The document discusses causes and management of post-treatment endodontic disease. It identifies several potential causes of post-treatment apical periodontitis including persistent or reintroduced intraradicular microorganisms, extraradicular infection, foreign body reaction, and true cysts. Persistent intraradicular infections are the major cause, with bacteria able to survive through biofilm formation, entering dormant states, and activating stress response genes. Extraradicular infections may also develop through biofilm formation on root surfaces. While some case reports have suggested non-microbial causes, microbes are often difficult to rule out as a contributing factor.

1. Causes and management of post treatment
Praveen Jangid.
endodontic disease
1

2. Introduction
In recent years the number of people seeking endodontic
treatment has dramatically increased because of conservative
tendency towards root canal treatment over tooth extraction
(Ruddle 2002)
The aim of root canal treatment is to clean and disinfect the root
canal system in order to reduce the number of micro-organisms,
remove necrotic tissue, and finally seal the system to prevent
recontamination.
Success rates up to 97% have been reported for endodontic
initial treatment (Friedman 2004)
2

3. Prevalence of apical periodontitis and other post-treatment
periradicular diseases can exceed 30% of all root-filled teeth.
(Boucher 2002; Eriksen 2002; Friedman 2002; Dugas 2003)
In the past, undesirable outcomes of endodontic therapy were
described as failures.
Friedman states 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.”
He has suggested using the term posttreatment disease to describe
those cases that would previously have been referred to as treatment
failures.
Principles and practice of endodontics, ed 4, St. Louis, 2009.
3

4. Post-treatment apical periodontitis,
which can be categorised as-
• If developed after
treatment
Emergent
• If persisted despite
treatment
Persistent
• If developed after
having healed
Recurrent
B Dent J.; 2014;216 (6); 305-311
4

5. Etiology of Post treatment Disease
To effectively plan treatment, the clinician may place the
etiologic factors into four groups
1) Persistent or reintroduced intraradicular microorganisms
2) Extraradicular infection
3) Foreign body reaction
4) True cysts
Essential Endodontology.Prevention and treatment of apical
periodontitis, New York, 2008,
5

6. Causes of post-treatment apical periodontitis
Microbial cause – intraradicular infection
Microbial cause – extraradicular infection
Non-microbial cause
Procedural errors and
6

7. Microbial cause – intraradicular infection
Highly associated with intraradicular infection by studies using
microscopy, culture or molecular methods.
J Endod 2009; 35: 169–174.
Bacteria resisting the effects of treatment usually located in areas
of difficult access, to instruments and irrigants, and often in
direct contact with a source of nutrients from the periradicular
tissues.
Include the
Apical part of the root canal,
Lateral canals,
Apical ramifications,
Isthmuses
Dentinal tubules.
7

8. Microbial cause – intraradicular infection…..
Akehashi et al. (1965) exposed the dental pulps of conventional
and germ-free rats to the oral cavity and reported that pulp
necrosis and periradicular lesions developed only in
conventional rats with an oral microbiota.
Sundqvist (1976) confirmed the important role of bacteria in
periradicular lesions in a study using human teeth, in which
bacteria were only found in root canals of pulpless teeth with
periradicular bone destruction.
The chances of a favourable outcome with root canal treatment
are significantly higher if infection is eradicated effectively
before the root canal system is obturated.
However, if microorganisms persist in the root canal at the time
of root filling or if they penetrate into the canal after filling, there
is a higher risk that the treatment will fail (Byström et al. 1987,
Sjögren et al.1997).
8

9. Microbial cause – intraradicular infection…..
Risk of reinfection will be is dependent on the quality of the root
filling and the coronal seal (Saunders & Saunders 1994).
A radiograph of a seemingly well-treated root canal does not
necessarily ensure the complete cleanliness and/or filling of the
root canal system (Kersten et al . 1987).
To survive in the root-filled canal, microorganisms must
withstand intracanal disinfecting measures and adapt to an
environment in which there are few available nutrients.
9

10. Microbial cause – intraradicular infection…..
Bacteria entombed by the root filling
usually die or are prevented from
gaining access to the periradicular
tissues.
Some bacterial species will probably
survive for relatively long periods,
deriving residues of nutrients from
tissue remnants and dead cells.
If the root canal filling fails to provide
a complete seal, seepage of tissue
fluids can provide substrate for
bacterial growth.
If growing bacteria reach a significant
number and gain access to the
periradicular lesion, they can continue
to inflame the periradicular tissues.
10

11. Microbial cause – intraradicular infection…..
Several regulatory systems play essential roles in the ability of
bacteria to withstand nutrient depletion.
These systems are under the control of determined genes, whose
transcription is activated under conditions of starvation.
Under conditions of nitrogen starvation, the activation of the
Ntr gene system enables bacteria that require ammonia as a
nitrogen source to scavenge even small traces of ammonia.
Under high concentration of ammonia, the Ntr gene system is
uncoupled.
Int Endod J 2001; 34, 1–10.
11

12. Microbial cause – intraradicular infection…..
Some facultative bacteria may activate the Arc system
(aerobic respiration regulatory ), under conditions of low
concentrations of molecular oxygen.
So that a shift can occur from aerobic to anaerobic
metabolism.
Under low concentrations of glucose, some bacteria can
activate the catabolite repressor system, under control of the
genes Cya (adenylate cyclase) and Crp (catabolite repressor
protein), which induce the synthesis of enzymes for the
utilization of various other organic carbon sources.
12

13. Microbial cause – intraradicular infection…..
Under conditions of phosphate starvation triggered by low
concentrations of inorganic phosphate, cells turn on genes for
utilization of organic phosphate compounds and for the
scavenging of trace amounts of inorganic phosphate.
Int Endod J 2001; 34, 1–10.
Heat-shock proteins are family of highly conserved proteins
whose main role is to allow microorganism to survive under
stressful conditions.
13

14. Microbial cause – intraradicular infection…..
The microbiota associated with failed cases differs markedly
from that reported in untreated teeth (primary root canal
infection).
T.denticola, P.alactolyticus, T.forsythia, P.gingivalis, T.
socranskii, P.endodontalis.
Fungi are not found.
The reduction of Gram-negative organisms following endodontic
treatment and the subsequent proportional increase of Gram-positives
facultatives.
Streptococci ( Streptococcus mitis, Streptocoocus gordonii,
streptococcus anginosus, Streptococcus sanguinis and
streptococuus oralis), Parvimonas micra, Actinomyces species,
Propionobacter species, Pseudoramibacter alactolyticus,
lactobacilli, E faecalis.
14 JOE 2008; 34(11), 1296

15. Microbial cause – intraradicular infection…..
15

16. Microbial cause – intraradicular infection…..
Möller (1966), reported a mean of 1.6 bacterial species per root
canal. Anaerobic bacteria corresponded to 51% of the isolates.
Enterococcus faecalis was found in 29% of the cases.
E. faecalis strains have been demonstrated to be extremely
resistant to several medicaments, including calcium hydroxide
(Jett et al . 1994, Siqueira & Uzeda 1996, Siqueira & Lopes 1999).
It has been shown that some bacteria, such as E. faecalis, can
enter a viable but noncultivable state, which is a survival
mechanism adopted by many bacteria when exposed to
environmental stresses like low nutrients concentrations, high
salinity, and extreme pH
16

17. Microbial cause – intraradicular infection…..
Sedgley et al showed that E. faecalis has the capacity to recover
from prolonged starvation state in the root canal treated teeth;
when inoculated into the canals, this bacterium maintain viability
for 12 months without additional nutrients.
Thus viable E. faecalis entombed at the time of root canal filling
may provide a long term nidus for subsequent infection.
Yeast-like microorganisms have also been found in root canals of
obturated teeth in which treatment has failed (Nair et al. 1990a).
In fact, it has been demonstrated that Candida spp. are resistant
to some medicaments commonly used in endodontics (Waltimo
et al . 1999).
17

18. Microbial cause – intraradicular infection…..
Persistent infections are the major cause of post-treatment apical
periodontitis does not preclude secondary infections due to
coronal leakage.
Cross-sectional studies indicate that the best outcome is achieved
in teeth with adequate root canal fillings associated with
adequate coronal restorations.
J Endod 2013; 39: 600–604.
It is advisable to treat the tooth as a continuum, placing a well-adapted
permanent coronal restoration as soon as possible after
finishing root canal treatment.
18

19. Microbial cause – extraradicular infection
Extraradicular infection may be associated with chronic
inflammation and lead to endodontic treatment failure.
By defending themselves against the action of the complement
system, avoiding destruction by phagocytes, causing
immunosuppression, changing antigenic coats, and inducing
proteolysis of antibody molecules (Siqueira 1997).
Int Endod J, 2001; 34, 1–10,
May be associated with –
A biofilm formation on the external root surface
Endod Dent Traumatol 1990; 6: 73–77.
Sometimes showing calculus-like calcifications,
Int Endod J 2005; 38: 262–271.
or forming cohesive actinomycotic colonies within the body of the
lesion.
Endod Dent Traumatol 1986; 2: 205–209.
19

20. Microbial cause – extraradicular infection…..
The extraradicular infectious process can be dependent on or
independent of the intraradicular infection.
Dependent infection- maintained by constant proliferation and
invasion of the periradicular tissues by bacteria present in the
intraradicular infection.
Cannot sustain itself without the intraradicular component.
Independent infections - that are no longer fostered by an
intraradicular infection and as such may not respond to adequate
root canal treatment.
Endodontic Topics 2003; 6: 78–95.
20

21. Microbial cause – extraradicular infection…..
One of the most significant mechanisms of evasion from
the host defence system is the microbial arrangement in a
biofilm.
A biofilm can be defined as a microbial population attached to an
organic or inorganic substrate, surrounded by microbial
extracellular products, which form an intermicrobial matrix
(Costerton et al )
Biofilm formation is a step-wise procedure ,its formation occurs
in the presence of microorganisms, fluid and solid surface.
21

22. Microbial cause – extraradicular infection…..
Organized in biofilms, microorganisms show higher resistance to
both antimicrobial agents and host defence mechanisms when
compared with planktonic cells.
(Costerton et al 1987, 1994, Gilbert et al. 1997).
By examining teeth refractory to root canal treatment, Tronstad
et al. (1990) reported the occurrence of bacterial biofilms
adjacent to the apical foramen and bacterial colonies located
inside periradicular granulomas.
Int Endod J, 2001; 34, 1–10.
22

23. Microbial cause – extraradicular infection…..
The major consideration regarding treatment of periradicular
biofilms is that the clinician cannot detect a biofilm in any
particular clinical case.
Theoretically, microbiological sample could inform the clinician
if the root canal is bacteria free or if there are persistent
intracanal microorganisms.
Once root canal samples yield negative cultures, the canal is
obturated. If subsequent healing does not occur, then one may
suspect extraradicular infection.
It is well known that intracanal disinfection procedures or
systemically administrated antibiotics can not easily affect
bacteria located outside the apical foramen.
23

24. Microbial cause – extraradicular infection…..
The placement of endodontic medicaments into the periradicular
tissues in order to eliminate microorganisms and to decompose
periradicular biofilms does not appear to be an adequate
procedure.
First, it is currently difficult or even impossible to clinically
diagnose extraradicular infections.
Secondly, most endodontic medicaments are cytotoxic and/or
may have their antimicrobial effects neutralized after apical
extrusion.
The development of a nonsurgical strategy to combat biofilms
appears questionable.
Therefore, extraradicular infections, if present, must be treated
by means of periradicular surgery.
24

25. Microbial cause – extraradicular infection…..
So far, there is no clear evidence that an extraradicular infection
can exist as a self-sustained process independent of the
intraradicular infection.
J Endod 2008; 34: 1124–1129
Ricucci et al. evaluated several treated teeth with post-treatment
apical periodontitis and could not detect any case of independent
extraradicular infection.
J Endod 2009; 35: 493–502.
25

26. Sjogren’s study on Success vs. Failures
Sjögren and his associates - study of 356 endodontic patients, re-examined
8 to 10 years later
Reported a 96% success rate if the teeth had vital pulps prior to
treatment.
The success rate dropped to 86% if the pulps were necrotic with
periradicular lesions.
They dropped still lower to 62% if the teeth had been re-treated.
They concluded by stating that “teeth with pulp necrosis and
periradicular lesions and those with periradicular lesions
undergoing re-treatment constitute major therapeutic problems…
J Endod 1990;16:498–504
26

27. Clinician Versus Bacteria
What treatment does What bacteria do to survive
Mechanical effect (irrigants) form biofilm firmly adhere to canal
wall
colonizes in isthmus, ramifications
and dentinal tubules.
Mechanical effect (instruments) ----as above
Chemical effect ( irrigants) -----as above Plus they are protected
by
tissue remnants, dentin, serum or
dead cells, all of which have
activity to reduce effect of
intracanal medicament.
JOE 2008; 34(11), 1296
27

28. What treatment does What bacteria do to survive
Chemical effect ( interappointment
resistant to antimicrobial T/t,
dressings)
Form biofilm structures
enclosed by protective
polysaccharide matrix.
Ecological effect : ( nutrient
deprivation)
Turning on several genes
Enter viable noncultivable state.
Forms new pair and partnership.
28 JOE 2008; 34(11), 1296

29. Non-microbial cause – fact or myth?
There are few case reports that suggest that some lesions may not
heal because of endogenous or exogenous non-microbial factors.
Crit Rev Oral Biol Med 2004; 15: 348–381.
Endogenous causes include cholesterol crystals and true cysts,
Exogenous causes comprise foreign-body reactions to apically
extruded filling materials, paper points or food.
J Endod 2009; 35: 493–502.
In most of these cases it is very difficult to rule out the
concomitant presence of infection as the cause of disease.
Therefore, the participation of non-microbial factors as the
exclusive cause of treatment failure has still to be consistently
proven.
29

30. Although in the past the toxicity of the root filling materials had
been considered as the cause of persistent inflammation when
apically extruded.
Arch Oral Biol 1966; 11: 373–383.
apical extent of root canal fillings seems to have no correlation
with treatment failure, provided infection is absent.
Int Endod J 1997; 30: 297–306.
Disease associated with overfilled root canals is generally caused
by a
Concomitant infection in cases where a proper apical seal is missing,
Favouring nutrient supply to residual bacteria in the canal,
or when infected dentinal debris are projected extraradicularly as a
result of previous overinstrumentation.
B Dent J.; 2014;216 (6); 305-311
30

31. Procedural errors and post-treatment disease
The major problem with a procedural accident arising during
chemomechanical procedures is when it prevents or makes it
difficult for the clinician to properly disinfect the apical part of
the root canal.
Such as-
Missing canal,
Fractured instrument,
Ledge
Perforation
Overfilling
31

32. Management of post-treatment apical
periodontitis
Teeth with post-treatment apical periodontitis can be managed
by either nonsurgical endodontic retreatment or periradicular
surgery, some teeth are extracted, but many remain untreated in
spite of the evident pathosis.
These two approaches differ significantly in rationale –
retreatment is an attempt to eliminate root canal infection,
whereas apical surgery is an attempt to enclose the infection within
the canal.
To foster confidence and appropriate management, definitive
criteria are required to select cases for extraction, retreatment or
apical surgery
32

33. Considerations are unique to retreatment cases
(i) An extensive restoration may have to be sacrificed and remade;
(ii) Potential for future disease may have to be considered ;
(iii) Morphologic alterations resulting from the previous treatment
may present unusual technical and therapeutic challenges ;
(iv)The healing rate is generally lower than after initial treatment.
because of greater difficulty in eliminating the infection ;
(v) Patients may be more apprehensive than with the "routine“
initial treatment.
The above considerations complicate the subjective process of
case selection
J. O. E. 1986; 12: 28-33.
33

34. Case Selection
Diagnosis.
Presence or absence of disease is determined according to
clinical and radiographic findings.
Assessment of outcome of root canal treatment
Should be assessed at least after 1 year and subsequently as
required.
Favorable outcome:
Absence of pain, swelling and other symptoms, no sinus tract,
no loss of function.
Radiological- normal periodontal ligament space around the
root.
Quality guidelines European Society of Endodontology
34 IEJ,39, 921–930, 2006

35. Uncertain outcome:
lesion has remained the same size or has only diminished in size.
In this situation it is advised to assess the lesion further until it
has resolved or for a minimum period of 4 years.
If a lesion persists after4 years the root canal treatment is usually
considered to be associated with post-treatment disease.
Unfavorable outcome:
1) The tooth is associated with signs and symptoms of Infection.
2) A radiologically visible lesion has appeared subsequent to
treatment or a pre-existing lesion has increased in size.
3) A lesion has remained the same size or has only diminished in
size during the 4-year assessment period.
4) Signs of continuing root resorption are present.
In these situations it is advised that the tooth requires further
treatment.
IEJ,39, 921–930, 2006
35

36. Non-endodontic disease or a healing process should be carefully
considered as a differential diagnosis .
The case history is reviewed,
Noting previous radiographs when available.
Past symptoms.
Time elapsed since previous treatment and
Previous attempts at retreatment or apical surgery
36

37. In the past, it was the clinician's responsibility to select and
then provide the most appropriate treatment.
Currently, it is the patient who selects the treatment.
The clinician's responsibility is to communicate the
information and thus facilitate the patient's decision making
process, and to provide the selected treatment.
37

38. Patient Considerations
People's attitudes towards disease and necessity of treatment
differ significantly
Int Endodod J 1998: 31: 358-63.
38

39. Tooth Considerations
Site of infection-
For root canal infection prognosis is best with retreatment.
For periapical (extraradicular) infection independent of the root
canal flora, prognosis is best with apical surgery.
In contrast, when a vertical crack or fracture is present, prognosis is
hopeless with both procedures .
Differential diagnosis is required, therefore, to establish the likely
site of infection.
Typical manifestation of periapical actinomycosis - one or more
sinus tracts, and that of vertical crack/ fracture - isolated, narrow
defect along the root
39

40. Root canal complexities
The potential of retreatment to
capacitate healing is actualised mainly
when root canal patency can be regained
throughout.
Feasibility of overcoming these
complexities must be assessed.
40

41. Perforation
Perforation of the pulp chamber or root comprises a pathway of
infection and impairs the prognosis.
Retreatment in conjunction with internal repair of the perforation
is warranted to curtail the infection.
when healing appears unlikely or does not occur, surgery may be
required, including external repair of the perforation and
possibly an attempt at guided tissue regeneration.
Restorative, periodontal and aesthetic factors.
Teeth considered to have hopeless restorative or periodontal
prognosis should be extracted.
With compromised periodontal support, surgery may result in an
unfavourable crown-root ratio; therefore, retreatment is selected.
41

42. Clinician considerations
Clinicians vary with regards to-
Capability- Procedure that can be performed best by the
attending clinician is selected,
Armamentarium- The instruments required to perform either
procedure are available, that procedure is selected.
Time availability- In specific circumstances (remote areas,
community clinics) an excessive practice load prevents a
clinician from undertaking a lengthy retreatment of one complex
case, surgery is selected
42

43. Previous Treatment Attempts
If a previous retreatment or apical surgery procedure did not
result in healing, the quality of the treatment provided should be
accessed.
If it is considered that the initial case selection was appropriate
but the quality can be significantly improved, the same
procedure is selected again.
Otherwise, the alternative procedure is selected, considering that
it may better address the site of the infection and capacitate
healing
43

44. Prevention of potential disease
Endodontically treated teeth may appear to be free of any signs
of disease and yet harbor microorganisms in the canal.
The factors that may affect emergence of post-treatment
endodontic disease are listed below:
 The adequacy of the coronal seal;
 The adequacy of the root filling
 The need for a new restoration
44 Endodontic Topics 2002, 1, 54–78

45. When both the root filling and the coronal seal are suspect, and a
new restoration is needed.
In these cases retreatment is indicated, as it offers the benefit of
preventing post treatment disease.
When a new restoration is not needed and only the root filling is
suspect, emergence of post-treatment disease is less likely, and
retreatment offers a lesser or no benefit.
In these cases only follow-up is indicated; retreatment, and
associated possible complications, can be avoided.
45 Endodontic Topics 2002, 1, 54–78

46. Endodontically treated tooth
Evaluation of treatment results
Established failure Potential failure
Feasibility of coronal access
unfeasible
Surgery
Feasible
Evaluation of obturation quality
Needed Not needed
Retreatment new restoration
Satisfactory
Follow up
Unsatisfactory
Needs new restoration
Follow up
46

47. Outcome of endodontic retreatment
success rate of retreatment as revealed by well-controlled studies
ranges from 62% to 84%.
J Endod 2004;30: 745–50
The approximately 10-20% lower success rate to be related to
the following:
Inability of completely removing the previous obturation or
Correcting previous errors, which may limit access to residual
bacteria;
Difficulties to reach persistent bacteria located in areas distant
from the main root canal; and
Resistance of persistent bacteria to the antimicrobials used.
47

48. Outcome of periradicular surgery
Teeth that had previous root canal obturation categorised as
inadequate, presents a significantly better outcome than well-treated
teeth.
J Endod 2004; 30: 627–633.
Inadequately treated teeth may not respond so well to
retreatment, periradicular surgery may then arise as a good
therapeutic alternative.
Studies have reported a high success rate for surgery (87%-92%)
when performed using magnification, ultrasonic root-end
preparation, and root-end fillings with materials such as mineral
trioxide aggregate (MTA), intermediate restorative material
(IRM) or Super ethoxy benzoic acid (SuperEBA).
48 Int Endod J 2003; 36: 520–526.

49. Rubinstein and Kim reported a 91.5% success rate over 5–7
years. These percentages are significantly better than those
quoted in the earlier studies of endodontic periapical surgery
Int Endod J 2003; 36: 193–8
In summary, the best success rate can be achieved if orthograde
retreatment is done first followed by periapical surgery, if
indicated.
49

50. Nonsurgical Vs surgical retreatment
At the 1-year follow up the success rate for surgical treatment was
slightly better than non-surgical.
When the follow up was extended to 4 years the outcome for the two
procedures became similar.
Cochrane 50 Database Syst Rev. 2007 Jul 18;(3):CD005511

51. Interestingly, the percentage of teeth still in ‘function’ ranged
from 78% to 97%. This is a similar term to ‘implant survival’
which many implant studies have used as a measure of implant
treatment outcomes.
The survival rate of dental implants has been reported as ranging
from 76% to 94% ‘Survival’ or ‘functional’, however, do not
necessarily equate to biological success.
Clin Oral Implants Res 2004; 15: 8–17
51

52. Conclusion
The main aim of root canal treatment is to clean and disinfect the root
canal system, thereby reducing the bacterial load, removing necrotic
tissue and creating an environment in which periapical healing can
occur.
Identify the possible causes of post-treatment apical periodontitis and
approach these cases accordingly.
Nonsurgical retreatment is considered to provide a better opportunity to
disinfect the root canal system than a surgical approach, as it is
generally not possible to clean the coronal part of the root canal system
during endodontic surgery.
The best success rate can be achieved if orthograde retreatment is done
first followed by periapical surgery, if indicated.
52

53. Thank you
53