2. Introduction
History
Ultrasound
Biophysical Effects of Ultrasonics
Ultrasonic Tips
Application in Endodontics
Guidelines
Conclusion
References
2
3. During the past few decades endodontic treatment has
benefited from the development of new techniques and
equipment, which have improved outcome and predictability.
Ultrasonics (US) have found indispensable applications in a
number of dental procedures in periodontology, to a much
lesser extent in restorative dentistry, while being very
prominently used in endodontics.
3
4. Since its introduction, US has become increasingly more
useful in applications such as gaining access to canal
openings, cleaning and shaping, obturation of root canals,
removal of intracanal materials and obstructions, and
endodontic surgery.
4
5. The use of ultrasonics was first introduced in dentistry in 1951 for
cavity preparations using an abrasive slurry. It never became
popular, because it had to compete with the much more effective
and convenient high-speed handpieces.
1955- Zinner reported the use of an ultrasonic instrument to remove
deposits from the tooth surface. This was improved upon by
Johnson and Wilson, and the ultrasonic scaler became an established
tool in the removal of dental calculus and plaque.
5
6. The concept of using US in endodontics was first introduced by
Richman in 1957, who first wrote about its application to root canal
therapy and root resection.
During the 1960s, researchers investigated the use of ultrasonics for
cleaning instruments, removing stains from acrylic resin dentures,
and in precision metal casting for dental purposes.
In 1976, the term endosonics was coined by Martin and
Cunningham and was defined as the ultrasonic and synergistic
system of root canal instrumentation and disinfection.
6
7. 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.
Subsequently the so-called low-frequency ultrasonic
handpieces operating from 1 to 8 kHz were developed, which
produce lower shear stresses, thus causing less alteration to the
tooth surface.
7
8. There are two basic methods of producing ultrasound. The
first is magnetostriction, which converts electromagnetic
energy into mechanical energy.
The principle of magnetostriction was discovered by James
Joule in 1847.
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.
8
9. The second method is based on the 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.
The tips of these units work in a linear, back-and-forth,
“piston-like” motion, which is ideal for endodontics
9
12. The physical effects created by the production of ultrasound
are acoustic microstreaming, heat, cavitational activity.
12
13. The file oscillations are primarily responsible
for the production of acoustic streaming,
which is the movement of fluid in a vortex-
like motion around the file when pressure
waves are projected through it.
Acoustic streaming may also be associated
with the occurrence of cavitation.
13
14. Cavitation refers to the oscillatory motions of gas-filled
bubbles in an acoustic field, bubbles that are powered by
energy from the ultrasonic field.
The microscopic bubbles are formed and then collapse and
explode, resulting in localized areas of pressure and heat
production.
This transient type of cavitational activity has been shown to
occur around the tips of ultrasonic scalers.
14
15. Thermal imaging has been used to show that piezoelectric
ultrasonic devices, as well as magnetostrictive ultrasonic units,
produce heat when in contact with tooth structure or dental
materials due to friction.
The general heating effect can be minimized by using low and
medium power settings, and also light contact, but water
should be used to cool the tooth structure.
15
16. Ultrasonic activation is also able to increase the temperature of
the surrounding irrigant in a root canal up to 10 degrees
Celsius.
It has been shown that heating sodium hypochlorite greatly
increases tissue dissolution.
16
17. When an ultrasonic device is used with water coolant, aerosols are
produced that can contain microorganisms and even blood
contamination.
These aerosols can remain airborne for some time. The use of an
extraoral high-volume evacuation is able to significantly reduce the
aerosols produced.
The use of a preprocedural mouthrinse of 0.12% chlorhexidine or
0.05% cetylpyridinium chloride has also been shown to significantly
reduce the microbial content of dental aerosols.
17
18. The current evidence on the effect of ultrasonic dental
equipment on cardiovascular implantable electronic devices
(pacemakers) is inconclusive.
Current guidelines recommend the avoidance of
magnetostrictive devices on those patients with pacemakers,
whereas the use of piezoelectric devices does not appear to
affect pacemakers.
18
19. A great variety of ultrasonic tips are commercially available
for endodontic, periodontal, surgical, and general practice
uses.
The tips manufactured by various companies are often able to
be used on different piezoelectric ultrasonic devices, but one
must check that the thread pattern on the unit and the tip is
compatible.
19
20. Two different thread patterns, an 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.
20
21. Almost every ultrasonic tip for endodontic use incorporates a
contra-angle bend that allows the clinician to have a virtually
unobstructed view into the working area, and is most easily
used with the aid of a surgical operating microscope.
21
ProUltra Endo Tips
22. Surgical endodontic ultrasonic tips incorporate a second bend
placed closer to the end of the tip in order to allow parallel
access to the root canal when creating retro-preparations.
22
ProUltra Surgical Endo Tips
23. 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.
23
24. The ProUltra Endo Tips are numbered from 1 through 8, and
are designed to address most intracoronal and intracanal
procedures.
These were designed by Dr. Clifford Ruddle.
24
25. ProUltra Endo Tips #1 through #5 are made of stainless-steel
and are zirconium nitride-coated instruments for increased
efficiency in cutting.
ProUltra Endo Tips #6, #7, and #8 (20 mm, 24 mm, and 27
mm, respectively) are made from a titanium alloy.
25
26. ProUltra Endo #1 (17 mm) and #2 (17 mm) can be
used from medium to high power, and feature a wider
tip and design features suited to coronal disassembly,
post removal, and the removal of larger pulp stones.
ProUltra Endo #3 (17 mm), #4 (19 mm), and #5 (24
mm) are used from low to medium power, and feature
increasingly longer and finer tips, suited to searching
for hidden canals, troughing fine fins and narrow
isthmuses, and removing separated instruments within
the root canal. 26
27. ProUltra Endo Tips #6, #7, and #8 (20 mm, 24 mm,
and 27 mm, respectively) are made from a titanium
alloy and are used in the lower power range only.
Due to the titanium alloy construction, these end-
cutting tips have inherent flexibility and are mainly
used for apical obstructions.
27
28. The ProUltra Endo Tips do not have a water port; water is
used intermittently to wash away debris or for its cooling
effects.
The CPR line of tips from Obtura Spartan, also numbered
from #1 to #8, are of similar design but are coated with
diamond grit and have a water port.
28CPR Ultrasonic Tips
29. Specialized tips designed specifically for the vibration
of posts, such as the VT tip by SybronEndo or the
VibraPost by B&L Biotech, feature a wide and blunt end
designed to be placed, at maximum power, against a
metal post.
29SybronEndo VT B&L Biotech VibraPost
30. The BUC tips from Obtura Spartan are also a series of six
access refinement tips.
The range of six BUC tips feature a rounded tip, a flat disk-
like tip for planing smooth pulp chamber floors, and a pointed,
active tip for apical cutting.
They are diamond-coated and contain a water port.
30
31. The ProUltra Surgical Endo Tips are a set of six
instruments made from stainless-steel coated with
zirconium nitride, like the ProUltra Endo Tips.
However, the surgical tips have a water port, placed
near the tip for better water delivery. When used
during microsurgery, the various double angles allow
specific tips to be used in certain quadrants of the
mouth, and to reach difficult areas.
The tip allows a 3 mm retropreparation to be made.
31
32. The KiS microsurgical tips by Obtura Spartan are a similar set
of ten tips.
These tips are also double-angled, feature a water port, have a
3-mm cutting surface and 0.5-mm tip diameter, but are coated
with diamond grit.
32
33. The BK-3 tips from SybronEndo feature a microsurgical tip with
three angled bends, providing access and visibility.
The CT Tips, UT Tips, and SJ Tips from SybronEndo each address
larger, moderate, and very fine retro-preparations, respectively.
Designed by Dr. Gary Carr, they are made of stainless-steel, are
uncoated, and feature a water port. Several of these tips are also
available in a diamond-coated version.
33
UT Tips
SJ Tips
BK-3 Tips
34. Recently, two ultrasonic irrigation needles have been available
in the commercial market that have the additional feature of
delivering irrigant during use either by a hand-held syringe or
a peristaltic pump.
They have been found to be at least as effective or more
effective than other irrigation methods.
34
35. One such needle, the ProUltra® PiezoFlow™ Ultrasonic Irrigation Needle,
is a 25-gauge flat open-ended needle made from stainless steel that is
tightened into the ultrasonic handpiece with a wrench and used in the mid-
range power setting in fully instrumented canals.
A syringe or other irrigation source is attached to the Luer-lock connection
on the ultrasonic needle through which irrigant is delivered.
35
36. The VPro™ Stream Clean Ultrasonic Irrigation System (Vista)
is a similar system except that the ultrasonic irrigation needle
is a 30-gauge flat open-ended needle that is constructed from
nickel–titanium.
Much caution needs to be exercised when using an irrigation
needle with a flat open-ended needle; the apical pressures
created with a flat open-ended needle can be several-fold
higher at irrigation flow rates exceeding 4 mL/min than when
closed-ended side-vented needles are used.
36
37. The following is a list of the most frequent applications of US
in endodontics, which will be reviewed in detail:
1. Access refinement, finding calcified canals, and removal of attached pulp
stones.
2. Removal of intracanal obstructions (separated instruments, root canal
posts, silver points, and fractured metallic posts).
3. Increased action of irrigating solutions.
4. Ultrasonic condensation of gutta-percha.
37
38. 5. Placement of mineral trioxide aggregate (MTA).
6. Surgical endodontics: Root-end cavity preparation and refinement and
placement of root-end obturation material.
7. Root canal preparation
38
39. 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.
In conventional access procedures, ultrasonic tips are useful for access
refinement, location of MB2 canals in upper molars and accessory canals
in other teeth, location of calcified canals in any tooth, and removal of
attached pulp stones.
39
40. One of the most important advantages of ultrasonic tips is that they do not
rotate, thus enhancing safety and control, while maintaining a high cutting
efficiency.
This is especially important when the risk of perforation is high.
Care should be exercised while searching for canal orifices, as aggressive
cutting may cause an undesired modification of the anatomy of the pulp
chamber.
40
41. Clinicians are frequently challenged by endodontically treated teeth that
have obstructions such as hard impenetrable pastes, separated instruments,
silver points, or posts in their roots.
If endodontic treatment has failed, these obstructions need to be removed
to perform nonsurgical retreatment.
Ultrasonic energy has proven effective as an adjunct in the removal of
silver points, fractured instruments, and cemented posts.
It has often been advocated for the removal of broken instruments because
the ultrasonic tips or endosonic files may be used deep in the root canal
system.
41
42. The removal of an obstacle from a root canal must be performed with a
minimum of damage to the tooth and the surrounding tissues.
Too much destruction of tooth structure will complicate the restorative
phase and as a result will most likely decrease the overall prognosis.
42
43. US has provided clinicians with a useful adjunct to facilitate post removal
with minimal loss of tooth structure and root damage.
Several studies point to the fact that ultrasonic vibration of posts facilitates
their removal while conserving tooth structure and reducing the possibility
of fractures or root perforations.
43
44. 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.
44
45. The only effective way to clean webs and fins is through movement of the
irrigation solution, as they cannot be mechanically cleaned.
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.
The flushing action of irrigants may be enhanced by using US. This seems
to improve the efficacy of irrigation solutions in removing organic and
inorganic debris from root canal walls.
45
46. The ability of NaOCl to dissolve collagen is enhanced with heat; therefore,
the effect of heat on the irrigant produced by ultrasonic action plays an
important role.
Furthermore, van der Sluis et al. have postulated that ultrasonic irrigation
should be more effective in removing debris from root canals with greater
tapers.
It appeared to be important to apply the ultrasonic instrument after canal
preparation had been completed.
Thirty seconds to 1 minute of ultrasonic activation seems to be sufficient to
produce clean canals, whereas others recommend 2 minutes.
46
47. The technique of ultrasonic activation of an irrigant after instrumentation
has been completed has been referred to as passive ultrasonic irrigation.
The term passive is used to denote the intention to simply activate the
irrigant, and not to cut or contact the dentin with the activated file, thus
differentiating it from previous efforts to ultrasonically instrument the root
canal walls.
However, a recent study has shown that the file-to-wall contact during
passive ultrasonic irrigation was actually rather significant; the file was in
contact with the wall 20% of the activation time. As a result, it was
recommended amending the term “passive ultrasonic irrigation” to
“ultrasonically activated irrigation.” 47
48. Continuous ultrasonic irrigation is achieved by simultaneously and
continuously delivering irrigation during ultrasonic activation through a
water port incorporated into the ultrasonic tip.
Unlike passive ultrasonic irrigation, the replenishment of irrigant with a
conventional syringe between ultrasonic file activations is not required.
Continuous ultrasonic irrigation has been shown to be more effective in
clearing apically placed debris than other irrigation modalities.
When comparing passive ultrasonic irrigation and continuous ultrasonic
irrigation, both modalities have been shown to perform similarly in the
removal of debris in a root canal.
48
49. In another study, both modalities performed comparably and better than
conventional syringe irrigation in the penetration of irrigant into simulated
lateral canals.
Infected lateral canals are a possible cause of recurrent or late endodontic
treatment failure; delivering irrigant to the entire root canal system,
including lateral canals, is important for the predictable long-term success
of endodontic treatment.
49
50. Ultrasonically activated spreaders have been used to thermoplasticize
gutta-percha in a warm lateral condensation technique.
In some in vitro experiments, this was demonstrated to be superior to
conventional lateral condensation with respect to sealing properties and
density of gutta-percha.
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.
This technique has also been evaluated clinically with favorable results.
50
51. Witherspoon and Ham described the use of US to aid in the placement of
MTA.
It was demonstrated that, with the adjunct of US, a significantly better seal
with MTA was achieved.
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.
51
52. Recent developments of new instruments and techniques have significantly
enhanced the treatment outcome in apicoectomy with retrofilling.
As the prognosis of endodontic surgery is highly dependent on good
obturation and sealing of the root canal, an optimal cavity preparation is an
essential prerequisite for an adequate root-end filling after apicoectomy.
Since sonically or ultrasonically driven microsurgical retrotips became
commercially available in the early 1990s, this new technique of retrograde
root canal instrumentation has been established as an essential adjunct in
endodontic surgery.
52
53. The first root-end preparation using modified ultrasonic inserts following an
apicoectomy is attributed to Bertrand et al.
Ultrasonic retrotips come in a variety of shapes and angles, thus improving
some steps during the surgical procedures.
At first glance, the most relevant clinical advantages are the enhanced access to
root ends in a limited working space. This leads to a smaller osteotomy for
surgical access because of the advantage of using various angulations and the
small size of the retrotips.
Ultrasonic tips can also be used to polish root end material and apical surfaces.
Utilizing specific ultrasonic tips for refinement of the external radicular surface
may be beneficial in the elimination of extraradicular bacteria, which may be
responsible for infection
53
54. It is recommended that ultrasonic tips be used with a light
touch and be kept moving during use, as an excessive force
can significantly reduce the displacement amplitude of the tip.
Studies have used a range of different contact loads, from 15-
200 g of force, but a recent study has determined that the
average trained endodontist uses 15 g of downward force
during ultrasonic instrumentation.
54
55. Excessive forces or use of the tip in extremely narrow canals
can also cause the ultrasonic tip to stall, in which case contact
with the material being cut should be momentarily broken in
order to allow the oscillations to re-establish themselves
through the tip.
The use of inappropriately high power settings can result in
breakage of a tip in as little as 10seconds.
55
56. One final concern in the safe use of ultrasonic tips is the
generation and transmission of heat to the supporting dental
structures.
The production of heat is not necessarily a terrible
consequence and can be harnessed for a beneficial purpose,
such as to increase the temperature of irrigants during
ultrasonically activated irrigation.
However, it has been shown that a temperature rise in the
supporting bone beyond 47°C for a certain period of time can
produce irreversible damage.
56
57. Intermittent use of the ultrasonic, with copious air or water
coolant, has been shown to be effective in reducing the
potential for serious heat-related injury to the periodontal
tissues.
57
58. The piezoelectric ultrasonic device has the potential to become
routinely incorporated into almost every component of
endodontic treatment, re-treatment, and apical microsurgery.
It is already indispensable as a precise tool with which the
most challenging clinical situations, such as finding hidden
root canals and removing root canal obstructions, can be done
with relative ease, predictability, and conservancy.
58
59. Finally, integration of new technologies such as US, leading to
improved techniques and use of materials, has changed the
way endodontics is being practiced today.
It can be concluded that ultrasonics is a good adjunct for
irrigation, but cannot be recommended for routine root canal
preparation. Ultrasonics can be helpful in selected situations.
59
60. Cohen’s Pathways of the Pulp: 11th Edition.
Ingle’s Endodontics: 7th Edition.
Gianluca Plotino et al. Ultrasonics in Endodontics: A Review
of the Literature. Journal of Endodontics 2007, 33(2):81-95.
Ellen Park. Ultrasonics in endodontics. Endodontic Topics
2013; 29; 125–159.
60
