2. Endodontic Retreatment
Dr. Nithin Mathew

3. Endodontic Retreatment – Dr. Nithin Mathew
Contents
• Introduction
• Definition
• Etiology
• Evaluation
• Indications & Contraindications
• Treatment planning
• Nonsurgical Endodontic Retreatment
• Coronal Access Cavity Preparation
• Post removal
• Regaining access to periapical area 3
• Removal of separated instruments
• Management of canal impediments
• Repair of perforations
• Heat generation
• Conclusion
• References

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Introduction
• Friedman stated that “Most patients can relate to the concept of disease-treatment-healing,
whereas failure, apart from being a negative and relative term, does not imply the necessity to
pursue treatment.”
• Suggested using the term posttreatment disease to describe those cases that would
previously have been referred to as treatment failures.
• RCT : success rates : 86% - 98% (Friedman 2003, 2004)

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• Success – defined by the following criteria:
1. Patient should be asymptomatic and be able to function equally well on both sides
2. The periodontium should be healthy, including a normal attachment apparatus
3. Radiographs should demonstrate healing or progressive bone fill overtime
Principles of restorative excellence should be satisfied.
( C.J.Ruddle )

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Definition
• A procedure to remove root canal filling materials from the tooth, followed by cleaning,
shaping and obturating the canals.
( GET – AAE )
• Non surgical retreatment is an endodontic treatment procedure used to remove materials
from the root canal space and, if present, address deficiencies or repair defects that are
pathologic or iatrogenic in origin.
( C.J.Ruddle )

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Washington Study
• Study carried out at the University of Washington, school of Dentistry to evaluate treated
endodontic cases and ascertain their success rate.
Results
• Periapical repair was frequently not complete for the middle aged and elderly patients within
1 year.
• Age of the patients also affected the failure rates.
• Higher for patients in the first decade and sixth decade of life.
• Lower for patients between second to fifth decade of life.
• No significant difference in the success rates of cases treated surgically or non-surgically.

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Toronto Study
• The Toronto Study Project, established in 1993,
• Was a continuous prospective investigation of the 4 to 6-year outcome of endodontic
treatment performed by graduate endodontics students in a university clinic environment.
• This modular design provides cumulative data with the completion of each successive phase,
with the aim of amassing a sufficient sample to study the prognostic value of various factors.

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• Strindberg related treatment outcomes to biologic and therapeutic factors.
• Some of the factors that influence outcome include the
• Presence of apical pathosis
• Extension of the obturation (short or long)
• Quality and technique of obturation
• Observation period
• Type of intracanal medication and bacterial status of the canal before obturation

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Causes for Failure
Preoperative causes
• Incorrect oral examination & misinterpretation
• Sinus tract, pain, vitality test, periodontal problems
• Misinterpretation of radiographs
• Odontogenic, developmental lesions, anatomic landmarks
• Physical injury
• Improper case selection
• Patient cooperation
• Technical difficulties
• Patient systemic condition
• Grossly destructed teeth
• Root resorption
• Inadequate sterilization of instruments

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Operative causes
• Failure to obtain Biomechanical objectives
• Access preparation
• Perforation
• Underextended preparation
• Overextended preparation
• Canal preparation
• Perforations
• Ledge formation
• Canal blockage
• Instrument separation & foreign objects

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• Failure To Obtain Biological Objectives
• Removal Of Potential Irritants From
• Coronal Portion
• Root Canal System
• Periapical Tissues
• Defective Obturation
• Overextended Filling
• Underextended Filling
• Periodontal Involvement- Lateral And Accessory Canals

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Post-Operative causes
• Trauma & fracture
• Impaired periapical healing
• Superimposed Non-endodontic involvement
• Excessive orthodontic forces, periodontal disease
• Poor post-endodontic restoration

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• In order to plan treatment effectively, the clinician may place the etiologic factors into four
groups :
• Persistent or reintroduced intraradicular microorganisms
• Extraradicular infection
• Foreign body reaction
• True cysts

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Persistentor Reintroduced Intraradicular Microorganisms
• RC space and dentinal tubules
• Contaminated with microorganisms or their by-products
• Pathogens are allowed to contact the Periradicular tissues
• Persistent or reintroduced microorganisms : Major cause of posttreatment disease
• Iatrogenic complications : Ledge/instrument separation : Persistence of bacteria
• Previous RCT : Short Obturation : Untreated necrotic infected pulp
• Classic “failed” root canal therapy (Sundqvist et al 1998)

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Persistentor Reintroduced Intraradicular Microorganisms
• If the resultant microbial ecosystem is amenable to bacterial survival, a lesion may not heal
and root canal treatment would be deemed to have failed.
• If the root canal filling fails to provide a complete seal, seepage of tissue fluids could
theoretically provide a substrate for bacterial growth.
• Relationship between the quality of the coronal restoration and the root canal obturation
• No matter what is used to obturate the canals, if the coronal seal is compromised, it may
lead to failure.

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Extraradicular Infection
• Bacteria invade periradicular tissue either by
• Direct spread of infection from the root canal space
• Extrusion of infected dentin chips
• Contamination with overextended, infected endodontic instruments.
• Host response : destroy organisms
• Some microorganisms : resist the immune defenses and persist in the periradicular tissues
• 2 species : Actinomyces israelii and Propionibacterium propionicum
• Exist in the periapical tissues and may prevent healing after root canal therapy.

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True Cysts
• Incidence of periapical cysts : 15% to 42% of all periapical lesions
• 2 types of periapical cysts :
• Periapical true cyst
• Periapical pocket cyst.
• True cysts
• Contained cavity or lumen within a continuous epithelial lining : isolated from the tooth
• Pocket cysts
• Lumen is open to the root canal of the affected tooth.
• True cysts, due to their self-sustaining nature, probably do not heal following nonsurgical
endodontic therapy : Usually require surgical enucleation

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Methods of Evaluation
Clinical
HistologicRadiographic

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Clinical Criteria for Success
• According to Bender et al
• Absence of pain and swelling
• Disappearance of sinus tract
• No loss of function
• No evidence of soft tissue destruction, including probing defects
• Persistent findings like (swelling or sinus tract) indicates failures

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• To make a correct diagnosis, the clinician must
• Rule out non-odontogenic etiology
• Perform all of the appropriate tests
• Properly interpret the patient’s responses to these tests
• Derive at a definitive diagnosis
• Decide on treatment options

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• Subjective assessment
• Previous treatment : aseptic techniques
• Objective assessment
• Visual extraoral and intraoral examination
• Aided by magnification and illumination
• A thorough periodontal evaluation
• Comparative : pulpal and Periradicular status.
• Percussion, bite, and palpation
• Pulp vitality tests : less value in endo treated tooth

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Radiographic Assessment
• Radiographic assessment is obligatory
• In cases with previous endodontic therapy, radiographs are useful in
• Evaluation of caries, defective restorations, periodontal health
• Quality of the obturation
• Existence of missed canals
• Impediments to instrumentation
• Periradicular pathosis
• Perforations, fractures, resorptions
• Canal anatomy
• Multiple angulated films should be used to determine endodontic etiologies
• CBCT : Untreated canals, root fractures, resorption

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• Classified as
• Success
• Failure
• Questionable
• Success
• Absence of a radiographic resorptive apical lesion.
• A lesion present at the time of treatment has resolved or that lesion not present at the time
of treatment has not developed.
• So success is evident by an eliminated or non-developed area of rarefaction after a post
treatment interval of 1 to 4 years.

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• Failure
• Persistence or development of radiographically evident pathosis.
• Radiolucent lesion that has enlarged, has persisted or has developed since the
treatment.
• Questionable
• A state of uncertainty
• Situation (radiolucent lesion) has neither become worse not significantly improved
• A questionable status reverts to failure if the situation (non-resolution) continues,
generally after a period of 1 year.

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Histologic Examination
• Evidenced by reconstitution of periapical structures and an absence of inflammation.
• Routine histologic evaluation of periapical tissues on patients is impractical.
• Thus, clinical findings (signs and symptoms as well as radiographic findings) are the only
means of assessing success and failure.

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When to evaluate
• Lack of consensus on the criteria for assessing success or failure, the length of time necessary
for adequate post-operative follow-up also remains controversial.
• Suggested period : 6 months – 4 years

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Indications
• Periapical radiolucencies even after 4 years
• Tenderness to percussion
• Apical pain to pressure
• Fistula formation
• Swelling of soft tissue
• Incomplete root canal filling – for prosthetic restoration even being asymptomatic

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Contraindications
• Vertical fracture
• Poor periodontal status
• Non restorable teeth
• Access is difficult
• Patients with TMJ dislocation problems
• Resorption
• Anatomical limitations
• Non strategic position

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Treatment Plan
• The patient harbouring true endodontic posttreatment disease has four basic options for
treatment :
• Do nothing
• Extract the tooth
• Nonsurgical retreatment
• Surgical retreatment

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NONSURGICAL ENDODONTIC RETREATMENT
• Primary goal: regain access to the periapical area (endotreated tooth)
• Principals of endodontic therapy followed : completion of case
• Coronal access needs to be completed
• All previous root-filling materials need to be removed
• Canal obstructions must be managed
• Impediments to achieving full working length must be overcome
• Cleaning and shaping procedures : for effective obturation and case completion

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NonSurgical Endodontic Retreatment : Coronal Disassembly
• Retreatment access is called coronal disassembly
• Removal of the coronal restoration includes
• Full coverage restoration
• Core build-up material
• Post placed into the canal
• Advised to remove the existing coronal restoration if it has
• Poor marginal adapatation
• Secondary caries
• To avoid procedural errors
• To maintain form, function and esthetics

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• Re-access to the pulp chamber through the existing restoration
• If it is judged to be functionally designed, well fitting and esthetically pleasing.
• Removal is based on whether additional access is required to facilitate disassembly and
retreatment.
• Preparation type
• Restoration design and strength
• Restorative material used
• Cementing agents
• Removal device

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• Coronal disassembly devices:
• Grasping instruments
• Percussive instruments
• Active instruments

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Grasping instruments
• Appling inward pressure on two opposing handles
• Proportionally increases the instrument’s ability to grip a restoration.
• Strong purchase while reducing dangerous slippage.
• Handle pressure α Instrument ability to grip restoration
• E.g.:
• Trident crown Placer/ remover
• K.Y. Pliers
• Wynman Crown Gripper
• Removing provisional restorations

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Percussive instruments
• Selective and controlled percussive removal force
• Deliver impact directly to restoration or indirectly to another securely engaged prosthetic
removal device
• Eg:
• Ultrasonic Energy
• Crown- A-Matic (Peerless)
• Coronaflex
• Removal or provisional & definitive restoration

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Active instruments
• Actively engage a restoration, enabling a specific dislodgement force to potentially lift off the
prosthesis.
• Requires a small occlusal window to facilitate mechanical action of the instrument.
• Creates a lifting force : separating crown & preparation
• E.g:
• Metalift
• Kline Crown Remover
• Higa Bridge Remover

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Post Removal
• Common to encounter a post : increase in frequency
• Factors influencing post removal
• Operator judgment
• Training & Experience
• Technique & devices
• Post type - parallel/ tapered, active/ passive
• Cementing agent

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• Steps:
• Core restorative material is removed
• A less aggressive instrument, such as a tapered bur in a slow-speed handpiece or a
tapered, midsized ultrasonic tip, should be used to remove the last of the embedding
core material.
• Magnification and illumination
• Minimal restorative material remaining, smaller sized ultrasonic instrument should be
used
• To minimize the risk of removing unnecessary tooth structure
• Thinning of the post.
• More post that is left, the more options for removal
• More tooth structure that is left, the more options for restoration

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• Techniques for post removal :
• Ultrasonic vibration
• Rotosonic vibration
• Mechanical devices

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Ultrasonic vibration
• Piezo electric ultrasonic systems in conjuction with specific instruments.
• Instrument at the interface between the post and the tooth (the cement line)
• Constantly moved around the circumference of the post
• Disrupt the cement structure along the post/canal wall interface and decrease post
retention
• Tip should be removed from the access every 10 to 15 seconds
• To allow the use of an air/water syringe
• To clean the area of debris
• To reduce the temperature produced that could potentially cause damage to the
periradicular tissues.

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Ultrasonic vibration
• Area around the post may be flooded with a solvent (chloroform) prior to activating the
ultrasonic instrument
• Dissolve the cement around the post
• Ultrasonic energy produced will set up shock waves in the solvent and make it penetrate
deeper into the canal space, exerting a faster solvent action on the cement
• One study has shown that heat generation with ultrasonic vibration may help to decrease
retention of resin cemented posts. (Garido et al 2004)
• But concern for heat generated periodontal ligament damage. (Swartz et al 2004)

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Rotosonic vibration
• Rotosonics is a method to potentially loosen and remove a fully exposed post.
• The regular tip Roto-pro Bur (Ellman International, Hewlett, NY) is a high-speed, friction
grip bur whose six sides utilize six edges which when rotated in one revolution produce six
vibrations per revolution.
• Rotated at 200,000 rpm, it produces 1.2 million vibrations per minute.

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Mechanical Devices
• If retention reduction does not remove the post, some form of vice is needed to pull the post
from its preparation.
• Gonon post removing system (Thomas Extracteur De Pivots,
Ffdmpneumat, Bourge, France)
• Effective instrument for removing parallel or tapered,
nonactive preformed posts
• Kit utilizes a hollow trephine bur aligned with the long axis of
the post and placed over its exposed end

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Ultrasonic exposure of
the post
Fractured post in a
lower incisor
Domer bur creating a shape that
the trephine bur can engage
Trephine bur milling
the post
Extraction device tapping a
thread onto the post
Vice applied. Turning the screw on the
vice opens the jaws, creating the
extraction force.

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• Drawbacks:
• Size of the vice that can make access in the molar region and between crowded lower
incisors difficult.
• If the extraction force applied is not directed in the long axis of the root, root fracture
may occur
• This method is effective because
• All the force is applied to the bond between the tooth and the
post, ideally in the long axis of the root.

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• Other Post Removal Systems (PRS) :
• Thomas Screw Post Removal Kit
• Ruddle Post Removal System
• Universal Post Remover
• JS Post Extractor
• Post Puller (Eggler Post Remover)

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Removal Of Fibre Posts
• Ultrasonic / gonon kit : none works for fibre post removal
• Use of a high-speed bur to channel down through the post may result in a high rate of root
perforation.
• A new bur Gyrotip has been designed for the specific purpose of
removing fiber-reinforced composite posts.
• Drills consist of a heat generating tip designed to soften the matrix
that binds the fibers within the fiber-reinforced post.

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• Fibers within the post are parallel, which assists the axial travel of the
drill through the center of the post.
• Fluted zone of the drill allows the fibers to be safely removed, creating
access to the root canal filling.
• Above the fluted zone, a layer of plasma bonded silica carbide reduces
the heat generation
• This abrasive zone also provides for a straight-line access preparation
and facilitates the placement of a new post

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• Ceramic and Zirconium posts : Impossible to retrieve.
• They are more fragile than metal posts, and though ceramic posts may be removed by
grinding them away with a bur.
• High risk of root perforation
• Zirconium has a hardness approaching that of diamond and cannot be removed by this
method.
• Removal of a fractured zirconia post by ultrasonic vibration has been found to cause
temperature rise of the post and on the root surface
• Great white Z bur (SS White) : For Zirconia Posts

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Potential Complications of Post Removal
• Fracture of the tooth, leaving the tooth nonrestorable
• Toot perforation
• Post breakage
• Inability to remove the post
• An additional concern is ultrasonically generated heat damage to the periodontium.

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Gutta Percha Removal
• Initially removed from the canal in the coronal one third, then the middle one third and
finally eliminated from apical one third.
• Following methods or combination of methods are used.
• K-files or H-files
• Gutta-percha solvent
• Combination of paper points and gutta-percha solvent
• Rotary instruments
• Specialized rotary instruments designed for retreatment
• Heat transfer devices
• Soft tissue laser

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• K & H files
• Allows for a gross removal of gutta-percha especially from large canals, which
are poorly compacted allowing files to bypass the obturating material and
‘bite’ into the mass
• Micro-debriders (Dentsply Maillefer) are small files having 90-degree bend at
the working end and an attached handle.
• It may also be used to substitute standard K-files and H-files.

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Solvents
• Chloroform
• Methyl chloroform
• Eucalyptol oil
• Halothane
• Turpentine
• Xylene
• Orange wood oil
• Chloroform
• Proven to be most successful
• Evaporates rapidly
• Potential carcinogenicity

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• Eucalyptol:
• Less irritating than chloroform
• Antibacterial
• Least effective GP solvent
• Xylene:
• Highly toxic
• Evaporates too slowly
• Dissolving effect less than chloroform
• Orange wood oil:
• Contraindicated – over extended fillings
• Halothane:
• Longer time for dissolving than chloroform

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Rotary Removal
• Gates Glidden Drill and Peeso Reamer
• GPX Gutta-percha Remover (Prestige Dental)
• Specially designed file
• Slowspeed handpiece.
• Plasticizes by frictional heat and facilitates its removal by its H-file like
flute design.
• ISO 25–50
• Recently introduced NiTi GPX -curved canals

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• NiTi Rotary instruments
• Advantage of removing gutta-percha as well as shaping the root canals in an
under-prepared tooth, simultaneously.
• Several studies carried out for comparing the gutta-percha removal efficacy
of rotary with the hand instrumentation, have shown both techniques to be
almost equally effective
• The use of rotary devices in retreatment should be followed by hand
instrumentation.

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• NiTi Rotary Instruments
• Rotary : Reach the whole working length easily
• Plasticize through frictional heat.
• Hand instruments : refine and complete the removal.
• Recommended to be used at rotational speed of 3-4 times more than that for
routine cleaning and shaping.

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Specialized Rotary Instruments Designed for Retreatment
• ProTaperUniversal Retreatment Kit (Dentsply)
• D1 File : 30/0.09 NiTi file (one white ring) of 16 mm : Coronal third
• D2 File : 25/0.08 NiTi file (two white rings) of 18 mm : Middle third
• D3 File : 20/0.07 NiTi file (three white rings) of 22 mm : Apical third
• R-Endo (Micro-Mega)
• Made up from a round blank
• Cross-section is characterized by three equally spaced cutting edges.
• Speed of 300-400 rpm along with gutta percha solvent.
• Series of six files named as Rm, Re, R1, R2, R3 and Rs
61

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• Mtwo Retreatment Kit (Sweden and Martina)
• S-shaped cross-section
• 2 instruments with cutting tips designed to reach the apex.
• Mtwo R 15/.05
• Mtwo R 25/.05
• Advantage of shaping the root canal in an under-prepared tooth, simultaneously.
62

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Heat Transfer Devices
• Heat Carrier Tips
• System B
• Endotec
• EndoTwinn
• Touch’NHeat
• DownPak
• Heat generated on the tip : soften guttapercha mass.
• More effective in well prepared canals.
• Alternatively, the hand spreaders can also be used in the similar manner, however, the
amount of heat transferred to these instruments is not consistent. 63

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• Ultrasonics
• Piezoelectic ultrasonic system, produces heat that thermo softens GP
• It will float coronally into the pulp chamber
• Tips available for ultrasonic
• Condensation of GP or specialized re-treatment tips
64

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• Soft Tissue Lasers
• The studies, conducted on effectiveness of the Nd: YAG laser for removal of gutta-
percha, have shown that it is capable of softening gutta-percha.
• Lower settings (100 mJ, 15 Hz, 1.5 W)
• Fairly clean root canals, but an incomplete elimination of gutta-percha from
dentinal walls.
• Increased power levels (100 mJ, 20 Hz, 2 W)
• More effective on the canal walls, cleaning them better
• The addition of solvents have not shown any improvement in their efficiency in terms
of time required for removal of GP.
65

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• Paper point and chemical removal
• Drying solvent filled canals with paper points is known as “wicking”
• It is always the final step of gutta percha removal.
• Wicking action removes residual gutta percha end sealer out of fins, cul de sac and
aberrations of the root canal.
• Wicking takes place by pulling dissolved materials from periapical to central. 66

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Carrier Based gutta percha removal
• After careful access and complete circumferential exposure of the carrier a
suitable grasping pliers is selected and a purchase is obtained on the carrier.
• Carrier is grasped with the pliers and extrication is attempted using fulcrum
mechanics, rather than a straight pull out of tooth.
• If enough canal space exists, a 4 or 5 ultrasonic instrument can be used along
side carrier to produce heat and thermosoften the G.P.
67

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Silver Point Removal
• Easily removed : chronic leakage greatly reduces the seal and hence
lateral retention.
• The coronal heads of silver points are within pulp chambers and are
entombed in cements, composites or amalgam cores.
• Initial access with high speed surgical-length cutting tools.
• Subsequently, ultrasonic instruments may be carefully used within the pulp chamber to
brush cut away restorative materials and progressively expose the silver point.

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• Pliers removal
• Stieglitz Plier used gently pull to confirm its relative tightness.
• When grasping a silver point, rather than trying to pull it straight out of the
canal the plier is rotated using fulcrum mechanics and levered against the
restoration or tooth structure to enhance removal efforts.
• Indirect Ultra Sonic
• Used when a segment of silver point is encountered below the orifice and
space is restricted.

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• Indirect Ultra Sonic
• Care must be used so that ultrasonic instruments are not used directly on silver points
because elemental silver is soft and rapidly erodes during mechanical manipulation.
• Once the surrounding material is removed, ultrasonic energy then may be transmitted on a
grasping plier to synergistically enhance the retrieval efforts.

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• Braided file technique
• Using Hedstrom files
• Sealer is dissolved
• Files are negotiated as apically as possibly in two to three areas around the silver point.
• The spaces surrounding the silver point are carefully instrumented to size 15.
• Then small Hedstrom files are gently screwed in as far as possible
apically.
• The flute design of Hedstrom file allows for better engagement
into the silver point.
• Files are then twisted together and pulled out through the access.

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• Caufield silver point retrievers
• When not much of the silver point exposed in the chamber, the clinician can attempt to
remove it using the Caufield silver point retrievers (Integra Miltex).
• Instrument is 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 to the point where it may be
grasped by forceps.
• Available in three sizes:
• 25, 35 and 50

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Paste Removal
• When evaluating a paste case for retreatment, it is useful to clinically understand that the
coronal portion of the paste in the canal is most dense (the material is progressively less
dense moving apically).
• Ultrasonic energy
• Ultrasonic instruments in conjunction with the microscope, afford excellent control in
removing paste from the straight portions of a canal.
• To remove paste apical to a canal curvature, precurved file is attached to a specially
designed adapter that mounts on and is activated by the ultrasonic hand piece.

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• Rotary instruments
• Stainless steel O.O2 tapered hand files to negotiate through paste fillers.
• These files can potentially create a pilot hole for safe ended, Ni Ti rotary instruments to
follow.
• Solvents and Hand Files
• Reagents like Endosolv ‘R’ and Endoslov ‘E’ can be helpful in chemically softening hard
paste.
• These reagents can be placed interappointment.

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• Micro debriders
• To precisely remove residual paste materials
• Offset handles, 0.02 tapers with 16mm of efficient hedstrom type cutting blades.
• Solvents and paper points
• After paste removal, paper point wicking in the presence of specific paste solvents is
important

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Broken Instrument Removal
• Incidence of hand instrument separation has been reported to be
0.25% and for rotary instruments it ranges from 1.68% to 2.4%.
(Iqbal et al 2006)
• A common cause for instrument separation is improper use.
• Overuse and not discarding an instrument and replacing it with a new one when
needed.

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List of guidelines for when to discard and replace instruments :
1. Flaws, such as shiny areas or unwinding, are detected on the flutes
2. Excessive use has caused instrument bending or crimping
• NiTi instruments : tend to fracture without warning
• Constant monitoring of usage is critical
3. Excessive bending or precurving has been necessary
4. Accidental bending occurs during file use.
5. Corrosion is noted on the instrument.
6. Compacting instruments have defective tips or have been excessively heated.

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Factors influencing broken instrument removal:
1. Cross sectional diameter of the canal
2. Length of the canal
3. Root morphology – thickness of dentin and the depth of external concavities.
4. Curvature of the canal
• Straight portion of canal : removed usually.
• Around canal curvature : removal is possible if the access if established to its most
coronal extent.
• Apical to curvature : removal may not be possible.
5. Type of material that obstructs the canal
• SS files do not fracture during removal
• NiTi breaks again because of heat build up caused by ultrasonic devices.

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Technique for broken instruments removal
• Steps:
1. Coronal access
• Done with high speed, friction grip surgical length burs
2. Radicular access
• Hand files, and GG drills used
• GG drills maximize visibility coronal to the obstruction
3. Create staging platform
• Modified GG is used.
• Cutting the bud of GG perpendicular to its long axis at its
maximum C-S diameter.
• This creates a small staging platform that facilitates the introduction
of ultrasonic instruments.

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• Ultrasonic instrument moved lightly in a CCW direction around the obstruction
• This will remove the dentin and trephines around the obstruction
• Gently, wedging the energized tip between the file and canal wall will remove the
instrument
• Deeper in the canal the obstruction is, the longer and thinner an ultrasonic tip must be.
• Thin tips must be used on very low power settings to prevent tip breakage

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MICROTUBE DEVICES
• Instrument Retrieval System (IRS)
• Small staging platform : Further reduced by ultrasonics until enough of the separated
instrument is exposed to retrieve.
• Microtube is inserted into the canal and 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.

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• The insert wedge is placed through open end of microtube and passed down its internal
lumen until it contacts the broken obstruction.
• The broken instrument is secured by turning the insert wedges handle screw in a clockwise
rotation.

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• Wire Loop & Tube Removal Method :
• 25-gauge dental injection needle
• 0.14-mm-diameter steel ligature wire.
• Needle is cut to remove the beveled end
• Both ends of the wire are then passed through the needle from the
injection end until they slide out of the hub end, creating a wire loop
• Once the loop has passed around the object to be retrieved, a small
hemostat is used to pull the wire loop up and tighten it around the
obstruction
• Complete assembly is withdrawn from the canal.

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• Other Methods:
• Endo Extractor (Brasseler USA)
• Masserann Kit (Medidenta International)
• Extractor System (Roydent)
• Separated Instrument Retrieval System (SIRS)

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• Specifically for use with Microscopes :
• Cancellier instrument (Sybron Endo)
• Mounce extractor (Sybron Endo)

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Management of Canal Impediments
• Iatrogenic mishaps resulting from
• Vigorous instrumentation short of the appropriate working length
• Failure to confirm apical patency regularly during instrumentation.
• Includes:
• Blocked canals
• Ledge Formation

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Managing Blocked canals
• Well-angulated radiographs
• Coronal portion of the canal should be enlarged
• To enhance tactile sensation
• Remove cervical and middle third obstructions in the canal space
• Canal should be flooded with irrigant, and instrumentation to the level of the
impediment should be accomplished using non-end-cutting instruments
• Precurved #8 or #10 file used in pecking motion
• Determine if there are any “sticky” spots that could be the entrance to a
blocked canal.

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• Directional rubber stop should be used
• Very short amplitude, light pecking strokes to be used
• Short amplitudes - ensure safety, carry irrigant deeper, and
increase the possibility of canal negotiation
• File's handle whose tip is engaged, should never be excessively rotated.
• Frequent evacuation of the irrigant and using a lubricant, such as RC
prep.
• Risk of deviating from the original canal path, creating a ledge, and
ultimately a false canal leading to zip perforation.
• Working radiograph taken when some apical progress made

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• Occasionally, clinical situations arise where the aforementioned
techniques have been carefully attempted, but either the file is not
progressing apically or is not maintaining the true pathway of the canal.
• If the tooth is asymptomatic and symptoms are not masked by a
pharmaceutical agent, and if the periodontium is healthy and there are
no lesions of endodontic origin, then the preparation may be finished to
the level of the obstruction and obturated.

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Ledge Formation
• An artificially created irregularity on the surface of the root canal wall that prevents the
placement of instruments to the apex of an otherwise patent canal.
• A deviation from the original canal curvature without communication with the PDL,
resulting in a procedural error is termed ledge formation or ledging.
(JOE, 33, 2007)

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Recognition of a Ledge :
• Root canal instrument can no longer be inserted into the canal to full
working length.
• Loss of tactile sensation of the tip of the instrument binding in the lumen.
• Instrument point hitting against a solid wall
• Radiograph with instrument in place.

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Management :
• Locating the ledge
• Irrigate, smaller instruments are preferred.
• No. 10 or 15 with a distal curve at the tip can be used
• Pointed towards the wall opposite to the ledge
• “Tear shaped” silicone stops can be used.
• Watch-winding motion
• If resistance is felt, retract slightly, rotate and advance again, until it
bypasses and reach apically.
• Confirmed with a radiograph
• If ledge cannot be bypassed, then clean, shape and obturate till obstruction.

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Prevention of Ledge :
• Proper examination of the diagnostic radiographs.
• Awareness of canal morphology
• Frequent recapitulation and irrigation
• Precurving the instrument and not forcing it.
• Using instruments with not cutting tip
• Using NiTi files in case of curved canals
• Modified instruments:
• Flex R files
• Safety Hedstrom files
• Flexofile

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Endodontic Perforation
• Perforations in all locations can be caused by 2 main errors:
1. Creating a ledge in the canal wall during initial preparation and perforating through
the side of the root at the point of obstructions / root curvature.
2. Using too large or too long an instrument and either perforating directly through the
apical foramen or wearing a hole in the lateral surface of the root by over
instrumentation.

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Factors influencing repair
Considerations influencing perforation repair:
1. Level
2. Location
3. Extend of perforation
4. Potential for successful management
• Level:
• Coronal / furcation perforation : threaten sulcular epithelium
• In general, more apical the perforation, more favourable the prognosis

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• Location:
• Can occur circumferentially on the buccal, lingual, mesial and distal aspects of roots.
• Location of the perforation is not so important when non-surgical treatment is
selected.
• Position is critical and may preclude surgical access if this approach is considered.
• Extend & Size of Perforation:
• Size greatly affects the clinician’s ability to establish a hermetic seal.
• The area of a circular shaped perforation can be mathematically described as πr2.
• Therefore doubling the perforation size with any bur or instrument increases the
surface area to seal four-fold.
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• Time:
• Regardless of the cause, a perforation should be repaired as soon as possible to
discourage further loss of attachment and prevent sulcular breakdown.
• Esthetics:
• Perforations in the anterior region can definitely impact esthetics.
• Tooth colored restoratives are chosen and selected from the best materials
currently available in adhesive dentistry.
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• Periodontal condition :
• If the attachment apparatus is intact without pocketing, timing is critical and the
treatment is ideally directed toward non-surgically repairing the defect.
• Decision should be made for periodontal breakdown teeth, to go for surgical or non-
surgical or both together.
• Longstanding defect with periodontal lesion: surgery with guided tissue regeneration
• Most cases, nonsurgical retreatment and internal perforation repair prior to surgery will
be beneficial to the treatment outcome.
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Management
• Difficulty of the repair : Level of perforation
• Furcal floor of a multirooted tooth or in the coronal one third of a straight canal (access)
• Considered to be easily accessible
• Middle one third (strip or post perforations) : Difficulty increases
• Apical one third (instrumentation errors)
• Predictable repair
• Frequently, apical surgery will be needed.

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Barrier Materials For Perforation Repair
• Barriers help produce a ‘‘dry field’’ and also provide an internal matrix or ‘‘back stop’’ against
which to condense restorative materials.
• Absorbable
• Collagen materials (colla cote)
• Calcium sulfate (cap set)
• Non-Absorbable
• MTA
• Other restoratives (amalgam, super EBA resin cement, composite restoratives, calcium
phosphate cement)

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• Hemostatics to control bleeding.
• Small area : sealed from inside the tooth
• Large area : seal from inside, then surgical repair
• Where esthetics is a concern, a calcium sulfate barrier along with composite restoration
is generally used.
• Super EBA have been used when esthetics not an issue.
• Presently MTA is restorative of choice because of its many desirable attributes.
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Management of Coronal Third

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• By nature of occurrence, these defects are ovoid in shape and typically
represent relatively large surface area to seal.
• Access to midroot perforation is most often difficult, and repair is not
predictable.
• Successful repair depends upon the adequacy of the seal established by
the repair material.
• The repair should be immediate, to protect the perforated site from
saliva and other contaminants.
• Barrier material of choice is MTA.
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Management of Middle Third

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• Overinstumentation :
• Re-establish the WL and enlarge with larger instrument.
• Apical barrier: Ca(OH)2, MTA, Dentin Chips, Hydroxyapatite
• Apical Perforation :
• Negotiate
• Perforation site as the new apical opening and obturation is done to seal of the
foramen
• Surgery is necessary, if a lesion present apically
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Management of Apical Third

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• Surgical Approach:
• A combined intracoronal and surgical approach involves repairing the defect
intracoronally, then reflecting a surgical flap to remove the inevitable
overextension of the repair material from the periodontal space.
• In case of failing furcation repairs,
• Bicuspidation
• Hemi-Section
• Intentional Replantation can be considered as treatment options.
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Management of Apical Third

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Heat generation during treatment procedures
• Several procedures in endodontic therapy that generate heat
• Greatest risk with Non-surgical retreatment
• Use of heat to soften canal filling materials
• Use of ultrasonics to dislodge posts and separated instruments
• Can potentially generate enough heat to raise the temperature of the external root surface by
10° C or more.
• Temperature elevations of the periodontal ligament in excess of 10° C can cause damage to
the attachment apparatus.
(Eriksson et al 1983, Saunders et al 1989,1990)

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• Accepted that the heat-induced damage to periradicular tissues
during the usage of ultrasound energy for post removal is Time
Dependent.
• Study has showed that ultrasonic vibration for post removal
without coolant can cause root surface temperature increases
approaching 10° C in as little as 15 seconds.
(Dominici et al 2005)

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Recommendations for the use of ultrasound energy during the removal of canal obstructions :
• Use ultrasonic tips with water ports whenever possible
• If ultrasound device does not have tips with waterports, have your assistant use a continuous
water/saline irrigation during usage.
• Take frequent breaks to let the tooth cool down.
• Avoid using the ultrasound on the high power setting.

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Conclusion
• Posttreatment endodontic disease does not preclude saving the involved tooth.
• In fact, the majority of these teeth can be returned to health and long-term function by
current retreatment procedures.
• In most instances the retreatment option provides the greatest advantage to the patient
because there is no replacement that functions as well as a natural tooth.
• Armed with the information in the preceding section, appropriate armamentaria, and the
desire to do what is best for the patient, the clinician will provide the foundation for long-
term restorative success.

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References
• Pathways of the Pulp – Cohen
• Textbook of Endodontics – Ingle
• Endodontic practice - Grossman

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