This document discusses the use of ultrasound in endodontics. It describes two main methods of ultrasound production: magnetostriction and piezoelectric. Piezoelectric units are preferred as they produce linear motion without heat. Applications of ultrasound include access preparation, removing obstructions, activating irrigants, condensing gutta-percha, placing MTA, and surgical procedures like root-end cavity preparation and placement of root-end filling material. Ultrasound offers benefits like cleaner canals, less invasive surgery, and better filling of materials. A variety of tips are available for different procedures.

1. ULTRASONIC IN ENDODONTIC
PREPARED BY
ASSIST.PROF DR.NIAZ HAMAGHAREEB
B.D.S,M.SC,PH.D

2. Ultrasound is sound energy with a frequency above the
range of human hearing, which is 20 kHz.
The frequencies originally employed in ultrasonic units
ranged between 25 and 40 kHz;
later on, low-frequency ultrasonic handpieces operating
from 1 to 8 kHz were developed, to produce lower shear
stresses, in order to reduce risk for alteration to the tooth
surface.
The first to introduce the concept of ultrasound in
endodontics was Richman,around 1957

3. :
THERE ARE TWO BASIC METHODS FOR
ULTRASOUND PRODUCTION
MAGNETOSTRICTION
Magnetostriction converts electromagnetic energy into
mechanical energy.
A stack of magnetostrictive metal strips in a handpiece
is subjected to a standing and alternating magnetic
field, as a result of which vibrations are produced.
A magnetostrictive device creates more of an elliptical
motion, which is not ideal for either surgical or
nonsurgical endodontic use and have also the
disadvantage that the stack generates heat, thus
requiring adequate cooling.

4. PIEZOELETRIC

Based on the piezoelectric principle, which uses a crystal that
changes dimension when an electrical charge is applied.
Deformation of this crystal is converted into mechanical oscillation
without heat production.

Piezoelectric units have some advantages with respect to earlier
magnetostrictive units as 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
applications.
Piezoelectricity is the process of using
crystals to convert mechanical energy
into electrical energy, or vice versa

5. SONIC
 Besides ultrasonic devices, also sonic instruments are
used in endodontics, with a frequency from 1500 to 6000
hz (Micro-Mega Sonic Air, KaVo SonicFlex Endo)
 for detection and preparation of the canal orifices,
 for removal of soft materials and
 for canal preparation with continuous irrigation.

6.  Another sonic device (EndoActivator) is used to
activate intra-canal irrigants during endodontic
treatment.

7. PIEZOSURGERY
 Piezosurgery devices have been developed for bone
surgery, and have found applications in endodontic
surgery:
 for osteotomy,
 root-end resection and
 retropreparation.
piezosurgery results :
 in less bleeding,
 less swelling and
 less postoperative pain.

8. STANDARD CLASSIFICATION FEATURES

To this day, a variety of ultrasonic tips have been
introduced on the market, both for orthograde and
retrograde RCT.
 All of these can normally be used on different
piezoelectric ultrasonic devices, but one must check
that the thread pattern on the unit and the tip is
compatible (E-thread and an S-thread are currently
used).
 The tips are also manufactured from a range of
metal alloys, such as stainless-steel and titanium
alloys, and can be coated with an abrasive such as
diamond or zirconium nitride in order to increase
the cutting efficiency of the tip.
 Many of the tips incorporate a built-in water port so
that debris can be washed away and cooling can
take place if desired.
 As a result of the variety of tips available, there is an
appropriate tip design for virtually every step of
endodontic treatment, from access to obturation,
each to be used in the recommended power
setting range.

9. ACTIVE TIP /
SMOOTH TIP
•
The active tip makes an extremely effective tool when
used for fiber post and obstacles present in pulp
chamber removal and in all the circumstances in
which there is a good view and a low risk of creating
iatrogenic injury.
• The smooth tip is useful in the cases in which cutting
action is not necessary on the tip but is exerted by the
body of the instrument. This is useful in pulp stone
and intracanal obstructions (such as post) removal.

10. DIAMOND COATED / NON DIAMOND COATED

The diamond coating of an ultrasonic tip makes it much
more effective and abrasive.
 This kind of tip, especially if used without irrigation, tend to
get soiled with dentinal debris thus loosing cutting efficacy.
Furthermore, the diamond part is likely to, overtime, get
consumed and to detach from its site.
 Surface coatings on ultrasonic tips are intended to
increase efficiency and durability; diamond-coated tips
have been shown to require less time than stainless-steel
tips or zirconium nitride tips to cut similar preparations.

11. SMOOTH / MILLED

Among the uncoated diamond tips we can find those
with a smooth surface and those milled surface.
 The tips with milled surface have a higher lateral
cutting ability and longer lasting even compared to
the coated diamond tips.

12. STAINLESS STEEL / NICKEL TITANIUM

The ultrasonic tips Nickel-Titanium are much more
fragile than stainless-steel, are used to work at a low
intensity within the channel. They should be
activated when in contact with the canal walls
otherwise they tend to fracture.

13. ULTRASONIC FILES

The endodontic instruments as
K-files mounted on Endochuck
or as independent files inserts
may be used for:
 - Activation of irrigants to
increase its effectiveness
 - Removal of obstacles
intracanal, especially
positioned in the medium-
apical third canal (like
broken files)
 - Allow the achieving and
positioning of MTA in the
third apical canal

14.  As for the root canal instruments, also for the use of the
ultrasonic instruments, it is appropriate to make a
clinical classification according to the tooth section
in which they must operate.
Therefore the choice of each tip type (active/non active,
smooth/milled), the intensity of use, the use with or
without water will be in close relationship with the area in
which it will have to work.

15. THE FOLLOWING IS A LIST OF THE MOST FREQUENT APPLICATIONS OF US IN
ENDODONTICS, WHICH WILL BE REVIEWED IN DETAIL
 Access refinement, finding calcified canals, and removal of
attached pulp stones

Removal of intracanal obstructions (separated instruments, root
canal posts, silver points, and fractured metallic posts)
 Increased action of irrigating solutions
 Ultrasonic condensation of gutta-percha
 Placement of mineral trioxide aggregate (MTA)
 Surgical endodontics: Root-end cavity preparation and refinement
and placement of root-end obturation material
 Root canal preparation :
ultrasonically or sonically
prepared teeth have significantly
cleaner canals than teeth prepared
by hand instruments

16. ACCESS REFINEMENT, FINDING CALCIFIED CANALS, AND
REMOVAL OF ATTACHED PULP STONES
 One of the challenges in endodontics is
to locate canals, particularly in cases in
which the orifice has become occluded
by secondary dentin or calcified dentin
secondary to the placement of
restorative materials or pulpotomies.
 With every access preparation in a
calcified tooth, there is the risk of
perforating the root or, when incorrectly
performed, of complicating each
subsequent procedure.
 A lack of a straight-line access is
arguably the leading cause of
separation, perforation, and the inability
to negotiate files to the radiographic
terminus

18.  Removal of Intracanal Obstructions
(a) The BUC-1 is an example of diamond-coated
spreader tip of medium length that can be used for
gross dentin removal, moving access line angles,
cutting a groove in the mesial access wall to drop
into MB2 canals, and quickly and carefully
unroofing pulp chambers.
(b) The BUC-3 is similar to the BUC-1 with a sharper
tip and a water port for increased washing and
cooling of the operative site. It is used for chasing
canals or for digging around a post or carrier-based
obturator with the objective to remove it.
(c) This diamond-coated pear tip is used to find
canals, remove coronal obstructions or restorative
materials, or remove calcifications, temporary and
permanent cements, and posts. It creates a smooth,
clean flat troughing groove that facilitates canal
location.

20. (d) This diamond-coated ball tip provides fine
cutting control when preparing a troughing
groove and is less aggressive than the pear tip
shown in c, yet it has the same clinical
indications.
(e) A classic spreader tip with a diamond coating,
which offers a side as well as an end cutting
action. This is needed to flare the walls of a
troughing groove in an axial direction.

21. (f) A fine spreader tip indicated for
troughing and removal of broken
instruments.
(g) An extra-fine spreader tip used for
extremely fine and deep troughing or
removal of a separated instrument in
the middle or apical third of the canal.
(h) A spreader tip designed for multiple
uses such as instrument or silver point
removal, troughing, removal of
calcifications, provisionals, cements,
buildup materials, etc.
(i) Vibrator tip specifically
designed for post removal.

22.  Separated Instruments
 Management of a broken instrument requires an orthograde or a
surgical approach. The three orthograde approaches are
 (a) attempt to remove the instrument;
 (b) attempt to bypass the instrument; and
 (c) prepare and obturate to the fractured segment

23. Root Canal Posts
Nonsurgical endodontic retreatment of teeth restored
with intraradicular posts continues to present a challenge
because of the inherent difficulties of removing posts
without weakening, perforating, or fracturing the
remaining root structure .
Many techniques and instruments have been described
to aid in the removal of posts ,US has provided clinicians
with a useful adjunct to facilitate post removal
with minimal loss of tooth structure and root damage .

24. . Preoperative image (a) and radiograph (b) of a mandibular first molar with three gold cast posts
and cores and full-crown coverage. The patient presented with pain and swelling. The
preoperative diagnostic radiograph revealed signs of radiolucency in the furcal area toward the
mesial root. The metal-ceramic crown was sectioned (c) and removed (d), and the gold cast posts
were separated to facilitate their removal (e, f). The three posts were removed (g) by vibrating
with an ultrasonic tip to disrupt the cement seal (h). This clinical image revealed two perforations
in the mesial root canal (h). Perforations were repaired using gray MTA compacted with an
ultrasonic tip (i). Root canals were filled with gutta-percha and sealer (l), and the coronal
portions of the mesial canals were further filled with MTA to enhance the seal of the perforations
(m). Postendodontic preprosthetic restoration was performed using a fiber-reinforced post in the
distal canal and a dual-cure resin composite buildup material (n).

25.  Increased Action of Irrigating Solutions
 The effectiveness of irrigation relies on both the
mechanical flushing action and the chemical
ability of irrigants to dissolve tissue .
 Furthermore, the flushing action of irrigants
helps to remove organic and dentinal debris
and microorganisms from the canal .
 The flushing action from syringe irrigation 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 been shown that irrigants can only
progress 1 mm beyond the tip of the needle .

26.  An increase in volume does not significantly improve
their flushing action and efficacy in removing debris .
 In larger apical canals, the debridement and disinfection
of canals is improved . However, thorough cleaning of the
most apical part of any preparation remains difficult .
 Using thinner needles (30 gauge) may facilitate reaching
the apical area directly. Although conclusive evidence is
still lacking, the introduction of slim irrigating needles
with a safety tip placed to working length or 1 mm short
of it is a promising approach to improve irrigant efficacy.
 US is a useful adjunct in cleaning these difficult
anatomical features. It has been demonstrated that an
irrigant in conjunction with ultrasonic vibration, which
generates a continuous movement of the irrigant, is
directly associated with the effectiveness of the cleaning
of the root canal space

27.  Ultrasonic Condensation of Gutta-Percha
 Ultrasonically activated spreaders have been
used to thermoplasticize gutta-percha in a warm
lateral condensation technique.
 Ultrasonic spreaders that vibrate linearly and
produce heat, thus thermoplasticizing the gutta-
percha, achieved a more homogeneous mass
with a decrease in number and size of voids and
produced a more complete three-dimensional
obturation of the root canal system .

28.  Placement of Mineral Trioxide Aggregate (MTA)
 The inherent irregularities and divergent nature
of some open apices may predispose the
material to marginal gaps at the dentin
interface.
 Placement of MTA with ultrasonic vibration and
an endodontic condenser improved the flow,
settling, and compaction of MTA. Furthermore,
the ultrasonically condensed MTA appeared
denser radiographically, with fewer voids .

29. SURGICAL ENDODONTICS: ROOT-END
CAVITY PREPARATION AND REFINEMENT
AND PLACEMENT OF ROOT-END OBTURATION
MATERIAL
This leads to a smaller osteotomy for surgical access because of the
advantage of using various angulations and the small size of the retrotips .
advantages of this technique:
1- deeper and more conservative cavities that follow the original path of the
root canal more closely .
2- A better-centered root-end preparation also lessens the risk of lateral
perforation .
3- the geometry of the retrotip design does not require a beveled root-end
resection for surgical access
4- decreasing the number of exposed dentinal tubules
5-minimizing apical leakage .
6- They also enable the removal of isthmus tissue present between two
canals within the same root .
7- It is considered a timesaving technique.
8- lower failure rate