This document discusses procedural accidents that can occur during root canal therapy and how to manage them. It defines procedural accidents as unwanted circumstances that can affect the prognosis of treatment. Examples discussed include instrument separation, ledge formation, perforations, and underfilled or overfilled canals. The document provides details on the causes, prevention, and treatment of specific accidents like perforations during access preparation and ledge formation. It emphasizes the importance of informing patients about any incidents and their potential effects.

1. Procedural Accidents

2. Learning Objectives

3. Definition
 An operator may encounter unwanted or
unforeseen circumstances during root canal
therapy that can effect the prognosis.
These mishaps are collectively termed
procedural accidents

4. Examples
 Swallowed or aspirated instruments
 Crown or root perforation
 Ledge formation
 Separated instruments
 Underfilled or overfilled canals
 Vertically fractured roots

5. Inform Patient
 Incident
 Procedure for correction
 Alternative treatment modalities
 Effect of incident on prognosis

7. Perforation during access
preparation

8. Cont.:
 Causes
 Prevention
 Recognition and Treatment
 Prognosis

9. Causes
 Failure to direct the bur parallel to the long
axis of tooth
 Searching for the pulp chamber or orifices of
canals through an underprepared access
cavity
 Failure to recognize when the bur passes
through a small or flattened (disklike) pulp
chamber in multi-rooted teeth
 Access through a cast crown often is not
aligned in the long axis of the tooth

10. A misdirected bur created severe gouging and near-
perforation during an otherwise routine access cavity
preparation.

11. A, Inadequate access cavities not only result in compromised
preparation and obturation but also may cause procedural
accidents such as chamber perforation, canal ledging, and (B)
root perforation.

12. A, Failure to recognize when the bur passes through the roof of the pulp
chamber in a calcified pulp chamber may result in gouging or perforation of
the furcation. The use of apex locators and angled radiographs is
necessary for early perforation detection. Early detection reduces damage
and improves repair B, Use of a “safe-ended” access bur will prevent
perforation of the chamber floor.

14. Prevention
 Clinical Examination
 Thorough knowledge of tooth morphology
 Identification of tooth angulation to adjacent
teeth
 Proper reading of the preoperative
(diagnostic) radiograph to get information
about the size and extent of pulp chamber and
internal changes (calcification, resorption)
 Radiograph from different angle

15. Perforation of the mesial tooth surface caused by failure
to recognize that the tooth is tipped and failure to
align the bur with the long axis of the tooth. This is a
common error in teeth with full crowns. Even when these
perforations are repaired correctly, they usually cause a
permanent periodontal problem because they occur in a
difficult maintenance area

17. Operative Procedures
 Access without rubber dam or using “split
technique” is preferred in specific cases
 Failure to recognize when the bur passes through
the calcified chamber ( safe ended, Endo Z bur)
 Use of electronic apex locator and angled
radiographs for early perforation detection
 Placement of bur in the preparation hole to
orient access and then radiograph
 Use of fiberoptic light and magnification
(Magnify glass, loupes, operative microscope)

18. Rubber dam can be applied in the anterior region without
placing the clamp on the tooth that is undergoing root canal
therapy or in posterior regions by quadrant isolation if a distal
tooth can be clamped.

19. A small bur is placed during access preparation when orientation
is a problem. This provides information about such data as
angulation and depth of bur penetration.

20. Recognition
 Early signs of perforation into PDL or
bone include one or more of following:
1. Sudden pain during WL determination
2. Sudden hemorrhage
3. Burning pain or bad test during
irrigation with sodium hypochlorite
4. Radiograph
5. Apex locator

21. A, A search for the MB canal in a partially calcified chamber resulted in a
furcation perforation and extrusion of filling materials into the periapical
tissues. An apex locator reading or an angled radiograph would have
detected this type of error. B, The initial treatment was redone and the
perforation was sealed with MTA Cont.:

22. C, Radiograph 3 years later shows no evidence of pathosis in
the repaired area.

24. Treatment
 Lateral root perforation
 Location
 Size
 A. At or above crestal bone, prognosis
is good
 Restorative treatment

25. Cont.:
B. Perforation below the height of
crestal bone in the coronal third of root,
poor prognosis
 The treatment goal is to position the
apical portion of the defect above
crestal bone by orthodontic extrusion
or crown lengthening
 Internal repair by MTA is also possible

26. Furcal Perforation
A. Direct Perforation
Treatment: Material used are amalgam, gutta percha,
zinc oxide eugenol, cavit, calcium hydroxide, freeze-
dried-bone
immediate sealing with suitable restorative material
(MTA) is best
B. Stripping perforation
Usually results from excessive flaring with files or GG
drills
Non surgical treatment by immediate sealing using
MTA

27. Furcation perforation caused by failure to measure the distan
between the occlusal surface and the furcation. The bur
bypasses the pulp chamber and creates an opening into the
periodontal tissues. Perforations weaken the tooth and cause
periodontal destruction. They must be repaired as soon as
they are made for a satisfactory result

28. Immediate repair of a perforation in the furcation of a dog premolar with
MTA results in the formation of cementum (arrow) adjacent to the
material

29. A, Radiograph shows stripping perforation (arrow) in the mesiobuccal
root of the first mandibular molar. B, The mesial roots were filled with
MTA and the distal root with gutta-percha and root canal sealer.
Cont.:

30. C, A radiograph taken 1 year later shows no periradicular pathosis.

31. A. Periapical radiograph shows
a furcation perforation in the
first mandibular molar
B. The root canal was retreated
and the perforation was
repaired with MTA Cont.:

32. Radiograph taken 26 months later shows no evidence of furcal
pathosis

33. Surgical Treatment
 Complex restorative procedure
 Good oral hygiene
 Repair by MTA if accessible by surgical
approach
 Not accessible or repairable by surgical
approach, then hemisection,
bicuspidization, root amputation or
intensional replanatation
 Extraction when prognosis poor

34. A. Pt. is percussion sensitive and
periapical lesions are present
after endo.treatment. 7mm
periodontal pocket present .
Fracture is suspected and
extract-replant was performed
for diagnostic reasons. Tooth
extracted and fracture found
on mesial root.
B. The mesial root was resected
and tooth was replanted after
retro-filling of the distal root with
MTA. Cont.:

35. Radiograph 1 year
later shows osseous
repair and restoration
of this tooth. The
periodontal pocket
healed

36. Prognosis
 Factors affecting long term prognosis:
 Location of defect in relation to crestal bone
 Length of the root trunk
 Accessibility for repair
 Size of the defect
 Presence or absence of a periodontal
communication to the defect
 Time lapse between perforation and repair
 Sealing ability of the restorative material
 Subjective factors such as:
 Technical competence of dentist
 Attitude and Oral hygiene practice of the patient

39. Cont.:
 Ledge formation
 Artificial canal creation
 Root perforation
 Instrument separation
 Extrusion of irrigating solution periapically.

40. Ledge Formation
 When the WL can no longer be
negotiated and the original patency of
the canal is lost

41. 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 of debris in the apical portion
of the canal

42. Inadequate access preparation. The
lingual shoulder was not removed, and
incisal extension is incomplete. The file
has begun to deviate from the canal in
the apical region, creating a ledge

43. Prevention of a Ledge
 Preoperative Evaluation
 Curvatures
 Length
 Initial size
 Technical Procedures

45. Management
 Difficult to correct
 Bypass with a No.10 steel file to regain
WL
 File tip (2 to 3 mm) sharply bent and
worked in the canal in the direction of
curvature
 ‘Picking motion’
 Reaming motion and short up and
down movements

46. A. Preoperative radiograph. B. Ledges have been formed in the mesial and
distal canals with steel files. Ledges can be bypassed only with small,
curved steel files

47. C. Ledges are bypassed and proper length is established. D. Final
radiograph shows complete obturation of root canals

48. Prognosis
 Amount of debris in the uninstrumented and
unfilled portion of the canal
 Amount depends on when ledge formation
occurred during the cleaning and shaping
 Short and clean ledges good prognosis
 Teeth with vital pulp tissue better prognosis
than necrotic , infected tissue apical to ledge
 Future appearance of clinical symptoms or
radiographic evidence require apical surgery
or retreatment

49. Artificial Canal Creation
 Cause and Prevention
 Deviation from the original pathway of
root canal system and creation of
artificial canal cause an exaggerated
ledge
 Aggressive use of SS files is the most
common cause

50. Cont.:
 Management
 Prognosis

51. Root Perforations
 Apical perforation
 Middle perforation
 Coronal

52. Apical Perforations
 Apical Perforations
A. Over instrumentation
B. Through body of the root (perforating
new canal)

53. Etiology
a. Apical perforation through apical foramen:
Caused by instrumentation of the canal
beyond the apical constriction ( incorrect WL)
b. Apical perforation through the body of the
root in the apical third:
Caused as a result of operator insistence to
manage a ledge in the apical third (especially
in curved canals)

54. Ledge with perforation

55. Indicators
 Hemorrhage in the canal
 Pain during canal preparation in
previous asymptomatic tooth
 Sudden loss of apical stop
 Radiograph
 Electronic apex locator

56. Prevention
 Proper WL must be established and
maintained throughout the procedure
 Verify WL with apex locator after
cleaning and shaping

57. Treatment
 Establishing new WL , creating apical
stop and obturating to new length
 Placement of MTA as an apical barrier can
prevent extrusion of obturating materials
 In case of apical perforation through the
body of the root in the apical third, try to
negotiate the original canal

58. Lateral (Midroot) Perforations
 Etiology and Indicators
 Degree of canal curvature and size
 Inflexibility of the larger files, especially ss
files
 Indicators are same fresh hemorrhage in
the canal , sudden pain and deviation of
instruments from original course.
Penetration of instrument out of the root
radiographically or apex locator

60. Treatment
 Renogciate the original canal, same steps
as for bypassing ledge
 If unsuccessful, the clean, shape and
obdurate coronal segment of the canal.
 Low conc. of sodium hypochlorite (0.5%) or
saline used in a perforated canal.
 Prognosis

61. Coronal Root Perforation
 Etiology and indicators
 During access preparation to locate canal orifices
 During flaring procedures with files, GG drills or
pesso reamers
 Treatment and prognosis
 Repair of stripping perforation in coronal third of
root has poorest long term prognosis
 Defect is usually inaccessible for adequate repair
 Attempt should be made to seal defect internally
 Patency of canal maintained during repair process

63. Etiology
 Limited flexibility and strength of
Intracanal instruments
 Improper use
 Excessive force applied to files
 Over use

64. Recognition
 Removal of shortened file form the canal
 Loss of canal patency
 Radiograph is essential for confirmation
 Patient informed and effect on prognosis
 Documentation for medical-legal considerations

65. Prevention
 Limitations of files is critical
 Continued lubrication with irrigating solution or
lubricants is required
 Each file is examined before use (file distortion)
 Small files must be replaced often
 To minimize binding , each file size is worked in canal
until it is very loose before the next file size is used
 Ni-Ti files do not show visual signs of fatigue similar
to the “untwisting” of ss files discarded before seen

66. Each steel file should be inspected for fluting distortion before use in the canal.
Only untwisted files will show a shiny spot (arrow). This file must be discarded.
Nickel titanium files will not show this distortion and must be discarded after three
to six uses.

67. Treatment
 Three approaches to manage Intracanal
instrument separation
1. Attempt to remove the instrument
2. Attempt to bypass it
3. Prepare and obturate to the segment coronal
to the instrument
 Prognosis

68. A, A file is separated in the mesiobuccal canal of the second mandibular
molar. B, The separated instrument is bypassed and removed Cont.:

69. C, Both canals are cleaned, shaped, and obturated. Prognosis is good.

71. A, Nickel-titanium file was broken inside the mesiobuccal canal of the
mandibular first molar. B, Because of patient discomfort, the segment was
removed surgically and MTA was used as root-end filling material Cont.:

72. C, A periapical radiograph 32 months later shows complete healing

73. Other Accidents
 Aspiration or ingestion
 Extrusion of Irrigants

74. A swallowed broach caused removal of a patient’s appendix and a
subsequent lawsuit against a dentist who did not use a rubber dam
during root canal therapy.

75. A, NaOCl was inadvertently expressed through an apical perforation in a
maxillary cuspid during irrigation. Hemorrhagic reaction was rapid and
diffuse. B, No treatment was necessary; the swelling and hematoma
disappeared within a few weeks

77. Underfilling
 Etiology
 Natural barrier in the canal
 Ledge
 Insufficient flaring
 Poorly adapted master cone

78. Cont.
 Treatment and Prognosis
 Confirmatory MAC radiograph
 If displacement of MAC is suspected,
a radiograph is made before excess
gutta percha removal
 Removal and retreatment

79. Overfilling
 Causes tissue damage and inflammation
 Etiology
 Over instrumentation
 Open apex
 Uncontrolled condensation forces
 Prevention
 Avoid over instrumentation
 Prepare apical matrix
 Confirmatory MAC radiograph

80. A, Lack of proper length measurements resulted in overfilling of the distal
root and under filling of the mesial root. The patient remained percussion
sensitive. B, Surgical curettage, apical root resection, and root end filling
with MTA were necessary to correct the technical deficiencies.

81. Treatment and Prognosis
 Apical surgery
 Long term prognosis
 Quality of apical seal
 The amount and biocompatibility of
extruded material
 Host response
 Toxicity and sealing ability of the root
end filling material

83. Vertical root Fracture
 Etiology
 Post cementation
 Excessive applied force during GP
condensation
 Prevention
 Appropriate (conservative) canal preparation
 Balance pressure during condensation
 Finger spreaders produce less stress and distortion of
root than do their hand counterparts

84. Cont.
 Indicators
 Narrow periodontal pocket or sinus tract
stoma
 Lateral radiolucency extending to the apical
portion of VRF
 For confirmation must be visualized
 Surgical exploration

85. A “tear-drop” lateral radiolucency and a narrow probing defect extend
to the apex of a tooth with vertical fracture.

86. Cont.:
 Prognosis and Treatment
 Complete VRF poorest prognosis
 Removal of the involved root in
multirooted teeth and extraction
of single rooted teeth

88. Prevention
 Gutta percha removal using heated
pluggers
 Drills should be used in sequence
 Knowledge of root anatomy is
necessary for determing the size and
depth of posts

89. Cont.:
 Indicators
 Blood during preparation
 Sinus tract stoma or probing defects extending
to the base of post
 Lateral radiographic radiolucency along root or
perforation site

90. Cont.:
 Treatment and Prognosis
 Non surgical if post can be removed
 Surgical repair if post can not be
removed and perforation accessible
 Prognosis depends on root size,
location of perforation relative to
epithelial attachment and accessibility
of repair

91. A, Lateral root perforation is evident in a patient who has had a previous root
canal therapy. B, After removal of the post and retreatment of previous
therapy, the perforation was repaired with MTA Cont.:

92. C, Postoperative radiograph taken 5 years later shows absence of any
periradicular pathosis.