About failures of root canal treatment and retreatment. This presentation describes about various techniques for gutta percha removal, posts removal, pastes removal, and removal of separated instrument
Presented by : Dr. Arpit Viradiya
Guided by : Dr. Ashutosh Paliwal
• Since long, many studies are being conducted
to determine success and failure of
• Different studies have shown that the success
rate for a root canal treatment ranges from 54
to 95 percent.
• Success is defined by goals established to be
• The usual goal of endodontic therapy is to
prevent or heal the disease.
• Accordingly, endodontic treatment outcomes
should be defined in reference to healing and
Definitions related to endodontic
• Healed : In which both clinical and
radiographic presentations are normal.
• Healing : It is a dynamic process, reduced
radiolucency combined with normal clinical
• Disease : Means no change or increase in
radiolucency, clinical signs may or may not be
present or vice versa.
• A clear definition of what constitute a failure
following endodontic therapy is not yet clear.
• Failures cannot be subscribed to any particular
criteria of evaluation.
• Instead success or failures after endodontic
therapy could be evaluated from combination
of various criteria like clinical,
histopathological and radiographical criteria.
Clinical criteria of success of
• No tenderness on percussion/palpation.
• Normal tooth mobility.
• No evidence of subjective discomfort.
• No sign of infection/swelling.
• No sinus tract or integrated periodontal
• Tooth having normal form, function and
• The radiographic criteria for failures are
development of radiographic periapical areas
of rarefaction after endodontic treatment, in
cases where they were not present before the
• Or increase in size of
radiolucency after endodontic
Histological criteria of success of
• Absence of inflammation.
• Regeneration of PDL fibers.
• Presence of osseous repair.
• Repair of cementum.
• Repair of previously resorbed areas.
• Absence of resorption.
Factors affecting success or failure
• Diagnosis and treatment planning.
• Radiographic interpretation.
• Anatomy of tooth and root canal system.
• Debridement of the root canal space.
• Asepsis of treatment regimen.
• Quality and extent of apical seal.
• Systemic health of the patient.
• Skill of the operator.
• Presence of infected and necrotic pulp tissue
in root canal acts as the main irritant to the
• For success of endodontic therapy, thorough
cleaning of root canal system is required for
removal of these irritants.
Incomplete debridement of the root
• It is a principle factor contributing to
• The main objective of root canal therapy is the
complete elimination of the microorganisms
and their byproducts from the root canal
• The poor debridement can lead to residual
microorganisms, their byproducts and tissue
debris which further recolonize and contribute
to endodontic failure.
• Small haemorrhages during endodontic
procedure are repaired without incident.
• Extirpation of pulp and instrumentation
beyond periapical tissues lead to excessive
• Mild inflammation is produced because of
local accumulation of blood.
• The extravasated blood cells and fluids must
be resorbed otherwise they act as foreign
• Also the extravasated blood acts as nidus for
bacterial growth especially in presence of
• Instrumentation beyond
apical foramen causes
decrease in the prognosis of
because of trauma to
periodontal ligament and
• When instrumentation of the root canal
system remains within the confines of root
canals, the chances of success of endodontic
therapy are more. (Strindberg et al 1956)
• During endodontic
medications are used as
dressing in root canal.
• Their functions are to
eliminate or reduce
microbial flora, prevent or
lessen pain, reduce
inflammation or stimulate
• They decrease the prognosis of endodontic
therapy if get extruded in the periapical
Int J Periodont Restorative Dent 17:75, 1997
• Schilder et al reported that
– If instrument separation occurred in tooth with
presence of vital pulp before treatment, prognosis
was not much affected.
– but if instrument separation occurred in teeth
with pulpal necrosis, prognosis was found to be
poor after treatment.
J Endod 24:38, 1998
• Basically separated instruments impair the
mechanical instrumentation of infected root
canals apical to instrument, which contribute
to endodontic failure.
Canal blockage and ledge formation
• Canal blockage can occur due to accumulation
of dentin chips or tissue debris which prevents
the instrument to reach its full working length.
• Ledge formation usually occurs
by using straight instruments in
• All these lead to working short
of the canal terminus and thus
bacteria and tissue debris may
remain in non-instrumented
area contributing to endodontic
• It is a mechanical communication between
root canal system and the periodontium.
• It occurs by
– Lack of knowledge of internal anatomy of tooth
– Lack of attention while operating
– Misdirection of instruments
• Prognosis of endodontically treated tooth with
perforations depend on many factors
J Am Dent Assoc 131:196, 2000
• Location : Depends on its closeness to gingival
• Time : which has elapsed before defect is
• Adequacy of perforation seal
• Size of perforation
Incompletely filled teeth
• It occurs due to
– Incomplete instrumentation
– Ledge formation
– Improper measurements of WL
• Several studies have shown poorer prognosis
of teeth with underfillings, especially those
with necrotic pulps.
J Endod 28:454, 2002.
• Remaining infected necrotic tissue,
microorganism and their byproducts in
inadequately instrumented and filled teeth
cause continuous irritation to the periradicular
tissues leading to endodontic failure.
Overfilling of root canals
• It occurs because of
– Apical root resorption
– Incompletely formed roots (open
– Over instrumentation of root
• Overfilling causes continuous
irritation of the peri-apical
• The filling material acts as a foreign body
which may generate immunological response.
• Several studies have shown biofilms formation
on extruded material which contains
treatment resistant bacteria.
J Endod 30:54, 2004
Corrosion of root canal fillings
• Corrosion is the
tendency of most of the
metals to revert to their
lower form by oxidation.
• Silver cones have shown
to produce corrosion.
• The main area of corrosion of silver cones is
coronal and the apical portions, the areas
which contact tissue fluids via periapical
exudation or saliva.
• The corrosion products are cytotoxic and may
act as tissue irritants causing persistent
• Presence of overly curved
canals, calcifications, numerous
lateral and accessory canals,
bifurcations, aberrant canal
anatomy like C or S shaped
canals may pose problems in
adequate cleaning and shaping.
• These can lead to endodontic
• Endodontic failures can occur by partial or
complete fractures of the roots.
• Prognosis of teeth with vertical root fracture is
poorer than horizontal fractures.
• Traumatic occlusion has also been reported to
cause endodontic failures because of its effect
• An endodontic failure may occur because of
communication between the periodontal
ligament and the root canal system.
• Also the recession of attachment apparatus
may cause exposure of lateral canals to the
oral fluids which can lead to reinfection of the
root canal system because of percolation of
• The systemic disease may
influence the local tissue
resistance and thus interfering
with the normal healing process.
• When systemic disease is present,
the response of the periapical
tissues may get intensified if there
is increase in concentration of
irritants during endodontic
• Thus severe reaction may occur following
cleaning and shaping.
• Healing is also impaired in patients with
• Various systemic factors can interfere with
success of endodontic therapy are
– Nutritional factors
– Diabetes mellitus
– Renal failure
– Blood dyscrasias
– Hormonal imbalance
– Autoimmune disorders
– Opportunistic infections
– Patients on long term steroid therapy
• Thus before starting endodontic therapy, a
complete medical history is essential to predict
the prognosis of the tooth.
Before going for endodontic
retreatment following factors should
• If patient is asymptomatic even if treatment is
not proper, the retreatment should be
• Patient’s needs and expectations.
• Strategic importance of the tooth.
• Periodontal evaluation of the tooth.
• Other interdisciplinary evaluation.
• Chair time and cost.
Before performing retreatment
following points should be considered
• Retreatment may be performed to prevent the
• To gain access into root canal extensive
coronal restoration has to be removed.
• Technical problems may result from previous
treatment or aberrant canal anatomy.
• Even after retreatment sometimes better
results may not be achieved.
• Root canal filling materials have to be
removed during retreatment.
• Prognosis of retreatment could be poorer than
the initial endodontic therapy.
• Patient might be more apprehensive than with
• Definition : Endodontic retreatment is a
procedure performed on a tooth that has
received prior attempted definitive treatment
resulting in a condition requiring further
endodontic treatment to achieve a successful
Int Endod J 37:272, 2004
Steps in retreatment technique
• Access to root canal
– Through crown
– By removal or crown
• Access to apical area
– By removal of root canal filling material
– By removal of separated instruments.
• Antimicrobial treatment.
• Clinicians generally access the pulp chamber
through the existing restoration if it is
functionally well designed, well fitting and
• If the restoration is inadequate or if additional
access is required, the restoration should be
There are several important removal
devices which may be divided into
1. Grasping instruments : K.Y. Pliers and
Wynman Crown Gripper
K. Y. Plier
• Percussive instruments : Crown-a-Matic and
• Passive-active instruments : Metalift and the
Higa Bridge Remover.
• Clinicians must clearly define the risk versus
benefit with patients before removal of an
• Gaining access through existing restoration
helps in :
– Facilitating rubber dam placement
– Maintaining form, function and esthetics
– Reducing cost of replacement
• Disadvantages of retaining a restoration include:
– Reduced visibility and accessibility
– Risks of irreparable errors
– Risks of microbial infection if crown margins are
Establish access to root canal system
• In some cases post and core needs to be
removed for gaining access to the root canal
• Factors affecting post removal :
– Post type
– Cementing medium
– In occlusal space
– Existing restoration
– Position of coronal most aspect
TECHNIQUES FOR POST REMOVAL:
• Successful post removal requires removing all
circumferential restorative material from pulp
• commonly used methods and techniques for
removal of post are
– Ultrasonic technique
– Masserann technique
– PRS option
• Piezo electric ultrasonic systems offers the
clinician certain advantages in endodontic
disassembly and retreatment.
• Generally, the CPR -2 ultrasonic instrument is
used on full intensity to remove the remaining
core materials periphery to the post.
• CPR - 3,4, & 5 instruments are
designed to work in small, restricted
and confined spaces.
• If space is severely restricted, CPR - 6,
7 & 8 titanium ultrasonic instrument
can be used on low intensity.
• Once the post has been fully exposed,
rotosonics can be used to loosen and
remove the post.
• The regular ROTOTIP (Ell man
international Hewlett N.Y.) is a high
speed Friction grip 6 sided
• When rotated, it produces vibration
to loosen and remove the post.
• If efforts are unsuccessful, the
clinician should select CPR - 1 because
of its superb energy transfer.
• CPR-1 has a ball at its working end which is
kept in contact with post to maximize energy
• This is used with full intensity and is moved
around the post circumferentially with up &
Removing canal obstructions and
• Patency of canal can be regained by removing
obstructions in the canal which can be in the
form of silver points, gutta-percha, pastes,
sealers, separated instruments and posts.
Silver point removal
• Silver points can be retrieved from
canal by following methods:
– Using microsurgical forceps – Its use is
ideal especially when cone heads are
sticking up in the chamber.
– Using ultrasonic – In this ultrasonic file
is worked around the periphery of silver
point to loosen it with vibration.
• Using hedstroem files : In this headstroem
files are placed in the canal.
• These files are twisted around each other by
making clockwise rotation.
• This will make grip around silver point which
then can be removed.
• Using hypodermic needle which
is made to fit tightly over the
silver point over which
cyanoacrylate is placed as an
• When it sets, needle is removed
• By tap and thread option using
microtubular taps from post
removal system kit.
• By using instrument removal
• The relative difficulty in removing GP varies
according to the
– Canal length
– Canal c/s dimensions
– Canal curvature.
• Regardless of the technique, its best removed
in a progressive manner to prevent
displacement of irritants periapically.
• Dividing the root into three parts G.P. is
initially removed from canal in coronal 1/3,
then middle 1/3 & finally eliminated from
apical 1/3 of the canal.
• In canals that are relatively large & straight,
single cones can be removed in one motion.
• Single cone:
• They can be removed by using
– A headstroem file
– Steiglitz forceps
• H file method : largest H-files that will fit the
cone should be used to reduce the risk of
• The file is gently screwed into the canal
(obturated) until resistance is met.
• At this point the instrument is withdrawn from
canal along with G.P. cone.
• Endosonics can also be used.
• It loosen the cement around the single cone,
there by aiding removal.
• If cones are accessible they can be gripped
with Tweezers / Steiglitz forceps for removal.
• CONDENSED GUTTA PERCHA
• Condensed G.P. can be removed using a
– G.G drills
– Niti rotary instruments
– Hand instruments such as H files
– Paper points
• Traditionally power source in conjunction with
specific heat carrier instrument such as Touch
- N - Heat / system B has been used to thermo
soften & remove fragments of G.P from root
• Disadvantage: It limits its ability to place into
under-prepared systems and around pathways
• Technique: Activate the instrument until it is
red hot, then place it into the coronal most
aspect of G.P.
• The heat carrier is
• And as it cools,
withdrawal will result
in removal of attached
fragment of G.P.
• The process is
repeated as long as it
Heat & Instrument removal
• In this method a hot instrument is placed into
G.P. & immediately with drawn to heat soften
the material .
• A size 35, 40/45 H-file is then selected gently
screwed into the thermo softened mass.
• When GP cools, it will freeze on flutes of file.
• In poorly obturated canals, removing the file
can, at times, eliminate the engaged G.P in
• This technique is good in those cases where
G.P. extends beyond the foramen.
• Solvents include chloroform, xylene,
rectified turpentine, chloroform &
• There has been some concern expressed
in literature about carcinogenic potential
of the chloroform.
• Rectified turpentine is a useful
• Eucalyptus is heated and used in order
to be as effective as chloroform.
• Solvents should be used only in small amounts
and must be contained with in R.C. system.
• Using solvent too early in treatment leaves a
messy layer of dissolved G.P. coating the root
canals & pulp floor, which can be difficult to
• If most of G.P. has been removed
mechanically, then a minimal amount of
solvent is required to dissolve the remaining.
FILE & CHEMICAL REMOVAL
• It is the best option to remove G.P from small
& curved canals.
• The technique involves filling the pulp
chamber with chloroform, selecting a
appropriate size file & gently picking into
chemical softened G.P.
• Initially, a size 10 or 15 SS file is used to pick
into G.P. occupying the coronal 3rd.
• Frequent irrigation creates a pilot hole and
sufficient space for the serial use of larger file
to remove G.P.
• This method is continued until G.P is no longer
evident on cutting flutes when the files are
with drawn from solvent filled canal.
• After G.P. has been removal from coronal 3rd,
repeat the technique in middle 1/3 & finally
• This progressive removal technique helps
prevent extrusion of chemically softened
Paper point & chemical removal
• G.P. & most sealers are miscible in chloroform
& once in solution can be absorbed and
removed with appropriately sized paper
• Drying solvent filled canals with paper point is
known is “Wicking” & is always the final step
of G.P. removal.
• This wicking action is essential in removing
residual G.P. & sealer out of fins, cul de sacs &
aberrations of R.C. systems.
• In this technique, the canal is
1st flushed with chloroform &
solution is then absorbed &
removed with appropriately
sized paper points.
• Paper points “wick” by
pulling dissolved material
from periphery to central.
• Process is repeated as long as it continues to
be visibly productive.
• After chloroform wicking procedures, canal is
flushed with 70% isopropyl alcohol, & wicked
for further elimination of chemically softened
• Active Niti rotary files (dentsply) are the most
effective & efficient instruments for G.P.
• Disadvantages: Should be used with caution
in under-prepared canals & are generally not
selected for removing G.P in canals that do
not accept them passively.
• When attempting for removal, the R.C. should
be divided to 3 parts.
• Select appropriately sized rotary instrument
that will fit passively in these canals.
• To soften & engage G.P. mechanically rotary
instrument must turn at speeds between
• Rotational speed is based on friction required
to mechanically soften G.P.
• Piezoelectric ultrasonic system represents a
useful technique to rapidly remove G.P.
• Ultrasonic instrument produces heat and
• Specially designed ultrasonic instrument are
carried into canals, that have sufficient shape
to receive them.
• This method will float G.P coronally into pulp
chamber where it can be sub subsequently
G.G.Drills / Burs:
• G.G. drills are extremely efficient for removing
G.P. from coronal parts of well compacted root
• They need to be rotated in a slow speed hand
piece generating frictional heat that will aid
Carrier Based Gutta Percha Removal
• Techniques are same as for G.P & silver point.
• Initially it used to be metal & file like
• Yet over the past several years they have been
manufacturing easier to remove plastic
• After careful access and complete
circumferential exposure of the carrier, suitable
grasping pliers are selected and a purchase is
obtained on the carrier.
• Carrier is grasped with the pliers and removal is
attempted using fulcrum mechanics rather than
a straight pull out of the tooth.
• Ultrasonic tip can be used to produce heat and
thermosoften the G.P.
• The activated ultrasonic instrument is gently
moved apically and carrier is often times
displaced and floated out coronally.
• Once the carrier is removed, the remaining G.P.
can be removed using solvents.
• When evaluating a paste case for retreatment,
it is useful to chemically understand that
pastes can generally be divided into
• a) Soft, Penetrable & Removable
• b) Hard, impenetrable, unremovable
• However, it is important to understand that
because of the method of placement, the
coronal portion of paste in the canal is most
• Abrasive coated ultrasonic instruments can be
used for the safe removal of hard &
• Heat, end-cutting rotary NiTi instruments and
small sized hand files with solvents such as
Endosolv R and Endosolv E are used to remove
soft & penetrable paste.
Broken Instrument Removal
• During R.C. preparation procedures, the
potential for instrument breakage is
• Many clinicians associate “Broken
instrument” with separated files, but
the term could also apply to a silver
point, a lentulospiral, a G.G. drill, or any
obstruction left behind in the canal.
• Historically, the consequences of leaving / by
passing broken instruments have been
discussed and varieties of approaches for
removing these obstructions have been
• Because of technologic advancements in
vision, ultrasonic instrumentation and
microtube delivery methods, separated
instruments can usually be removed.
Factors influencing broken instrument
• Cross sectional diameter, length & curvature of
– If 1/3 of overall length of obstruction can be exposed
can be removed.
– If its just in straight portion of canal - can be removed
– When the separated instrument lies partially in the
canal curvature still possible to remove.
– If entire segment is apical to curvature - safe access
cannot be accomplished and removal is not possible.
• Type of material comprising the obstruction
– S.S. files - easier to remove as they do not #
during removal process.
– NiTi files - may explode and break again due to
heat build up caused by ultrasonic devices.
• 1st step Coronal access
• High speed friction grip surgical length burs
are selected to create straight line access to
• 2nd step Radicular Access
• If radicular access is limited - hand files are
used serially (small to large) to create
sufficient space to safely introduce G.G. drill’s.
• These G.G drills are then used like “brushes”
to create additional space and maximize
visibility coronal to obstruction.
• If greater access required, then bud shaped tip
of GG can be modified and used to create a
circumferential “staging platform”.
– This is done by selecting a G.G. with maximum c/s
diameter that is slightly larger than the visualized
– The bud of G.G. is altered by cutting it perpendicular to
long axis at its maximum C/S diameter.
– The “modified” G.G. is rotated at 300 rpm, gently
carried to canal and directed apically, until it lightly
contacts the coronal aspect of obstruction.
• This clinical action creates a small
“Staging Platform” that facilitates the
insertion of zirconium nitride coated
• 3rd Step Removal
• Before performing any removal
especially when treating a multi-rooted
teeth the potential problem is that the
#ed segment floating out of one canal
and finding its way into one of the other
• So, to prevent this it is wise to place cotton
into the other orifice.
• Once the ultrasonic instrument is selected,
based on depth of broken file and space
availability, the instrument should be
activated at the lowest power setting.
• Dry field is preferred, so that clinician has
constant vision between tip and broken
• Then the selected tip is moved
lightly in counter clockwise direction
around the obstruction and
trephines around the coronal few
mm of obstruction.
• Typically during ultrasonic use
the obstruction begins to unwind,
loosen and spin.
• On occasion where this ultrasonic
technique doesn’t work the
microtube device can be selected to
engage and remove the obstruction
Apical Obstructions / Blockage
• When canals have been under filled,
obstructive calcification might be found apical
to unfilled portion.
• After coronal pre-enlargement and relocation
of the canal orifice with G.G. drills, the coronal
part of the canal is copiously irrigated with
NaOCl and then thoroughly dried with paper
• At this stage if possible the intracanal anatomy
should be inspected carefully under
• Then a small size precurved K file in
association with a lubricating gel is inserted
with a slight pecking motion to try to find a
• As long as catch is felt at tip of K file, apical
progression should be continued and checked
periodically with radiograph until the canal
terminus is launched.
• Often a ledge has been formed at the end of
the previous obturation of the canal.
• Most of the time ledge is the result of an
inadequate angle of access to the R.C.
• Preflaring the coronal portion of the canal
with K files and relocating the canal with G.G.
are preliminary steps to by pass.
• Flood the canal with irrigating solution.
• Select a no. 10 S.S. K file place a sharp 1mm
curvature at the tip and orient the rubber
stopper toward the file tip.
• Insert the file in the canal with the tip directed
toward the canal curvature.
• Pick gently with very short strokes, searching
for a catch.
• This procedure will remove the irrigant and
help to disintegrate the dentine mud.
• If Unsuccessful, rebend the file tip and repeat
the same procedure while slightly reorienting
• When a catch is felt, it is moved in and out of
the canal utilizing ultra-short push-pull
• When the file moves freely, it may be turned
clockwise on withdrawal to smoothen or
eliminate the ledge.
• Training proctol and technology allow
clinicians to greatly expand their abilities in
non surgical retreatment. Clinicians need to
weigh risk versus benefit and recognize that at
times surgery / extraction might be in
patient’s best interest.
• When choosing non surgical retreatment
careful assessment and treatment planning
with each case is the corner store of success.