Dr. Jagadeesh. K
P.G 3rd year
• CLASSIFICATION OF ENDODONTIC MISHAPS
• ACCESS RELATED MISHAPS.
• INSTRUMENTATION RELATED MISHAPS.
• OBTURATION RELATED MISHAPS.
• MISCELLANEOUS ACCIDENTS.
• DETECTION, CORRECTION AND PREVENTION.
Endodontic mishaps or procedural accidents are those
unfortunate occurrences that happen during treatment,
some owing to inattention to detail, others totally
• Re evaluate the prognosis
• First step in the management.
• Clinical observation.
• Radiographic observation.
• Patients complaint
Depending on type and extent of the procedural accident.
Effects of the entire treatment plan.
Involve Dento-legal consequences.
• Incident and nature of mishap.
• Procedures to correct it.
• Alternative treatment options.
• Prognosis of the affected tooth.
Inform the patient
Access related Instrumentation
Obturation related Miscellaneous
1. Treating wrong
2. Missed canals
3. Damage to existing
4. Access cavity
5. Crown fractures
1. Ledge formation
2. Cervical canal
3. Midroot perforations
4. Apical perforations
6. Canal blockage
1. Over- or
2. Nerve paresthesia
3. Vertical root
1. Post space
2. Irrigant related
Treating a wrong tooth
• Isolating the wrong tooth
• Realizing the mistake after rubber dam removal.
• Persistence of symptoms.
• Mistakes in diagnosis can be avoided by, obtaining at least three
good pieces of evidence supporting the diagnosis for example,
# Radiograph showing a tooth with an apical lesion.
# Lack of response to electric pulp testing.
# Draining sinus tract leading to the tooth apex proved
radiographically with a GP point inserted in the tract.
• Includes appropriate treatment of both teeth one incorrectly
opened and the one with the original pulpal problem.
• When a mistake does happen, the safest approach, is to explain to
the patient what happened and how the problem can be corrected.
• The embarrassing situation of opening the wrong tooth can be
prevented by marking the tooth to be treated with a pen before
isolating it with a rubber dam.
– Lack of thorough knowledge of root canal anatomy along with its
– Inadequate access cavity preparation.
– During treatment, an instrument or filling material may be noticed
to be other than exactly centered in the root, indicating the
presence of another canal.
• Well angulated periapical film taken with cone directed straight
on, mesioblique and distoblique reveals 3-D morphology of the
• In addition to standard radiographs, digital radiography
• Computerized digital radiography - hidden calcified, or untreated
• Magnifying loupes, Microscope
• Accurate access cavity preparation
• Use of ultrasonics
• Use of dye such as methylene blue
• Use of sodium hypochlorite- “champagne bubble” test.
• Good radiographs taken at different horizontal angulations.
• Good illumination and magnification.
• Adequate access cavity preparation.
• Clinician should always look for additional canals in every tooth
Dyes Methylene Blue dye,
ophthalmic dyes such as fluorscein
sodium and rose bengal
White line test: In necrotic teeth, dentinal dust moves into orifices,
fins and isthmus when performing Ultra sonic procedure without
water. This dust can form white dot/ line that provides a visible road
Red Line test:
• In vital teeth, blood emanates from orifices, fin and isthmus area
and serves to map and visually aid in identifying anatomy below
the pulpal floor
• Circumferentially probing the sulcus around the tooth is an
important strategy for locating canal.
• Gives information as to emergence profile of clinical crown and
orientational alignment of underlying root
Not all MB2 orifices lead to a true canal, a true MB2 orifice
Was present in only 84% of molars in which a second orifice
Magnification has been found to increase the detection rate of MB2 canals from
17.2% with the naked eye, to 62.5% with loupes and 71.1% using the
surgical operating microscope
Fast break guideline
A “fast break” is a term used to describe a situation where a root
canal disappears on a radiograph as you move apically. This
happens when the main canal splits into multiple smaller canals
that are not discernible on a radiograph. CBCT axial views are
indispensable determining the number and location of these canals
Damage to existing restoration
• An existing porcelain crown presents the dentist with its own
– Clamp adjacent tooth
– Remove all temporary crowns.
• To remove existing permanently cemented crown before
The Metalift Crown and Bridge
Removal System removes inlays,
three-quarter crowns, full crowns,
and fixed bridges without
destroying them, thus allowing
them to be reused.
Minor porcelain chips can be repaired by bonding composite
resin to the crown.
• Crown Dissembly Devices:
a. Grasping instruments
b. Percussive instruments
c. Active instruments
Indirectly helps in breaking cement seal
A CT4 tip (Sybron endo) can be used to remove cement lute from
around the margins of a poorly fitting crown
The KaVo CORONAFLEX pneumatic crown and bridge
Access cavity perforations
Access cavity perforation:
• Above pdl attachment: Presence of leakage
• Into the pdl space: Presence of bleeding
• Place a small file through the opening and take a radiograph.
Materials recommended for perforation repair:
3. Calcium hydroxide paste,
4. Super EBA,
5.. Glass ionomer cement,
7. Tricalcium phosphate,
• Sinai proposed that the prognosis depends on:
– Location of perforation
– Length of the time the perforation is open to contamination
– The ability to seal the perforation
– Accessibility to the main canal
• Thorough examination of diagnostic preoperative radiographs
• Checking the long axis of the tooth and aligning the long axis of
the access bur with the long axis of the tooth
• The presence, location, and degree of calcification of the pulp
chamber noted on the preoperative radiograph
• A close attention to the principles of access cavity preparation:
adequate size, and correct location, both permitting direct access
to the root canals.
• Usually by direct observation.
• Infractions are often recognized first after removal of existing
restoration in preparation of the access.
• If the fracture is more extensive, the tooth may not be restorable
and needs to be extracted.
• Crowns with infractions should be supported with
• Is likely to be less favorable than for an intact tooth, and the
outcome is unpredictable.
• Crown infractions may lead to vertical root fractures.
• is simple. i.e. reduce the occlusion
• -Bands and temporary crowns are also valuable.
‘’A ledge is 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”
It is a deviation from the original canal curvature without
communication with the periodontal ligament, resulting in a
procedural error termed ledge formation or ledging.
(1) Not extending the access cavity sufficiently to allow adequate
access to the apical part of the root canal
(2) Complete loss of control of the instrument if the endodontic
treatment is attempted via a proximal surface cavity or through
a proximal restoration
(3) Incorrect assessment of the root canal direction
(4) Erroneous root canal length determination
(5) Forcing and driving the instrument into the canal
(6) Using a noncurved stainless steel instrument that is too large
for a curved canal
(7) Failing to use the instruments in sequential order .
(8) Rotating the file at the working length (that is, overuse of a
(9) Inadequate irrigation and/or lubrication during
(10) Over-relying on chelating agents
11) Attempting to retrieve broken instruments
(12) Removing root filling materials during endodontic retreatment
(13) Attempting to prepare calcified root canals
(14) Inadvertently packing debris in the apical portion of the canal
during instrumentation (that is, creating an apical blockage)
Jafarzadeh and Abbott, J Endod 2007
• Root canal instrument can no longer be inserted into the canal
to full working length.
• loss of normal tactile sensation of the tip of the instrument
binding in the lumen.
• Radiographically, if the instrument point appears to be directed
away from the lumen of the canal
• The use of a small file, No. 10 or 15, with a distinct curve at the
tip can be used to explore the canal to the apex.
• Tear-drop shaped silicone instrument stopper and watch-
winding motion are valuable.
• Use a lubricant, irrigate frequently to remove dentin chips,
maintain a curve on the file tip, and, using short file strokes,
press the instrument against the canal wall where the ledge is
• Accurate interpretation of diagnostic radiographs should be
completed before the first instrument is placed in the canal.
• Finally, precurving instruments and not “forcing” them is a sure
• Using instruments with noncutting tips and nickel-titanium files
• Patency of the canal should be maintained throughout the cleaning
and shaping procedure.
• Work sequentially increasing sizes of instruments without
jumping to large numbers
Zipping and Elbow formation
• Zipping is the transportation of the apical portion of the canal.
Etiology: commonly seen in curved canals
• Failure to precurve the files
• Forcing the instrument in curved canal
• Use of large stiff instrument to bore out the canal
Precurve the initial small sized instruments
Use incremental filing technique
Use flexible files
Never rotate the instruments in curved canal
• When a file is rotated in the curved canal at the apical area, a
biomechanical defect results in the form of elbow.
• In this case, the apical foramen will tend to become a tear drop
shape or elliptical & be transported from the curve of the canal.
• The wide apical portion of the elliptical portion is known as the
zip while the narrow coronal portion is the elbow.
• Elbow prevents optimal compaction in the apical portion and
obturation ends at the elbow.
• An artificial opening in a tooth or its root, created by boring,
piercing , cutting or pathologic resorption, which results in a
communication between the pulp space and the periodontal
• Perforation is defined as the mechanical and or pathological
communication between the root canal system and the external tooth
- Resorptive defects
- Mechanical or Iatrogenic events- like inserting larger size
stainless steel straight file in a curved canal
Root canal perforation: Cervical canal,
Classification of root perforations, proposed by Fuss & Trope
• Fresh perforation– treated immediately or shortly after
occurrence under aseptic conditions, Good Prognosis.
• Old perforation– previously not treated with likely bacterial
infection, Questionable Prognosis.
• Small perforation (smaller than #20 endodontic instrument) –
mechanical damage to tissue is minimal with easy sealing
opportunity, Good Prognosis.
• Large perforation– done during post preparation, with
significant tissue damage and obvious difficulty in providing an
adequate seal, salivary contamination, or coronal leakage along
temporary restoration, Questionable Prognosis.
• Coronal perforation– coronal to the level of crestal bone and
epithelial attachment with minimal damage to the supporting
tissues and easy access, Good Prognosis.
• Crestal perforation– at the level of the epithelial attachment
into the crestal bone, Questionable Prognosis.
• Apical perforation– apical to the crestal bone and the epithelial
attachment, Good Prognosis.
- Endodontic Topics 2006
Cervical canal perforations
• Process of locating and widening the canal orifice or
inappropriate use of Gates-Glidden burs.
• often begins with the sudden appearance of blood.
• Rinsing and blot drying allows direct visualization
• Magnification with either loupes, an endoscope, or a microscope
is very useful
• It may be necessary to place a small file and take a radiograph of
• Electronic apex locators
Correction: :of the perforation may include both internal and
• may be achieved by reviewing each tooth’s morphology prior
to entering its pulp space
must be considered to be reduced in these types of perforations
• Occur mostly in curved canals, either as a result of perforating
when a ledge has formed during initial instrumentation or along
the inside curvature of the root as the canal is straightened out.
• “Stripping” is a lateral perforation caused by over
instrumentation through a thin wall in the root and is most likely
to happen on the inside, or concave, wall of a curved canal, such
as the distal wall of the mesial roots in mandibular first molars
• Stripping is easily detected by the sudden appearance of
hemorrhage in a previously dry canal or by a sudden complaint
by the patient.
Correction: Access to midroot perforation is most often
difficult, and repair is not predictable.
• Repair of strip perforations has been attempted both
nonsurgically and surgically.
Prognosis: Both “stripping” perforation and direct lateral
perforation of the root result in a reduction of the prognosis
Loss of tooth structure and integrity of the root wall can lead to
subsequent fractures or microleakage
• Result of the file not negotiating a curved canal or not establishing
accurate working length and instrumenting beyond the apical
• The patient suddenly complains of pain during treatment,
• The canal becomes flooded with hemorrhage,
• The tactile resistance of the confines of the canal space is lost
• Overinstrumentation Re-establish the tooth length
short of the original length and then enlarge the canal,
with larger instruments, to that length.
• Create artificial apical barrier
• With successful repair, apical perforations have less adverse
effect on prognosis than more coronal perforations.
• Most commonly files and reamers are involved in these types of
Common errors leading to this mishap are:
- using a “stressed” instrument,
- Inadequate lubrication
- placing exaggerated bends on instruments, and
- forcing a file down a canal before the canal has been opened
sufficiently with the previous, smaller file
Sotokawa’s classification of instrument
Type I- Bent instrument.
Type II- Stretching or straightening of twist
Type III- Peeling-off metal at blade edges.
Type IV- Partial clockwise twist.
Type V-Cracking along axis.
Type VI- Full fracture.
1. Attempt to remove the instrument fragments .
2. Attempt to bypass it with a small file or reamer.
3. if instrument does not extend beyond the apex, prepare and
obturate till the segment (true blockage)
4. If the fragment extends past the apex, the corrective treatment
will probably include apical surgery.
• Essential prerequisites for instrument separation management
– Dental operating microscope
Instrument Fractured Coronally:
• Can be bypassed, a small file is 1st introduced alongside it.
• Use of Stieglitz plier or small haemostat (mosquito forceps) if
the tip grasp can be obtained.
• Endosonics is used to loosen the instrument within the root
canal then fine ultrasonic tips such as CPR 4& CPR 5 are
placed on the lateral surface of fractured instrument.
Instrument Fractured Below Orifice Level:
Access is modified using a non end cutting tungsten carbide bur
such as Endo Z or LA access bur.
Ruddle’s method of instrument removal:
• 25 guage dental injection needle is taken
• 0.14mm steel ligature wire
• Needle is cut at the bevel end and opposite end of wire is passed
Tube & Headstroem file method (spinal tap needle):
• By Suter
• Space is created around the object.
• A tube is then located over it & two are locked
together by gently screwing a H-file down the
center of the tube.
Modified needle technique (lasso &
Extractor system: Roydent
• System consists of only bur and 3 extraction devices.
• Bur is very conservative and removes minimal amount of
• The extractor surrounds the obstruction with small prongs that
can be tightened onto the object enabling removal.
Brasseler Endo extractor kit:
• Includes 4 sizes of trephine burs and extractors
• Cyanoacrylate adhesive is used to bond hollow tube to the
exposed end of the file.
• Snugness between the tube and obstruction plays a
key role; minimal 2mm overlap is required.
• Time required for adhesive to set
5min snug fit & 10min for loose fit
– Trephine burs are larger
– Burs cut very aggressively when
new and dull out rapidly.
Consists of a series of graded hollow tubes that are held in a long
• Cyanoacrylate cement (Superglue) is used to bond the point &
tube together before removal.
• Adhesive requires a setting time of 5min for maximum
Endo Eze System:
A cheaper alternative to the Cancellier kit is Endo-Eze tips.
These come in different gauges and can be used in a
similar manner. The tip of the needle is very malleable and
can easily be bent so that the magnified view into the root canal
is not obscured.
• Hand held instruments which can be used with dental operating
• Similar to ball burnisher where slots are cut into the ball end.
• Cyanoacrylate is used to bond the extractor & file for its
• Can mostly be used in coronal aspect of the canal.
The Meitrac System:
Consists of Trephines, Extractors designed to remove
intraradicular obstructions of different diameters.
Meitrac I – remove instruments with diameter 0.15 -0.5mm
Meitrac II – retrieval of silver points of diameter 0.5-0.9mm
Instrument Retrieval System ( IRS)
2 different sizes of
with 45˚bevel and a
window at the tip and
• The kit consists of a series of trephining drills and 2 sizes of
tubular extractors (1.2 & 1.5mm)
• Create a space in the root canal around the coronal 2mm of the
• Extractor tube passes over it.
• Extractor plunger is screwed down locking the object against a
knurled ring in the tube wall.
Studies by Yoshitsugu on separated file removal concluded
• Separated files > 4.5 mm in any canals, or those in curved canals
> 60°, were extremely difficult to retrieve with ultrasonics alone;
it took longer than 9 minutes to remove them,
• Separated files shorter than 4.5 mm long were easy to retrieve
with ultrasonics alone and the removal time was within the range
of 5 minutes.
• If ultrasonic removal time exceeds 5 minutes, different technique
should be used to retreive it such as loop device.
• May not change very much if the instrument can be bypassed.
• If surgical correction is needed, the prognosis may be reduced.
• Careful handling of instruments.
• Discard stressed instruments
• Instruments No. 08 and 10 should be used only once.
• Sequential instrumentation, using the “quarter-turn” technique
• Increasing file size only after the current working file fits loosely
into the canal without binding
• Blockage occurs when files compact apical debris into a
hardened mass during enlargement.
• Fibrous blockage occurs when vital pulp tissue is compacted
and solidified against the apical constriction.
• when the confirmed working length is no longer attained.
• Starting with the smallest file in the quarter-turn technique using
a chelating agent.
• If block out occurs at the curve, Precurve the instrument and
• Depends on the stage of instrumentation completed when the
block out occurs.
• Teeth with vital pulps better prognosis than those with necrotic
Prevention: frequent irrigation during canal preparation and use of
Loss of Working Length
• It is actually secondary to the other procedural errors like ledges,
canal transportation and fractured instruments.
• In most instances, loss of working length can be attributed to
rapid increase in the file size, overreliance on chelating agent &
the accumulation of dentinal debris in the apical third of the
• Usually seen in curved canals due to straightening out of canal
during cleaning and shaping procedure.
1. OVER- OR -UNDEREXTENDED ROOT CANAL
Cause: Apical perforation with loss of apical constriction against
which gutta-percha is compacted.
• Failure to fit the master gutta-percha point accurately due to
poorly prepared canal in the apical third.
Recognition: By a post-treatment radiograph
• Of underextended filling is accomplished by re-treatment.
• Of an overextended filling , if attempted to remove, the point
will break off leaving a fragment loose in the periradicular tissue.
• It may cause foreign body gaint cell reaction which may support
formation of biofilms.
• if asymptomatic and not associated with lesions- do not require
• If symptomatic- surgical removal of the excess material
Prognosis: depends on presence or absence of periradicular
lesion and the content of the root canal segment that remains
unfilled (necrotic and infected)
• Accurate working lengths and care to maintain them will help
• Confirmation and adherence to canal working length
throughout the instrumentation procedure
• Radiograph during the initial phases of the obturation to allow
for corrective action
• Overextensions and/or overinstrumentations are the causative
factors most often found in paresthesia secondary to orthograde
• The nerve damage may be transient or permanent.
• Through nonintervention and observation
• The most important process the dentist can practice is
Vertical root fractures
• Instrumentation, obturation and post placement.
• In both lateral and vertical condensation techniques, the risk of
fracture is high if too much force is exerted during compaction.
• The sudden crunching sound, is a clear indicator that the root
• “Teardrop” radiolucency
• A deep periodontal pocket of recent origin in a tooth with a
long-present root canal filling
• Periodontal probing,
• Transillumination test,
• Bite test
• Exploratory surgery is a good way to visualize the fracture
Prevention: involves avoidance of overpreparing canals and the
use of a passive, less forceful obturation technique and seating of
1.POST SPACE PERFORATION:
Recognition: similar to instrumentation related lateral root
perforations; sudden presence of blood in the canal or radiographic
Prognosis is least affected if the perforation is totally within bone.
• If it is closer to the gingival sulcus, the risk of periodontal pocket
formation is high.
Prevention is associated with a good knowledge of root canal
anatomy and planning the post space preparation based on
radiographic information regarding the location & direction of root.
• An unfortunate sequence of events is triggered after the irrigating
solutions are injected forcibly into the periradicular tissues.
• Becker et al. described the damaging effects of an accidental
injection of sodium hypochlorite beyond the apex.
• Bhat reported the same effects with hydrogen peroxide. Injection
of hydrogen peroxide causes tissue emphysema.
• Patient may immediately complain of severe pain, and
swelling can be violent and alarming.
• Depends on type of solution used, the concentration,
and amount of exposure.
• The initial response stage may be characterized by
swelling, pain, interstitial hemorrhage, and ecchymosis.
• It is advisable to prescribe antibiotics in addition to analgesics
• Ice packs applied initially to the area, followed by warm saline
• The use of intramuscular steroids, and, in more severe cases,
hospitalization and surgical intervention with wound
debridement, may be necessary.
Prevention of inadvertent extrusion of irrigants past the apex can
be attained by using passive placement of a modified needle.
The needle must not be wedged into the canal, and the solution
should be delivered
slowly and without pressure.
• Favorable, but immediate treatment, proper management, and
close observation are important.
• Long term effetcs: paresthesia, scarring, and muscle weakness.
• Tissue space emphysema has been defined as the passage and
collection of gas in tissue spaces or fascial planes.
• Common etiologic factor is compressed air being forced into the
Two procedures in endodontics:
• During canal preparation, a blast of air to dry the canal, and
• During apical surgery, air from a high-speed drill can lead to air
Recognition: Rapid swelling, erythema, and crepitus.
• Tissue space emphysema remains in the subcutaneous
connective tissue and usually does not spread to the deep
• Migration of air into the neck region could cause respiratory
difficulty, and progression into the mediastinum could cause
Diagnostic signs of mediastinal emphysema:
-Sudden swelling of the neck.
-Difficulty breathing and voice will sound brassy.
-Characteristic crackling can be induced when the swollen
regions are palpated.
• From palliative care and observation to immediate medical
attention if the airway or mediastinum is compromised
-using paper points to dry root canals.
-If the air syringe is to be used, Jerome suggested horizontal
positioning over the access opening, using the “Venturi effect” to
aid in drying the canal.
- In surgical procedures, apical access can be made with the slow-
speed or high-speed handpieces that do not direct jets of air into
Instrument aspiration and ingestion
• Endodontic instruments used in the absence of a rubber dam, can
easily be aspirated or swallowed if inadvertently dropped in the
• The patient must be taken immediately to a medical emergency
facility for examination. (Radiographs of the chest and abdomen).
Prevention: can best be accomplished by strict
adherence to the use of a rubber dam during all phases of endodontic
• Aspiration of a loosened clamp can be avoided by
attaching floss to the clamp before placement
A successful operator learns from the past
experiences and applies them to future
challenges ultimately the beneficiary will be the
patient, who will receive the best care
• Ingle’s Endodontics - 5th edition
• Advanced Endodontics –John S Rhodes
• Advanced Endodontics- Nageswar Rao
• Endodontics – Problems Solving In Clinical Practice – Pitt Ford,
• Textbook of Endodontics- Nisha garg
• Diagnosis and treatment of accidental root perforations,
Endodontic Topics 2006
• Ledge Formation: Review of a Great Challenge in Endodontics. J
• Identifying root canals, Endodontic Strategies by Clifford ruddle
• Complications following an accidental sodium hypochlorite
extrusion: A report of two cases. J Clin Exp Dent.
• Separated file removal: Yoshitsugu 2012 Dentistry today.