1. Success rates for initial endodontic treatment range from 54-95% depending on studies and definitions of success. 2. Factors affecting success or failure include diagnosis, root canal anatomy, debridement, quality of filling, and systemic health. 3. Causes of endodontic failure include residual bacteria, incomplete debridement, hemorrhage, iatrogenic errors, and systemic factors. 4. Retreatment involves removing previous fillings and obstructions, regaining patency, and thoroughly cleaning and refilling canals. Outcomes depend on regaining patency and quality of

1. endodontic failures
and retreatment

2. Introdution
• In different studies success rate ranges from 54
percent to 95 percent.
• The definition of success is ambiguous
- stringent : radiographic and clinical normalcy
- lenient : only clinical normalcy

3. Endodontic treatment
outcome
• Healed:
both clinical and radiographic presentations are
normal
• Healing:
it’s a dynamic process, reduced radiolucency
combined with normal clinical presentation
• Disease:
No change or increase in radiolucency, clinical
signs may or may not be present or vice versa

4. Evaluation of success
• Success or failures following endodontic therapy
could be evaluated from combination of clinical,
histopathological and radio graphical criteria.

5. Clinical evaluation for
success
• No tenderness to percussion or palpation
• Normal tooth mobility
• No evidence of subjective discomfort
• Tooth having normal form, function and
aesthetics
• No sign of infection or swelling
• No sinus tract or integrated periodontal disease
• Minimal to no scarring or discoloration

6. Radiographic evaluation
for success
• Normal or slightly thickened periodontal ligament
space
• Reduction or elimination of previous rarefaction
• No evidence of resorption
• Normal lamina dura
• A dense three dimensional obturation of canal
space

7. Histological evaluation for
success
• Absence of inflammation
• Regeneration of periodontal ligament fibers
• Presence of osseous repair
• Repair of cementum
• Absence of resorption
• Repair of previously resorbed areas

8. Causes of the endodontic
failures
 Bacteria somewhere in the root canal system
 Divided into local and systemic

9. Factors affecting success or
failure of endodontic therapy
in every case
• Diagnosis and the treatment planning
• Radiographic interpretation
• Anatomy of the tooth and root canal system
• Debridement of the root canal space

10. Factors affecting success or
failure of endodontic therapy
in every case
• Quality and extent of apical seal
• Quality of post endodontic restoration
• Systemic health of the patient
• Skill of the operator

11. Factors affecting success or
failure of a particular case
Factors affecting success or
failure of a particular case
• Pupal and Periodontal status
• Size of periapical radioleucency
• Canal anatomy
• Crown and root fracture

12. Factors affecting success or
failure of a particular case
Factors affecting success or
failure of a particular case
• Iatrogenic errors
• Extent and quality of the obturation
• Quality of the post endodontic restoration
• Time of post treatment evaluation

13. Local Factors causing
endodontic failures
• Infection
• Incomplete debridement of the root canal system
• Excessive hemorrhage
• Chemical irritants
• Iatrogenic errors

14. Infection
• infected and necrotic pulp tissue→main irritant to
the periapical tissues
• The host parasite relationship 、 virulence of
microorganisms , ability of infected tissues to
heal→influence the repair of the periapical tissues
• Endo success →debridement

15. Incomplete debridement of
the root canal system
• Main objective of root canal therapy→complete
elimination
of the microorganisms and their
byproducts
• Poor debridement → residual
microorganisms 、 byproducts and
tissue debris → recolonize

16. Excessive hemorrhage
• Extirpation of pulp and instrumentation beyond
periapical tissues
• Local accumulation of the blood→mild
inflammation
• Extravasated blood cells and fluid ： foreign body
nidus for bacterial growth

17. Over instrumentation
• Instrumentation beyond apical foramen→PDL
and alveolar bone trauma→the prognosis of
endodontic treatment ↓

18. Chemical irritants
• Intracanal medicaments and irrigating solution
→extruded in the periapical tissues→the
prognosis of endodontic treatment ↓
• One should take care while Using medicaments to
avoid their periapical
extrusion

19. Iatrogenic errors
• Separated instruments—
• Caused by improper or overuse of
• instruments and forcing them in curved
canals
• Prognosis ： no much affected in vital pulps
poor in necrotic tissue.

20. Iatrogenic errors
• Canal blockage and ledge formation—
• Accumulation of dentin chips or tissue debris
prevent the instruments to reach its
full working length
• Ledge formation—straight instruments in
curved canals
• These lead to bacteria & debris remained
endo failure

21. Iatrogenic errors
• Perforations—
• Lack of knowledge of anatomy of the tooth,
attention, misdirection of the instruments
• Prognosis ： location, time, perforation seal and
size
• Poor prognosis  remaining
infected tissue

22. Iatrogenic errors
• Incompletely filled teeth—
• Teeth filled more than 2mm short of apex
• Several studies shown ：
• poor prognosis—underfillings with necrotic
pulps
• Overfilling of root canals—
• Overfilling extending ≧ 2mm beyond
• radiographic apex
• Continuous irritation of the periapical
• tissues endo failure

23. Iatrogenic errors
• Anatomic factors—
• Such as ： overly curved canals, calcifications,
• numerous lateral and accessory canals,
• bifurcations, C or S shaped canals
• Problems in cleaning and shaping &
• incomplete filling of root canals
•  endodontic failure

24. Iatrogenic errors
• Root fractures—
• Partial or complete fractures of roots
• Prognosis of teeth ：
• vertical root is poor than horizontal fractures
• Traumatic occlusion –
• Cause endo failures because of its effect on
• periodontium

25. Systemic factors causing
endodontic failures
• Nutritional • Autoimmune disorders
deficiencies • Opportunistic
• Diabetes mellitus infections
• Renal failure • Aging
• Blood dyscrasias • Long term steroid
• Hormonal imbalance therapy

26. Endodontic retreatment
 Before going/performing
 Case selection
 Prognosis ,Contraindications and problems
 Steps

27. Before going to endodontic
retreatment
• when should Treatment be considered
• Patient’s needs
• Strategic importance of the tooth
• Periodontal evaluation of the tooth
• Chair time & cost

28. Before performing to
endodontic retreatment
• May to prevent the potential disease
• Remove/remade extensive coronal restoration
• Technical problems
• May not achieve better results
• Filling materials have to be removed
• Prognosis could be poorer
• Patient might be more apprehensive

29. Case selection
• Careful history
• Anatomy of root canal , canal curvature,
calcifications,unusual configurations
• Quality of obturation
• Iatrogenic complications
• Cooperation of the patient

30. Factors affecting prognosis
of endodontic treatment
• Periapical radiolucency
• Quality of the obturation
• Apical extension of the obturation material
• Bacterial status
• Observation period
• Postendodontic coronal restoration
• Iatrogenic complication

31. Contraindications of
endodontic retreatment
• Unfavorable root anatomy
• Untreatable root resorptions or perforations
• Root or bifurcation caries
• Insufficient crown/root ratio

32. Problems of endodontic
retreatment
• Unpredictable result
• Frustration
• Cost factor
• Time consuming

33. Steps of Retreatment
1. Coronal disassembly
2. Establish access to root canal system
3. Remove canal obstructions
4. Establish patency
5. Thorough cleaning, shaping and obturation of
the canal

34. 1. Coronal Disassembly
• Removal of existing • Access made through
coronal restoration coronal restoration

35. Disadvantages of
Advantages of gaining retaining a
access through restoration:
original restoration:
a. Reduce visibility and
a. Facilitate rubber dam
accessibility
placement
b. Increased risks of
b. Maintaining form,
irreparable errors
function and aesthetics
c. Increased risks of
c. Reducing the
microbial infection if
cost of replacement crown margins are
poorly adapted

36. Advice:
Remove the existing restoration
Especially: poor marginal
adaptation, secondary caries
Place temporary crown
to maintain form, function
and aesthetics.

37. 2. Establish Access to Root
Canal System
Teeth restored with post and
core:
1.Post and core need to be
removed for gaining access to
root canal system
2.Post and core can be perforated
to gain access

38. Posts can be removed by:
1. Weakening retention of
posts by use of ultrasonic
vibration.
2. Forceful pulling of posts but it increases the risk
of root fracture
3. Removing posts with the help of special pliers
using post removal systems

39. Post Removal System(PRS)

40. Post Removal System(PRS)
• 5 various designed trephines
• Corresponding taps(microtubular tap)
• Torque bar
• Transmetal bur
• Rubber bumpers
• Extracting plier

41. 1-Transmental bur
Effeciently dooming of the post head

42. 2-Add lubricant
• EX: RC Prep
• Be placed on the post head to further facilitate the
machining process

43. 3-Trephine bur
Use the largest bur to machine down
the coronal 2-3 mm of the post.

44. 4-Rubber bumper
inserted on the tab & pushed on the occlusal
surface.
Act as a cushion, distribute the loads and
protect thetooth during the removal
procedure.

45. 5-Microtubular tap
• Inserted against the post head.
• Screwed it into post with counter clockwise
direction and strongly engage the post.

46. Post removal plier
• Mount the post removal plier on tubular tap
• Ultrasonic instrument using/torque bar inserting
Ultrasonic instrument
Screw knob Tubular tap
Rubber bumper
plier

47. Post removal plier
1 -Nonsurgical Removal of Posts Broken Instruments - YouTube_x264.mp4

48. Removing Canal
Obstructions and
Establishing Patency

49. Silver Point Removal
A- Microsurgical forceps

50. Silver point removal
B-Ultrasonic

52. Siver point removal
C- Using Hedstroem files(H-files)

53. Silver Point Removal
E- Post removal system kit.
D- Instrument removal system(IRS).

54. Gutta-Percha Removal
• The relative difficulty in removing gutta-percha is
influenced by some factors of canal system:
 Length
 Diameter
 Curvature
 Internal configuration
• Progressive Manner :
gutta-percha is best removed from canal in
progressive manner to prevent its extrusion
periapically

55. Gutta-Percha Removal
• Coronal portion of gutta-percha should always be
explored by Gates-Gliddens to:
 Quickly : Remove gutta-percha quickly
 Solvent : Provide space for solvents
 Convenience : Improve convenience form
• Gutta-percha can be removed by using:
 Solvents
 Hand instruments
 Rotary instruments
 Microdebrider

56. 1. Solvents
• GP is soluble in:
 Chloroform ： most effective but carcinogenic with
high concentratin , excessive filling in pulp
chamber is avoided
 Methyl chloroform
 Benzene
 Xylene
 Eucalyptol oil
 Halothane
• GP dissolution should be supplemented by using
hand instruments

57. 2. Hand Instruments
Used mainly in apical portion of the canal.
• Hedstroem files
• Hot endodontic instrument like Reamer or files
Poorly condenced GP can be pulled easily

58. 3. Rotary Instruments
•They are Safe to be used in straight canals
Recently:
•ProTaper universal systems
 Consisting of file :D1 D2 D3
 500-700 rpm

59. Protaper universal system
• D1 :
Remove filling from the coronal third
• D2 :
Remove filling from the middle third
• D3 :
Remove filling from appical third

60. Microdebriders

A small files with 90 degrees bends

Removing remaining gutta-percha on the sides
of canal walls

61. Pastes and Cement

Soft setting pastes

Penetrated by endodontic instruments

Hard setting cements

Softened by solvents: xylene, eucalyptol......
Then removed by files .

Ultrasonic devices

62. Separated Instruments and
Foreign Objects

Coronal third – attempt retrieval

Middle third – attempt retrieval or bypass

Apical third – surgical treat

63. Separated Instruments and
Foreign Objects

Attempt retrieval

Mechanism → Stieglitz pliers, Massermann
extractor

Vibration → Ultrasonics

Accessibility → Modified Gates Glidden
bur

Bypass

Reamers or files with copious irrigation

Surgical treat

Apicoectomy

64. Ultrasonic
4-endo(instrument removal) - YouTube_x264.mp4

65. Instrument removal system (IRS)
Can be used to remove the
broken files
microtube screw wedge

66. The beveled end of the microtube The introduction of the screw wedge which is
oriented toward the outer wall of the rotated CCW to engage and displace the head
canal to “scoop up” the head of the of the file out the side window.
broken file.

68. Completion of the
Retreatment

Thorough cleaning, shaping and obturation

The outcome of retreatment

Short-term: no pain and swelling

Long-term: depended regaining canal patency &
obturation of the root canal system

Retreatment is mostly associated with procedural
complication.

Effective communication is required b/t dentist & patient.