2. INTRODUCTION
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The use of Ultrasonic (US) OR ultrasonic
instrumentation was first introduced to dentistry for
cavity preparation using abrasive slurry.
Although the technique received favorable reviews, it
never became popular, because it had to compete with
the much more effective and convenient high-speed
handpiece.
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The term ( Endosonics ) defined as the ultrasonic and
Synergistic system of root canal instrumentation and
disinfection.
Ultrasound is sound energy with a frequency above the
range of human hearing, which is 20 KHz.
The range of frequencies employed in the original
ultrasonic units, was between 25 and 40 kHz.
4. THERE ARE TWO METHODS OF
ULTRASOUND
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• The first one is ( Magnetostriction ) which
converts electromagnetic energy into mechanical
energy.
• The second one is based on ( piezoelectric )
principle, in which a crystal is used that
changes dimension when an electrical charge is
applied. Deformation of this crystal is converted
into mechanical oscillation without producing
heat.
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Peizolelectric units have some advantages
compared with earlier magnetostrictive units
because they offer more cycles per second, 40
versus 24 kHz. The tips of these units work in
a linear, back-and-forth,
“ piston-like “ motion, which is ideal for
endodontic.
Magnetostrictive units on other hand, creates
more of a figure eight motion ( elliptical ) ,
which is not ideal for nonsurgical or surgical
endodontics.
6. APPLICATIONS OF US IN ENDODONTICS
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1.Access refinement, finding calcified canals, and
removal of attached pulp stone.
2.Increased action of irrigating solutions
3.Removal of intracanal obstructions
4.Ultrasonic condensation of gutta percha
5.Placement of MTA
6.Surgical Endodontics ( root end cavity preparation )
7.Root canal preparation
7. ACCESS REFINEMENT, LOCATING CALCIFIED CANALS
AND REMOVAL OF ATTACHED PULP STONES
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One of the challenges in endodontics is to locate the canals, particularly in
cases in which the orffice has become occluded by secondary dentin.
With every access preparation in a calcified tooth, there is the risk of root
perforation.
In difficult to treat teeth such as molars, US has proven to be useful for
access preparation, not only for locating canals but also for reducing the
time of treatment.
US tips are useful for locating the MB2 canals in upper molars and
accessory canals in other teeth.
When locating the MB2 canals in upper molars, US is an excellent means
for removal of secondary dentin on the mesial wall using a troughing tip.
8. REMOVAL OF INTRACANAL OBSTRUCTIONS
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Separated Instruments
Management of a broken instrument requires an
orthograde or a surgical approach. The three orthograde
approaches are:
• attempt to remove the fractured instrument
• Attempt to bypass the FI
• Prepare and obturate to the FI
• In most cases removal of FI from the canal is hopeless
US has often advocated for the removal of removal of
broken instruments from the deep narrow curved canals
10. INCREASED ACTION OF IRRIGATING
SOLUTION
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the effectiveness of irrigation relies on both the mechanical flushing of irrigants
and the chemical ability to dissolve the tissue.
The flushing action from irrigation syringe is relatively weak and dependent not
only on the anatomy of the root canal but also on the depth of placement and the
diameter of the needle.
It has shown that irrigants can only progress 1 mm beyond the tip of the needle.
The only effective way to clean the canals is through movement of the irrigation
solution.
US is useful in cleaning these difficult anatomical features. It has been
demonstrated that an irrigant in conjunction with US vibration which generates a
continuous movement of irrigant is directly with effectiveness of cleaning.
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Cameron stated that there is synergistic effect between
sodium hypoclorite and US, the ability of NaOCL to
dissolve the collagen enhanced with the heat that
produced by ultrasonic action.
Thirty second to 1 minute of US activation seems to be
excellent to produce clean canals
Medium power is suggested for Irrigation.
12. ULTRASONIC CONDESATION OF
GUTTA-PERCHA
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Ultrasonically activated spreaders have been used to thermoplasticize gutta
percha in a warm lateral condensation technique.
US spreaders achieve more homogenous mass with a decrease in number
and size of voides and produce a complete three dimentional obturation of
the root canal system.
The obturation technique using US consists of initial placement of gutta-
percha cone to the full working length followed by cold lateral condensation
of two or three accessory cones using finger spreader.
The US spreader is then placed into the center of the gutta percha mass 1
mm shorter than full WL and activated at intermediate power tot prevent
the charring of the root surfaces or fracture of the spreader.
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After activation the US spreader is removed and an additional accessory
cone is placed, followed by energizing with the activated US spreader,
This process is repeated with each cone until canal is filled, during each
subsequent step, the US spreader should be placed slightly more coronally.
14. PLACEMENT OF MTA
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Placement of MTA with ultrasonic vibrating and an endodontic
condenser improved the flow, settling and compaction of MTA.
Furthermore, the ultrasonically condensed MTA Appeared
denser radiographically with fewer voides .
The method consists of selecting a condenser tip, then picking up
and placing the MTA with US tip, followed by activating the tip
and slowly moving the MTA MATERIAL down using 1 to 2 mm
vertical motion.
Direct US energy will vibrate and generate a wavelike motion,
which facilitates moving and adapting the cement to the canal
wall.
