Safety and Efficacy Considerations in Endodontic ... - IneedCE.com

Publication date: January 2011
Expiry date: December 2013
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Safety and Efficacy Considerations
in Endodontic Irrigation
A Peer-Reviewed Publication
Written by Gary Glassman DDS, FRCD(C)
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Educational Objectives
The overall goal of this article is to provide the reader with
information on endodontic irrigation.
On completion of this course, the reader will be able to:
1. List and describe the challenges for successful endodontic
treatment
2. List and describe the different types of root canal irrigants,
their relative advantages and disadvantages
3. List and describe root canal irrigation systems
4. Describe and explain a sodium hypochlorite incident
5. List and describe the steps that can be taken to avoid a
sodium hypochlorite incident.
Abstract
Endodontic treatment is a predictable procedure with
high success rates. Success depends on a number of factors,
including appropriate instrumentation, successful
irrigation and decontamination of the root canal space to
the apices and in areas such as isthmuses. These steps must
be followed by complete obturation of the root canals, and
placement of a coronal seal, prior to restorative treatment.
Several irrigants and irrigation systems are available, all
of which behave differently and have relative advantages
and disadvantages. Common root canal irrigants include
sodium hypochlorite, chlorhexidine gluconate, alcohol,
hydrogen peroxide and ethylenediaminetetraacetic acid
(EDTA). In selecting an irrigant and technique, consideration
must be given to their efficacy and safety.
Introduction
With the introduction of modern techniques, endodontic
success rates of up to 98% are being achieved. 1
The ultimate goal of endodontic treatment per se is the
prevention or treatment of apical periodontitis such
that there is complete healing and an absence of infection,
2 while the overall long-term goal is the placement
of a definitive, clinically successful restoration and
preservation of the tooth. For these to be achieved,
appropriate instrumentation, irrigation and decontamination,
and root canal obturation must occur,
as well as attainment of a coronal seal. There is clear
evidence that apical periodontitis is a biofilm-induced
disease. 3 A biofilm is an aggregate of microorganisms
in which cells adhere to each other and/or to a surface.
These adherent cells are frequently embedded within
a self-produced matrix of extracellular polymeric substance.
The presence of microorganisms embedded in
a biofilm and growing in the root canal system is a key
factor for the development of periapical lesions. 4,5,6,7
Additionally, the root canal system has a complex
anatomy that consists of arborizations, isthmuses, and
cul-de-sacs that harbor organic tissue and bacterial
contaminants. 8
The challenge for successful endodontic treatment has
always been the removal of vital and necrotic remnants of
pulp tissues, debris generated during instrumentation, the
dentin smear layer, microorganisms, and microtoxins from
the root canal system. 9
Figure 1. Root canal complex
Courtesy of Dr. Charles J. Goodis. In: Mandibular Molar Endodontic Treatment.
Even with the use of rotary instrumentation, the nickel-titanium
instruments currently available only act on the central
body of the root canal, resulting in a reliance on irrigation
to clean beyond what may be achieved by these instruments.
10 In addition, Enterococcus faecalis and Actinomyces
israelii—which are both implicated in endodontic infections
as well as in endodontic failure—penetrate deep into the
dentinal tubules, making their removal through mechanical
instrumentation impossible. 11,12 Finally, Enterococcus faecalis
commonly expresses multiple drug resistance, 13,14,15 further
complicating treatment.
Therefore, a suitable irrigant and irrigant delivery system
are essential for efficient irrigation and the success of
endodontic therapy. 16 Not only should root canal irrigants
be effective for dissolution of the organic component of the
dental pulp, they must also effectively eliminate bacterial
contamination and remove the smear layer—the organic and
inorganic layer that is created on the wall of the root canal
during instrumentation. The ability to deliver irrigants to the
root canal terminus in a safe manner without causing harm to
the patient is as important as the efficacy of those irrigants.
Root Canal Irrigants
Over the years, many irrigating agents have been used
and tried in order to achieve tissue dissolution and bacte-
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ial decontamination. The desired attributes of a root canal
irrigant include the ability to dissolve necrotic and pulpal
tissue, bacterial decontamination and a broad antimicrobial
spectrum, the ability to enter deep into the dentinal tubules,
biocompatibility and lack of toxicity, the ability to dissolve
inorganic material and remove the smear layer, ease of use,
and moderate cost.
Table 1. Desirable root canal irrigant attributes
Bacterial decontamination
Broad spectrum antimicrobial activity
Ability to enter deep into dentinal tubules
Ability to dissolve necrotic tissue
Ability to dissolve inorganic material
Safety
Biocompatibility
Lack of toxicity
Ease of use
Moderate cost
Root canal irrigants currently in use include hydrogen
peroxide, sodium hypochlorite, ethylenediaminetetraacetic
acid (EDTA), alcohol, and chlorhexidine gluconate.
Chlorhexidine gluconate offers a wide antimicrobial spectrum,
the main bacteria associated with endodontic infections
(Enterococcus faecalis and Actinomyces israelii) are
sensitive to it, and it is biocompatible with no tissue toxicity
for the periapical or surrounding tissues. 17 Chlorhexidine
gluconate, however, lacks the ability to dissolve necrotic
tissue, which limits its usefulness. Hydrogen peroxide as
a canal irrigant helps to remove debris by the physical act
of irrigation as well as through effervescing of the solution.
However, while an effective antibacterial irrigant, hydrogen
peroxide also does not dissolve necrotic intracanal tissue,
and exhibits toxicity to the surrounding tissues. Cases of
tissue damage and facial nerve damage have been reported
following use of hydrogen peroxide as a root canal irrigant. 18
Alcohol-based canal irrigants also have antimicrobial activity,
but will not dissolve necrotic tissue.
Table 2. Common root canal irrigants
Chlorhexidine gluconate
Sodium hypochlorite
Alcohol
Hydrogen peroxide
EDTA
The irrigant that satisfies most of the requirements for
a root canal irrigant is sodium hypochlorite (NaOCl). 19,20
It has the unique ability to dissolve necrotic tissue and the
organic components of the smear layer. 19,21,22 It also kills
sessile endodontic pathogens organized in a biofilm. 23,24
There is no other root canal irrigant that can meet all these
requirements, even with the use of methods such as lowering
the pH, 25,26,27 increasing the temperature, 28,29,30,31,32 or
adding surfactants to increase the wetting efficacy of the irrigant.
33,34 However, although sodium hypochlorite appears
to be the most desirable single endodontic irrigant, it cannot
dissolve inorganic dentin particles and thus cannot prevent
the formation of a smear layer during instrumentation. 35
Calcifications hindering mechanical preparation are
frequently encountered in the canal system, further complicating
treatment. Demineralizing agents such as EDTA
have therefore been recommended as adjuvants in root
canal therapy. 20,36 Thus, in contemporary endodontic practice,
dual irrigants such as sodium hypochlorite (NaOCl)
with EDTA are often used as initial and final rinses to circumvent
the shortcomings of a single irrigant. 37,38,39 These
irrigants must be brought into direct contact with the entire
canal wall surfaces for effective action, 20,37,40 particularly for
the apical portions of small root canals. 9
The combination of sodium hypochlorite and EDTA
has been used worldwide for antisepsis of root canal systems.
The concentration of sodium hypochlorite used for
root canal irrigation ranges from 2.5% to 6%, depending
on the country and local regulations; it has been shown,
however, that tissue hydrolyzation is greater at the higher
end of this range, as demonstrated in a study by Hand et
al comparing 2.5% and 5.25% sodium hypochlorite. The
higher concentration may also favor superior microbial
outcomes. 41 NaOCl has a broad antimicrobial spectrum, 20
including but not limited to Enterococcus faecalis. Sodium
hypochlorite is also second to none among irrigating agents
that dissolve organic matter. EDTA is a chelating agent that
aids in smear layer removal and increases dentin permeability,
42,43 which will allow further irrigation with NaOCl
to penetrate deep into the dentinal tubules. 44
The combination of sodium hypochlorite and EDTA has
been used worldwide for antisepsis of root canal systems.
General Safety Precautions
Regardless of which irrigant and irrigation system is employed,
and particularly if an irrigant with tissue toxicity is
used, there are several general precautions that must be followed.
A rubber dam must be used and a good seal obtained
to ensure that no irrigant can spill from the pulp chamber
into the oral cavity. If deep caries or a fracture is present
adjacent to the rubber dam on the tooth being isolated, a
temporary sealing material must be used prior to performing
the procedure to ensure a good rubber dam seal. It is also
important to protect the patient’s eyes with safety glasses
and protect clothing from irrigant splatter or spill.
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It is very important to note that while sodium hypochlorite
has unique properties that satisfy most requirements for
a root canal irrigant, it also exhibits tissue toxicity that can result
in damage to the adjacent tissues, including nerve damage
should sodium hypochlorite incidents occur during canal
irrigation. Furthermore, Salzgeber reported in the 1970s that
apical extrusion of an endodontic irrigant routinely occurred
in vivo; 45 this highlights the importance of using devices and
techniques that minimize or prevent this. Sodium hypochlorite
incidents are further discussed later in this article.
Regardless of which irrigant and irrigation system is used,
a rubber dam must be used and a good seal obtained.
Irrigant Delivery Systems
Root canal irrigation systems can be divided into two categories:
manual agitation techniques and machine-assisted agitation
techniques. 9 Manual irrigation includes positive pressure
irrigation, which is commonly performed with a syringe and
a side-vented needle. Machine-assisted irrigation techniques
include sonics and ultrasonics, as well as newer systems such
as the EndoVac® (Discus Dental, Culver City, CA) , which
delivers apical negative pressure (ANP) irrigation, 46 the plastic
rotary F® File (Plastic Endo, Lincolnshire, IL), 47,48 the
Vibringe® (Vibringe BV, Amsterdam, The Netherlands), 49
the RinsEndo® (Air Techniques Inc., NY), 9 and the Endo-
Activator® (Dentsply Tulsa Dental Specialties, Tulsa, OK). 9
Two important factors that should be considered during
the process of irrigation are whether the irrigation system
can deliver the irrigant to the whole extent of the root canal
system, particularly at the apical third, and whether the irrigant
is capable of debriding areas that could not be reached
with mechanical instrumentation, such as lateral canals and
isthmi. When evaluating irrigation of the apical third, the
phenomenon of apical vapor lock should be considered. 50,51,52
Apical Vapor Lock
Since roots are surrounded by the periodontium, and unless
the root canal foramen is open, the root canal behaves like
a close-ended channel. This produces an apical vapor lock
effect that resists displacement during instrumentation and
final irrigation, thus preventing the flow of irrigant into
the apical region and adequate debridement of the canal
system. 53,54 Apical vapor lock also results in gas entrapment
at the apical third. 9 During irrigation, sodium hypochlorite
reacts with organic tissue in the root canal system, and
the resulting hydrolysis liberates abundant quantities of
ammonia and carbon dioxide. 55 This gaseous mixture is
trapped in the apical region and quickly forms a column
of gas into which further fluid penetration is impossible.
Extension of instruments into this vapor lock does not reduce
or remove the gas bubble, 56 just as it does not enable
adequate flow of irrigant.
Apical vapor lock prevents the flow of irrigant into
the apical region of roots and also results in gas
entrapment at the apical third.
The phenomenon of apical vapor lock has been confirmed
in studies where roots were embedded in a polyvinylsiloxane
(PVS) impression material to restrict fluid flow through the
apical foramen, simulating a close-ended channel. The result
in these studies was incomplete debridement of the apical
part of the canal walls with the use of a positive pressure
syringe delivery technique. 57,58,59,60 Micro-CT scanning and
histological tests conducted by Tay et al have also confirmed
the presence of apical vapor lock. 60 In fact, studies conducted
without ensuring a close-ended channel cannot be regarded
as conclusive on the efficacy of irrigants and the irrigant system.
61,62,63 The apical vapor lock may also explain why, in a
number of studies, investigators were unable to demonstrate
a clean apical third in sealed root canals. 59,64,65,66
Figure 2a. Close-ended channel Figure 2b. Open-ended channel
Courtesy of Dr. Franklin Tay
In a paper published by Chow in 1983, based on research
he determined that traditional positive pressure irrigation
had virtually no effect apical to the orifice of the irrigation
needle in a closed root canal system. 67 Fluid exchange and
debris displacement were minimal. Equally important to his
primary findings, Chow set forth an infallible paradigm for
endodontic irrigation: “For the solution to be mechanically
effective in removing all the particles, it has to: (a) reach the
apex; (b) create a current (force); and (c) carry the particles
away.” 67 The apical vapor lock and consideration for the patient’s
safety have always prevented the thorough cleaning of
the apical 3 mm. It is critically important to determine which
irrigation system will effectively irrigate the apical third as
well as isthmi and lateral canals, 16 and in a safe manner that
prevents the extrusion of irrigant.
An effective irrigant must reach the apex, create a current
and remove particles.
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Manual Agitation Techniques
By far the most common and conventional set of irrigation
techniques, manual irrigation involves dispensing of an irrigant
into a canal through needles/cannulae of variable
gauges, either passively or with agitation by moving the
needle up and down the canal space without binding it on
the canal walls. This allows good control of needle depth and
the volume of irrigant that is flushed through the canal. 9,63
However, the closer the needle tip is positioned to the apical
tissue, the greater the chance of apical extrusion of the irrigant.
67,68 This must be avoided; if sodium hypochlorite were
to extrude past the apex there is a chance that a catastrophic
accident could occur. 69
Manual-Dynamic Irrigation
Manual dynamic irrigation involves gently moving a well-fitting
gutta-percha master cone up and down in short 2 mm to
3 mm strokes within an instrumented canal, thereby producing
a hydrodynamic effect and significant irrigant exchange. 70
Recent studies have shown that this irrigation technique is
significantly more effective than an automated-dynamic irrigation
system and static irrigation. 9,71,72
Figure 3. Manual Dynamic Max-I-Probe®
Machine-Assisted Agitation Systems
Sonic Irrigation
Sonic activation has been shown to be an effective method
for disinfecting root canals, operating at frequencies of 1-6
kHz. 73,74 There are several sonic irrigation devices on the
market. The Vibringe allows delivery and sonic activation
of the irrigating solution in one step. It employs a 2-piece
syringe with a rechargeable battery. The irrigant is sonically
activated, as is the needle that attaches to the syringe.
The EndoActivator System is a more recently introduced
sonically driven canal irrigation system. 9,75 It consists of a
portable handpiece and three types of disposable polymer
tips of different sizes. The EndoActivator has been reported
to effectively clean debris from lateral canals, remove the
smear layer, and dislodge clumps of biofilm within the
curved canals of molar teeth. 9
Figure 4. Sonic irrigation systems
Ultrasonics
Ultrasonic energy produces higher frequencies than sonic
energy but low amplitudes, oscillating at frequencies of 25-
30 kHz. 9,76 Two types of ultrasonic irrigation are available
for use. The first type is simultaneous ultrasonic instrumentation
and irrigation (UI), and the second type is referred
to as passive ultrasonic irrigation operating without simultaneous
irrigation (PUI). The literature indicates that it is
more advantageous to apply ultrasonics after completion of
canal preparation rather than as an alternative to conventional
instrumentation. 9,20,77 PUI irrigation allows energy
to be transmitted from an oscillating file or smooth wire to
the irrigant in the root canal by means of ultrasonic waves. 9
There is consensus that PUI is more effective than syringe
. needle irrigation in removing pulpal tissue remnants and
dentin debris. 78,79,80 This may be due to the much higher
velocity and volume of irrigant flow that are created in the
canal during ultrasonic irrigation. 9,81 PUI has been shown
to remove the smear layer; there is a large body of evidence
with different concentrations of NaOCl. 9,80,82,83,84 In addition,
numerous investigations have demonstrated that the
use of PUI after hand or rotary instrumentation results in
a significant reduction of the number of bacteria, 9,85,86,87 or
achieves significantly better results than syringe needle irrigation.
9,84,88,89
Studies have demonstrated that effective delivery of irrigants
to the apical third can be enhanced by using ultrasonic
and sonic devices. 79,81,90,91,92 However, some recent studies
have shown that once a sonic or ultrasonically activated tip
leaves the irrigant and enters the apical vapor lock, acoustic
microstreaming and/or cavitation becomes physically
impossible, 93 which is not the case with the apical negative
pressure irrigation technique. 46,94
Consider the erroneous idea that acoustic microstreaming
or cavitation that occurs during PUI can clean any part
of the apical portion filled with gas (apical vapor lock).
Acoustic microstreaming is defined as the movement of fluids
along cell membranes, which occurs as a result of the ultrasound
energy creating mechanical pressure changes within
the tissue. Cavitation is defined as the formation and collapse
of gas- and vapor-filled bubbles or cavities in a fluid.
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This process (cavitation) results from the creation and collapse
of microbubbles in the liquid. Acoustic microstreaming
or cavitation is only possible in fluids/liquids, not in
gases. Therefore, as previously mentioned, it is physically
impossible for acoustic microstreaming and/or cavitation
to disrupt the apical vapor lock.. 56
Other studies have shown that sonic or ultrasonic activation
might allow a better removal of pulpal tissue remnants
and debris from isthmi and fins. 79,81 Although ultrasonics
can effectively clean debris and bacteria from the root canal
system, they still have the drawback of not being able to
effectively get through the apical vapor lock in the apical 3
mm of the canal.
Ultrasonics can effectively clean debris and bacteria from
the root canal system, but cannot effectively get through
the apical vapor lock.
The Plastic Rotary F File
Although sonic or ultrasonic instrumentation is more effective
in removing residual canal debris than rotary endodontic
files 95 and irrigation solutions are often unable to remove
this during endodontic treatment, many clinicians still do
not incorporate it in their endodontic instrument armamentarium.
The common reasons given for not using sonic or
ultrasonic filing are that it can be time-consuming to set up,
an unwillingness to incur the cost of the equipment, and lack
of awareness of the benefits of this final instrumentation step
in endodontic treatment.
It is for these reasons that an endodontic polymer-based
rotary finishing file was developed. This new, single-use,
plastic rotary file has a unique file design with a diamond
abrasive embedded into a nontoxic polymer. The F File will
remove dentinal wall debris and agitate the sodium hypochlorite
without further enlarging the canal.
Pressure Alternation Devices
RinsEndo irrigates the canal by using pressure-suction
technology. Its components are a handpiece, a cannula with
a 7 mm exit aperture, and a syringe carrying irrigant. The
handpiece is powered by a dental air compressor and has an
irrigation speed of 6.2 ml/min. Research has shown that it
has promising results in cleaning the root canal system, but
more research is required to provide scientific evidence for
its efficacy. Periapical extrusion of irrigant has been reported
with this device. 96,97
Figure 5. RinsEndo
The EndoVac Apical Negative Pressure System
The EndoVac apical negative pressure irrigation system has
three components: The Master Delivery Tip, MacroCannula
and MicroCannula. The Master Delivery Tip simultaneously
delivers and evacuates the irrigant. The MacroCannula is used
to suction irrigant from the chamber to the coronal and middle
segments of the canal. The MacroCannula or MicroCannula
is connected via tubing to the high-speed suction of a dental
unit. The Master Delivery Tip is connected to a syringe of irrigant
and the evacuation hood is connected via tubing to the
high-speed suction of a dental unit. 56 The plastic MacroCannula
has an ISO size 0.55 mm diameter open end with a .02
taper and is attached to a Handpiece for gross, initial flushing
of the coronal and mid-length parts of the root canal. The
MicroCannula contains 12 microscopic holes and is capable of
evacuating debris to full working length. 97 The ISO size 0.32
mm diameter stainless steel MicroCannula has four sets of
three laser-cut, laterally positioned, offset holes adjacent to its
closed end, 100 microns in diameter and spaced 100 microns
apart. This is attached to a Fingerpiece for irrigation of the apical
part of the canal when it is positioned at the working length.
The MicroCannula can be used in canals that are enlarged
with endodontic files to ISO size #35/.04 or larger.
Figure 6a. EndoVac Multi-Port Adapter
Figure 6b. EndoVac instruments
Master Delivery Tip
MacroCannula
MicroCannula with venting
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During irrigation, the Master Delivery Tip delivers irrigant
to the pulp chamber and siphons off the excess irrigant to
prevent overflow. Both the MacroCannula and MicroCannula
exert negative pressure that pulls irrigant from its fresh
supply in the chamber, down the canal to the tip of the cannula,
into the cannula, and out through the suction hose.
Thus, a constant flow of fresh irrigant is being delivered by
negative pressure to working length. A recent study showed
that the volume of irrigant delivered was significantly higher
than the volume delivered by conventional syringe needle
irrigation during the same time period, 46 and resulted in
significantly more debris removal at 1 mm from the working
length than did needle irrigation. During conventional root
canal irrigation, clinicians must be careful when determining
how far an irrigation needle is placed into the canal.
Recommendations for avoiding NaOCl incidents include
not binding the needle in the canal, not placing the needle
close to working length, and using a gentle flow rate when
using positive pressure irrigation. 98 With the EndoVac, in
contrast, irrigant is pulled into the canal at working length
and removed by negative pressure. Apical negative pressure
has been shown to enable irrigants to reach the apical
third and help overcome the issue of apical vapor lock. 46,99
In addition, with respect to isthmus cleaning, although it is
not possible to reach and clean the isthmus area with instruments,
it is not impossible to reach and totally clean these
areas with NaOCl when the method of irrigation is safe
and efficacious. In studies comparing the EndoActivator, 100
passive ultrasonic, 100 the F File, 100 the Manual Dynamic
Max-I-Probe, 100,101 the Pressure Ultrasonic, 95 and the EndoVac,
101 only the EndoVac was capable of cleaning 100% of
the isthmus area.
The EndoVac uses negative pressure, pulls irrigant
into the canal to working length and
removes it with suction.
Apart from being able to avoid air entrapment, the EndoVac
system is also advantageous in its ability to safely deliver
irrigants to working length without causing their undue
extrusion into the periapex, 46,97 thereby avoiding sodium
hypochlorite incidents. It is important to note that it is
possible to create positive pressure in the pulp canal if the
Master Delivery Tip is misused, which would create the
risk of a sodium hypochlorite incident. The manufacturer’s
instructions must be followed for correct use of the Master
Delivery Tip.
Sodium Hypochlorite Incidents
Although a devastating endodontic sodium hypochlorite (Na-
OCl) incident is a rare event, 102 the cytotoxic effects of sodium
hypochlorite on vital tissue have been well established. 103 The
associated sequelae of NaOCl extrusion have been reported to
include life-threatening airway obstructions, 104 facial disfig-
urement requiring multiple corrective surgical procedures, 105
permanent paresthesia with loss of facial muscle control, 69
and—the least significant consequence—tooth loss. 106
Table 2. Potential sequelae of sodium hypochlorite extrusion through the apex
Ecchymosis
Widespread tissue trauma
Tooth loss
Facial disfigurement
Permanent paresthesia
Loss of facial muscle control
Irreversible muscle atrophy
Life-threatening airway obstruction
Although the exact etiology of the NaOCl incident is
still uncertain, based on the evidence from actual incidents
and the location of the associated tissue trauma, it would
appear that an intravenous injection may be the cause. The
patient shown in Figure 7 demonstrates a widespread area
of tissue trauma that is in contrast to the characteristics of
sodium hypochlorite incident trauma reported by Pashley.
103,107 This extensive trauma, and particularly involving
the pattern of ecchymosis around the eye, could only occur
if the sodium hypochlorite were introduced intravenously to
a vein close to the root apex through which extrusion of the
irrigant occurred, and the irrigant then found its way into
the venous complex. This would require positive pressure
apically that exceeded venous pressure (10 mg of Hg). In
one in vitro study, which used a positive pressure needle irrigation
technique to realistically mimic clinical conditions
and techniques, the apical pressure generated was found to
be 8 times higher than the normal venous pressure. 108
Figure 7. Widespread tissue trauma
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Figure 8. Irreversible musculature atrophy
This does not imply that NaOCl can or should be excluded
as an endodontic irrigant; in fact, its use is critical, as has been
discussed in this article. What this does imply is that it must
be safely delivered.
Safety First
To compare the safety of six current intracanal irrigation delivery
devices, an in vitro test was conducted using the worstcase
scenario of apical extrusion, with neutral atmospheric
pressure and an open apex. 97 The study concluded that the
EndoVac did not extrude irrigant after deep intracanal delivery
and suctioning of the irrigant from the chamber to full
working length, whereas other devices did. The EndoActivator
extruded only a very small volume of irrigant, the clinical
significance of which is not known.
Figure 9. Comparative extrusion of irrigant using irrigation devices
100
Extrusion of irrigant (%)
80
60
40
20
0
MicroCannula
MacroCannula
EndoActivator
Max-I-Probe
Positive Pressure
Ultrasonic
RinsEndo
Mitchell and Baumgartner Irrigation tested system irrigant used(NaOCl)
extrusion
from a root canal sealed with a permeable agarose gel. 109 Significantly
less extrusion occurred using the EndoVac system
compared with positive pressure needle irrigation. A well-controlled
study by Gondim et al found that patients experienced
less postoperative pain, measured objectively and subjectively,
when apical negative pressure irrigation was performed (EndoVac)
rather than apical positive pressure irrigation. 110
The use of apical negative pressure needle irrigation
results in safer delivery of sodium hypochlorite, and less
post-operative pain.
Efficacy
In vitro and in vivo studies have demonstrated greater removal
of debris from the apical walls and a statistically cleaner result
using apical negative pressure irrigation in closed root canal
systems with sealed apices. In an in vivo study of 22 teeth by
Siu and Baumgartner, less debris remained at 1 mm from
working length using apical negative pressure compared to use
of traditional needle irrigation, while Shin et al found in an in
vitro study of 69 teeth comparing traditional needle irrigation
with apical negative pressure that these methods both resulted
in clean root canals but that apical negative pressure resulted
in less debris remaining at 1.5 mm and 3.5 mm from working
length. 46, 99,111 When comparing root canal debridement using
manual dynamic agitation or the EndoVac for final irrigation
in a closed system and an open system, it was found that the
presence of a sealed apical foramen adversely affected debridement
efficacy when manual dynamic agitation was used, but did
not adversely affect results when the EndoVac was used. Apical
negative pressure irrigation is an effective method to overcome
the fluid dynamic challenges inherent in closed canal systems. 112
Apical negative pressure irrigation results in greater
removal of debris and a cleaner result at working length.
Microbial Control
Hockett et al tested the ability of apical negative pressure to
remove a thick biofilm of Enterococcus faecalis, finding that
these specimens rendered negative cultures obtained within
48 hours while those irrigated using traditional positivepressure
irrigation were positive at 48 hours. 94 Figure 10
shows a scanning electron microscope image of decontaminated
dentinal tubules after use of apical negative pressure
irrigation with sodium hypochlorite and use of EDTA.
Figure 10. SEM of decontaminated dentinal tubules
Courtesy of Dr. Jeffrey L. Hockett and Dr. Nestor Cohenca
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One study found apical negative pressure irrigation
resulted in similar bacterial reductions to use of apical positive
pressure irrigation and a triple antibiotic in immature
teeth. 113 In a study comparing the use of apical positive
pressure irrigation and a triple antibiotic that has been
utilized for pulpal regeneration/revascularization in teeth
with incompletely formed apices (Trimix=Cipro, Minocin,
Flagyl) versus use of apical negative pressure irrigation with
sodium hypochlorite, it was found that the results were statistically
equivalent for mineralized tissue formation and the
repair process. 114 Using negative apical pressure and sodium
hypochlorite also avoids the risk of drug resistance, tooth
discoloration, and allergic reactions. 115,116
Conclusion
Since the dawn of contemporary endodontics, dentists have
been syringing sodium hypochlorite into the root canal
space and then proceeding to place endodontic instruments
down the canal in the belief that they were carrying the
irrigant to the apical termination. Biological, SEM, light
microscopy, and other studies have proven this belief to be
in error. Sodium hypochlorite reacts with organic material
in the root canal and quickly forms micro gas bubbles at
the apical termination that coalesce into a single large apical
vapor bubble with subsequent instrumentation. Since the
apical vapor lock cannot be displaced via mechanical means,
it prevents further sodium hypochlorite flow into the apical
area. Additionally, acoustic microstreaming and cavitation
are limited to liquids and have no effect inside the vapor
lock. The only method yet discovered to eliminate the apical
vapor lock is to evacuate it via apical negative pressure. This
method has also been proven to be safe because it always
draws irrigants to the source via suction—down the canal
and simultaneously away from the apical tissue in abundant
quantities. 117 When the proper irrigating agents are
delivered safely to the full extent of the root canal terminus,
thereby removing 100% of organic tissue and 100% of the
microbial contaminants, success in endodontic treatment
may be taken to levels never seen before.
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Author Profile
Gary Glassman DDS, FRCD(C)
Dr. Gary Glassman graduated from
the University of Toronto School
of Dentistry in 1984 and graduated
from the Endodontology Program
at Temple University in 1987 where
he received the Louis I. Grossman
Study Club Award for academic
and clinical proficiency in Endodontics.
The author of numerous publications, Dr. Glassman
lectures globally on endodontics and is on staff at the
University of Toronto, Faculty of Dentistry in the graduate
department of endodontics. Gary is a Fellow of the Royal
College of Dentists of Canada, and the endodontic editor
for Oral Health dental journal. He maintains a private practice,
Endodontic Specialists, in Toronto, Ontario, Canada.
He can be reached through his website www.rootcanals.ca.
Disclaimer
The author of this course has no commercial ties with the
sponsors or the providers of the unrestricted educational
grant for this course.
Reader Feedback
We encourage your comments on this or any PennWell course.
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www.ineedce.com.
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1. Endodontic success rates of up to _______
are being achieved.
a. 68%
b. 78%
c. 88%
d. 98%
2. There is clear evidence that apical
periodontitis is a _______ disease.
a. fungal
b. viral
c. biofilm-induced
d. all of the above
3. The root canal system contains _______.
a. cul-de-sacs
b. arborizations
c. isthmuses
d. all of the above
4. _______ from the root canal is one of
the challenges for successful endodontic
treatment.
a. The removal of pulp tissue
b. The removal of debris and the smear layer
c. The removal of microorganisms and microtoxins
d. all of the above
5. The nickel-titanium instruments currently
available act on the _______ of the
root canal.
a. isthmi
b. central body
c. lateral body
d. all of the above
6. _______ penetrates deep into the dentinal
tubules.
a. Actinomyces israelii
b. Candida albicans
c. Enterococcus faecalis
d. a and c
7. To be effective, root canal irrigants must
_______.
a. eliminate bacterial contamination
b. remove the smear layer
c. dissolve the organic component of the dental pulp
d. all of the above
8. _______ is a desired attribute for a root
canal irrigant.
a. Bacterial decontamination
b. A broad antimicrobial spectrum
c. The ability to enter deep into dentinal tubules
d. all of the above
9. _______ is currently used as a root canal
irrigant.
a. Chlorhexidine gluconate
b. Hydrogen peroxide
c. Sodium hypochlorite
d. all of the above
Questions
10. Chlorhexidine gluconate _______.
a. offers a wide antimicrobial spectrum
b. is biocompatible
c. lacks the ability to dissolve necrotic tissue
d. all of the above
11. Hydrogen peroxide _______.
a. is an effective antibacterial irrigant
b. exhibits no tissue toxicity
c. dissolves necrotic tissue
d. a and c
12. The irrigant that satisfies most of the
requirements for a root canal irrigant is
_______.
a. polyalkenoic acid
b. sodium hypochlorite
c. saline
d. chlorhexidine gluconate
13. Sodium hypochlorite _______.
a. dissolves necrotic tissue
b. dissolves the organic components of the smear
layer
c. kills sessile endodontic pathogens
d. all of the above
14. EDTA has been recommended as an
adjuvant in root canal therapy because it
is a _______.
a. remineralizing agent
b. dilutant
c. demineralizing agent
d. b and c
15. The combination of _______ has been
used worldwide for antisepsis of root canal
systems.
a. sodium hypochlorite and calcium chloride
b. EDTA and chlorhexidine gluconate
c. sodium hypochlorite and EDTA
d. all of the above
16. _______ is a general safety precaution
prior to root canal irrigation.
a. Use of a rubber dam
b. Protecting the patient’s eyes with safety glasses
c. Use of a temporary sealing material if deep caries is
present adjacent to a rubber dam
d. all of the above
17. Apical extrusion of an endodontic
irrigant _______ occurs.
a. never
b. rarely
c. routinely
d. always
18. Root canal irrigation systems are available
that work using _______.
a. manual agitation techniques
b. manual rotation techniques
c. machine-assisted agitation techniques
d. a and c
19. When irrigating the root canal system, it
is important to consider if _______.
a. the irrigation system can deliver the irrigant to the
whole extent of the root canal system
b. the irrigant can debride areas that cannot be
reached mechanically
c. the irrigant contains any dye
d. a and b
20. An apical vapor lock effect _______.
a. prevents the flow of irrigant into the apical region of
the root canal
b. results in gas entrapment at the apical third
c. resists displacement by instrumentation
d. all of the above
21. The _______ of sodium hypochlorite
liberates ammonia and carbon dioxide.
a. dessication
b. hydrolysis
c. cross-linking
d. none of the above
22. An apical vapor lock occurs in root
canals with _______.
a. an open-ended channel
b. a close-ended channel
c. multiple isthmuses
d. all of the above
23. _______ have confirmed the presence of
apical vapor lock.
a. Histological tests
b. Micro-CT scans
c. Radiographs
d. a and b
24. For a root canal irrigant to be
mechanically effective in removing all the
particles, it has to _______.
a. reach the apex
b. create a current
c. carry the particles away
d. all of the above
25. The apical vapor lock and consideration
for the patient’s safety has always
prevented the thorough cleaning of the
_______.
a. apical 3 mm
b. lateral 3 mm
c. apical 5 mm
d. lateral 5 mm
26. The most common and conventional set
of irrigation techniques is _______.
a. mechanical irrigation
b. manual irrigation
c. hydrodynamic theory irrigation
d. all of the above
www.ineedce.com 13

27. Manual dynamic irrigation produces
_______.
a. a hydrodynamic effect
b. effervescence
c. significant irrigant exchange
d. a and c
28. Sonic activation has been shown to be
an effective root canal irrigation method,
operating at frequencies of _______.
a. 1-6 kHz
b. 2-7 kHz
c. 3-8 kHz
d. none of the above
29. Ultrasonic energy _______.
a. produces higher frequencies than sonic energy
b. produces low amplitudes
c. results in oscillations at frequencies of 25-30 kHz
d. all of the above
30. The literature indicates that it is more
advantageous to apply ultrasonics
_______.
a. as an alternative to conventional instrumentation
b. after completion of canal preparation
c. after initial root canal preparation
d. a and c
31. Passive ultrasonic irrigation _______.
a. operates without simultaneous irrigation
b. allows energy to be transmitted from an oscillating
file or smooth wire to the irrigant
c. is the only type of ultrasonic irrigation
d. a and b
32. Passive ultrasonic irrigation _______.
a. effectively removes pulpal tissue remnants
b. effectively removes dentin debris
c. results in a significant reduction of the number of
bacteria
d. all of the above
33. Studies have demonstrated that effective
delivery of irrigants to the apical third can
be enhanced by using _______ devices.
a. ultrasonic
b. sonic
c. air abrasion
d. a and b
34. Acoustic microstreaming is defined as
the movement of _______.
a. sound along cell membranes
b. fluids along cell membranes
c. gases along cell membranes
d. all of the above
35. Once a sonic or ultrasonically activated tip
leaves the irrigant and enters the apical vapor
lock, _______ becomes physically impossible.
a. acoustic microstreaming
b. cavitation
c. cell death
d. a and/or b
Questions
36. Ultrasonics _______.
a. can effectively clean bacteria from the root canal
system
b. can effectively clean debris from the root canal
system
c. cannot effectively get through the apical vapor lock
d. all of the above
37. _______ is a common reason given for
not using sonic or ultrasonic filing.
a. The time required for set-up
b. An unwillingness to incur the equipment costs
c. Lack of awareness of the benefits of this final
instrumentation step
d. all of the above
38. Sonic or ultrasonic activation might
allow a better removal of _______.
a. pulpal tissue remnants
b. debris from isthmi
c. debris from fins
d. all of the above
39. An apical negative pressure system
contains a _______.
a. Master Delivery Tip
b. MacroCannula
c. MicroCannula
d. all of the above
40. A pressure alternation device consists of
_______.
a. a handpiece
b. a cannula with a 7 mm exit aperture
c. a syringe carrying irrigant
d. all of the above
41.With an apical negative pressure system,
the cannulae in the canal _______.
a. exert negative pressure
b. pull irrigant from its fresh supply in the
chamber, down the canal to the tip of the
cannula
c. pull irrigant into the cannula and out through the
suction hose
d. all of the above
42. Apical negative pressure has been shown
to _______.
a. enable irrigants to reach the apical third
b. help overcome the issue of apical vapor lock
c. remove the risk of sodium hypochlorite incidents
d. all of the above
43. A sodium hypochlorite incident occurs
when the irrigant _______.
a. extrudes through the root canal foramen
b. is at a concentration above 3%
c. is mixed with a second irrigant
d. all of the above
44. Recommendations for avoiding sodium
hypochlorite incidents include _______.
a. not binding the needle in the canal
b. not placing the needle close to working length
c. using a gentle flow rate
d. all of the above
45. _______ is a sequela of a sodium
hypochlorite incident.
a. Life-threatening airway obstruction
b. Permanent paresthesia
c. Facial disfigurement
d. all of the above
46. Based on the evidence from actual
sodium hypochlorite incidents and the
location of the associated tissue trauma,
it would appear that an _______may be
the cause.
a. anatomical anomaly
b. intravenous injection
c. arterial injection
d. a and b
47. In an in vitro study comparing
intracanal irrigation delivery devices, only
the use of a device using _______ resulted
in no extrusion at the apex.
a. ultrasonics
b. apical positive pressure
c. apical negative pressure
d. sonics
48. The presence of a sealed apical foramen
was shown in one study to adversely affect
debridement efficacy when _______ was
used.
a. manual dynamic agitation
b. apical negative pressure
c. water
d. all of the above
49. The only method yet discovered to
eliminate the apical vapor lock is to
evacuate it via _______.
a. apical positive pressure
b. apical negative pressure
c. acoustic microstreaming
d. all of the above
50. Proper root canal irrigation should result
in _______.
a. safe delivery of the irrigating agent(s)
b. removal of 100% of the organic tissue in the canal(s)
c. removal of 100% of the microbial contaminants
d. all of the above
14 www.ineedce.com

ANSWER SHEET
Safety and Efficacy Considerations in Endodontic Irrigation
Name: Title: Specialty:
Address: E-mail:
City: State: ZIP: Country:
Telephone: Home ( ) Office ( ) Lic. Renewal Date:
Requirements for successful completion of the course and to obtain dental continuing education credits: 1) Read the entire course. 2) Complete all
information above. 3) Complete answer sheets in either pen or pencil. 4) Mark only one answer for each question. 5) A score of 70% on this test will earn
you 3 CE credits. 6) Complete the Course Evaluation below. 7) Make check payable to PennWell Corp. For Questions Call 216.398.7822
Educational Objectives
1. List and describe the challenges for successful endodontic treatment
2. List and describe the different types of root canal irrigants, their relative advantages and disadvantages
3. List and describe root canal irrigation systems
4. Describe and explain a sodium hypochlorite incident
5. List and describe the steps that can be taken to avoid a sodium hypochlorite incident
Course Evaluation
Please evaluate this course by responding to the following statements, using a scale of Excellent = 5 to Poor = 0.
1.Were the individual course objectives met? Objective #1: Yes No Objective #3: Yes No
Objective #2: Yes No Objective #4: Yes No
Objective #5: Yes No
2.To what extent were the course objectives accomplished overall? 5 4 3 2 1 0
3. Please rate your personal mastery of the course objectives. 5 4 3 2 1 0
4. How would you rate the objectives and educational methods? 5 4 3 2 1 0
5. How do you rate the author’s grasp of the topic? 5 4 3 2 1 0
6. Please rate the instructor’s effectiveness. 5 4 3 2 1 0
7.Was the overall administration of the course effective? 5 4 3 2 1 0
8. Do you feel that the references were adequate? Yes No
9.Would you participate in a similar program on a different topic? Yes No
10. If any of the continuing education questions were unclear or ambiguous, please list them.
___________________________________________________________________
11.Was there any subject matter you found confusing? Please describe.
___________________________________________________________________
___________________________________________________________________
12.What additional continuing dental education topics would you like to see?
___________________________________________________________________
___________________________________________________________________
If not taking online, mail completed answer sheet to
Academy of Dental Therapeutics and Stomatology,
A Division of PennWell Corp.
P.O. Box 116, Chesterland, OH 44026
or fax to: (440) 845-3447
AUTHOR DISCLAIMER
The author of this course has no commercial ties with the sponsors or the providers of the
unrestricted educational grant for this course.
SPONSOR/PROVIDER
This course was made possible through an unrestricted educational grant from Discus
Dental. No manufacturer or third party has had any input into the development of
course content. All content has been derived from references listed, and or the opinions
of clinicians. Please direct all questions pertaining to PennWell or the administration of
this course to Machele Galloway, 1421 S. Sheridan Rd., Tulsa, OK 74112 or macheleg@
pennwell.com.
COURSE EVALUATION and PARTICIPANT FEEDBACK
We encourage participant feedback pertaining to all courses. Please be sure to complete the
survey included with the course. Please e-mail all questions to: macheleg@pennwell.com.
PLEASE PHOTOCOPY ANSWER SHEET FOR ADDITIONAL PARTICIPANTS.
INSTRUCTIONS
All questions should have only one answer. Grading of this examination is done
manually. Participants will receive confirmation of passing by receipt of a verification
form. Verification forms will be mailed within two weeks after taking an examination.
EDUCATIONAL DISCLAIMER
The opinions of efficacy or perceived value of any products or companies mentioned
in this course and expressed herein are those of the author(s) of the course and do not
necessarily reflect those of PennWell.
Completing a single continuing education course does not provide enough information
to give the participant the feeling that s/he is an expert in the field related to the course
topic. It is a combination of many educational courses and clinical experience that
allows the participant to develop skills and expertise.
COURSE CREDITS/COST
All participants scoring at least 70% on the examination will receive a verification
form verifying 3 CE credits. The formal continuing education program of this sponsor
is accepted by the AGD for Fellowship/Mastership credit. Please contact PennWell for
current term of acceptance. Participants are urged to contact their state dental boards
for continuing education requirements. PennWell is a California Provider. The California
Provider number is 4527. The cost for courses ranges from $49.00 to $110.00.
Many PennWell self-study courses have been approved by the Dental Assisting National
Board, Inc. (DANB) and can be used by dental assistants who are DANB Certified to meet
DANB’s annual continuing education requirements. To find out if this course or any other
PennWell course has been approved by DANB, please contact DANB’s Recertification
Department at 1-800-FOR-DANB, ext. 445.
For immediate results,
go to www.ineedce.com to take tests online.
answer sheets can be faxed with credit card payment to
(440) 845-3447, (216) 398-7922, or (216) 255-6619.
Payment of $59.00 is enclosed.
(Checks and credit cards are accepted.)
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31.
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36.
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38.
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AGD Code 074
RECORD KEEPING
PennWell maintains records of your successful completion of any exam. Please contact our
offices for a copy of your continuing education credits report. This report, which will list
all credits earned to date, will be generated and mailed to you within five business days
of receipt.
CANCELLATION/REFUND POLICY
Any participant who is not 100% satisfied with this course can request a full refund by
contacting PennWell in writing.
© 2011 by the Academy of Dental Therapeutics and Stomatology, a division
of PennWell
SAFE0111DE
www.ineedce.com Customer Service 216.398.7822 15

Kills microbes dead.
100% Safe. * 100% Kill. 1 Single Visit.
Single-Visit Disinfection is now a Reality
Time is valuable for both your patients and your practice. Fortunately,
the EndoVac is clinically proven to deliver 100% bacterial kill levels 1
with complete safety 2 and significantly less post-operative pain 3
for your patients. EndoVac delivers dead-on success, the first time
around. If the bugs are dead, close the case.
“...the present results demonstrated that reliable disinfection can be achievable with
efficient and safer irrigation delivery systems, such as the EndoVac system, and that
the use of intracanal antibiotics might not be necessary.”
Cohenca OOOOE 2010 Jan;109:e42-46
Irrigation Protocol. Easy as 1, 2, 3...
1. EndoVac Master Delivery Tip
— Gross Debridement
& Disinfection
Provides a constant flow of
irrigant without the risk of
overflow. The MDT is used
after each instrument change
to remove gross debris arising
from instrumentation.
Call today to schedule an in-office demo.
(800) 451-8176
discusdental.com
2. EndoVac MacroCannula —
Debridement & Disinfection
Deep in the Canal
Removes coarse debris
deep inside the canal after all
instrumentation is completed.
SPECIAL
IntroduCtory
offEr!
Mention Code:
SP2017
3. EndoVac MicroCannula
— Complete Apical
Debridement & Disinfection
at Working Length
Maximum microbial control
using a 0.32 mm cannula
and negative pressure to
safely draw irrigants to the
apical termination and create
a vortex-like cleaning of the
apical third.
(1) Journal of Endodontics 2008;34:1374-1377
(2) Journal of Endodontics 2009;35:545-549
(3) Journal of Endodontics 2010;36:1295-1301
* The claim “100% Safe” refers to the finding that the EndoVac MicroCannula and MacroCannula
produced no extrusion of irrigant apically in the study reported in J Endod 2009;35:545-549.
The EndoVac is intended only for the irrigation of root canals during endodontic treatment and only
for use according to manufacturer’s instructions.
© 2010 Discus Dental, LLC. All rights reserved. ADV-3172 120910 20-2653