Microsurgical Triad
Three advantages offered by microsurgery to the operator are as follows ([Fig. 1]):
Fig. 1 Microsurgical triad.
-
a. Magnification System
-
b. Illumination
-
c. Increased Precision
a. Magnification System
The human eye is the most efficient visual detector when it comes to imaging speed
and resolution. Together with the muscles and cornea, an optical image is projected
onto the retina. A sharp image of focal length 20 cm is produced. Due to the little
ability of the eye's lens to change shape, images of objects close to the eye cannot
be brought into focus on the retina. The closest the object can be viewed by the naked
eye is ∼10 cm due to the fact that the viewing angle becomes extremely small; this
is the reason the nearest object is blurred. Similarly, an object at a great distance
cannot be viewed with fine details due to the viewing angle being too small to reach
the retina.[3] The magnification system has the capability to magnify the image that is displayed
on the retina by increasing the visual angle.
Total magnification = Objective magnification x eyepiece magnification
Dr. McQuillen, during his time as a student of dentistry, identified the value of
magnifying glasses while observing late Prof. Elisha Townsend employing magnifying
glass to observe the margin of restorations. From that time up to the present, his
enduring work character was largely ascribed by other dentists.[4] Choice of magnification system depends upon the task that needs to be achieved and
the level of the experience that the operator holds.[5]
a.1 Loupes
The most common form of magnification system currently being used, with two side-by-side
monocular lenses angled to focus on the operating field. It can be adjusted according
to the need and is available as a headband or the front frame-mounted system ([Fig. 2]).[6]
Fig. 2 Loupes.
Types of loupes available[7]
[8]:
-
i. Simple Loupes
-
ii. Compound Loupes
-
iii. Prism Loupes.
-
iv. Galilean Loupe
-
i. Simple Loupes:
These loupes comprise of a pair of single lenses those are attached to two refracting
surface side by side.
Advantage:
Disadvantage:
-
Primitive
-
This can lead to spherical and chromatic aberration, leading to a distorted image.
-
Heavyweight with a magnification range of 1.5x is not particularly applicable in dentistry.
This type of loupes consists of multiple lenses providing auxiliary refracting power.
Compound loupes are made comprised of two pieces of glass that are held together with
resin.
Advantages:
Disadvantages:
These are optically advanced loupes currently in use, consisting of a rooftop prism
that lengthens the path of light by virtually folding the light. The range of magnification
provided by these loupes is 1.5x-6x.[10]
Advantages:
-
Cheap
-
Simple to operate
-
Lightweight
Disadvantages:
Adjusting Magnifying Loupes
Along with various advantages, it also consists of impediments to adjust to the eye.
Therefore, to avoid double vision, the operator has to adjust loupes respective to
the eyes. Unadapted position of loupes will converge and dilate to focus and will
attempt to accommodate the error. This may cause fatigue to the ciliary and extraocular
muscles resulting in eyestrain.
a.2 Microscope ([Fig. 3])
Fig. 3 Surgical operating microscope.
The term microscope was coined by Giovani Faber for the compound microscope. Operating
microscopes are superior when compared with loupes. It has been widely used in the
medical field but in dentistry, its use was limited to endodontics until microscope
in performing plastic periodontal surgery became prevalent. The microscope provides
stereoscopic vision with 4x-40x magnification and better illumination of the working
area. A surgical microscope consists of a few important components: optical component,
supporting structure, a lightning unit, binocular tube, and eyepiece.[11]
Currently, two types of microscopes are widely used: Greenough and Galilean type.
Greenough type consists of two side-by-side arranged monocular microscopes at a specific
angle so that the two objectives can focus on the same object. Prolonged use of this
type of microscope results in eye strain and fatigue. Hence, came the Galilean type
microscope that consists of a binocular viewing system in combination with magnifying
loupes. Dental microscopes are designed on the Galilean principle that incorporates
achromatic lenses and fully coated optics.
Parts of Operating Microscope
a) Supporting Structure
The supporting structures of a microscope are available as the wall or ceiling mounted
or even can be safely placed on the floor. A microscope placed on the floor is much
preferable as it can be easily moved from one place to other. The operating microscope
consists of arms that can be adjusted and angulated with the help of a built-in spring
for precise visualization.[12]
b) Eyepiece
The body of the microscope consists of an eyepiece with a magnification of 10x, 12.5,
16x, and 20x. It also consists of a diopter that can be set from –5 to +5 to focus
the lens. Diopter setting and interpupillary adjustment should be made prior to the
use by the operator and should remain unchanged.[13]
c) Light Source
Light source is on salient features of an operating microscope, the presence of which
helps provides coaxial illumination. Some microscopes can provide illumination to
a smaller area, ∼6 cm in diameter.[12]
d) Binocular Tube
The microscope provides two different types of binocular tubes: the straight tube
that gives a parallel view of direction and inclined tubes that are in 45-degree inclination
from the axis of the microscope.
Loupes versus Surgical Operating Microscope ([Fig. 4])
Fig. 4 Microscope versus loupes.
Loupes and microscope despite having many common features also come along with limitations.
Loupes provide magnification from 1.5x to 3.5x but magnification where 4x and more
is required in particular, loupes are considered to be inefficient and a microscope
comes into play with a magnification range from 4x to 40x. Loupes can cause loss of
4% of the transmitted light due to surface reflection and without coating may lead
to a 50% reduction in brightness. This problem of light reflection can be minimized
by the use of a microscope. In spite of the loupe's usefulness, this high-power instrument
also causes discomfort to the clinician due to its heavy weight. This can also influence
the posture. The microscope on the other hand is mounted to the different platform
does not cause fatigue to the clinician and also ensures good posture throughout the
procedure.[14]
Microscope with its higher magnification provides increased precision in surgical
skills and extreme accuracy but it also comes with a limitation of restricted vision.
It is difficult to carry a microscope from one place to another; therefore, loupes
serve better option. Also, a microscope is very expansive in comparison to loupes.[15]
Illumination plays a major part in the operating field. Selection of an appropriate
accessory light source also involves consideration of its quality brightness, focusing
ability, and ease of transport between the surgeries.[16] Light focusing quality in the surgical area was improved with the introduction of
fiber optic technology. A surgical microscope uses coaxial fiber optic illumination.
This fiber optic is capable of producing, uniformly illuminated, bright, free of shadow,
a circular spot of light that can be adjusted according to requirement. This technology
can be installed in the instrument or the loupes and is now considered a standard
feature of a surgical microscope. Halogen lamps have recently been bought in practice.[17]
Microsurgery provides advanced surgical skills, tissue handling ability, proper wound
approximation and to attain this level of experience, consistent application of techniques
used in basic microsurgery is very important.
Physiological tremor is one unintended movement of hands that can occur due to anxiety,
lack of practice, or some medical condition. To avoid this microsurgeon must be seated
in a comfortable posture, stabilize the hand, and hold the instrument in a stable
position. With the head in a straight upright position, movements of the hand are
made purposefully and deliberately.[18] The instrument is held in the form of a pen grip.[19]
[20] Thumb, index, and middle fingers form a tripod providing a precisional hand grip.
The middle finger firmly rests over the ring finger and helps hold the instrument
to stabilize any unwanted movement. The intrinsic muscles rotate the hand, while flexor
and extensor muscles of the hand are relaxed, which results in accurate movement of
the instrument.[21]
[22] Instrument held in internal precision grip helps in opening and closing of instruments
smoothly. Regardless of the correct posture of the clinician, if the handgrip is not
correct it can lead to stiffness of the body. Therefore, exact hand movement and the
correct hand grip are crucial to achieving precision in microsurgery.
A proper ergonomics approach will be useful in providing better visual feedback, accuracy
in hand movements, handgrip for precision in work, and microsurgical instrument care.
The term ergonomics was introduced by K. F. H Murrell in 1965.[23] In 1949, ergonomics research society in England was formed due to the rising interest
in equipment design, workplace layout, and environmental conditions.[24]
Visual information is an important part of ergonomics. Where touch is masked by the
presence of gloves and also diluted by instruments, the use of a microscope magnifies
the vision 5 to 40 times
A study on most comfortable positioning for dental operating microscope done in 2004
indicated that shorter operators had to adopt a strained position for mandibular observation
but become comfortable if using a short objective lens. Between the target structure
and the optical lenses, a minimum distance of 18 cm exists.
This is one of the important parts of proper ergonomics. The limb support should be
closer to the work providing greater control and accuracy in the movement and smaller
amplitude of tremor. The limb support along with the forearm decreases the loading
weight and aggravation in tremor.[25]
Unbalanced and incorrect posture can result in fatigue after a prolonged period of
work hours. The microscope should be adjusted in a way so that it can allow vertical
alignment of the head and neck without flexion. The level of the forearm should allow
adduction of the shoulder and support the trunk.[25]
Armamentarium in Microsurgery
The instrument used in microsurgery is smaller in size compared with the instrument
used in conventional surgery. A set of instruments that are being constantly used
in periodontal microsurgery are ophthalmic knives, microscissors, microsurgical forceps,
micro-needle holders, smaller size needles, fine sutures, microscalpel holders, and
elevators.
There is a wide range of needles available for surgery with specific lengths and curvatures.
In periodontal microsurgery, the most preferred needles that are bought underuse are
reverse cutting or spatula needles with microtips.[26] Needles are now available in different shapes, ranging from straight to curved.
To ensure perpendicular penetration in areas with narrow margins like the marginal
gingiva and interdental papilla, a curved needle serves as the best option. ⅜ curvature
of the needle provides optimum result in most periodontal microsurgery.[27]
Commonly used knives in periodontics are lamellar, crescent, blade breaker, sclera,
and spoon knife. Ophthalmic knives being smaller in size, chemically etched, and extremely
sharp can provide a precise wound edge in comparison to the no. 15 blade used in conventional
surgeries.[28] The crescent knife consists of a unilateral bevel measuring from 2.4 to 3.7mm that
is used for intrasulcular incision and root coverage procedures to obtain connective
tissue graft from a donor site. The spoon knife is also beveled on one side and is
used for effectively undermining the lateral sulcular region in preparation for the
placement of connective tissue grafts. Its unbeveled design helps track through the
tissue adjacent to the bone. Ophthalmic knives efficiently make sharp incisions leaving
sharp wound edges; this results in less trauma and faster wound healing.[29]
Suture material that is made up of natural or artificial fiber is used to keep wound
together by approximating the wound margin until they hold them sufficiently well.
Silverstein L.H in 1999 said that any strand of material utilized to ligate blood
vessels or approximate tissues is called a suture. The goal is to provide adequate
tension to the wound closure to avoid dead spaces but not cause ischemia. This allows
healing by primary intention and reduces postoperative pain. The ideal suture material
is the one with a uniform tensile strength that can hold the wound margin securely
with minimal tissue reaction and no cut, tear, or shrinking of the tissue. Penetration
of needles causes trauma to the tissue and the presence of foreign material can increase
the susceptibility to infection; therefore, the choice of the right suture material
is very important.[30]
A suture can be classified as absorbable or nonabsorbable, natural or synthetic; it
can also be monofilamentous or multifilamentous. A multifilament thread consists of
a high capillarity characteristic; hence, monofilament materials are the most preferable
suture material to be used.[31]
Ideally, a small diameter suture should be selected in surgical practice that can
hold the mending tissues.[32] In conventional periodontal surgeries, 3–0 to 5–0 sutures are frequently used but
for the periodontal microsurgery suture, 6–0 to 9–0 sutures are an ideal choice.[33] Suture materials that are indicated for periodontal surgery are polyglactin 910,
poliglecaprone 25, surgical gut, and polydioxanone. According to some studies, poliglecaprone
25 and polyglactin 910 are considered superior to surgical gut sutures,[34]
[35] where nonabsorbable suture needs removal after a period of time by the surgeon;
the absorbable suture has the ability to resorb on its own.
A microneedle holder is used to grasp the needle, push and pull it through the tissues,
and also helps in tying a knot. It should be held from the distal tips between its
middle and lower thirds fingers. To provide high precision, microsurgical instruments
are designed to be light-weighted not more than 15 to 20 g to avoid the fatigue of
arms and hands, circular in cross-section, and smaller in size with ∼18 cm in length.[36] Due to its improved visual acuity, smaller instruments provide more precision than
the instrument used in conventional surgeries.[37] The needle holder also consists of a lock with a locking force of 0.5N or 50 g.[36] All microinstruments are color coated to avoid unwanted reflection of light directed
from the microscope.[38]
Microscissors are 14 to 18 cm in length. This instrument helps in the dissection of
tissue tags, blood vessels, and even nerves. A 9 cm long microscissor is preferred
for the removal of delicate tissue parts. Microscissor can be either straight or curved
depending upon the area or the type of tissue that needs to be managed.
For the handling of the tissue at the time of dissection or during holding of a fine
suture and tying a knot, microforceps are considered to be an effective instrument.
Basic Microsurgical Suturing
Suturing technique used in periodontal microsurgery slightly differs from the one
used in conventional surgeries. Needle penetration is perpendicular to the tissue
and exits at an equal distance from the margin. To achieve proper wound approximation,
the size of the bite is kept 1.5 times the thickness of the tissue.[39] With the help of magnification, the discrepancy that occurs during suturing in microsurgery
can be scrutinized. With the help of the above geometric standards of the suturing,
a proper coaptation of the wound can be achieved.
After placing suture, with the microsurgical needle holder in the dominant hand and
microforceps in the other hand, a knot is tied under the microscope.[37] A preferred knot is a surgeon's knot then comes the square knot. To achieve the
integrity of the knot, square knots are used. Well-tied knots will resist the functional
loads during mastication and will remain stable resisting loosening of the knot. Excess
tying will not increase the strength of the knot but will only result in excess bulk.[40]
The most commonly used suturing technique in periodontics is interrupted suture, vertical,
and horizontal internal/external mattress suture, single-sling and double-sling suture,
and continuous locking suture.[41]
Periodontal Implications of Microsurgery
All mucogingival surgical techniques are operator sensitive and have different results
to different procedures. The microsurgical principle has its application in many periodontal
surgical procedures, resective or regenerative procedures. Magnification when used
along with the minimally invasive techniques provides good results.[36]
Application in Scaling and Root Planning
Microscope with its property of higher magnification and illumination helps in accomplishing
basic periodontal treatment like scaling and root planning in the critical areas like
furcation and with ease.[42] The success of any periodontal therapy depends upon the thoroughness of the debridement
of the root surface.[43]
[44] To achieve a calculus-free surface, sometimes surgical access was required.[45] Fourteen to twenty-four percent of cases treated with surgical access showed less
calculus when observed under a stereomicroscope.[46]
[47] Therefore, all the research done provides enough evidence suggesting that root debridement
can be better performed under magnification. Comparative evaluation of scaling and
root planning with the use of scanning electron microscopy resulted in more efficiency
in removing the calculus than the unaided group.[48] Another study where the evaluation of the effectiveness of scaling and root planning
when done using atomic force microscopy and scanning electron microscopy suggested
its efficacy. Microanalysis of the root surface identified alteration within cementum
when observed under atomic force microscope. Therefore, proving that use of an operating
microscope is the best aid in removing debris from the tooth surface.[49]
Application in Root Coverage Procedure
Gingival recession is the apical displacement of the gingival margin, which results
in the exposure of the root surface.[50] Root coverage procedure is an integral aspect when there is the need to restore
the gingival esthetics. Microsurgery offers a view that can identify minute discrepancies
and help treat periodontal problems. Root coverage procedure where class III and class
IV marginal surgeries were treated using conventional technique gave better results
when performed under magnification. Therefore, the use of microsurgery has made the
root coverage procedure that either involves procuring a graft or placement of regenerative
material extremely reliable.[51] Reconstruction of gingival tissue is more predictable by the use of gold standard
treatment subepithelial connective tissue graft. A systematic review on the effect
of magnification on root coverage procedure pointed out that magnification can increase
the percentage of root coverage in the root coverage procedure.[52] Use of surgical microscope to enhance the root coverage procedure with subepithelial
connective tissue graft demonstrated 98% of root coverage under a microscope, compared
with the cases performed by the unaided eye, which was found to be 88.3%. Therefore,
both the approaches were good; however, one performed under a surgical microscope
provides additional clinical benefits.[53]
Application in Restoring Edentulous Ridge
Restoration of the edentulous ridge is very important when one is planning to place
a dental implant in the future. To achieve an adequate vertical height of the edentulous
ridge, sufficient soft tissue thickness creation is mandatory. Application of magnification
in regenerative therapy permits proper excess and minimal trauma with increased accuracy.[54] A microsurgical approach using guided tissue regeneration on intrabony defects demonstrated
closure of interdental spaces in 92.3% along with gain in clinical attachment level,
reduction in probing depth, and increase in gingival recession. Therefore, the microsurgical
approach in periodontal regeneration provides with high ability of wound closure along
with the barrier membrane and gives optimum results.[55]
Minimally Invasive Surgery along with Magnification
Minimally invasive surgery was first introduced by Harrel in 1999.[56] As the name suggests minimally invasive surgery involves a much smaller incision
to gain access to the surgical area and debridement of the defect, preserving blood
supply in the interdental area when compared with the traditional approach. This is
very useful when single or multiple isolated defects have to be treated. In medically
compromised patients like a patient suffering from diabetes mellitus, minimally invasive
surgery is a boon when it comes to the healing wound.[57] Minimally invasive surgery when combined with the use of magnification has shown
better results compared with that done without the use of loupes or a surgical operating
microscope. Minimally invasive surgery of prediagnosed type 2 diabetes mellitus under
3x magnification successfully achieved periodontal tissue regeneration approximately
at the level in a patient without diabetes mellitus.[58]
Application of Magnification in Implant Surgery
Placement of implant in dentistry is a unique art to restore normal function, contour,
esthetics, speech, and health regardless of atrophy, disease, or injury of stomatognathic.[59] Despite its advancement, implant surgery complications are frequently resulting
in several poor treatment outcomes. The overall frequency of complication is 13.9%
that can occur due to wrong angulation, improper implant location, or can also be
due to nerve injury or sinus membrane complication.[60] Therefore, the use of the microscope in all phases of an implant can help recognize
the problem and plan a predictable surgery. It can also help in the seating of implant
in an anatomically correct position and reduce the surrounding tissue trauma.[61] The success rate of the sinus lift procedure is 97% when performed under a microscope,[62]
[63] providing indirect visualization of sinus membrane and reducing the risk of perforation.
The altered sensation caused by injury to the nerve can be reduced by the incorporation
of a microscope during implant placement.[64]
Macro- or Microsurgery?
One question that arises is whether the difference between macro and microsurgery
can be practically useful. In contrast to classic microsurgical procedures, the microsurgical
techniques that are used in periodontal treatment meet the requirement of being delicate
to provide atraumatic therapy with a precise adaptation of fragile oral mucosa. Since
the introduction of the microsurgical approach in reconstructive periodontal therapy
in the 1990s, many scientific shreds of evidence have emerged to propose the superiority
of the microsurgical approach ([Table 2]).
Table 2
Studies comparing micro- and microsurgical approach
|
Year
|
Researcher
|
Observation
|
|
|
|
Micro
|
Macro
|
|
2005
|
Burkhardt and Lang[71]
|
Fluorescence angiograms were performed to evaluate the degree of vascularization along
with other clinical parameters in the subepithelial connective tissue graft procedure
for root coverage
|
After 3 days and 7 days, the vascularization was 53.3 ± 10.5% and 84.8 ± 13.5%, respectively.
Percentage of root coverage 99.4 ± 1.7%
|
Vascularization evaluated was 7.95 ± 1.8%/44.5 5.7% and 64.0 ± 12.3%, respectively
Percentage of mean root coverage 90.8 ± 12.1%
|
|
2010
|
Andrade et al[72]
|
Clinical parameters like percentage of root coverage, the width of keratinized tissue
(WKT), and thickness of keratinized tissue (TKT) were evaluated after 6 months of
root coverage procedure using coronally repositioned flap and enamel matrix derivative
|
Percentage of root coverage 92%
Statistically significant difference from baseline to 6 months in Mean WKT and TKT
2.23 ± 0.69 and 0.80 ± 0.39 at the baseline and 2.92 ± 0.92 and 1.11 ± 0.32 after
6 months
|
Percentage of root coverage 83%
No statistically significant difference
|
|
2011
|
Bittencourt et al[53]
|
Comparison of esthetic, postoperative morbidity, and root coverage after subepithelial
connective tissue graft
(SECT) technique for gingival recession with or without the use of a surgical microscope
|
The average percentage of root coverage after 12 months 98%
Esthetically at the end of the experimental period 24 patients (100%) patient was
satisfied with the results of the surgery
|
Average root coverage 88.3%
19 out of 24 patients (79.1%) were satisfied with the results esthetically
|
|
2020
|
Liao et al[73]
|
Mechanical and biological properties by analyzing immunofluorescence assay and cell
proliferation of root surface after instrumented with and without the use of a microscope
|
Increased clearance of bacterial deposit and calculi
moderate cell morphological changes
|
Loss of normal surface structure, formation of groove defects was observed.
Flattened and shrank cells on the root surface
|
Abbreviation: Sub-epithelial connective tissue graft (SECT)
Advantages of Use of Microscope in Periodontal Treatment
-
Minimizes the surgical time, reduces patient discomfort
-
Improves incision and approximation of wound by use of suture (6–0 to 9–0) and promotes
wound healing
-
Helps in osseous surgery
-
Accurate procuring of graft from the donor site to the suturing of it in the recipient
site
-
Availability of high-resolution video and photography for patient education, keeping
documentation, and training purposes.[65]
Future of Microsurgery
Recent advancements in the use of microscopes from three-dimensional microsurgery
systems to the development of instrumentation, the ease of working, and accuracy in
work have also increased, including the introduction of robotic microsurgery. In 1997,
Jacques Himpens and Guy Cardiere performed robotic-assisted surgery that was the first
robotic surgery of its time.[61] This bought a drastic change in the use of robotic surgery compatible with modern-day
medicine. Robotic microsurgery serves to be a novel adjunctive tool that can provide
enhanced magnification along with high-level precision.[66] The use of robotic microsurgery is yet to be introduced in periodontal treatment.
How Can I Learn Microsurgery?
To make use of a microscope in day-to-day procedures, proper training and hands-on
programs are being incorporated. The primary focus of teaching should be on developing
clinical skills, stabilizing hands to reduce physiologic tremors, subsumed with correct
posture. Microsurgery can be taught in brief, well-organized laboratory workshops.
It is very important to understand that to make proper use of a microscope in nonsurgical
or surgical procedures, continuous practice is very important.
