4. When an accident occurs during root canal treatment, the
patient should be informed about:
(1) the incident.
(2) procedures necessary for correction,
(3)alternative treatment modalities.
(4) the effect of this accident on prognosis.

5. In addition, the practitioner who
knows his or her limitations will
recognize potentially difficult cases
and will refer the patient to an
endodontist.

6. Accidents During Access Preparation
Accidents During Cleaning and Shaping
Accidents During Obturation
ACCIDENTS DURING POST SPACE
PREPARATION

7. Classification of Procedural Accidents
Accidents During Access Preparation
• Perforations During Access
Accidents During Obturation
Preparation •Underfilling
• Causes •Overfilling
• Prevention •Vertical Root Fracture
• Recognition and Treatment
• Prognosis
Accidents During Post Space
Accidents During Cleaning and Shaping Preparation
• Ledge formation •I ndicators
• Cervical canal perforations •Treatment and Prognosis
• Midroot perforations
• Apical perforations
• Separated instruments and foreign
objects
• Canal blockage

9. Perforations During Access
Preparation
 The prime objective of an access cavity is to provide an
unobstructed or straight-line pathway to the apical
foramen.
 Accidents such as excess removal of tooth structure or
perforation may occur during attempts to locate
canals.
 Failure to achieve straight-line access is often the main
etiologic factor for other types of intracanal accidents.
 Perforations must be recognized early to avoid
subsequent damage to the periodontal tissues with
intracanal instruments and irrigants.

10. Perforations
There are two types:
1. Lateral root perforation 2. Furcation perforation

11. Causes
1. Failure to direct the bur parallel to the long axis of the
tooth.
2. Searching for canals through an underprepared access
cavity.
3. Access through a small or flattened (disk-like) pulp chamber
in a multirooted tooth.
4. Access through a cast crown often is not aligned in the long
axis of the tooth.

12. Disk-like pulp chamber (arrow)

13. Prevention
Clinical examination
1. Thorough knowledge of tooth morphology and outlines of
the access cavities .
2. Identification of tooth angulation according to the adjacent
teeth.
3. Proper reading of the preoperative (diagnostic) radiograph
to get information about the size and extent of the pulp
chamber and internal changes (calcification or resorption).
4. Radiograph from different angles .

14. Bur held alongside radiograph to estimate the depth
of penetration

15. Operative procedures
1. Access without rubber dam or using “split technique” is
preferred in specific cases
2. Use of fiberoptic light and magnifiers
3. Removal of restorations when possible
Split dam technique

16. Recognition
1. Sudden pain
2. Sudden hemorrhage
3. Radiograph
4. Apex locator
5. Taste of irrigant during irrigation

17. Treatment
Lateral root perforation
A- Perforation at or above the height of crestal bone
Treatment: restorative treatment
Supracrestal perforation repair

18. B- Perforation below the height of crestal bone in the coronal
third of the root
The treatment goal is to position the apical portion of the
defect above crestal bone by orthodontic extrusion or crown
lengthening .
Internal repair by mineral trioxide aggregate (MTA) is also
possible .

19. Furcation perforation
A- Direct perforation
Treatment: immediate sealing using the suitable restorative
material (MTA)
Furcation repair using mineral trioxide aggregate (MTA)

20. B- Stripping perforation
- Usually results from excessive flaring with files or drills
(Gates Glidden)
- Treatment:
non-surgical treatment by immediate sealing using MTA
surgical treatment: hemisection, bicuspidization, and root
amputation

21. Repair of stripping perforation (arrow)

22. Nonsurgical Treatment
1. The site of the perforation must be found,
2. the floor of the preparation cleansed,
3. the bleeding stopped,
4. mineral trioxide aggregate (MTA) applied to the
perforation .
5. Because it takes MTA more than 3 hours to set,
it should be covered with a fast-setting cement.
6. The other canal orifices should be protected by
placing paper points or an instrument in the
canals to prevent blockage.

23. In the event MTA cannot be
immediately applied,
A. it is best to stop the bleeding,
B. place calcium hydroxide over the “wound,”
C. place a good temporary filling,
D. set an appointment with the patient, the sooner
the better.
E. The perforation area will be dry at the next
appointment;
F. MTA can be applied
G. treatment continued.

24. Surgical Treatment
Surgery treatment requires:-
1. more complex restorative procedures .
2. more demanding oral hygiene from the patient.‘
Surgical alternatives are hemisection, bicuspidization,
root amputation, and intentional replantation.
Indicated:
1.when the defect is inaccessible.
2.when multiple problems exist, such as a perforation
combined with a separated instrument.
3. when the prognosis with other surgical procedures is
poor .

25. Dentist and patient must recognize that the
prognosis for treatment of surgically altered
teeth is guarded because of the increased
technical difficulty associated with restorative
procedures and demanding oral hygiene
requirements.

26. PROGNOSIS
Factors affecting the long-term prognosis of teeth after
perforation repair include:-
1. the location of the defect in relation to crestal bone.
2. the accessibility for repair.
3. the size of the defect.
4. the presence or absence of a periodontal communication
to the defect.
5. the time between perforation and repair.
6. the sealing ability of restorative material.
7. subjective factors such as:-
I. the technical competence of the dentist.
II. The attitude and oral hygiene of the patient

27. Treatment of the Wrong Tooth
• Treatment of the wrong tooth can be so easily
prevented. One should make sure through
testing, examining, and radiography that one
has confirmed which tooth requires treatment
• Open the access cavity before applying the
rubber dam

28. Damage to an Existing Restoration
• Porcelain crowns are the most susceptible to
chipping and fracture.
• When one is present, use a water-
cooled, smooth diamond point and do not
force the bur, let it cut its own way .
• Also, do not place a rubber dam clamp on the
gingiva of any porcelain or
porcelain-faced crown

29. Missed Canals
• Additional canals in the mesial roots of
maxillary molars and the distal roots of
mandibular molars are the most frequently
missed.
• Second canals in lower incisors, and second
canals in lower premolars, as well as third
canals in upper premolars are also missed.
• One must be prepare adequate occlusal
access.

31. Ledge Formation
Definition
a ledge has been created when the working length can
not longer be negotiated and the original patency
of the canal is lost.

32. Causes
1. inadequate straight-line access into the
canal.
2. inadequate irrigation or lubrication.
3. excessive enlargement of a curved canal with
files.
4. packing debris in the apical portion of the
canal.

33. Prevention
Preoperative evaluation
1. Curvature
2. Length

34. Technical procedures:
 Straight line access.
 Accurate working length measurement .
 Frequent recapitulation and irrigation.
 Use of lubricant like RC-PREP.
 Use of flexible Ni-Ti files in curved canals .
 Each file must be used until it is loose before a larger size is
used .
 Avoid application of severe forces during instrumentation .

35. Management of ledge
• A ledge is difficult to correct.
• An initial attempt should be made to bypass the
ledge with a No. 10 steel file to regain working
length.
• The file tip (2 to 3 mm) is sharply bent and
worked in the canal in the direction of the canal
curvature.
• Lubricants are helpful.
• If the original canal is located, the file is then
worked with a reaming motion and occasionally
an up-and-down movement to maintain the
space and remove debris
• If the original canal cannot be located by this
method, cleaning and shaping of the existing
canal space is completed at the new working
length.

36. Prognosis
The failure depends on the amount of debris left
in the uninstrumented and unfilled portion of the
canal.
The amount depends on when ledge formation
occurred during instrumentation.
In general, short and cleaned apical ledges have
good prognoses.
 Future appearance of clinical symptoms or
radiographic evidence of failure may require
referral for apical surgery or retreatment.

37. Root Perforations
Apical perforation
Types
A. Apical perforation through the apical foramen
(overinstrumentation)

38. B- Apical perforation through the body of the root in the
apical third
Ledge apical perforation

39. Etiology
a. Apical perforation through the apical foramen:
- It is caused by instrumentation of the canal beyond the
apical constriction (incorrect working length)
b. Apical perforation through the body of the root in the
apical third:
- It is caused as a result of operator insistence to manage a
ledge in the apical third (especially in curved canals)

40. Indicators
1. Hemorrhage in the canal
2. Bleeding at the tip of paper point
3. Sudden pain
4. Sudden loss of the apical stop
5. Radiograph
Bleeding at the tip of paper point

41. Prevention
To prevent apical perforation, proper
working lengths must be established and
maintained throughout the procedure.

42. Treatment
- In case of overinstrumentation, corrective treatment includes
reestablishing tooth length short of the original length and
then enlarging the canal, with larger instruments, to that
length.
- Placement of MTA as an apical barrier can prevent extrusion of
obturation material
- In case of apical perforation through the body of the root in the
apical third, try to negotiate the original canal .

43. - One is now dealing with two foramina: one natural, the other
iatral. Obturation of both of these foramina and of the main
body of the canal requires the vertical compacting techniques
with heat-softened gutta-percha

44. Non-surgical repair of apical perforation through the body of the root

45. Prognosis
• Success of treatment depends primarily on
the size and shape of the defect. An open apex
or reverse funnel is difficult to seal and also
allows extrusion of the filling materials.

46. Lateral (midroot) perforations
Etiology
- There are two types of midroot perforations:
a. Direct perforation as a result of pressure and force applied
to a file during negotiation of ledged canals, or through post
space preparation using cutting-end bur
b. Stripping perforation is a lateral perforation caused by
overinstrumentation using files or drills like Gates-Glidden
through a thin wall in the root and is most likely to happen
on the inside (inner) wall of a curved canal, such as the
distal (inner) wall of the mesial roots in mandibular first
molars

47. Stripping perforation

48. Danger zone and safety zone

49. Indicators
- They are similar to those of apical perforation
The area of hemorrhage on the point indicates the area where the
strip has occurred.

50. Prevention
To avoid these perforations some factors should
be considered:
1. degree of canal curvature and size .
2. inflexibility of the larger files, especially
stainless steel files.

51. Treatment
- The main goal is to instrument and obturate the entire root
canal system
- Perforation repair surgically or non-surgically using suitable
restorative material (MTA)
Repair of stripping perforation using MTA

52. Prognosis
It depends on several factors:
- Remaining amount of undebrided and unobturated canal.
- Perforation size.
- Surgical accessibility.
• Obturation is difficult because of lack of a stop , and gutta-percha
tends to be extruded during condensation.
• Teeth with perforations close to the apex after complete or partial
débridement of the canal have a better prognosis than those with
perforations that occur earlier.
• In addition to the length of uncleaned and unfilled portions of the
canal, size and surgical accessibility of perforations are important.
• In general, small perforations are easier to seal than large ones.

53. Coronal root perforation
Etiology
- Direct perforation happens during access preparation while
the operator attempts to locate the canals
- Stripping perforation happens during flaring procedures by
files or Gates-Glidden
Prevention
- It is similar to what described earlier in the prevention of
perforation during access preparation
- Careful and conservative flaring, especially during using
Gates-Glidden, is also recommended

54. Treatment & Prognosis
• Repair of a stripping perforation in the coronal third of the
root has the poorest long-term prognosis of any type of
perforation.
• The defect is usually inaccessible for adequate repair. An
attempt should be made to seal the defect internally, even
though the prognosis is guarded. Patency of the canal system
must be maintained during the repair process.
 MTA is a promising material to repair
almost all types of perforations

55. Separated Instruments

56. Etiology
- Limited flexibility
- Over use
- Excessive forced applied to files
- Improper use
Notice: any instrument may break either steel, NiTi, hand or
rotary

57. Recognition
- Removal of shortened file from the canal
- Loss of canal patency
- Radiograph is essential for confirmation.

58. Prevention
• limitations of files is critical.
• Continual lubrication with either irrigating solution or
lubricants is required.
• Each instrument is examined before use ( flutes distortion).
• Small files must be replaced often.
• To minimize binding, each file size is worked in the canal until
it is very loose before the next file size is used.
• Nickel-titanium files usually do not show visual signs of fatigue
similar to the “untwisting” of steel files, they should be
discarded before visual signs of untwisting are seen .

59. Signs of instrument distortion (arrows)

60. Treatment
- There are three approaches:
1. Attempt to remove the instrument (using small file to
bypass the instrument then retrieve it, using ultrasonic tips,
or using especially designed pliers)
Pliers

61. 2- attempt to bypass it.
3- prepare and obturate to the segment coronal to the
instrument.
The operator should attempt to bypass the separated
instrument. After bypassing the separated instrument,
ultrasonic files broaches, or Hedstrom files are used to
remove the segment.
If removal of the separated piece is unsuccessful, then the
canal is cleaned, shaped, and obturated to its new working
length.
If the instrument cannot be bypassed, preparation and
obturation should be performed to the coronal level of the
fragment.

62. A, Arrow pointing to a separated instrument in the mesiolingual canal
B, Postobturation film with an arrow identifying “tunneling” that was created with an
ultrasonic instrument to remove the separated instrument

63. Removal of broken instrument extended beyond the apex (arrow)

64. Prognosis
 It depends on how much undbrided and unobturated canal
remains.
 The prognosis is best when separation of a large instrument
occurs in the later stages of preparation close to the working
length.
 Prognosis is poorer for teeth with undébrided canals in
which a small instrument is separated short of the apex or
beyond the apical foramen early in preparation.
 For medical-legal reasons, the patient must be informed of
an instrument separation.
 If the patient remains symptomatic or there is a subsequent
failure, the tooth can be treated surgically.

66. Instrument Aspiration or
Prevention Ingestion
- Rubber dam

67. Indicators
- Instrument disappearance followed by severe coughing or
gagging by the patient
- Radiograph
Treatment
- When the lost instrument is readily accessible, high volume
suction, hemostat, or cotton pliers may help to retrieve the
instrument. Otherwise, referral to a medical service is
required and major surgical intervention may also be
required

68. Swallowed endodontic file ended up in appendix and led to acute appendicitis
and appendectomy. Rubber dam would have prevented this tragedy.

70. Extrusion of Irrigant
• Wedging of a needle in the canal or out of a
perforation with forceful expression of irrigant causes
penetration of irrigants into the periradicular tissues
and inflammation and discomfort for patients.
• Loose placement of irrigation needles and careful
irrigation with light pressure or use of a perforated
needle precludes forcing the irrigating solution into the
periradicular tissues.
• Sudden prolonged and sharp pain during irrigation
followed by rapid diffuse swelling (the “sodium
hypochlorite accident”) usually indicates penetration of
solution into the periradicular tissues.

71. Severe swelling caused by injecting hydrogen peroxide irrigant into tissues.

72. A B
A, Hemorrhagic reaction caused by NaOCl accident
B, Healing within few weeks

73. Treatment
- Because of the potential for spread of infection related to
tissue destruction, it is advisable to prescribe antibiotics in
addition to analgesics for pain
- Antihistamines can also be helpful
- Ice packs applied initially to the area, followed by warm
saline soaks the following day, should be initiated to reduce
the swelling
- In more severe cases, hospitalization and surgical
intervention with wound débridement, may be necessary
- Patient reassurance

74. Prognosis
- Generally is favorable
- In some cases, the long-term effects of irrigant injection into
the tissues have included paresthesia, scarring, and muscle
weakness

76. Undefilling
Causes
- Natural barrier in the canal.
- Ledge.
- Insufficient flaring.
- Poorly adapted master cone.

77. Prevention
- Confirmatory MAC radiograph .
- If displacement of the MAC is suspected, a radiograph is
made before excess gutta-percha removal .
Treatment
- Re-treatment

78. Overfilling
Causes
- Overinstrumentation
- Open apex
- Uncontrolled condensation forces

79. Prevention
- Avoid overinstrumentation.
- Prepare apical matrix (seat).
- Confirmatory MAC radiograph.
- If displacement of the MAC is suspected, a radiograph is
made before excess gutta-percha removal.
- In case of wide (open) apex, a solvent customized cone
technique is preferred .

80. Treatment
- In case of endodontic failure, apical surgery may be required
to remove the extruded material
Prognosis
- It depends on some factors: quality of the apical seal, amount
and biocompatibility of extruded material, and host response

81. Usually, slight over extension of GP cone beyond the apex
(around 2 mm) doesn’t cause problem and doesn’t need
further treatment.

82. Surgical removal of extended gutta-percha beyond the apex

83. Gross paste overfilling

84. Vertical Root Fracture

85. Causes
- Overflaring
- Screw post placement
- Post cementation
- Excessive applied forces during gutta-percha condensation
Prevention
- Appropriate (conservative) canal preparation
- Balanced applied forces during condensation
- Finger spreaders produce less stress than hand fingers during
obturation

86. Indicators
- Sudden sound and pain during obturation
- Narrow periodontal pocket or sinus tract stoma
- “Halo” radiographic radiolucency
- Surgical exploration
Narrow periodontal pocket “Halo” radiographic radiolucency Surgical exploration

87. Treatment
- Removal of the fractured root in multi-rooted tooth and
extraction of single-rooted tooth

89. Root Perforation
Prevention
- Gutta-percha removal using heated pluggers.
- Good knowledge of root canal anatomy, location of the
root, and its direction in the alveolus.
- Gates-Glidden and Peeso reamer are safe, however, they can
lead to excessive removal of tooth structure and therefore can
potentially lead to “stripping” perforation or root fracture.
- High speed burs shouldn’t be used at all in post space
preparation

90. Indicators
- Bleeding during preparation
- Sinus tract or pocket extended to the post base
- Lateral radiographic radiolucency
radiographic radiolucency caused
root perforation during post space preparation

91. Treatment
- Non-surgical repair if the post can be removed (as stated in
management of root perforation)
- Surgical repair if the post cannot be removed and the
perforation is accessible
- Otherwise extraction is required

92. Non-surgical repair using MTA of perforation caused during post space preparation

93. Prognosis
- It depends on: perforation size, surgical accessibility, and
perforation location ( apical perforation has better prognosis
than that close to the gingival sulcus)