INTRODUCTION

"There is a thin line between excellence and perfection".

Since time immemorial, dentistry in general, and endodontics in

particular has strived to bridge that thin gap in the quest to achieve

perfection. Brilliant developments, pains taking research and landmark

break thorough have characterized endodontics relentless march towards

the ideal.

The development of various aids to arrive at the right diagnosis, the

introduction of different armamentarium to achieve good access and

thorough cleaning and shaping of canals, the advent of myriad obturating

techniques and materials, and advances in surgical endodontics coupled

with the explosion in the understanding of anatomy, histology,

inflammation & healing, host responses, microbiology & pathology etc.,

have been spawned by the constant endeavors to achieve the best & have in

turn made the highly specialized field of endodontics extremely predictable

& immensely successful.

Today endodontics is a highly successful & widely practiced branch

of dentistry. However it seems to have reached a plateau, the success &

popularity of endodontics have brought with it numerous complications

and exciting new challenges. The focus has now shifted to not just

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achieving excellence but in achieving perfection. It is in this scenario that

the technological marvel of microscopes has blitzkrieg into endodontics.

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."

Microscope has been around for a long time. It may be surprising

that the microscope is not a high-tech instrument. It has been used in

medical field for over 50 years; the microscope was first introduced to the

otolaryngology around 1950’s, then to neurosurgery in1960’s and to

endodontics in the early1990’s. As in medicine, the incorporation of the

microscope in the clinical endodontics has had the profound effects on the

way endodontics is done & has changed the field fundamentally. For this

reason, in 1998 ADA accreditation requirement change states that all the

accredited United States post-graduate programs must teach the use of

microscope in non-surgical & surgical endodontics. This was a giant step

forward in the advancement of endodontics.

Now a days, if we wish to offer an endodontic treatment with all the

problems that may be encountered such as locating hidden canals,

management of calcified canals, perforation repairs, retrieval of broken

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instruments, final examination of the canal preparation etc., the surgical

operating microscope is an integral part of the therapy process.

The microscope has opened up the hitherto hidden world and helps

us visualize what till now escaped undetected. It has literally become the

third eye of the astute clinician. The range of magnification that this

instrument produces enables a wide vista of versatility. From the field of

dental diagnosis to the intricate art of surgery, the field of restorative

dentistry, oral pathology & microbiology and the highly precise branch of

endodontics, every specialty is being benefited by the intricate application

of this technology.

Operating microscope is the answer to the daily challenges in

dentistry. There are no limits to the clinical applications in diagnosis and

therapy e.g., for the removal of initial caries with maximum protection of

the tooth concerned of for the preparation of gingival margins. The

diagnosis with the dental microscope has attained unparalleled heights of

precision. Coming to restorative dentistry, the microscope will permit the

optimum cosmetic outcome for a maximum patient satisfaction. It gives an

outstanding contrast, excellent depth orientation, and relaxed stereoscopic

vision.

The operating microscope can give a successful endodontics as the

tooth structure and all the root canals are precisely and clearly visible. The

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result: optimum therapy for conventional endodontics to microsurgical

apicectomy. Thus, the exacting science of endodontics demands the utility

of such high precision instrument.

“You can treat what you see and you won’t what you don’t”

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HISTORY OF MICROSCOPE IN ENDODONTICS

In 1922, Carl Nylen, did the pioneering work at the university of

Stockholm with the development of a monocular microscope for ear

surgery. (From this beginning, microsurgery has spread to literally all the

surgical disciplines).

In 1953, Carl Zeiss company of west Germany marketed the first

binocular operating microscope, this historical development of operating

microscopes provides an instructive perspective.

It wasn't until 1978, Apothekar, DMD, & Jako, MD, pooled their

efforts to produce a DOM (Dental Operating Microscope) or Dentiscope.

Their designs were incorporated in 1981 into the first commercially

available DOM (Dentiscope, Chayes-Virginia Inc., Evansville, IN). This

two developers, in conjunction with Chayes-Virginia, offered the first

course in the clinical hands-on course for use of Dentiscope at the Harvard

Dental School, Boston, Massachusetts, on September 25th, 1982.

In 1986, in those early years, interest among endodontists in the

DOM seemed to have been spotty at the best. As a result of disappointing

sales, Chayes-Virginia stopped selling the Dentiscope.

In March 1993, 11 years after the introduction of Dentiscope, the

first symposium on microscopic endodontic surgery was held at the

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university of Pennsylvania school of Dental Medicine. This heralded the

beginning of serious attention to DOM.

By 1995, there was an obvious increase in DOM use by the

Endodontists, which was sparked in large measure by the proliferation in

the 1990s of numerous commercially available scopes suitable for office

use. These new scopes offered the advantage of the choice of multiple

steps of magnification, as well as other sophisticated features. This led to a

workshop for endodontic program directors, sponsored by the American

Association of Endodontists (AAE), on teaching microscopy. This

preceded an anticipated ruling to mandate the scope’s inclusion in program

standards by the Commission on Dental Accreditation (CODA) of the

American Dental Association. The wheels of change started to move

rapidly in 1995 as the AAE formally recommended to CODA that

microscopy training be included in the new Accreditation Standards for

Advanced Specialty Education Programs in Endodontics. At the

Commission’s January 1996 meeting, the proposal was agreed upon. The

new standards, making microscopy training mandatory, became effective

in January 1997.

Microscopy in endodontics has certainly come of age, but its

gestation period was surprisingly long. Isn’t it surprising how long

sometimes it takes for a new technology to take hold? That DOM is a good

example of a technology that experienced a slow acceptance.

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HOW OPERATING MICROSCOPE WORKS

One of the most important developments in endodontics has been the

introduction of the operating microscope.

Initially conventional surgical telescopes or loupes were used for

magnification along with surgical headlamps. They were available with

limited magnification, so came the operating microscope which has a

capacity of magnification ranging from 3x to 30x and beyond. The lower

magnifications (2.5x to 8x) are used for orientation to the operating /

surgical field and allow a wide field of view. Mid range magnifications

(10x to 16x) are used for conventional endodontic and surgical procedures.

Higher range of magnifications (20x to 30x) are used for observing final

details.

To appreciate what a DOM can do, it is important to understand how it

works. The four areas to be discussed are:

1. Magnification

2. Illumination

3. Documentation

4. Accessories.

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I. Magnification:

Magnification is determined by four factors, this includes:

1. Power of the eyepiece,

2. The focal length of the binoculars,

3. The magnification changer factor and

4. The focal length of the objective lens.

i. Power of the eyepiece: eyepieces are generally available in powers of

6.3X, 10X, 12.5X, 16X, 20X.

The viewing side of an eyepiece has a rubber cup, which is turned

down if the surgeon wears eyeglasses. Eyepieces also have adjustable

diopter settings. Diopter settings range from -5 to +5 and are used to adjust

for accommodation, which is the ability to focus the lens of the eyes. The

ability to accommodate decreases as people age. Diopter settings also

adjust for refractive error, which is the degree to which a person needs to

wear corrective eyeglasses.

ii. The function of the binoculars is to hold the eyepieces. As in a typical

pair of field binoculars, adjusting the distance between the two binocular

tubes sets the interpupillary distance. Once the diopter setting and the

interpupillary distance adjustment have been made, they should not have to

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be changed until a surgeon with the different optical requirements uses the

microscope.

Binoculars often come in different focal lengths. In choosing

binocular focal lengths, it is important to remember that the longer the

focal length, the greater the magnification and the narrower the field of

view. Shorter length binoculars allow the operator to have a wider field of

view and to be a little closer to the patient. Binoculars are available with

straight, inclined, or inclinable tubes.

Straight tube binoculars are oriented so that the tubes are parallel to

the head of the microscope. Straight tube binoculars are suggested because

they allow the operator to look through the microscope directly at the

surgical field. Ear, nose and throat (ENT) surgeons use this system. Similar

to endodontists, ENT surgeons use the chair to position the patient so that

they can use direct vision while operating. The chair is placed below the

operator for maxillary surgery and slightly above the operator for

mandibular surgery. This allows the clinician to look down the axial plane

of the root in maxillary teeth and up the axial plane of the root in

mandibular teeth.

Straight tube binoculars have the advantage of allowing the use of

direct vision in both the arches. Straight tube binoculars gain even more

versatility when a 135-degree inclined coupler or variable inclined coupler

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is placed between the mounting arm and the microscope. This coupler

provides additional axis of rotation and aligns the microscope so that

straight tube binoculars provide direct vision whether the patient is sitting

up or lying down

Inclined binoculars are oriented so that the tubes are offset at 45

degrees to the head of the microscope. Inclined binocular tubes could be

used for maxillary surgery, but the operator would have to use indirect

vision through a mirror or position the patient's head sharply to the side

while performing mandibular surgery.

Inclinable tubes are adjustable between the straight tube and slightly

beyond the inclined tube positions up to and sometimes beyond 90 degrees.

Inclinable tube binoculars can often provide the operator with the

additional postural comfort during long procedures. The only

disadvantage of inclinable tube binoculars is that they are difficult to

engineer and as such can be quite expensive.

Ophthalmologists position the patient in such a fashion that the eye

is always facing up. Because it would be physically impossible for them to

work directly over the patient, eye surgeons use inclined or inclinable

binoculars tubes so that they can approach the patient from the side.

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iii. Magnification changers are available as either three or five-step

manual changers or power zoom changers. Some companies also make a

manual version of a power zoom changer. Magnification changers are

located within the head of the microscope.

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.

Power zoom changers avoid the momentary visual disruption or jump that

occurs with three or five-step manual changers as the clinician rotates the

turret and progresses up or down in magnification. Magnification changer

functions in power zoom microscopes are controlled by either a foot

control or a manual override control knob located on the head of the

microscope.

The operating microscope is focused similar to a laboratory

microscope. The manual focusing control knob is located on the side of the

microscope housing and changes the distance between the microscope and

the surgical field. As the control knob is turned, the microscope moves ups

and down along a focusing tract, and the subject is brought into focus.

Before the microscope can be used, it must be parfocal, meaning

that it is in focus throughout the entire of magnification. In addition, when

the microscope is parfocused, accessories such as cameras and auxiliary

binoculars are also in focus.

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iv. The focal length of the objective lens determines the operating

distance between the lens and the surgical field. With the objective lens

removed, the microscope focuses at infinity and performs as a pair of field

binoculars. A variety of objective lens is available with focal lengths

ranging from 100 to 400 mm. A 175-mm lens focuses at about 7 inches, a

200-mm lens focuses at about 8 inches, and a 400-mm lens focuses at

about 16 inches. A 200-mm objective is recommended because there is

adequate room to place surgical instruments and still be close to the

patient.

Charts are available that explain magnification as it relates to

eyepiece power, binocular focal lengths, magnification factors, and

objective lenses. In addition, they explain magnification as it relates to the

depth of field and field of view. These charts contain valuable information

that helps the clinician select the appropriate optical components to satisfy

his or her requirements. The information can be summarized as follows:

1. As you increase the focal length of the objective lens, you decrease

the magnification and increase the field of view. In addition, you

decrease the illumination because you are the further away from the

surgical field.

2. As you increase the focal length of the binoculars, you increase the

magnification and decrease the field of view.

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3. As you increase the magnification factor, you increase the

magnification and decrease the field of view.

4. As you increase the power of the eyepiece, you increase the

magnification and decrease the field of view.

5. As you increase the magnification, you decrease the depth of field.

After considering all the factors just described, a typical microscope

package could be one with 12.5X eyepieces, 125-mm straight or inclinable

tube binoculars, a power zoom magnification changer, and an objective

lens of 200 mm. This package would allow the clinician to operate

comfortably about 8 inches from the patient and in the magnification range

of about 3X to 26X. The power zoom feature would allow a smooth zoom

with an 8:1 ratio. The remote foot controls would allow magnification and

focus adjustments to be made without taking the hands or eyes away from

the surgical field.

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Calculating total magnification:

The equation for calculating total magnification is:

MT = ft / fo x Me x Mc

Where:

MT = Total magnification

ft = Focal length of the binocular tube

fo = Focal length of the objective lens

Me = Magnification of the eye piece

Mc = Magnification factor / factor of the magnification changer

II. Illumination:

To understand illumination, it is important to understand the path

light takes when it travels through the microscope. It has the light source

with a 100-watt xenon halogen bulb. The light intensity is controlled by a

rheostat and cooled by a fan. The light is then reflected through a

condensing lens to a series of prisms and then through the objective lens to

the surgical field. The microscope has a light field width of 45 mm. After

the light reaches the surgical field, it is reflected back through the objective

lens, through the magnification changer lenses, and through the binoculars

and then exits to the eyes as two separate beams of light. The separation of

light beams is what produces the stereoscopic effect that allows the

clinician to see depth of field.

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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 operator. In

addition to 50:50 beam splitters, other configurations are also available.

As the magnification is increased, the effective aperture of the

microscope is decreased, and therefore more light is needed. In addition,

optics absorbs more light at higher magnification. Two light sources

systems are commonly available:

1. The xenon halogen bulb used in a fan-cooled system and

2. The quartz halogen bulb.

A fan-cooled xenon halogen light system is recommended because

fiberoptic cables absorb light and have a tendency to be light deficient.

Whereas the quartz halogen bulb is found in the fiberoptic light

system used by ophthalmologists. In addition, xenon halogen is lighter and

warmer than quartz halogen and therefore projects a brighter and warmer

light against bone and soft tissues.

Illumination with the operating microscope is coaxial with the line

of sight. This means that light is focused between the eyepieces in such a

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fashion that the clinician can look into the surgical site without seeing any

shadows. This is made possible because the operating microscope uses

Galilean optics. Galilean optics focuses at infinity and sends parallel beams

of light to each eye. With parallel light, the operator's eyes are at rest as

though he or she were looking off into the distance. Because of this,

lengthy operations can be performed without eye fatigue.

III. Documentation:

The ability to produce quality slides and videos is proportional to

the quality of the magnification and the illumination systems within the

microscope. The beam splitter, which provides the illumination for the

photographic and video documentation, can be connected to the photo and

cine adapters. The function of these adapters is to attach the 35-mm and

video cameras to the beam splitter. Photo and cine adapters also provide

the necessary focal length so that the cameras record an image with the

same magnification and field of view as seen by the operator. Because the

35-mm camera gets only half the available light and because of the relative

intensity of color photographic film, it is usually necessary to supplement

the microscope's lighting systems by adding a strobe over the objective

lens. Several strobes are commercially available and can be adapted to the

operating microscope.

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In contrast to 35-mm color film, videotape is an extremely sensitive

format and does not need supplemental light. Many video cameras are

commercially available. They are generally capable of capturing about 340

lines of resolution. Cameras with more resolution are available but can be

quite expensive. The resolution of the video camera being used should

match to the recording capability of the video cassette recorder and the

resolution of the monitor. For example, an S-VHS format that records more

than 400 lines of resolution provides a better match for a 340-line camera

than a standard VHS format, which records only 230 lines. A video

monitor that can display 420 line of horizontal resolution is a good match

for a 340-line camera and S-VHS videocassette recorder. When

videotaping, a dental assistant can serve as video director and pause the

recording if he or she thinks the picture is off center or out of focus.

An addition to the final radiograph, a video print of the complete

case can be recorded. Video printers can readily be connected to a video

cassette recorder or the video camera on the microscope. A microcomputer

inside the video printer automatically analyzes the image, and prints are

created in 70 seconds by a high-density sublimation dye. The video prints

are 4 inches by 6 inches. If desired, different images can be digitized

during the surgery and later recorded on a single print. Video prints can be

used for patient education, medicolegal documentation, or reports to

referring dentists and insurance companies.

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IV. Accessories:

Many accessories are made for the operating microscope. Pistol

grips or bicycle-style handles can be attached to the bottom of the head of

the microscope to facilitate movement during surgery.

An eyepiece with a reticule field can be substituted for a

conventional eyepiece and can prove an invaluable aid for alignment

during videotaping and 35-mm photography. Observation ports can be

added to the microscope by a beam splitter and can be helpful in teaching

situations. Auxiliary monocular or articulating binoculars can also be

added and used by a dental assistant. Another accessory used to facilitate

an assistant's viewing is the LCD (Liquid Crystal Display) screen. The

LCD screen receives its video signal from the video camera. When

viewing the LCD screen, the assistant sees exactly what the surgeon sees

without having to take his or her eyes away from the surgical field. This

viewing system has an advantage over articulating binoculars because the

assistant does not have to move away from the microscope if it is necessary

for the surgeon to move the microscope during the surgery.

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MISCONCEPTIONS ABOUT OPERATING

MICROSCOPES

Magnification

A frequently asked question is how powerful is your ill microscope?

The question addresses the issue of usable power. Usable power is- the

maximum object magnification that can be used in a given clinical

situation relative to depth of field and field of view. As the magnification is

increased, the depth of field is decreased, and the field of view is narrowed.

The question then becomes how usable is the maximum power?

Magnification in excess of 30X, although attainable, is of little value in

periapical surgery. Working at higher magnification is extremely difficult

because slight movements by the patient continually throw the field out of

view and out of focus. The surgeon is then constantly recentering and

refocusing the in microscope.

Illumination

There is a limit to the amount of illumination a surgical microscope

can provide. As magnification is increased, the effective aperture of the

microscope is decreased, and therefore the amount of light that can reach

the surgeon’s eyes is limited. This means that as higher magnifications are

selected, the surgical field appears darker. In addition, if a beam splitter is

attached to the microscope, less light is available for the photo adapters and

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auxiliary binoculars. This is important to consider when producing 35-mm

photography. Photographic color film is not sensitive, and it may be

necessary to add a strobe to create quality images. Videotape is

significantly more sensitive than photographic film, and excellent videos

can be recorded without supplemental light.

Depth Perception

Before surgery can be performed with an operating microscope, the

clinician must feel comfortable receiving an instrument from the assistant

and placing it between the microscope and the surgical field. Learning

depth perception and orientation to the microscope takes time and patience.

Coordination and muscle memory are easily forgotten if the microscope is

used infrequently. As a general rule, the clinician should reorient himself

or herself to the microscope before beginning each surgery.

Access

The surgical microscope does not improve access to the surgical

field. If access is limited for conventional surgery, it is even more limited

when the microscope is placed between the surgeon and the surgical field.

Use of the-microscope, however, creates a much better view of the surgical

field. Because vision is enhanced so dramatically, cases can now be treated

with a higher degree of confidence.

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Flap Design and Suturing

Reflecting soft tissue flaps and suturing them back in place are not

hi magnification procedures. Although the microscope could be used at

low magnification, little is gained from its use in these applications. The

operating microscope is recommended predominately for osteotomy

curettage, apicectomy, apical preparation, retrofilling, and documentation

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OPERATING POSITIONS WHEN USING

OPERATING MICROSCOPE

The most appropriate operating position for a given surgeon is

actually a combination on of patient head position, dental chair position,

microscope position, surgeon position, assistant position, and assistant

observation devices. The dynamics of each of these divisions must be

thoroughly understood to arrive at operating positions that are comfortable

for the patient, assistant, and surgeon (Fig. No. 8).

Patient Head Position

No effort should be spared to insure that the patient will be

comfortable during the surgery. In addition to profound anesthesia,

attention must be given to insure that the head and neck muscles are not

strained or torqued during surgery. The occlusal plane should be parallel to

the floor for mandibular surgery and perpendicular to the floor for

maxillary surgery. The head should be comfortably centered or slightly

turned toward or -away from the surgeon.

Dental Chair Position

The dental chair can be maneuvered in a variety of positions.

Horizontal and vertical controls position the base of the chair and back

supports to regulate the distance from the head of the microscope. In

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addition vertically positioning the base of the chair can provide room for

the surgeon and assistant to position their legs. The adjustable headrest

should be used to position the head comfortably and maintain the proper

plane of occlusion.

The dental chair is positioned slightly below the operator for

maxillary surgery and slightly above the operator for mandibular surgery.

This allows the clinician to look down the axial plane of the root and

across the beveled surface in maxillary teeth and up the axial plane of the

root and across the beveled surface in mandibular teeth.

Microscope Position

Most endodontists prefer an operating microscope that is mounted

to the ceiling. Suspension arms support and position the microscope in

horizontal and vertical dimensions. Friction couplings position the

microscope and suspension arms in an infinite number of axes within

three-dimensional space. Loosening and tightening the couplings allows

for movement of the arms and flexible joints. Inserting a 135-degree

inclined coupler between the mounting arm and the head of the microscope

provides additional axis of movement and more versatiliy. As stated

earlier, Selection of binoculars is critical in determining correct microscope

position. Binoculars are available as straight tubes, inclined tubes, and

inclinable tubes. The surgeon should select a binocular that allows him or

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her to look down the axial plane of the root and across the beveled surface

in maxillary surgery and up the plane of the root and across the beveled

surface in mandibular surgery.

The combination of microscope position and dental chair position

places the microscope in three-dimensional space, which can be accessed

by the surgeon. The microscope must be positioned to provide the

necessary visual access to perform the surgery while allowing for postural

comfort for the surgeon and assistant.

Surgeon Position

The surgeon should use an adjustable operator stool. The surgeon's

thighs should be! parallel to the floor so that the large muscle groups are at

rest. The surgeon's arms should be relaxed and comfortable at his or her

side. Specially designed stools are available with arm supports that can be

used to provide additional comfort and minimize fatigue.

The surgeon should be facing the side of the patient. This may or

may not mean that the surgeon is seated on the affected side. Often the

surgeon can accomplish the same result by having the patient turn slightly

toward or away from him or her. It has been suggested that a right handed

surgeon positions himself or herself on the right side of the dental chair in

all situations except during mandibular left surgeries, when the surgeon

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should move to the left side of the dental chair. For a right-handed surgeon;

the monitor should be placed to the right and in front of the dental chair.

Assistant position:

A well-designed microsurgery may use three dental assistants. The

first assistant is primarily responsible for suctioning and is usually seated,

although he or she may prefer to stand in some situations. If seated, an

adjustable assistant’s stool is suggested, which ensures postural comfort.

The second assistant passes instruments and usually stands. This

assistant is positioned next to the surgeon’s dominant side to facilitate

instrument passing. If a front delivery system is used, the second assistant

can be positioned across from the surgeon and may pass instruments from

the tray over the patient. The third assistant functions as a charge nurse and

can leave the operatory to obtain additional instruments or materials if

necessary. The third assistant is also in charge of video and photographic

functions. The positions of the assistants may vary depending on their

visual access and which observation devices are being used.

Good communication is essential between the surgeon and the

assistants. The first or suctioning assistant must let the surgeon know if he

or she does not have good visual access to the surgical field. Positional

adjustments may be necessary for both the surgeon and the assistants at

times during the surgery depending on the location of the tooth being

treated.

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Assistant Observation Devices

In most clinical situations, the assistant has a choice of three

observation on devices: articulating assistant binoculars, LCD screens, and

high resolution monitors. Although -they provide the first or suctioning

assistant with the ability to see depth of field and have the same visual

acuity of the surgeon, articulating assistant binoculars have the

disadvantage of being quite costly. Each surgeon must weigh the cost

benefit and ask if it is necessary for the assistant to see a stereoptic view of

the surgical field. Another disadvantage is that every time the patient

moves his or her head, it is necessary for both the surgeon and the assistant

momentarily to break their concentration and reposition the microscope.

This can/become fatiguing and wasteful of time.

LCD screens can be placed in line with the video camera on the

microscope and mounted on a swivel arm so that it can be positioned in

front of the first assistant. Similar to the articulating assistant binoculars,

the LCD screen has the advantage of orienting the assistant toward the

surgical field. Among the disadvantages are the cost and the inability to see

depth of field.

It has been suggested to use of high resolution monitors because of

their affordability and practically. All three assistant have visual access to

the surgery. The only disadvantage is that the first assistant must

momentarily take his or her eyes away from the surgical field to view the

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monitor. For convenience, the monitor can be placed a mobile cart with the

video printer and video cassette recorder. In addition, a Jazy Susan can be

placed under the monitor so that it can easily be turned toward the

assistant. The mobile cart is usually placed at the foot of the dental chair

and angled toward the center of the operatory.

Operating Positions For A Right-Handed Surgeon Using Front Delivery System

1. Maxillary left position.

a. Surgeon positioned to the right and to the rear of the patient.

b. Occlusal plane perpendicular to the floor.

c. Patient looking slightly to the right.

d. Microscope angled down the axial plane of the roots.

e. Dental chair position low.

f. Surgeon position high.

2. Maxillary anterior position.

a. Surgeon positioned to the right and to the rear of the patient.

b. Occlusal plane perpendicular to the floor.

c. Patient looking straight ahead.

d. Microscope angled down the axial plane of the roots.

e. Dental chair position low.

f. Surgeon position high.

3. Maxillary right position.

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a. Surgeon positioned to the right and to the rear of the patient.

b. Occlusal plane perpendicular to the floor.

c. Patient looking slightly to the left.

d. Microscope angled down the axial plane of the roots.

e. Dental chair position tow.

f. Surgeon position high.

4. Mandibular left position.

a. Surgeon positioned to the left and to the side of the patient.

b. Occlusal plane parallel to the floor.

c. Patient looking straight ahead or slightly to the right.

d. Microscope angled up the axial plane of the roots.

e. Dental chair position high.

f. Surgeon position low.

g. First assistant stands or sits depending on comfort.

h. Instruments on a bracket tray behind the patient.

5. Mandibular anterior position.

a. Surgeon positioned to the right and toward the front of the patient.

b. Occlusal plane parallel to the floor.

c. Surgeon looking straight ahead.

d. Microscope angled up the axial plane of the roots.

e. Dental chair position high.

f. Surgeon position low.

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g. Second assistant moves to the left side of the chair to make room for the surgeon.

h. Surgeon rests right arm on the operating stool armrest.

6. Mandibular right position.

a. Surgeon positioned to the right and to the side of the patient.

b. Occlusal plane parallel to the floor.

c. Patient looking straight ahead or slightly to the left.

d. Microscope angled up the axial plane of the roots.

e. Dental chair position high.

f. Surgeon position low.

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PREREQUISITES FOR THE USE OF THE

MICROSCOPE IN NONSURGICAL ENDODONTICS

Rubber dam placement

The placement of a rubber dam prior to any endodontic procedure is

an absolute requirement for sterility purposes. This technique is being

taught at all dental schools. In endodontics. However, the purpose is

greater. Here, the rubber dam placement is necessary because direct

viewing through the canal with the microscope is difficult, if not

impossible. A mirror is needed to reflect the canal view that is illuminated

by the focused light and magnified by the lens of the microscope. If the

mirror were used for this purpose without a rubber dam, then the mirror

would fog immediately from the exhalation of the patient. Thus, the

powerful microscope magnification and illumination would be rendered

totally useless for the necessary visualization of the chamber floor and the

canal anatomy. To absorb reflected bright light and to accentuate the tooth

structure, it is recommended to use blue or green rubber dams.

Indirect view and patient head position

As mentioned previously, it is nearly impossible to view the pulp

chamber directly under the microscope. Instead the view seen through the

microscope lens is a view reflected by way of a mirror. To maximize the

access and quality of the view by this indirect means the position of the

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patient (especially the head position) is important. The optimum angle

between the microscope and the mirror is 45° and the clinician should be

able to obtain this angle without requiring the patient to assume an

uncomfortable position. The maxillary arch is rather easy for indirect

viewing. Basically, the patient's head is adjusted to create a 90° angle

between the maxillary arch and the binocular. In this position the mirror

placement will be close to 45° for best viewing.

Mouth mirror placement

It is always a good idea to use the best mirror for this purpose. If a

rubber dam has been placed, then the mirror must be placed away from the

tooth within the confines of the rubber dam. If the mirror is placed close to

the tooth, then it will be difficult to use other endodontic instruments.

Readjusting the mirror will necessitate refocusing of the microscope

making the entire operation time-consuming and, at times, frustrating. This

is especially true during a lengthy perforation repair with practice,

however, the “correct” placement of the mirror will become automatic.

Some key instruments

The ability to locate hidden canals is the most important and

significant benefit gained from using the microscope. To do this effectively

and efficiently, clinicians must use specially designed microinstruments.

An explorer can pick the entrance of a canal under the microscope, but

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negotiating the canal with a file can - be challenging because there is only

a tiny space between mirror and the tooth for a finger with a file to move

around. Files specially designed by Maileffer called micro-openers have

with different sized tips and can be extremely useful. These hand-held files

allow the clinician to initially negotiate the canal verifying that the "catch"

is truly a canal. After the canal is located in this manner, clinicians can

instrument the canal normally without the microscope. The use of Gates-

Glidden burs to enlarge the canal entrance prior to full instrumentation,

however, can be easily achieved under the microscope, facilitating the

subsequent steps of canal instrumentation.

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APPLICATIONS OF OPERATING MICROSCOPE

1. Uses in conventional Endodontics:

a. Preserving tooth substance during access preparation and

visualization of the canal entrances.

b. Localization and visualization of accessory canals and

locating calcified canals

c. Final examination of the canal preparation:

d. Removal of fractured instruments

e. Obturation with warm gutta-percha

f. Recognition and location of fractures

g. Perforation repair

2. Uses in surgical endodontics:

a. Soft tissue management

b. Root end procedures (apicectomy with retrograde filling)

c. Intentional Replantation

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Preserving tooth substance during access preparation and

Visualization of the canal entrances:

Before commencing the trepanation of a tooth, the dental

practitioner should plan his treatment strategy so that as little tooth

substance as possible, but as much as necessary, is removed. The

preservation of a healthy tooth substance is of decisive importance for a

favorable long-term prognosis. The classic access cavities still found in

many of today's textbooks must be slightly modified to take into account

our current status of knowledge in this field. The trepanation opening on

the maxillary 1st and 2nd molars, for example, is no longer triangular, but

must be quadrangular due to fourth canal, marked as MB2, which is also

frequently found.

Only with the use of operating microscope it is possible to recognize and

remove the structures that cover the fourth canal. As the substance is

ablated under direct visual control and with the appropriate magnification,

it is possible to preserve the healthy tooth substance not concealing the

canal entrances. At the end of the visualization of the access cavity, the

canal entrances should form the corners of the cavity.

Localization and visualization of accessory canals :

As it is now known that the upper 1 st molars have four canals in most

of the cases, the search for the MB2 should not be concluded until this

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fourth canal has been found. However, every endodontist must ask himself

the question whether he has found and been able to prepare the fourth canal

on every upper 1st molar with or without the use of a microscope. Needless

to say, apart from the regular anatomy in the maxillary molars, there are

also irregular root anatomies. Therefore it is always good to inspect the

prepared canals prior to filling in order to discover any concealed canal

entrances.

Finally at this point, it can be said that the operating microscope

alone cannot offer all the benefits required for success. Canal localization

or the visualization of the canal entrances is only possible with the use of

ultrasonic. Only with its assistance it is possible to ablate material under

visual control and with the appropriate magnification.

Locating Calcified Canals

The microscope has proven to be indispensable for the localization

of coronally obstructed canals. There is no longer any need for guesswork

when searching for calcified canals or canals occluded by restorative

materials. The microscope can bring the practitioner right onto the pulp

chamber floor, with high-intensity light revealing in intimate detail an area

that was once under-illuminated and which required guesswork and great

caution. Practitioners can proceed with confidence and skill because they

can see. Subtle and minute differences in color and calcification patterns

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become immediately obvious, serving as a road map in removing the

obstructions. For example, fourth canals of upper molars can be localized

and instrumented in minutes, using an ultrasonic retrotip and high

magnification. In most cases, the shape and orientation of the canals, and

sometimes even the portals of exit, can be visualized, as well as some

accessory portals of exit. The ability to subject the canal space to such

critical visual scrutiny is especially helpful when there are root

dilacerations, mid root bifurcation or trifurcation, or sharp demarcations

or curvatures. More importantly, the clinician can examine and evaluate his

or her own shaping skills and make rapid improvements in technique

simply by observing the end result of instrumentation activities. The

process of mental imaging, so necessary in developing sophisticated

endodontic skills, is greatly assisted by observing, at close quarters, the

final result of one's work.

Final examination of the canal preparation:

It takes a simple step to see whether the canal is completely cleaned. Under

the microscope, a small amount of sodium hypochlorite, a popular

irrigation solution, is deposited into the canal and observed carefully at

high magnification. If there are bubbles coming from the prepared canal,

then there are still remnants of pulp tissue in the canal. In short the canal

needs more cleaning.

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Removing Fractured Instruments

Separation of an instrument inside the confines of the canal is one of

the most common problems in endodontics. Iatrogenic accidents of this

sort subject the patient and treating doctor to harmful stress level, provide

the legal profession with cases and frequently lead to further damage in

attempting to remove or bypass the obstruction.

Traditionally, fractured instrument cases are handled by attempting

to bypass the instrument with other instruments, thereby running the risk of

perforation or the separation of additional instruments. Other methods rely

on trephine burs or extractors using cyanoacrylic glue or pinch-pressure

devices to remove the offending instrument. These methods are ingenious,

but unfortunately the scale of these devices is often too large for the task

and frequently results in perforations or gross destruction of root structure.

Using the operating microscope and a specially designed ultrasonic

unit and tips, most instruments can now be easily removed. The instrument

is visualized using high magnification. Then a specialized ultrasonic tip is

energized, creating a trough around the coronal 2mm of the instrument.

The doctor has commanding visual control at all times during this

procedure, resulting in minimal loss of root dentin.

After the troughing procedure, the instrument is vibrated with the

side of the tip. It will begin to spin and move coronally because of its

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tapered shape. It can then be removed using microsurgical forceps that can

be manipulated in the pulp chamber because of their small size.

Instruments large and small can be removed in this manner whether

they are in the coronal, middle or apical third of a straight root. Instruments

separated apical to severe curvatures are not good candidates for this

procedure.

The important reason for the use of the operating microscope is to

maximize the preservation of tooth substance. After all, there is little point

in successfully removing the instrument if, at the same time, the root is

weakened or even perforated to such an extent that its length of stay in the

patient's mouth is severely limited.

Obturation with warm gutta-percha:

Filling prepared root canals with warm gutta-percha only makes

sense if the preparations can be made under visual control. The root filling

is condensed into the apical third of the root canals using special pluggers.

The microscope helps the clinicians to perform these work stages in a

controlled manner at any time.

Recognition and location of fractures :

The operating microscope is often very beneficial in the diagnosis of

pain symptoms. If inexplicable pain continues and cannot be eradicated by

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replacing the filling and abrasive measures, the tooth should be inspected

using the highest magnification. Often a fracture can only be recognized by

staining the tooth with methylene blue. For the patient the diagnosis means

that the tooth has to be extracted, but it also spares him further unnecessary

treatments which could not have had a successful outcome in any case,

would have caused much pain and cost a considerable amount of money.

Perforation repair :

If a dental operating microscope is not used, perforations with serious

consequences are often the result, especially when pins are being inserted.

In the past, the prognosis for these teeth was so bad that the extraction was

preferred. Today, with the availability of such new materials as Pro Root

from the firm Dentsply and the possibility of using these materials more

precisely under the operating microscope, we have an opportunity to save

many more teeth. What is important here is not only the precise application

of the filling material, but also the removal of the posts, the cleaning of the

tooth substance without losing even more hard tissue, and the handling of

the vital tissue in the transition area. In combination with micro-

instruments and ultrasonic attachments, the operating microscope provides

with the most reliable possibility of saving the tooth.

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Microscopes in Surgical Endodontics

Magnification, illumination and instrumentation constitutes a

microsurgical triad. The microscope and new microinstruments specific to

the means of endodontic microsurgery have made the microsurgical

approach reality. Apical surgery can now be performed with accuracy and

predictability eliminating the guess factor inherent in conventional

endodontic surgery.

The introduction of the operating microscope and ultrasonic

instruments has taken endodontic surgery to another level of sophistication:

the microsurgical approach. Magnification, illumination, and micro-

instruments constitute a microsurgery triad.

Of all the areas in endodontics, surgical endodontics has perhaps

benefited most by the introduction of the operating microscope. Although a

comprehensive discussion of its role in surgical endodontics is beyond the

scope, we can gain some appreciation of the tremendous advance this

instrument has provided by considering the following uses.

Surgical endodontics demands an entirely different set of skills than

conventional endodontics. The clinician must have a comprehensive

knowledge and understanding of the multiple parameters involved in the

management of both hard and soft tissue, as well as an appreciation for the

many factors involved in surgical wound healing. The operating

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microscope enhances surgical skill in both soft and hard tissue

management. Light and visibility are critical for any surgical procedure;

the operating microscope provides levels of illumination and magnification

that are appropriate for endodontic surgery.

Surgical correction of failing endodontic treatment has a checkered

history. Recent articles place the success rate for apicoectomy at 40 to 60

percent. The reasons for such a low success rate are unknown and are the

subject of much debate and speculation within the profession. There are

undoubtedly a multitude of reasons for surgical failure. Certainly one of

the main causes of periapical breakdown following surgery is the failure to

seal hermetically all portals of exit. This failure can be the result of

inadequate lighting, visibility and technique. The following is a brief

review of some of the errors commonly made in apical surgery and how

the operating microscope can help to avoid such mistakes and raise the

level of care.

Soft tissue management:

The most frequent error in flap management in endodontic surgery is

unnecessary trauma during incision, reflection, retraction and suturing.

When sulcular incisions are made, frequently the sulcular epithelium is

removed or crushed during the incision or elevation procedure. Preserving

this tissue is probably the single most important factor in ensuring rapid

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wound healing. Microsurgical scalpel blades, curved to confirm to the

cervical contour of the tooth, enable the surgeon to make a sulcular

incision without damaging the epithelial lining of the sulcus. When

performed under the microscope, sharp dissection and completely

atraumatic elevation of the papilla and interdental col area is accomplished.

Specially designed curettes allow for an undermining elevation of the flap.

By elevating a full thickness flap, maximum healing and reattachment

potential are preserved. When the flap is handled under the microscope, the

physical trauma is lessened and gentle manipulation is assured.

Microsurgical suturing techniques take advantage of smaller gauge

tapered-point needles and smaller suture sizes. Sutures sizes of 5-0 and 6-0

are handled with ease; sutures are placed much more accurately then with

the naked eye. If one follows an atraumatic microsurgical flap management

technique, sutures can be removed in 24 to 48 hours, with startling healing

rates evident.

Root end procedures ( apicectomy with retrograde filling ):

Although the introduction of the operating microscope to

endodontics is new, the surgical procedures that endodontist perform have

always been true microsurgical procedures. Like other areas of

endodontics, surgical endodontics is extremely technique sensitive, with

only a small margin for error. Traditionally, these procedures have been

done without the lighting and magnification needed to perform them

45

properly. Evaluation, preparation and filling of the root apex are a true

microsurgical procedure, and simply can’t be done predictably without

magnification. Recently introduced optical grade micro mirrors allow the

clinician to exam the beveled root apex in minute detail. The ability to

observe the beveled edge of the root at high magnification brings a whole

new world of detail into focus. Poorly condensed gutta-percha, leakage

around the sealer voids, eccentric and irregular canal shapes,

uninstrumented isthmus areas, accessory canals and canal fins and

circumferential resorption of prior retrofilling materials, all become very

obvious, helping the practioner’s design and implement a corrective design

to his retropreparation.

Based on a large number of microsurgical inspections of failed

apicoectomies, one of the most significant problems in apical surgery

responsible for such a high failure rate is poor design and preparation of

the retropreparation itself. Because instruments were not available to allow

preparation down the long axis of the root, almost all retropreparation were

placed obliquely into the root. This has the unfortunate consequence of

having to rely on the axial wall of the preparation to do the sealing, when

ideally it is the pulpal floor of the preparation, which should do the sealing,

with the axial walls only used for retention.

Because most roots sustain an exaggerated bevel at the time of their

resection, the needed preparation must become broad bucco-lingually. This

46

is exceedingly difficult to accomplish with conventional or microhandpiece

preparations as one move further lingually in the crypt.

Fortunately, the recent introduction of specialized ultrasonic tips solves this

problem. Now retorpreparations can be placed down the longitudinal axis

of the pulpal space and the preparations can be extended to the correct

bucco-lingual dimension with ease. Using the operating microscope and

retromirrors, we can now modify the bevel and section roots more

perpendicularly to the long axis of the root. We also have the ability to

inspect, prepare and seal the isthmus area between confluent canal systems.

This techniques decrease the probability of lingual root perforations when

the retropreparation must be extended lingually. Ultrasonic preparations

are G.V.Black-type slot preparations with parallel walls, which confirm to

the anatomic reality of the root canal system. The ability to cut

perpendicular to the long axis is especially helpful in cases where there is a

post placed deep into the canal and where a standard bevel would expose

the post and compromise the retrofilling procedure.

Intentional replantation:

The intentional replantation of teeth has been a part of the dental

armamentarium for many years, not always with the high success rate, but

rather considered as a procedure of last resort. The advent of operating

microscope and its uses during replantation with the current techniques for

47

performing intentional replantation has increased the success rate to

approximately 85%, making intentional replantation viable treatment

modality. With the use of operating microscope during replantation one

can be much more comfortable working in areas close to the vital anatomic

landmarks because they can be seen under great illumination and

magnification and therefore control their movements.

Treatment with an Operating Microscope still "lege artis”?

To sum up, the use of the OM must still be seen as "lege artis"

therapy. Or the question should be asked whether root treatment or

apicectomy without the use of the microscope can still be termed as lege

artis. This question is, of course, a very provocative one. However, a

decision must be made for the benefit of patients. The top priority must be

to provide them with the best possible therapy. However, it must not be

stressed that intensive training is required for the correct use of these

innovations. Courses are available to learn and apply these techniques. We

should use this opportunity / technology for the sake of our patients!…

Uses of magnification in stages of endodontic microsurgery

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ADVANTAGES AND DISADVANTAGES OF

OPERATING MICROSCOPE

Advantages:

Greater visual acuity with the operating microscope, wide range of

magnifications and bright illumination allows for a higher success rate,

because vision is enhanced so dramatically, cases can be treated with a

higher degree of confidence and accuracy…

Earlier surgical telescopes and surgical headlamps have benefited from

increased magnification and illumination, but efficient use of these aids

require a steady head and only incremental movements, a difficult habit

to acquire. The operating microscope, in contrast, is much easier to use,

especially with a low to mid range magnification (X3—X16)….

The important features of an endodontic operating microscope are Optics,

Maneuverability, Stability and Modularity.

Documentation by means of a video camera attached to the microscope is

valuable for communicating with referring dentists and for teaching

patients etc,………

An assistant observation scope attached to the main scope reduces the

maneuverability of the operating microscope and the effectiveness of

the assistant.

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The operating microscope can provide important benefits in clinical

practice in the following ways:

The surgical field can be inspected at the high magnification so

that minute details of the anatomical structure can be

identified and managed.

Surgical techniques can be evaluated.

Fewer or no radiographs may be needed during endodontic

surgery because the surgeon can inspect the apex or apices

directly and can record the procedures.

Video recording of the procedure can be used for patient

teaching, video libraries can be made for teaching programs,

video recording of different surgical procedures and

techniques can be effective teaching tools.

Communication with the referring dentists and insurance

company or companies can be improved.

Occupational stress can be reduced, use of O.M requires erect

posture, also, the clinical environment is less stressful when

clinicians can see what they are doing rather than guessing.

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1. The minimum requirements for an endodontic microsurgery are five

step magnifications, a light source carried by a fiber optic cable, and a

180-degree inclinable binocular.

2. A basic surgical microscope for dentistry should have the following

configuration:

3. 12.5 X eyepieces with reticule

4. 180-degree inclinable binocular

5. Five step manual magnification changer or power zoom

magnification changer.

6. Fiber optic illumination system

7. Audiovisual accessories (e.g.; video camera)

8. The loupes provide magnification in the range of (X2—X6), but with

operating microscope the overall magnification range is X3—X30. The

low magnification (X3—X8) produces a wider field of view and high

focal depth; this keeps the field in focus despite moderate movements,

this range therefore is useful for orientation within the surgical field and

for alignment of instrument tips.

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The midrange magnifications (X10—X16) provides moderate focal

depth. In endodontic these are the working magnifications; they provide

reasonably large magnifications.

Disadvantages:

1. It is costly

2. Its integration into the practice requires many changes in

instrumentation and procedures, operating room etc …

3. The surgeon / clinician and the staff must learn the new handling

and assisting requirements.

4. At the higher magnifications, the slightest movement by the patient,

sometimes even simple breathing, throws the field out of view and

out of focus. The surgeon must repeatedly recenter and refocus the

microscope, wasting time and creating unnecessary eye fatigue and

not really adding to the visibility of the surgical site.

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SUMMARY AND CONCLUSION

The simple premise for using the microscope is that light plus

magnification, equals to excellence. It certainly makes sense that if the

clinician can see something more clearly and magnified, he or she can

better evaluate and treat that object. As some surgeons say, “if you see it,

you can protect it”. This adage also applies to endodontics.

Many of the clinicians who perform endodontic procedures and do

not use dental microscope are still evaluating the benefits of its use.

Practicality is the key concern. How does one recoup the cost of the capital

expenditure and the time associated with training? Are the clinical benefits

worth the expenditure of time and money? To address this critical cost and

efficiency issue. We as a clinician should take an intensive training course

at the very beginning to make us more comfortable with handling the

microscope and work underneath it and also become totally committed to

using the microscope in each treatment cases, not just selected ones. Thus

practice is the fastest route towards proficiency, and the best way to

maximize the return on investment.

In addition to clinical benefits associated with the use of the

microscope in endodontics, after the initial learning curve, endodontics

procedures can be done in less time because of the greater visibility of the

root canal anatomy. Procedural errors can be greatly reduced, if not

eliminated and complicated cases becomes less under the microscope.

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In endodontics, the microscope is indispensable. Clinicians are

discovering that every facet of endodontics is better, safer, and easier. The

learning curve can be fairly steep, but it is one worth climbing. Future

controlled studies should document an improvement of endodontic

outcomes. This is becoming truer as dentistry becomes more extensive and

expensive, and needs to last longer and longer. The days of "easy cases"

are much fewer, even for the general practitioner. Lastly, there is a

groundswell conversation, at least in the endodontic community, that the

benefits of the microscope are beyond biology. Clinicians experience a

greater sense of personal and professional fulfillment because they are not

achieving what is "good enough," but aspiring to "what is possible."

The microscope has opened up the hitherto hidden world and helps

us visualize what till now escaped undetected. It has literally become the

third eye of the astute clinician. The range of magnification that this

instrument produces enables a wide vista of versatility, from the field of

dental diagnosis to the intricate art of surgery, the field of restorative

dentistry, oral pathology and microbiology and the most important the

highly precise branch of dentistry i.e. endodontics, every specialty is being

benefited by the intricate application of this technology.

“Microscopic endodontics is a new technology that emphasizes visual

information, rather than tactile information”.

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