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INTRODUCTION:
Retention of natural teeth in an asymptomatic clinical condition is the goal of
endodontic therapy. Root canal therapy consists of a cascade of scientifically based technical
procedures. Lack of knowledge, its poor application or a break in the chain of proper
procedures due to various causes can lead to failure of endodontic treatment.
These failures can be attributable to inadequacies in-
- Diagnosis,
- Isolation,
- Access preparation,
- Cleaning and shaping,
- Obturation,
- Post space preparation,
- Instrument separation,
- Missed canals,
- Persistent infections,
- Iatrogenic events or re-infection of the root canal system when the coronal seal is
lost after completion of root canal treatment.
Advances in endodontics as well as better trained dentists and specialists have led to
the increase in the number of patients seeking dental treatment as an alternative to extraction.1

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Regardless of the initial cause, the sum of all causes is leakage. When appropriate,
non surgical endodontic retreatment efforts are directed towards eliminating microleakage.
Thus the rationale for non-surgical retreatment is to remove the root canal space as a source
of irritation to the attachment apparatus.
Ruddle1
described this vast increase in the use of endodontics as the “good news,
bad-news dilemma”. The good news is that hundreds of millions of teeth are salvaged
through combinations of endodontics, periodontics and restorative dentistry. The bad news is
that tens of millions of teeth are endodontically failing for a variety of reasons.2
For example, the success rate for conventional endodontic treatment, ranges between
53%-94%. However, even if 90% of endodontic treatment is successful over time, the
reciprocal failure rate is still 10%. A 10% failure rate would result in failure of at least 2.4
million cases. Failure occurs as a result of many factors some of which can be controlled by
the operator while others are unavoidable.
Therefore, the future of endodontists will include dealing with the retreatment of
its failed cases.
ENDODONTIC SUCCESS:
Success should be determined on the basis of defined criteria, because the
conclusions drawn by the available resources that the treatment was well or badly performed
(suitable to the process of tissue repair of the pathology found), are based on clinical and
radiographic criteria. The histological criteria will be defined in a second moment by
microscopic examination, when opportune and necessary.

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With regard to the repair process after endodontic treatment, the etiological factors
for endodontic failure can be summed into:
LOCAL FACTORS:
1. Infection
2. Hemorrhage
3. Tissue destruction
4. Deficiency in blood supply
5. Presence of foreign body
SYSTEMIC FACTORS:
1. Nutrition
2. Stress
3. State of chronic waste
4. Hormones and vitamins
5. Dehydration
6. Age
EVALUATION OF ENDODONTIC SUCCESS :
Clinical and radiographic success should be observed after the elapse of an adequate period
of time after the treatment.

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Ingle and Taintor3
related that although endodontic treatments can demonstrate
failures in period up to 10 years, more often, it is evidenced in periods up to 2 years.
Stabholtz and Walton4
pointed out that follow up after treatment should be from 1 to 4 years.
As a clinical parameter, considering the initial radiographs to verify the result of
endodontic treatment, the period of up to 1 year for pulpal cases, and 2 years for the cases of
endodontic infections can be established. Longitudinal follow up is important because the
tooth restoration and patients general health can influence the success.
Bender et al5
enumerated some clinical and radiographic criteria representative of
successful endodontic treatment:
1. Absence of pain and edema.
2. Absence of drainage and fistula.
3. Tooth in function, with normal physiology.
4. Disappearance of Periapical bone rarefaction.
The value of radiograph is significant for identifying the quality of endodontic
treatment; however, one should be watchful, because some Periapical lesions can be present
without showing up clearly in radiographic examination.
The vestige to suspect a missed root canal in endodontically treated tooth can be
signaled by a persistent pain to thermal test.
The essential factors related to endodontic success are summed up as follows:
1. Clinical silence (absence of pain, edema, fistula).
2. Normal Periapical bone structure (uniformity of the lamina dura, absence or
interruption radicular resorption.
3. Tooth in function and presence of perfect coronal sealing.6

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ENDODONTIC FAILURE
One of the aspects responsible for adequate microbial control is effective root canal
preparation, achieved by adequate cleaning and shaping. The goal of mechanical action of
root canal instrumentation is removal of contaminated material from main root canal.
Irrigants are effective due to their antimicrobial properties, solvent capacity and tissue
tolerance. In addition to depth of their action, surface active volume and capacity- surface
tension are powerful allies. Associated with this stage, the intracanal dressing makes a
significant contribution to this antimicrobial process.6
Considering the endodontic micro biota present in the different pathological terms,
endodontic infections can be divided into:
1. Primary- infection observed in teeth not submitted to endodontic retreatment.
2. Secondary- infection present in endodontically treated teeth.
3. Persistent - an infectious process that does not respond positively to endodontic
treatment.7, 8-10
Sjogren et al studied the factors that affect the result of endodontic treatment 11
, after
a period from 8 to 10 years of treatment. Considering the preoperative state of the pulp and
periapical tissue, they verified a success rate of 96% when there was no periapical lesion,
86% success when it was present, 98% success in the cases of retreatment without periapical
lesion and 62% success in retreatment cases that presented periapical lesions. In the teeth
with preoperative apical periodontitis, when the instrumentation and filling went up to 2mm
of the apex, the prognosis was significantly better than the cases of over-filling, or when the
filling was more than 2 mm beyond the apex.
According to Nair et al8
, causes responsible for endodontic failure are:

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Causes of microbial origin
1. Intra canal factors:
a) Bacteria
b) Fungi
2. Extracanal factor
a) Actinomycosis
Causes of non-microbial origin
1. Exogenous factor (foreign-body-reaction type)
a) filling material
b) paper tips
2. Endodgenous factor
a) Cyst
b) Cholesterol crystals
According to Sundquist et al 12
, the microorganisms recovered from the root canals
after the removal of the filling material are:
MICROBIAL SPECIES Number of cases
Enterococcus fecalis 9
Streptococcus anginosus 2
Streptococcus constellatus

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1 Streptococcus intermedius
1 Streptococcus mitis
1 Streptococcus parasanguis
1 Peptostreptococcus micros
2 Actinomyces israelii
3 Bacteroides gracilis
3 Candida
albicans 2
ENDODONTIC RETREATMENT:
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 successful results.
RATIONALE FOR RETREATMENT:
The root canal system anatomy plays a significant role in endodontic success and
failure.13-15
These systems contain branches that communicate with the periodontal

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attachment apparatus furcally, laterally, and often terminate apically into multiple portals
of exit.16
Consequently, any opening from the root canal system to the periodontal
ligament space should be thought of as a portal of exit through which potential irritants
may pass. Improvement in the diagnosis and treatment of lesions of endodontic origin
occurs with the recognition of the interrelationships between pulpal disease flow and the
egress of irritants along these anatomical pathways.17
Endodontic failures can be
attributable to inadequacies in shaping, cleaning and obturation, iatrogenic events, or
reinfection of the root canal system when the coronal seal is lost after completion of root
canal treatment.18-21
Regardless of the etiology, the sum of all causes is leakage and
bacterial contamination.22
Except in rare instances, lesions of endodontic origin will
routinely heal following the extraction of pulpally involved teeth because the extraction
not only removes the tooth, but more importantly serves to eliminate 100 percent of the
contents of the root canal system. Endodontic treatment can approach 100 percent
success discounting teeth that are non-restorable, have hopeless periodontal disease or
have radicular fractures.17
DECISION MAKING IN RETREATMENT:

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Before beginning retreatment of a tooth, where the primary treatment has failed, it
is important to try to rule out the reason why it failed:
 Is there any endodontic mishaps?
 Is the coronal restoration inadequate or lost?
 Has a root canal been missed?
 Is the root canal inadequately instrumented?
 Is the root filling inadequate?
 Is the problem extra radicular infection?
If clear technical deficiencies with the primary are evident, chances are good that
the retreatment will be successful.
Following factors influence whether a tooth should be retreated or surgically retreated or
extracted.
1) Observation:
When retreatment is considered certain teeth with inadequate root canal
treatment may be watched rather than retreated.
2) Patients concern:
It is profoundly important to understand patients wants, needs &over all
expectations related to oral health.

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Clinicians need to spend sufficient time with patients before treatment to
establish rapport and trust to fully explain the treatment options and to discuss possible
outcomes.
Equipped with this knowledge, patients can choose the treatment options that best
fulfill their wishes.
3) Strategic importance of tooth:
Clinicians need to look carefully at a tooth that is failing endodontically and
decide with the patient and other members of dental team if the tooth is essential.
4) Restorative evaluation:
Fundamental to endodontic treatment is the ability to produce an esthetic well
designed and clinically functional restoration, often broken down teeth should be
evaluated for crown lengthening procedures so that the restorative dentist can achieve the
ferrule effect and establish a healthy biologic width.
5) Periodontal evaluation:
Endodontically failing teeth that are being evaluated for retreatment need to be
examined for pocket depth, mobility, crown to root ratio, hard & soft tissue defects and
any other anomalies that could preclude a healthy attachment apparatus.
6) Other interdisciplinary evaluation:
Most endodontically failing teeth can be successfully retreated with skill,
experience, materials and technologies that are present today.

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However, clinicians should not just focus on a specific tooth. Rather they should
appreciate how this tooth fits into a treatment plan that promotes oral health.
7) Chair time and economy:
The chair time and cost associated with any procedure must be carefully analyzed
and understood by the clinician and completely communicated to the patient.
8) Referral:
When evaluating teeth for endodontic role, a series of challenges must be
addressed to produce predictably successful outcomes.
Common errors in the diagnosis of endodontic failures
Conclusions drawn from a careful history and thorough examination should be
discussed with the patients and recorded.
Before retreatment pain of non odontogenic origin should be ruled out, like
Myofacial pain dysfunction syndrome (M.P.D.S), Temporo mandibular dysfunction
(T.M.D), vascular headaches, sinusitis, neurogenic pain, Central nervous system (C.N.S)
pathology, herpetic or other viral infection and psychosomatic pain.
Odontogenic pain may be of non endodontic origin. For example, endodontically
treated teeth subjected to occlusal trauma may remain persistently tender. Similarly
periodontally involved teeth may remain sensitive after successful endodontic therapy
especially to percussion and palpation. Teeth that present vertical and oblique crown -
root fracture will remain tender to percussion in all the cases.

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FACTORS INFLUENCING RETREATMENT
Successful endodontic treatment should never be guaranteed, although a consistently
high degree of success should be expected. The clinical application of a thorough knowledge
of canal anatomy and meticulous attention to treatment detail are essential to minimize
failure and the need for subsequent endodontic retreatment.3
Currently long term endodontic success can approach 100% 4
this phenomenal
improvement is related to a multitude of factors. Clinicians now have better understanding of
biologic principles and a greater knowledge, appreciation, and respect for root canal system
anatomy and the role it plays in the success and failure.
Improved training, breakthrough techniques, new technologies and attention to
restorative excellence enable clinicians to obtain superior results.
Armed with the necessary information, the clinician, relying on the knowledge of the
presentation of different diseases, makes a diagnosis. Then, a decision on treatment is made
on the:
 Clinician’s knowledge of the prognosis of disease
 Effect of different treatment options
 Anticipated outcome

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 Patient’s personal preference
Other factors will also come into play, affecting rational decision making, these include:
 Attitudes of both the clinician and patient
 Values: in particular, the cost/benefit to the patient
 Financial resources available, including the funding of alternative forms of
treatment.
It is considered important to review the information feeding into the decision making
process.
The “Praxis concept theory”, devised by Kvist et al in 1994, suggests that variations
in the dentist’s retreatment behavior may be explained by differences in their personal
thresholds at which intervention is deemed necessary along a health disease continuum.24

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A study conducted in 2005, support the explanatory potential of Praxis concept
theory in retreatment decision making in the group investigated, and suggest that factors
beside disease status alone, may contribute to the choices that clinicians make.25
OBJECTIVES OF RETREATMENT:
The primary aim of root canal treatment is the elimination and future exclusion of
infection of the root canal system. Endodontic failures usually result from failure to achieve
this primary aim and retreatment is intended to correct the inadequacies of initial treatment.
Depending on whether it is a primary or secondary infection, it may consist of cocci,
rods, spirochetes, filaments and fungi, often maintaining each other in ecological and
nutritional relationships. They may exist in two forms:

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• Biofilm – dense aggregates, forming plaques on and within the root canal
dentin wall.
• Planktonic-loose collections of microorganisms within the root canal lumen.
Unlike primary endodontic infections, which are polymicrobial in nature and
dominated by gram-negative anaerobic rods, the microorganisms involved in secondary
infection are composed of one or a few bacterial species.26-28
E. faecalis is persistent organism that, despite making up a small proportion of the
flora in untreated canals, plays a major role in the etiology of persistent periradicular lesions
after root canal treatment. It is commonly found in high percentage of root canal failures and
it is able to survive in the root canal as a single organism or as a major component of the
flora. 29
Love30
analysed the probable mechanism that allowed an explanation of how E.
faecalis can grow inside dentinal tubules and reinfect a filled root canal. The virulence factor
could be related to its ability to retain the capacity to invade dentin tubules and to adhere to
collagen in the presence of human serum.

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Currently use of a good aseptic technique, increased apical preparation sizes and
inclusion of full strength sodium hypochlorite and 2% Chlorhexidine irrigants are most
effective methods to eliminate E. faecalis. 29
Following steps have been suggested to eliminate the E. faecalis by
1. Good aseptic technique, pretreatment Chlorhexidine rinse, disinfection of
tooth and rubber dam, disinfection of gutta percha with sodium hypochlorite.
2. Adequate instrumentation (increased apical preparation size)
3. Canal irrigants: 6% NaOCl, 17% EDTA, 2% Chlorhexidine
4. Intracanal medicaments: 2% Chlorhexidine, 2% Chlorhexidine gel +
Calcium Hydroxide
5. Consider AH Plus or Grossman’s sealer. A well sealed coronal restoration is
essential. 29
Treatment planning for retreatment:

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If the decision must be made whether to save natural tooth by performing
retreatment, a patient has the right to know the prognosis of the proposed treatment to make
an informed decision.
A study conducted in 2005 evaluating the prognosis of the endodontic treatment after
instrument fracture in the canal and reported that in the hand of a skilled endodontist
prognosis was not significantly affected by the presence of a retained fractured instrument.31
The choice of nonsurgical retreatment versus apical surgery becomes the focus of the
decision in most instances. Outcome assessment studies provide some help in making this
decision. The reported healing rates of nonsurgical retreatment range between 74% and 98%,
32
but with apical surgery alone, only 59% heal completely.33
When apical surgery is preceded by orthograde retreatment, however, the incidence
of complete healing rises to 80%.33
In general, nonsurgical retreatment will be the preferred choice because it seems to
provide the most benefit with the lowest risk. It has the greatest likelihood of eliminating the
most common cause of posttreatment disease, which is intraradicular infection.
Nonsurgical retreatment is usually less invasive than surgery and has a less traumatic
postoperative course. There is less likelihood of incurring damage to adjacent vital structures,
such as nerves, adjacent teeth, and sinus cavities. However, nonsurgical retreatment may be
more costly than surgical treatment, especially if large restorations must be sacrificed during
disassembly procedures before the retreatment. In addition, the amount of time needed for

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retreatment is usually longer than surgical intervention. At times the clinician may not be able
to achieve the complete elimination of microorganisms from the canal space, and complete
Obturation may not be possible. 34
Each case should be approached as a unique set of considerations that must be
reviewed and interpreted before selecting a treatment method. Once the selected option is
undertaken, however, the prudent clinician is always watchful because additional pieces of
information can be discovered during treatment that may modify previous decisions.

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INDICATIONS FOR ROOT CANAL RETREATMENT:
Retreatment is indicated in the following circumstances:
a) Technical deficiency
b) Procedural errors
c) Pain, swelling or sinus tract
d) Persist symptomatic tooth
e) A new coronal restoration is planned.
Technical deficiency
If the root canal has failed simply because the canals are been inadequately
cleaned, shaped or filled, then the tooth should be retreated conventionally.
If failure has occurred because a canal has been missed, retreatment is necessary
to locate and treat the untreated canal. In a multi rooted teeth, it is prudent to retreat all
the canals, including those already filled previously, not just the missed canal alone.
Retreatment of the whole teeth ensures that all the canals and any communicating
channels are thoroughly cleaned and that there is a good quality root filling in all the
canals can be placed.
Procedural errors
If during the treatment, an obstruction, ledge, perforation or instrument fracture
has occurred, retreatment should be attempted in the first instance in an attempt to
remove or bypass the obstruction, close off the perforation and negotiate the canal down

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to the apex of this proves impossible or if the treatment result is deemed to be less than
satisfactory, then only surgery may be chosen as an option.
Iatrogenic procedural errors such as,
a) Poor access cavity design
b) Untreated canals (both major & accessory)
c) Canals that are poorly cleaned & obturated
d) Complications of instrumentation (ledges, perforations or separated instruments)
e) Over extensions of root filling materials
f) Coronal leakage & persistent intra canal & extra canal infection & radicular cysts.
Pain, Swelling and Sinus tract
These are common indications of a failed root canal therapy. A sinus tract,
whenever present, should be explored by inserting a gutta-percha cone and taking a
radiograph to trace the source of infection. It is always better to institute treatment once
failure has been diagnosed and before acute symptoms develop rather than to leave a
festering infection to cause permanent damage to the supporting tissues and jeopardize
the long term survival of the teeth.
Persistent symptoms
If a tooth continues to give symptoms, but the radiograph of the tooth and root
filling appears adequate and there is no obvious cause for failure, retreatment should be
considered. Possible reasons for failure may be coronal leakage, a cracked tooth, an
untreated accessory canal or a recalcitrant infection if the coronal restoration has been

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lost, or is leaking or has failed and the underlying root filling is exposed to saliva,
retreatment may be necessary.
New coronal restoration
When a new crown or bridge, which involves a root treated tooth, is planned, the
existing root canal filling should be checked and if it is judged to be of questionable
quality, the root canals should be retreated. It is always sensible to retreat the tooth
before placing a restoration, when access is not restricted and a good result is achievable,
so as to provide a suitable and secure foundation for the new restoration.
The provision of a new restoration may also require the use of its root canals for
retention. Post should not be inserted until a deficient root filling has been removed and
the tooth retreated.

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CORONAL DISASSEMBLY:
Disassembled teeth provide significant information and can be thoroughly evaluated
for microleakage and explored for complete or incomplete fractures, missed canals,
mechanical failures, blockages, ledges and perforations. Importantly, disassembled root
canals can usually be repaired, if necessary, and 3 – dimensionally cleaned, shaped and
packed, providing a superior seal compared to surgical correction alone.35
Clinicians typically access the pulp chamber through the existing restoration if it is
judged to be functionally designed, well fitting and esthetically pleasing. One study
compared the various techniques for access preparation and found air abrasion to be less
destructive and caused no catastrophic fractures, edge chipping or microcracks.36
Endodontically, the decision to remove any restoration is based primarily on whether
additional access is required to facilitate disassembly and retreatment. If the restorative is
deemed inadequate or additional access is required, the restoration should be sacrificed. The
desire to preserve a coronal restoration should not be at the expense of having to compromise
the requirements of satisfactory access, namely to:
 De roof the pulp chamber
 Straight line view of the canal entrances
 Allow instruments to negotiate canals unimpeded
 Help retain a temporary restoration

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It is pointless to try and preserve the existing restoration if it jeopardizes retreatment;
the consequences of retaining a coronal restoration may be great if, because of restricted
access, a technical error such as perforation occurs or effective infection control is not
achieved.
Factors influencing Restorative Removal:
The safe dislodgment of a restoration is based on five factors that must be considered: 2
1. Preparation type: preparations vary in retention, depending on the total surface area of
the tooth covered and the height, diameter, and degree of taper of the axial walls.
2. Restoration design and strength: the design and ultimate strength of a restorative is
dependent on its physical properties, thickness of material and the quality and techniques
of the laboratory technician.
3. Restorative material: the composition of a restoration ranges from different metals to
tooth colored restoratives, such as porcelain. How these materials react to the stresses and
strains required during removal must be appreciated.
4. Cementing agent: the retention of cements ranges from weak to strong, generally
progressing from zinc oxide eugenol to polycarboxylate to silicon phosphate to glass
ionomers to resin modified glass ionomers to bonded resins.

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5. Removal device: the safe and successful dislodgement of prosthetic dentistry requires
knowledge in the selection and use of a variety of devices. Clinicians need to identify and
become familiar with each device. Its safe application, effectiveness, limitations and cost.
Coronal disassembly devices
The tools used for disassembly have been arbitrarily divided into three categories.
They can be used alone or they may also be used in combination to attain removal
success synergistically.
 Grasping Instruments
 Percussive Instruments
 Active Instruments
i) Grasping Instruments:
Works by applying inward pressure on two opposing handless. Increasing the
handle pressure proportionally increases the instrument’s ability to grip a restoration.
The instrument should protect the restoration and provide a strong purchase while
reducing slippage.
Some e.g. are:
 Trident crown placer/remover (CK Dental Specialties, orange, CA)
 KY pliers (GC America, Alsip, IL)
 Wynman Crown Gripper. (Miltex instrument Co., Lake Success, NY)
 Roydent Bridge Remover

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K.Y Pliers: uses small replaceable rubber tips & emery powder to enable a firm grasp
of the crown without damaging it.
Roydent bridge remover: forceps designed specially to engage the margins of
the crown while using an adjacent tooth as fulcrum. Squeezing the handles together will
cause the crown to be elevated off the prepared tooth.
ii) Percussive Instruments:
This group of instruments uses a selected and controlled percussive removal
force. They deliver an impact either directly to another securely engaged prosthetic
removal device.
Eg:
1) Corona flex (KaVo America, Lake Zurich)
2) Pneumatic crown & bridge remover – creates impact from compressed air.
3) Henry Schein (Morrell Remover) - applies the force manually using a sliding
weighed handle.
4) Automatic crown & bridge remover – uses vibrations to break the bond between
crown to prepapred tooth surface.
5) Crown-A-Matic –delivers a shock impulse to loosen the crown.
However caution must be exercised when removing a tooth colored restorative
materials.
iii) Active Instruments:

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This category actively engages a restorative, enabling a specific dislodgement
force to potentially lift off the prosthesis. These devices require a small occlusal window
to be cut through the restorative to facilitate the mechanical action of the instrument. In
this method, the slight disadvantage of making and repairing the occlusal hole is
significantly offset by the advantage of saving the patient’s existing restorative.
Eg: - Metalift
- Kline crown remover
- Higa bridge remover
- Richwil Crown & Bridge remover
Metalift: Pilot holes are prepared in the two abutment teeth. The high pistons are placed
in the pilot holes until they contact dentin. Ortho wire is then placed under appropriate
pontic & inserted through a take up hole in the device. The hand crank is then turned,
rotating the take up roll &cinches up the wire. This intra oral wrench gradually hoists the
bridge then steadily increasing vectors of forces as the role is rotated. It’s used for both
metal and porcelain bridges.
Richwil Crown & Bridge remover: The small block of material is placed on the crown
to be removed, and the patient bites into this material until the resin cools & hardens, at
which point the patient opens his/ her mouth, generating enough force to pull the crown
off.

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MISSED CANALS:
Historically and still too often, surgical treatment has been directed toward
“corking” the end of the canal with the hopes that the retrograde material will incarcerate
biologic irritants within the root canal system over the life of the patient. 38
A significant percentage of failures are related to missed root canal systems.
These hold tissues and at times, bacteria and related irritants that inevitable contribute to
clinical symptoms and lesions of endodontic origin. 39-41
Although this scenario occurs
anecdotally, it is not nearly as predictable as nonsurgical retreatment. Endodontic
prognosis is maximized in teeth with root canal systems that are cleaned, shaped and
packed in all their dimensions.
The common variations that are encountered can be:
 Maxillary central incisors – one or more extra canals occasionally. 42, 43

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 Maxillary first bicuspids – may be 3 rooted having MB, DB and palatal canals. 44
 Maxillary second bicuspids – deep canal divisions or multiple apical portals of
exit. Although the orifices are commonly ribbon shaped.45
 Maxillary 1st
molar – MB root usually has 2 canals that oftentimes anatomically
communicate via an isthmus. This system can be identified and treated in over
75% of the cases without a microscope and in approximately 90% of the cases
with a microscope.46
 Maxillary 2nd
molar – should be suspected of having second canal in MB root. 46
 Mandibular incisors – lingual canal 45% of time47
access cavities should be
carried more lingual at the expense of the cingulum to address this potential
system.
 Mandibular premolars have roots that frequently hold complex root canal
systems. The anatomic variations include displaced orifices, deep divisions, loops
and branches and multiple portals of exit apically. 48
 Mandibular 1st
and 2nd
molars – variations are common that these are thought to
be normal anatomy of these teeth (2 canals in distal root). Clinicians need to
check the mesial root for a third system that may be displaced or located within
the groove between the mesiobuccal and mesiolingual orifices. 49

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 C – Shaped molars pose challenges in endodontic treatment and clinicians need to
be familiar with its aberrant canal form. Clinician must also be well aware of
radiographic features and the incidence of C-shaped molars within various
population groups. 50, 51
Armamentarium and Techniques:
When one is searching for missed canals, the following concepts, armamentarium
and techniques are the most helpful.
• Anatomic Familiarity is essential before preparing the access or reentering the
tooth.
• Radiographic method: Radiographic analysis is critical when evaluating an
endodontic failure. 52, 53
Well angulated IOPA’S should be taken with the cone
directed straight or mesioblique or distoblique. If the obturation materials appear
positioned asymmetrically, within the long axis of the tooth, a missed canal should be
suspected.52
• Computerized digital radiography (CDR) affords a variety of software features
which enhances radiographic diagnosis in identifying hidden, calcified or
untreated canals.
• Magnification: Vision is enhanced by magnifying glasses, head lamps and
transilluminating devices. The dental operating microscope affords extra
ordinary light and magnification, and it gives the clinician unsurpassed vision,
control and confidence in identifying or chasing extra canals. 49

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• Surgical length burs enhance the vision by moving the head of the hand piece
away from the occlusal table and improving vision along the shaft of the bur.
• Access cavities should be prepared and expanded so that their smallest
dimensions are dictated by the separation of the orifices on the pulpal floor and
their widest dimensions are at the occlusal table. The isthmus areas or
developmental grooves or both are firmly probed with an explorer in an effort to
find a “catch”.
• Piezoelectric ultrasonics in conjunction with the innovative CPR ultrasonic
instruments provides a breakthrough for exploring and identifying missed canals.
Advantages include:
 Elimination of bulky head of the conventional hand piece thereby enhancing
vision.
 Working ends are 10 times smaller than the smallest round bur.
 Abrasive coatings allow them to sand away dentin when exploring for missed
canals.
• Micro-openers (Dentsply Maillefer, Tulsa, Okla) are flexible, stainless steel;
150-sized land instruments that feature ergonomically designed offset hands.
Advantage includes:
 Limited-length cutting blades
 0.04 And 0.06 taper

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 Enhanced tensile strength
 Easier to locate, penetrate and perform initial canal enlargements
procedures.
 Unobstructed vision when operating teeth with limited access.
• Various dyes, like methylene blue, can be irrigated into the pulp chambers of
teeth to aid in diagnosis. The chamber is subsequently rinsed thoroughly with
water, dried and visualized to see where the dye has been absorbed. Frequently
the dye will be absorbed into orifices, fins and isthmus areas and it will road map
the anatomy.
Champagne test: Sodium hypochlorite can aid in diagnosis of missed or hidden canals
by means of the “champagne test”. After cleaning and shaping procedures, the access
cavity is flooded with NaOCl and the solutions are observed to see if bubbles are
emanating toward the occlusal table. A Positive “bubble” reaction signifies that NaOCl
is either reacting with residual tissue within a canal in treatment or reacting with a
residual chelator that is still present within the canal preparation or a missed canal. 49
POST REMOVAL:
Once the access is prepared it is common for clinicians to encounter a post in
endodontically treated teeth.54
Frequently these posts may have to be removed to
facilitate successful nonsurgical retreatment.
The various factors that can influence post removal can be:

32. Page | 32
i) Operator judgment, training and experience, as well as using best technologies and
techniques.
ii) Knowledge about the normal anatomy and likely variations in each tooth.
iii) Knowledge about root morphology, external concavities, root wall thickness and the
length shape and curvature of the canal. This can be appreciated by obtaining three well
angulated radiographs. Radiographic films also help the clinician to assess the length,
diameter and direction of the post and the coronal extension of the same into the pulp
chamber.
Important factors that influence clinician’s ability to remove are 55
a) Post type,
b) Adhesive used to cement post or cementing agent,
c) Location of the tooth in the arch.
Indication for post removal:
 Insufficient length of post
 Insufficient diameter of post relative to root canal diameter
 Insufficient retention of post in the root canal
 Insufficient retention for the coronal builds up
 Insufficient root canal filling apically.
Contraindication for post removal:
Extremely long, well-fitted posts where successful removal is difficult.
Extremely large posts, with only thin dentinal walls around. Removal probably would
weaken the root excessively.
Potential complications of post removal include:

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a) Fracture of the tooth
b) leaving the tooth non restorable
c) Root perforation
d) Post breakage
e) Inability to remove the post
f) Damage to periodontium due to ultrasonically generated heat damage
When evaluating a tooth for post removal, the clinician must weigh risk versus
benefit before proceeding with this procedure. As an example, the relative radiodensity
between a titanium or titanium alloy post can appear very similar, or even identical to
gutta percha when viewed radiographically. As such, when considering nonsurgical
retreatment, clinicians need to be familiar with the radiographic characteristics of these
nonmetallic posts. A root can be structurally weakened, perforated or fractured during
any phase of retreatment ranging from radicular disassembly to subsequent shaping and
filling procedures. In some instances, it may be wise to consider a surgical approach to
resolve an endodontic failure. However, surgery should not be performed promiscuously
because of lack of training in the best, presently developed, techniques utilized for post
removal.
Techniques for Post Removal:
Successful post removal involves eliminating all circumferential restorative
material from the pulp chamber as well as root canal can be removed. Once straight line
access into the pulp chamber is established, the restoratives circumferential to the post are

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removed. High speed surgical length burs are selected to section and eliminate the cores
because their added lengths improve vision during reentry into the pulp chamber.
1. Rotosonic vibration: it is a straight forward method to potentially loosen and remove
a fully exposed post. The Roto-Pro bur is a six- sided, non cutting instrument that comes
in two shapes: a) regular straight tip bur b) football- rounded bur when instrument is
rotated at 2,00,000 rpm, it produces 1.2 million vibrations per minute or 2,00,000
vibrations per second. The bur is kept in intimate contact with the obstruction and is
generally carried counter clock wise around the post.
Roto pro-bur
2. ULTROSONIC ENERGY: a piezoelectric generator may be utilized to transfer
energy and potentially dislodge a post.
Piezoelectric ultrasonic systems, in conjunction with specific instruments, afford the
clinician certain advantages in endodontic disassembly and retreatment.

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The CPR-2 instrument is used on full intensity within the pulp chamber to
eliminate the remaining core materials circumferential to the post. The smaller parallel-
sided CPR-3, 4 and 5 are more delicate and should be used in low intensity. These
instruments are designed to work in small, restricted and confined spaces.
If space is severely restricted within the field of operation, the CPR-6, 7 and 8
titanium ultrasonic instruments can be selected and used on low intensity. These
instruments provide the clinician thinner diameters and longer lengths as compared with
any other ultrasonic instrument line.
The CPR’s may be used to safely “brush” and “Sculpt” away materials, that upon
elimination, undermine the stability of the post. All these instruments are used in a dry
condition, to optimize vision. The assistant uses a Stropko three way adapter with White
Mac Tip to direct a continuous is an easy and economic method to potentially loosen and
remove it. The regular tip Roto-Pro bur is a high speed, friction-grip, six sided
instrument. When rotated, its edges produce six vibrations per revolution to potentially
loosen and remove a post. The bur is kept in contact with the post and removed around it
in CCW direction for 2-3 minutes.
If this is unsuccessful, a CPR-1 ultrasonic instrument can be resorted to. It is said
that, using a CPR-1, a post can be removed within 10 minutes (10 minute rule).

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The area around the post may be flooded with a solvent, such as chloroform,
before activating the ultrasonic instrument. This will help dissolve the cement around the
post.
MECHANICAL OPTION:
Devices have been made to add forces along the long axis of the tooth to enhance
post removal.

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Some examples of post removal devices are
a) Eggler post remover,
b) Gonon Post removing system
c) Thomas screw post removal system
d) JS Post extractor
e) Ruddle post removal system (PRS),
f) Masserann instrument.
The Gonon Post Puller and Ruddle Post Removal System are equipped with
trephine burs that allow for the milling of the coronal 1 mm to 3 mm of the post itself,
and have corresponding –sized tubular taps.
Masserann kit (Micromega;Besancon,France) and the post puller (Brasseler
USA;Savannah,GA) have had limited success because they frequently require the
excessive removal of tooth structure, which predisposes to ledges, perforations or root
fractures. Gonon post extractor represents a definite improvement over the Masserann
and the post puller devices in that it is less invasive and has enjoyed good success, but
regretfully, for a variety of reasons, by a limited number of clinicians. Masserann kit was
used to remove small posts fractured inside the root.
The PRS option: (Ruddle Post Removal System)
It is used for removal of parallel / tapered passive types of screw posts. This kit
uses a trephine bur to machine the post to a specific size.
The PRS kit affords simplicity in use, versatility and sizing during post removal
procedures. The PRS is designed to mechanically engage and remove different kinds of
post types or other intracanal obstructions whose cross sectional diameters are 0.60 mm

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or greater and provides extraordinary opportunity in predictably removing different kinds
of post systems and other intra canal obstructions.
The PRS kit contains
i) Extracting pliers,
ii) A Trans metal bur,
iii) 5 trephines of varying diameters,
iv) 5 corresponding tubular taps with internal diameters ranging 0.60 to 1.60 mm,
v) A torque bar,
vi) Rubber bumpers.

39. Page | 39

40. Page | 40
• Initial procedures include straight lines access and complete visualization
of the post within the pulp chamber once access has been achieved.
• Transmetal bur is used to round off and taper the coronal most aspect of
the post. “Doming’, the head of the post in this manner, will guide the
subsequent instruments over the post.
• A drop or two of chelator is placed on the head of the post to act as
lubricant to facilitate the subsequent machining process.
• To ensure circumferential milling, the largest trephine that will just
engage the post is selected.
• The trephine is used with a “peck” drilling motion to maintain rpm and to
keep the head of the post cooler so that it does not work-harden.
• The trephine is carried down over the head of the post ideally 2 to 3 mm
and machines a precisely round, cross-sectional diameter.
A tubular tap is selected and pushed against the milled down post head and is
screwed onto the post in a CCW direction. This will result in the tap engaging the post,
to a depth of 1-3 mm. After this, a protective rubber bumper is pushed down onto the
biting surface of the tooth.
Post removal pliers are then selected and its extracting jaws are mounted onto the
tubular tap. Instrument is held firmly with one hand and the jaws of the pliers are opened
by turning the screw knob clockwise.
If turning screw knob becomes difficult, a CPR-1 instrument can be used on the
tubular tap as close to the post as possible. This combination provides a better technique
for removal of posts.

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Clinicians also encounter, actively engaged threaded posts that require removal.
The post head is milled down and a tubular tap is threaded posts from the canal.
Thomas Screw Post Removal Kit:
It is an instrument designed specifically for the removal of active / screw posts. It
contains Trephine burs, Extraction mandrels. This mandrel is reverse threaded to enable
them to tap onto the screw post in a counter clockwise direction so that continued
torquing force while creating the tread will unscrew the post.
Post pullers:
The first device of this kind was described by Prothero in 1923, “Little Giant
Post Puller”. In 1979, Warren and Guttmann described the Post puller.
The first set of the jaws of the post puller are fastened onto the post while the
second jet of jaws push away from the tooth in line with the long axis of the tooth lifting
the post out of canal. The advantages of this system include conserving root structure and
reducing the risk of root fracture, root perforation and root torquing. The system has been
described as being safe and efficient for post removal in the anterior and posterior teeth.
Caution observed to remove strictly in line of the long axis of the tooth to prevent
fracture or torquing of the remaining tooth.
This device cannot be used on the mesial and distal portion or thin and brittle
walls which might fracture or do not allow correct positioning of the post puller. In such
cases the use of a supplementary device has been proposed. After taking an impression
an individually waxed and case base plate is fixed covering both the tooth to create

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endodontically and the adjacent teeth. The device allows correct and firm positioning of
the post puller.
Gonon Post puller: (Ron Chige Inc.,Boca Raton,FL,USA)
It is an effective instrument for removing parallel / tapered, non active preformed
posts.
• This kit uses a hollow trephine bur that is aligned with the long axis of the post &
placed over its newly exposed end.
• Once the extraction mandrel with its associated washer/ bumpers is attached to
the post, the extraction forceps or vise is applied to the tooth & post.
• Turning the screw on the handle of the vise applies a coronal force in a fashion
similar to way a corkscrew removes a cork from a bottle of wine. The top of the
post is reduced circumferentially and in height. A trephine is used to give the post
top the same size as the corresponding mandrel, which then is screwed onto the
post. Extracting pliers are fixed to the mandrel. Finally, the jaws of the pliers are
expanded by tightening a Knurled Knob, which will separate the post from the
tooth following the principle cork screw. These devices are difficult to use in
molar areas due to inaccessibility and also cannot be used for screw posts. For
screw posts a special kit of trephines and mandrels has been designed (Dental
Cash,Paris,France). After fixation of the mandrel on the post top this may be
extracted using counter clockwise rotation.

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A similar device, the Endo extractor, is a recently developed device also used for
post removal.
Bur-used for short and small posts: A channel is drilled through the post, loosening it
sufficiently so that it can be removed special long necked round ISO size 006 burs and D
205 LN bur are recommended High speed burs are not recommended for post removal.
Cemented posts: Round burs with long shanks used to remove cement as deep as
possible. Pliers or forceps may be used to pull out the posts. Only slight rotation force is
allowed. No lateral force must be used as this may result in dentinal cracks or even root
fracture. The cement bond is best broken by the use of ultrasonic.
Screw posts: Most retentive, but easier to remove. Best removed by Ultrasonics,
by working around the post in CCW direction.
Cast posts: Custom posts difficult to be removed. Only minimal gap filled with
cement, usually fabricated with soft metals which respond poorly to Ultrasonics.
In cases of the cores with more than one post especially if the posts are extremely
parallel it may be necessary to separate the posts with a bur prior to ultrasonic treatment.

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Cosmetic posts: Ceramic, Zirconium various types of Fiber reinforced
composites cannot be removed either with Gonon kit or the use of ultrasonic instruments,
where as the use of a high speed bur to channel down through the post may result in a
high rate of root perforation.
For removal of fiber reinforced composite posts instruments used are,
 Largo bur (Dentsply)
 Peeso drill,
 Gyro tip – for removing fiber reinforced composite posts
• Ceramic & Zirconium posts are usually impossible to remove. Ceramic posts may
be removed by grinding them away with a bur.
• Final step in exposing the underlying root filling is to ensure the removal of post
cement. This can be accomplished by visualizing the cement using magnification
& illumination & removing with ultrasonic tip.
Eggler Post Remover:
- Works similar to Gonon post puller.
-No trephine burs / extraction mandrels are present.
- Mainly used in cases where post and core are cast as one unit.
Procedure: the device consists of 2 sets of jaws that work independently of one
another.1st
set of jaws is attached to the post while the 2nd
set of jaws pushes away from
the tooth incline with the long axis of the tooth, removing the post from the canal.
Disadvantages: not recommended for removal of screw post.

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Removal of obturating material:
Main difference between root canal retreatment and initial root canal treatment is
the need to remove existing root canal fillings during canal negotiation. Only when
radicular access is achieved, and the root canals have become negotiable, can the
deficiencies of the original treatment be corrected. In canals that are relatively large and
straight, single cones can, at times, be removed with an instrument in one motion. For
other canals, there are number of possible gutta percha removal techniques. The
techniques include rotary files, ultrasonic instruments, hand files with heat or chemicals,
and paper with chemicals.56
1. Gutta percha removal:
The relative difficulty in removing gutta-percha varies according to the canal
length, cross-sectional dimensions, and curvature, Regardless of technique, GP is best
removed from a root canal in a progressive manner to prevent inadvertent displacement
of irritants periodically. Large, straight canals can be cleansed usually by hand
instruments.
Selection of gutta-percha removal technique depends upon the following
considerations:
1. Filling density: Retrieval of poorly condensed gutta percha may not require solvents.
Well condensed gutta-percha requires solvents unless rotary instruments can be used
safely.

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2. Canal Curvature: In curved canals, dissolving gutta-percha helps to prevent
transportation, ledging or perforation. In straight canals retreatment may be expedited by
using rotary instruments.
3. Apical extension: Dissolving an under extended obturation helps to prevent
ledging .Removal of over-extended gutta-percha requires engaging and retrieving master
cone, therefore solvents are contraindicated.
4. Degree of difficulty: removal of gutta-percha is complex when the canals are densely
curved, or ledged or when the obturation is over extended or under extended.
Solvents used for G.P removal
Solvents have been used to remove radicular portion of root canal.
Solvents used are 1) chloroform,
2) Eucalyptol,
3) Xylene,
4) Methyl chloroform,
5) Halothane,
6) Turpentine oil,
7) Pine needle oil,
8) White pine oil
9) Carbon disulfide
10) Essential oils
11) Benzene

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The efficacy of these solvents differs, as does the solubility of various brands of
gutta-percha. All these solvents have some level of toxicity, so their use should be
avoided if possible. Chloroform is the most effective solvent and has the advantage of
high volatility. Concerns have been expressed, however, about its carcinogenic potential,
although evidence is limited. Xylol may also be carcinogenic, whilst rectified turpentine,
methyl chloroform, and halothane have been suggested as safer alternatives. 57, 58
For the most efficient use of solvents, the pulp chamber and the coronal part of
the canal should be cleared of gutta percha with a Gates Glidden bur, a NiTi coronal
flaring rotary file or a heated instrument, to create a well. If the solvent is placed in the
pulp chamber instead of into the well, it will evaporate more quickly because of the
greater surface area. In addition, a well permits intimate contact between the solvent and
gutta percha.
Chloroform:
The strongest and most commonly used of the solvents-it is quickly effective. Its
rapid evaporation makes it a useful material, however in 1976, the U.S, FDA banned the
use of it because of reported carcinogenicity. Its carcinogenicity is unproven and its use
in dentistry is not prohibited. It is toxic and may be harmful to the periapical tissues
.Repeated exposure to chloroform vapors may have adverse health effects. Chloroform
unfortunately is classified as a beta-2-carcinogen. Therefore when used in retreatment,
appropriate precautions must be observed. The operator team wears protective masks,
and patient’s nose is covered with the rubber dam whenever the solvent is released into
the canal orifice. Chloroform was used successfully in bypassing gutta-percha in well

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sealed canals utilizing Canal finder System with K-files. With careful use, its toxicity
may be eliminated as a risk factor to both the patient & the personal in the operatory.
Xylene:
The dissolution of gutta-percha in xylene is considerably poorer than chloroform.
Because of its slow evaporation, xylene is impractical for use at chair side. It may be
used as an intracanal medication for long term dissolution of gutta-percha between
treatment sessions.
Eucalyptol:
It is less irritating than chloroform and it has antibacterial activity. It is toxic
when ingested and was found to be least effective gutta-percha solvent. It must be heated
to improve the solubility of the gutta-percha mass.
Methyl Chloroform:
Methyl Chloroform is the best alternative to chloroform. Compared with
chloroform it is less toxic and not carcinogenic and even though it is less effective as a
solvent than chloroform, it is more effective than xylene and eucalyptol. Chloroform is
the reagent of choice; this sequential technique involves filling the pulp chamber with
chloroform, selecting an appropriately sized K-type file and then gently “picking” into
the chemically softened GP. Initially, a size 10 or 15 SS file is used to ‘pick’ into the GP
occupying the coronal 1/3rd
of the canal. Frequent irrigation with chloroform creates a
pilot hole and sufficient space for the serial use of larger files to remove GP in this
portion of the canal. Once coronal 1/3rd
is completed, same procedure is done on middle
and apical 1/3rd
. This progressive removal technique helps prevent the needless extrusion
of chemically softened GP periodically.
Halothane: as effective as solvent as chloroform. Disadvantages include increased cost
& volatile, potential for idiosyncratic hepatic necrosis makes its use as a GP solvent.

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50. Page | 50
Rotary instruments used for removal of G.P
Ni-Ti 0.04 and 0.06 tapered rotary files are the most effective and efficient group
of instruments used for removing gutta-percha from a previously treated root canal.
- Should be used with caution in under prepared canals.
- Not used in canals that does not accept them passively.
When attempting GP removal, it is often wise to divide the root canal into thirds
and use the appropriate size instruments accordingly. To soften and to engage GP, the
rotary instrument should turn at speeds ranging between 1200-1500 RPM.
ProTaper Retreatment files:
D1: To remove filling material from coronal third
D2: To remove filling material from middle third
D3: To remove filling material from apical third

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Ultrasonic instruments used for removal of G.P:
This presents a useful technology to rapidly eliminate GP. The energized
instruments produce heat that thermally softens the GP. Specially designed ultrasonic
instruments are carried into canals that have sufficient shape to receive them and will
float gutta percha coronally into the pulp chamber where it can be subsequently removed.
Ketac -Endo (GI based endodontic sealer) is virtually insoluble in both chloroform
&halothane. It must be removed by using ultrasonic’s to debride the canal walls.
Heating instruments used for removal of G.P
A power source in conjunction with a specific heat carrier instruments such as
5004 Touch-N-Heat or System B has been used to thermo soften and remove “bites” of
GP from Root canal systems.

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The cross sectional diameter of the heat carrier limits its ability to plunge into
under prepared systems and around pathways of curvature, however, in larger canals, this
method works quite well.
It can cause damage to the periodontal ligament. Thus heat must be produced in
short bursts to allow the instrument to penetrate the gutta-percha mass. Technique is used
to activate the instrument so that it is red-hot, and then plunge it into the most coronal
aspect of gutta-percha. The heat carrier is then deactivated and as it cools, will freeze a
bite of GP on its working end. Instrument removal generally results in the removal of an
attached “bite” of GP.
Combination of Heat & instruments used for removal of G.P:
This method employs heat and H-files, a hot instrument is plunged into the GP
and immediately withdrawn the heat-soften the material. A size 35, 40 or 45 H file is
then selected and quickly, but gently, inserted into the thermo softened mass. When the
GP cools, it will freeze on the file.
In poorly obturated canals, removing the file can, at times, eliminate the engaged
GP in one motion. This technique is extremely effective in those cases where GP extends
beyond the foramen.
Combination of Files & Chemicals used for G.P removal:
Used to remove GP from small and curved canals, particularly when the
obturation terminates short of the apex and at the curve. The use of solvents eliminates
the need for the excessive force during the negotiation of the gutta percha obturated

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canals. Such a force can lead to undesired transportation of the canal space. On the other
hand extrusion of the solvent into the periapical tissues should be avoided and solvents
should not be used in retreatment of overextended gutta-percha fills.
A ‘well’ is made in the center of the defective filling and 1or 2 drops of solvent
are introduced from a syringe. The reaming and filing actions are much improved as the
gutta-percha dissolves. One must be careful, however, not to pump the liquefied mixture
out through the apical foramen. Larger files are used high in the canal, decreasing
markedly in size toward the apex. After the bulk of the old filling is removed, aggressive
filling is done in an attempt to remove all the gutta-percha and sealer from the walls.
Plaques of smear layer, debris and bacteria must be uncovered to ensure future success.
Instruments used are Hand files (#15, #20), C+ file (malliefer).
C+ file: It is a stainless steel, end cutting hand file i.e., twisted from a square blank. It is
stiff as the taper varies along the shaft, giving it rigidity & strength to cut through well
condensed GP efficiently. They can penetrate the GP more efficiently than flexible files.
Paper points and chemicals used for removal of G.P:
GP and most sealers are miscible in chloroform and once solution can be
absorbed and removed with appropriately sized paper points. Drying solvent-filled
canals with paper points is known as “wicking” and is always the final-step of GP
removal. The wicking action is essential in removing residual GP and sealer out of fins,
cul-de-sacs and aberrations of the root canal system.
In this technique, the canal is first flushed with chloroform and the solution is
then absorbed with appropriately sized paper points. Paper points “wick” by pulling

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dissolved materials from peripheral to central and their use in this manner liberates the
residual GP and sealer from the root canal system.
Residual GP and sealer can be still present, even if the paper points come out
clean, white and dry. At this point, the chamber is again flooded with chloroform,
wicking is continued. The canal is liberally flushed with 70% isopropyl alcohol and
wicked to further encourage the elimination of chemically softened GP residues.
REMOVAL OF OVER EXTENDED GUTTA-PERCHA
It can be attempted by inserting a new H-file into the extruded apical fragment of
root canal filling using a gentle clock wise rotation to a depth of 0.5-1mm beyond the
apical constriction. Then file is slowly & firmly withdrawn with no rotation, removing
the overextended material.
Rotary system removal:
Systems available: -The ProFile (Dentsply)
- The canal finder (Endo Technique Co,Tusin,CA),
- GPX (Brasseler)
These engine-driven instruments mechanically chop up the GP and sealer. While
thermo plasticizing the root filling mass using frictional heat to aid in removal.
Assessments of canal cleanliness and extruded apical debris generally indicated that there
were no overall differences between hand and mechanical GP removal.

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It is recommended that after rotary GP removal, subsequent hand instrumentation is
needed to remove the residual obturating materials completely from the canal.
Disadvantages: instrument fracture inside the canal. However, fracture of root is less
likely to occur when the instrument rotary speed was increased from 350 to 1500 rpm.
Laser removal of G.P:
Lasers are among the alternative methods used in endodontic treatment. Although
this treatment modality is still in its infancy, various laser wavelengths have properties
that may be useful when applied to access cavity preparation, cleaning and shaping of
root canal systems, and three dimensional obturation procedures. The use of lasers for
endodontics is becoming more reasonable with the development of different wavelengths
that remove or alter oral hard dental tissues (enamel, dentin) more predictably. The
following is a brief review of the laser systems available today and their ability to affect
the outcome of root canal treatment. Dental lasers currently in use operate in several
areas of the electromagnetic spectrum, including the infrared, visible, and ultraviolet
ranges. Each laser wavelength in a particular range allows the device to target various
tissues and carry out different procedures. For example, carbon dioxide (CO2) energy is
highly absorbed by tissues with a high water content. It therefore may be more effective
in removing or altering soft tissue in the oral cavity (e.g., gingiva). Other wavelengths,
such as Neodymium : Yttrium Aluminum Garnet (Nd:YAG), are absorbed by vascular
tissues, such as the dental pulp. An important part of root canal treatment is giving the
root canal system a specific shape while debriding it of organic contents; that is, cleaning
and shaping. Early attempts to carry out the cleaning and shaping function were less than
successful. Although the Nd:YAG laser used a contact probe that simulated a hand

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instrument, the probe was composed of a fused silica (glass) and could not be precurved.
It also could not be seen radiographically if it separated. In addition, the probe emitted
energy at its end rather than through the sides. The result was a preparation that was
neither fully clean nor shaped. Other lasers used noncontact probes that emitted the laser
beams through a system of mirrors in an articulated arm (wave guide with CO2); this was
effective several millimeters away from the walls of the root canal system. Improvement
in the use of these systems may lead to a device that accomplishes all the requirements of
a well-cleaned and shaped system and aids in three-dimensional obturation. Use of the
Nd:YAG laser to remove gutta-percha has been investigated in vitro. The time taken for
removal of the GP was within the range of other studies of mechanical GP removal and
addition of solvents did not improve the performance of the laser.
2. Resilon removal:
A thermoplastic polyester polymer RESILON that is bonded into the canal space
using an unfilled resin bonding system (EPIPHANY, Pentron Clinical Technologies).
The resin polymer is soluble in chloroform and may be removed by heat application
similar to gutta-percha. The unfilled resin sealer must be removed by resin solvent such
as Endosolv-R (Septodent,Paris)before instrumentation.
3. Solid core obturator removal:

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Obturating systems such as Thermafil, Densfil & the GT obturator have become
very popular as provides a rapid & simple technique for warm GP obturation. The nature
of the carrier will determine the method used & complexity of the retrieval.
-2-types of carriers are found in these systems.
1) Metal (stainless steel or titanium)
2) Plastic
Metal carrier removal:
The level at which the metal carrier is severed is important in its retrieval.
After careful access and complete circumferential exposure of the carrier, a suitable
grasping plier is selected and a purchase is obtained on the carrier. The relative tightness
of the carrier within the canal can be tested using the pliers. Removal of a metal carrier
is accomplished with initial use of heat application to the carrier that can soften the GP
surrounding it, facilitating its removal with Peet silver point forceps (Silvermans, New
York) or modified Steiglitz forceps (Union Broach,York).
The following techniques are used to remove carriers.

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• Carrier is grasped with pliers and extraction is attempted using fulcrum
mechanics, rather than a straight pull out of the tooth.
• If enough canal shape exists, a CPR-3, 4 and 5 ultrasonic instrument can be used
alongside the carrier to produce heat and thermo soften the GP. The activated
ultrasonic instrument is gently moved apically and the carrier is displaced and
floated out coronally.
• Indirect Ultrasonics can be performed by grasping the exposed carrier with pliers
and then placing an ultrasonic instrument against the pliers.
• Rotary instrumentation can be used to auger a plastic carrier effectively and
efficiently from a canal. This should be attempted if there is sufficient space to
passively accommodate the rotary instrument without engaging lateral dentin.
The IRS may be considered, in certain cases, to remove a carrier. This method of
removal is especially appropriate if the core of the carrier is metal and has cutting flutes
that are engaging lateral dentin.
Solvents will chemically soften GP and allow small files to work deeper,
progressively undermining and loosening a carrier for removal. Once the carrier is
removed, then GP removal can be attempted as if it were a normal retreatment case.
Plastic carrier removal:
Heat must be avoided to minimize the likelihood of damaging the carrier. The
older thermafil carriers were made of two different materials depending on the size. In

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the smaller sizes (up to size #40), the material used was Vectra, where as the larger sizes
used polysulfone, which is soluble in chloroform.
Solvents, on the other hand, seem not to affect the newer GT plastic carriers, so their use
can be recommended.
Recently, a technique for plastic carrier removal has been described using a
System B Heat Source (Sybron Dental Specialties) to soften the GP surrounding the
carrier without melting the carrier itself. The temperature is set at 225°c, and the heat
plugger is placed buccal and lingual to the carrier, after which #50-55 flex-R hand files
are placed around the carrier and is removed.
4. Silver point removal:
The relative ease of removing failing silver points is based on the fact that chronic
leakages greatly reduces the seal and hence, lateral retention.
Usually when a silver cone is used for obturation, the apical 2 to 3 mm would be
prepared relatively parallel and then flared coronal to apical zone. When clinicians
evaluate silver point failures, they should recognize that the silver point is parallel over
length, hope for a coronally shaped canal, and take advantage of this space discrepancy
when approaching retreatment.
Many techniques have been developed for removing silver points, primarily
because of their varying lengths, diameters and position they occupy within the root
canal space.
Access:

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Typically coronal heads of Silver points are within the pulp chambers and are
entombed planned and carefully performed so as to minimize the risk of in advertently
foreshortening the silver points. Initial access is accomplished by high speed, surgical
length cutting tools. Subsequently, ultrasonic instruments may be carefully used within
the pulp chamber to brush cut away the restorative materials and progressively expose
the Silver point.
Pliers Removal:
A suitable grasping instrument such as Stieglitz pliers (Henry Schein) is selected. When
grasping a silver point, rather than trying to pull it straight out of the canal, the pliers is
rotated using fulcrum mechanics and levered against the restoration or tooth structure to
enhance removal efforts.
Caufield silver point retrievers:
It’s a spoon with a groove in the tip that can engage the exposed end of the silver
point so it may be elevated from the canal or possibly elevated from the canal. It is
available in 3 sizes: 25, 35 and 50.

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Indirect ultrasonics: When a segment of Silver point is encountered below the
orifice and the space is restricted, the CPR-3, 4 and 5 ultrasonic instruments may be used.
This instrument is used to trephine circumferentially around the obstruction, break up
cement and safely expose as much as silver possible.
Caution should be exercised that the instrument should not be used directly over
the silver point because elemental silver is soft and rapidly erodes during the mechanical
manipulation. Once the surrounding material is removed, ultrasonic energy may then be
transmitted directly on grasping pliers to synergistically enhance the removal efforts.
This indirect method transfers energy along the Silver point, breaks up material deep
within the canal and enhances removal.
When an object cannot be bypassed or the silver point demonstrates a larger
diameter, then the following extracting devices are used -
1. Post Removal Systems (PRS):
a) The Microtube tap and threaded option:
The PRS contains certain microtubular taps that allow the clinician to
mechanically tap, thread and engage the most coronal aspect of any obstruction with a
diameter of 0.6 mm or greater. These microtubular taps contain a reverse thread and

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engage an obstruction by turning in a counterclockwise (CCW) motion. Because
intracanal space is often restrictive, this system is generally used to engage obstructions
that extend into the pulp chamber.
b) The microtube mechanics option:
Traditionally, a technique was employed to remove broken instruments using a
microtube and an appropriately sized H file. In this removal method, a microtube was
selected that could be placed over the exposed, coronal most aspect of the obstruction.
H-file was then passed down the length of the tube until it engaged itself tightly between
the obstruction and the internal lumen of the micro tube.
2. Endo extractor kit (Kerr Corp., Glendale, California) can be used. The Endo
Extractor Kit has four trephine burs that correlate to files with different diameter sizes.
The Cyanoacrylate adhesive aids in the adhesion of silver point to the extractor. The
trephine bur removes approximately 3 mm of surrounding dentin. An extractor with
adhesive in the canula is selected and placed over the object. With an overlap of 2mm
adhesive strengths of 2 to 5 kg may be achieved. This might be adequate for cone
removal under clinical conditions. Five minutes are allowed for glue to set. After the
adhesives are set, the extractor is checked for resistance the handle on the tube may then
be used to twist and lift the point from the seat.
Some other methods used are:
Manual: 1. Gold foil pliers
2. Splinter forceps
3. Mosquito hemostat.

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The needle-sleeve-technique as described by Taintor and co-workers use a
hollow gauge needle which is bonded to the silver point with Cyanoacrylate. A
modification of this technique is the use of a large hollow gauge needle that is fitted over
the silver cone with an H-file wedged between the needle and silver point.
A similar technique uses an orthodontic wire that is worked through a hollow
gauge needle like a lasso. These techniques may be useful when the silver cone extends
into the pulp chamber.
Silver cones can be retrieved with a braiding technique of multiple files technique
and first described by Glick. Here the silver cones that have been inserted with a paste
can be bypassed with three or more endodontic instruments. The handles of these
instruments are braided around the cones and the cone is pulled out. Only small files with
good torsional properties may be used for this technique. This technique is only practical
if the cone can be bypassed to a sufficient depth. As silver cones are commonly inserted
with sealers, the use solvents may be helpful.
Silver cones that have been inserted with a paste can be bypassed with 3 or more
endodontic instruments are braided around the cone and it is pulled out. This is known
as Glick’s braiding technique or Multiple-files technique.
The canal finder system and Masserann kit also can be used for the same
purpose.
The canal–finder system:
This mechanized device for root canal preparation is used when manual retrieval
of the silver cone is unsuccessful. This system which is working with a flexible, on rigid

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motion can be used only after an instrument can be worked some millimeters along the
silver cone into the root canal. Beginning with the finest instruments and using various
speeds and heavy irrigation, an attempt is made to penetrate the sealer and bypass the
cone. If bypassing to some depth is possible the hand piece is worked circumferentially
around the cone in order to gain space and loosen the cone. At higher speed the
instrument begins to vibrate which helps which helps in loosening.
The Masserann Kit: Another device for cone retrieval (Medidenta
Int.Inc.Woodside NY) used for large straight roots.
With a trepan bur the cone top is prepared free to some depth. Then the extractor
tube is put onto the top of the cone and fixed to it. The attempt to pull the cone out of the
canal may be supported by an ultrasonic scaler which is held against the extractor tube.
Additionally a Cyanoacrylate adhesive can be used to fix the tube to the cone top.
Frequent radiographs should be taken to check the instrument towards the desired
direction. This technique is easier or faster than manual one. According to Krell et al the
use of an ultrasonic scaler, in silver cone retreatment should be considered primary rather
than secondary methods.

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5. Paste removal
A great variety of pastes exists which differs only in the chemical formulation.
Originally, the intention for paste use was for those patients who could not afford
conventional Endodontics and this modality of treatment was considered a benevolent
alternative to extraction.
When evaluating a paste case for retreatment, it is prudent to know that pastes are
generally soft, penetrate and removable and hard, impenetrable and at times,
unremovable. It should be also known that because of the method of placement, the
coronal portion of the paste is most dense.
Depending on the consistency paste materials are divided into
a) Soft setting pastes (SSP)
b) Hard setting pastes (HSP)

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a) Soft setting pastes: easy to remove using crown down instrumentation with copious
hypochlorite irrigation to minimize extrusion.
b) Hard setting pastes: They usually require solvent to dissolve them, if the material is
resistant to solvents it requires mechanical means for its removal.
METHODS:
I) Ultrasonic energy
2) Heat
3) Rotary instruments
4) Solvents and Precurved hand files
5) Micro debriders
6) Solvent and paper points
Ultrasonic Energy:
Ultrasonic instruments in conjunction with the microscope, afford excellent
control in removing paste from the straightway portions of the canal. Specifically, the
CPR-3, 4 and 5 Zirconium nitride coated, ultrasonic instruments may be used below the
orifice to remove brick-hard, resin type paste. To remove paste apical to a canal
curvature, a precurved file is attached to a specially designed adapter that mounts on and
is activated by the ultrasonic hand piece.
Ultrasonically energized files are placed in the orifice of the obturated root canal
and activated with light apical pressure. The vibration results in the pulverization of the
cement while the continuous irrigation flushes the dispersed particles coronally out of the

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canals. The procedure is continued until the cement is completely removed from the
canal. In curved canals, alteration of the canals have may also occur, radiographs should
be taken frequently to monitor the path of the files. Since the vibrating action of the
ultrasonic device is the most important element in the procedure, those devices with the
highest vibration frequently are best suited.
Hard setting calcium oxide paste which seals well, but unacceptably high
incidence of root fracture because of the large amount of expansion on setting. EDTA
may soften and facilitate its removal.
Heat:
Certain resin pastes soften with heat. Heat carriers can be selected if this
modality of removal is chosen.
Rotary instruments:
Stainless steel 0.02 tapered hand files may be used to negotiate through paste
fillers. These files can potentially create a pilot hole for safe-ended, Ni-Ti rotary
instruments to follow and effectively auger the toxic material colonially. Dangerous, but
at times helpful, is the use of end-cutting Ni-Ti rotary instruments, to penetrate pastes.
Heat has some effect on soft porous material but is limited in its usefulness. Gates
Glidden burs are useful with soft materials .The use of end cutting nickel –titanium
rotary instrument such as the Quantec file (SybronEndo, Orange, California) can be

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advantageous. The end cutting files, although dangerous, can be helpful in penetrating
the filling material and facilitate its removal.
Solvents and Hand files:
Reagents like Endosolv ‘R’ and Endosolv ‘E’ can be chemically soften hard
paste.
R- Solution of choice for removal of resin based pastes.
E- Solution of choice for removal of Eugenolate-based pastes.
These reagents can be placed intra appointment against a paste-type material via
paper points or cotton pellets to promote shrinkage and facilitate subsequent removal.
Micro-Debriders:
After removal of pastes, it is axiomatic that residual paste will still be noted
within the irregularities of the root canal preparation.

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Micro-Debriders is specially designed instruments to precisely remove residual
paste materials from a root canal system. Because of their offer handles, these
instruments enhance vision, have Do diameter of 0.20 mm and 0.30 mm and are available
in 0.02 types with 16 mm of efficient H-type cutting blades.
Solvent and paper points:
After paste removal, paper point wicking in the presence of specific paste
solvents is important to further remove and liberate material from the irregularities of the
root canal system.
Broken instrument removal:
The potential for instrument breakage is always present during root canal
treatment. A variety of approaches for removing these obstructions have been presented.
The dental operating microscope affords remarkable vision into most aspects of root
canal system and fulfils the age-old adage, “If you can see it, you can probably do it”. In
consideration, microscopes and ultrasonic have driven “micro sonic” techniques that
have dramatically improved the potential for and predictability of removing broken
instrument safely.

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Factors Influencing Broken Instrument Removal:
• The ability to non surgically access and remove a broken instrument will be
influenced by several factors like;
• Cross-Sectional diameter, length and curvature of the canal.
• A general rule is that, if one-third of the overall length of an obstruction can be
exposed, it can be usually removed.
• If the fragmented instrument is in the straight or partially in the straight and
curved portions of the canal, then if access can be established to its more coronal
end, then instrument can be removed.
• If the fragment is beyond the curvature, removal would be difficult and surgery
may be the option.
• The type of material comprising an obstruction is another important factor to be
considered.
SS files tend to be easier to remove because they do not further fracture during
the removal process. Broken Ni-Ti instrument may explode and break again because of
the heat buildup caused by ultrasonic devices.
Techniques for Removal of Broken Instruments
Before beginning instrument retrieval efforts, attention should be given to
thickness of dentinal walls and root surface concavities.
 Coronal access using high-speeds friction-grip, surgical length burs.

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 Radicular access either rotary or hand files used serially to gain access to the broken
fragment.
 GG are introduced and are used like “brushes” to create additional space and
maximize visibility coronal to the obstruction. Increasingly larger GG’s are stopped
out of the canal to create a smooth, flowing funnel that is largest at the orifice and
narrowest at the obstruction.
 If greater access is required lateral to the most coronal aspect of the obstruction, then
the bud-shaped tip of the GG can be “modified” and used to create a circumferential
“staging platform”.59
The staging platform is made by selecting a GG with a
maximum cross-sectional diameter that is slightly larger than the visualized
instrument. The bud of the GG is altered by cutting it perpendicular to the long axis
at its max cross-sectional diameter.
The modified GG is rotated at 300 RPM, gently carried into the canal and
directed apically until it “lightly” contacts the most coronal aspect of the obstruction.
This will create a small staging platform that facilitates the introduction of Zirconium-
nitride coated CPR-3, 4 and 5 or the titanium. CPR 6, 7 and 8 ultrasonic instruments.
 Before starting the radicular removal, it is wise to keep cotton pellets over the other
canal orifices to prevent the reentry of the fragment into the nearby canal systems.
 Ultrasonic instrument is activated at low intensity and dry conditions. Continuous
air-stream is applied. The CPR is moved in CCW direction. This will finally loosen
the instrument, and wedging the energized tip between tapered file and the canal wall
often causes the broken instruments to abruptly “jump-out” of the canal.

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MICROTUBE REMOVAL METHOD:
There are several microtube removal methods, both old and new, that are
designed to mechanically engage an intracanal obstruction, like a broken instrument.
However, it must be understood and fully appreciated that many if not the most, of these
microtube removal methods frequently require the excessive removal of the dentine
and/or oftentimes prove ineffective. For clinicians, the critical distinction when
considering microtube removal is not the inside diameter of the device, but importantly,
it’s the outside diameter. Further, many of these methods occurred before the
introduction of microscopes, better designed ultrasonic instruments and innovative new
technologies. In fact, most of the time honored techniques and even many of the new
methods, even when successful, dangerously weakened the root because of overzealous
canal enlargement. Indeed an over-enlarged canal structurally weakens the root and
predisposes to a ledge perforation, or fracture. However, failure to remove a broken
instrument compromises shaping procedures and the potential to clean and fill the root
canal system. The following represents the various microtube removal methods and
techniques:
Lasso & Anchor: In this removal method, an appropriately sized microtube is selected
and a wire passed through the tube then looped at one end and passed back through the
tube. This loop can potentially lasso a coronally exposed obstruction and, when
successful, form a purchase by pushing the tube apically while simultaneously pulling
the wire ends coronally.60
Although reported in the literature, this removal method has
been essentially replaced with more practical and successful techniques.

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Tube & Glue: the Cancellier Extractor Kit (Sybron Endo) contains 4 different sized
microtubes with outside diameters of approximately 0.50, 0.60, 0.70 and 0.80 mm. An
abrasively coated ultrasonic instrument is typically used to trephine around and ideally
expose the coronal 3 mm of obstruction. The prefit microtube may now be bonded onto
the obstruction with an adhesive, such as core paste.60
The cancellier microtubes are
safely sealed for progressively deeper placement into the canals of posterior roots. This
removal method is quite effective for retrieving a non-fluted broken instrument or when
there is difficulty retrieving a separated file that is already loose. Caution should be
exercised not to use too much adhesive that could inadvertently block a canal.
Tap & Thread: The Post Removal System contains five microtube taps. The smallest
PRS tap has an outside diameter of about 1.5 mm and internally forms threads and
mechanically engages the most coronal aspect of any obstruction whose diameter is 0.6
mm or greater.2
However, the outside diameter of the smallest microtube tap generally
limits its use to radicular obstructions that extend coronally into the pulp chamber or the
coronal one third of larger canals.
Masserann: The Masserann kit represents a time-honored method to purchase and
remove a broken instrument. Although this device has been around for over 40 years, is
superbly made and can form a strong purchase, its smallest tubular extractors have
outside diameters of about 1.20 and 1.50 mm which limit safe use to generally larger
canals in anterior teeth.1
Spinal Tap Needle: A spinal tap needle in conjunction with its metal insert plugger or a
Headstroem file is another technique advocated to remove broken instruments. With
limitations, this method of removal involves sizing the correct microtube so it can be

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placed over an ultrasonically exposed obstruction. Microtube sizes that are clinically
relevant are 19, 21 and 23 gauge needles corresponding to outside tube diameters of
approximately 1.00, 0.80 and 0.60 mm respectively. Because of their unique ability to
engage, smaller sized Hedstroem files may be selected and inserted into the coronal most
aspect of the microtube.61
The Hedstroem file is passed down the length of the tube until
it wedges tightly between the obstruction and the internal lumen of the microtube.
However, because ISO files taper 0.32mm over 16mm of cutting blades, the taper of the
file oftentimes restricts its placement through a smaller sized microtube. In this instance,
the spinal tap needle’s metal insert plunger must be used to potentially form a purchase
on the obstruction. This method is quite effective when removing obstructions from
larger canals.1
Instrument Removal System (IRS):
Provided a breakthrough in the retrieval of broken instruments lodged deep
within the root canal space. IRS is composed of variously sized microtube and inserts
wedges that are scaled to fit and work deep within the root canal space. The microtube
has a small handle to enhance vision, and its distal end is constructed with a 450
beveled
end, and cut out window.

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• Coronal and radicular access
• Ultrasonic instrumentation for circumferential exposure of coronal 2-3 mm of
instrument fragment.
• Microtube is inserted into the canal and in case of curved canals, the long part of its
“beveled end” is oriented to the outer wall of the canal to “Scoop-up” the head of the
broken instrument and guide it into its lumen.
• The insert wedges is then placed through the open end of microtube and passed down
its internal lumen until it contacts the end of the broken instrument. The instrument is
engaged and secured by turning the insert wedge’s handle screw in a CW rotation.
Progressive rotation tightens wedges and often displaces the head of the instrument
through the microtube cutout window. The obstruction is retrieved by either lifting the
microtube and insert wedge assembly or by rotating the assembly in the appropriate
direction.
MANAGEMENT BLOCKS, LEDGES AND APICAL TRANSPORATIONS:

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On occasion blocks, ledges and apical transportations occur and are clinically
encountered. Failure to respect and appreciate the biologic and mechanical objectives of
cleaning and shaping increases the frustration and predisposes to needless complications
such as blocks, ledges, apical transportations and perforations.1
Technique for managing blocks:
When encountering a blocked canal, the tooth is first flooded with Sodium
Hypochlorite (NaOCl). Radiographs are evaluated for root curvature and apical
pathology. The clinician should appreciate that disease flow in a root canal system
occurs in a coronal to apical direction and the connection should be made that lesions of
endodontic origin form adjacent to the portals of exit.
The shortest file that can reach the working length is selected as they provide
increased stiffness and tactile control. An attempt is made to gently slide the file to
length. If this is unsuccessful, the clinician should pre enlarge the canal, irrigate and
slightly over curve the file to facilitate moving it to length. If an obstruction is felt, the
precurved file is used in an apically directed picking action.
Clinicians should use very short amplitude, light pecking strokes to negotiate the
canal terminus. Short pecking strokes ensure safety, carry irrigant deeper and increase the
possibility of canal negotiation. The handle of a file with a tip that is engaged should
never be excessively rotated, because the instrument may break because of the torsion
force. If the apical extend of a file “sticks” or engages handle motion is a minimal back
and forth wiggle. If the No. 10 file begins to move apically, if may be useful to move a
smaller instrument with a Do diameter of 0.08 and 0.06 mm.

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If no progress is made after 3 minutes, then the Sodium Hypochlorite is removed
from the root canal and replaced with a viscous chelator. The same technique is followed.
When the instrument travels to length, its tip is gently moved to and minutely through the
foramen. Pushing the instrument to length carries more chelator deeper into the canal,
places more debris into suspension and lubricates the file so that it will slip and slide to
length. Short amplitude pull and push strokes are continued until the file can slide and
glide to the terminus with ease and predictability.
At times there are clinical situations where the previously mentioned techniques
have been carefully attempted but the file is not progressing apically or is not tracking
the pathway of the physiologic canal. If the patient is a symptomatic and periodontium is
healthy, the preparation is finished and obturated to the level of obstruction. On other
hand, if the patient is symptomatic, periodontal breakdown or a lesion of endodontic
origin is present, again the canal is obturated. In both instances, the patient should be
informed about this less than ideal outcome, the importance of periodic recalls and the
possible need for future surgery, reimplantation or extraction.
Technique for Managing ledges:
An internal transportation of the canal is termed a “ledge” and frequently results
when clinicians work short of length and “get blocked”. Ledges are typically on the outer
wall of the canal curvature and are oftentimes bypassed using the techniques described
for blocks.62
Once the tip of the file is apical to the ledge, it is moved in and out of the
canal utilizing ultra-short push-pull movements with emphasis on staying apical to the
defect. When the file moves freely, it may be turned clockwise upon withdrawal to rasp,

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reduce, smooth or eliminate the ledge. During these procedures, try to keep the file
coronal to the terminus of the canal so the apical foramen (foramina) is handled
delicately and kept as small as practical. When the ledge can be predictably bypassed,
then efforts are directed towards establishing patency with a 10 file. Gently passing a
0.02 tapered 10 file 1 mm through the foramen insures its diameter is at least 0.12 mm
and paves the way for the 15 file.63
A significant improvement in ledge management is the utilization of nickel-
titanium (NiTi) hand files that exhibit tapers greater than ISO files.2
Certain NiTi
instruments have multiple increasing tapers over the length of the cutting blades on the
same instrument (ProTaper, Dentsply Tulsa Dental). Progressively tapered NiTi files can
be introduced into the canal when the ledge has been bypassed, the canal negotiated and
patency established. Bypassing the ledge and negotiating the canal up to a size 15, and if
necessary a 20, file creates a pilot hole so the tip of the selected NiTi instrument can
passively follow this glide path. To move the apical extent of a NiTi hand file past a
ledge, the instrument must first be precurved with a device such as Bird Beak orthodontic
pliers (Hu-Friedy). Ultimately, the clinician must make a decision based on pre-operative
radiographs, root bulk and experience whether the ledge can be eliminated through
instrumentation or if these procedures will weaken or perforate the root. Not all ledges
can or should be removed. Clinicians must weigh risk versus benefit and make every
effort to maximize remaining dentin.

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Techniques for Managing Apical Transportations:
Moving the position of the canals physiologic terminus to new iatrogenic
locations on the external root surface equates to a transportation of the foramen.
Foraminal strips, zips or tears are caused by carrying progressively larger and stiffer files
to length. If transportation has occurred, then the canal exhibits reversed apical
architecture and fails to provide resistance form for GP.
Apical transportations are classified into 3 types
• Type 1: represents a minor movement of the physiologic foramen to a new
iatrogenic location.
• Type 2: Represents a moderate movement of the physiologic foramen to a new
iatrogenic location.
• Type 3: represents a severe movement of physiologic foramen to a new iatrogenic
location on the external surface of the root.
Type 1:
Represents a minor movement of the physiologic foramen to a new iatrogenic
location. In these instances clinician weigh risk versus benefit when trying to create
positive apical canal architecture. Generating shape coronal to the foramen requires the
additional removal of dentin and could predispose to root weakening or a lateral strip
perforation. If sufficient dentin can be maintained and shape created above the foramen,
then these iatrogenic cases are can be 3 dimensionally cleaned, shaped and packed.

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Type 2:
Represents a moderate movement of the physiologic foramen to a new iatrogenic
location. In these cases, wet canals are common and attempts to shape coronal to the
transportation will weaken the tooth and has an increased risk of lateral perforation. In
treating such cases, a barrier can be selected to control bleeding and provide a backstop
to pack against during subsequent obturation procedures.
The barrier of choice in Type 2 transportation is mineral trioxide aggregate
(MTA) (Dentsply Tulsa Dental)65-67
commercially known ProRoot. Remarkably,
cementum grows over this non resorbable and radiopaque material, thus allowing for a
normal periodontal attachment. ProRoot is not compromised by moisture and typically
sets brick hard in 4-6 hours, creating a seal as good as or better than the best materials
used today.
The powder is mixed with anesthetic solution or sterile water to a heavy, cake
like consistency. Small aliquot of this mixed cement is picked up and introduced into the
prepared canal with a microtube carrying device, such as a customized spinal tap needle
or on the side of a West Perf repair instrument. ProRoot is gently tamped and coaxed
down the canal to approximate length using a customized, nonstandard gutta-percha cone
as a flexible plugger.
It can also be vibrated into the apical portion by using an ultrasonic instrument. A
dense 4-5 mm of apical extend of canal should be filled with MTA. If the canal has an
apical curvature, first a GP plugger is used to introduce the material to the canal. A
precurved no 15/20 file is used to carry the MTA to within 1-2 mm of the working

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length. Indirect ultrasonic with a CPR-1 at the tip of file is used to condense the MTA to
the apex and is confirmed radiographically.
ProRoot needs moisture for the setting and further hardening. The moisture
presents at the apex is sufficient for this purpose. However, a moist cotton pellet is
placed coronal to MTA within the canal. The tooth is temporized. At a subsequent visit,
the pellet is removed and MTA is firmly explored for its hardness and if found to be
brick hard, obturation is done against this barrier.
But in case, if the MTA is found to be soft the area is flushed, dried and a new
mix of ProRoot is placed. Upon subsequent reentry, a hard barrier should exist that will
provide a backstop to pack against.
Type 3:
Represents a severe movement of physiologic foramen to a new iatrogenic
location on the external surface of the root. In this situation, the terminal extent of the
foramen is so badly damaged that a barrier technique is not feasible; hence 3 dimensional
obturation would be impossible. If a tooth with this type of transportation is to be
salvaged, it requires obturation as best as possible with follow-up corrective surgery.
Severe foramen transportations that cannot be treated surgically are extracted.

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ENDODONTIC PERFORATIONS:
A perforation represents pathologic or iatrogenic communications between the
root canal space and attachment apparatus. The causes of perforations are:
- Resorptive defects
- Caries
- Iatrogenic events during endodontic treatment
Regardless of etiology, a perforation is an invasion into the supporting structures
that initially incites inflammation and loss of attachment and ultimately may compromise
the prognosis of the tooth. The interdisciplinary team must decide whether to extract or
direct efforts toward nonsurgical retreatment, surgical correction or both.
Immediate sealing of the perforation site enhances the repair process. Keeping a
perforated endodontically treated tooth is dependent on the prevention of the bacterial
infection of the perforation site.68
Considerations influencing perforation repair:
When evaluating a perforated tooth, a number of variables must be considered
individually and collectively to properly guide treatment.
The four dimensions of perforation are:
Treating clinicians must identify the four dimensions of a perforation and
understand how each of these entities critically affects treatment selection and prognosis.
Microscopes, paper points, electronic apex locators (eg: Root ZX) and a diagnostic