMicrofracturesCaries diagnosis microdentistry

Loupes

Dental loupes are becoming the must have accessory for every day practice.

Advantage - inexpensive system -learning curve 1 to 4 weeks

Disadvantage - plastic lenses are not always optically correct - increased image size depends on being closer to the viewed object musculoskeletal problems

Diopter systemRelies on simple magnifying lensDegree of magnification is measured in dioptersOne diopter means that a ray of light that would be focused at infinity would now be focused at 1 meter(100cm or 40inch)A lens with 2D designation would focus light at 50cm5D lens would focus light at 20cm

Galilean systemProvides a magnification range from 2x to 4.5x Small and lightCompact

Keplerian systemUse refractive prisms

They are actually telescopes with complicated light paths

Provides magnification upto 6x

Advantages of Galilean and KeplerianSuperior magnificationCorrect spherical and chromatic aberrationsExcellent depth of fieldIncreased focal lengthReducing eyestrain and head and neck muscle fatigueDisadvantages of loupesMaximum magnification is only about 4.5xLoupes with higher magnification are heavy and a limited field of view producing head , neck and back strain.AdvancesDentaloscopes

Endoscopes

Clinical practice with operating microscopes .not a fancy, but a necessity!

ConclusionThere has always been reluctance on clinician part to use microscope. However, after the initial learning curve, all procedures can be done in less time because of the great visibility of the operating area. Procedural errors can be greatly reduced, if not eliminated, and complicated case become easier under microscope.