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Endodontic failures

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Brief note on different terms defining success and failure, endodontic outcome studies, causes of failure

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Endodontic failures

  1. 1. Deepthi P.R.
  2. 2. • Introduction • Terms • Treatment Outcome studies • Persistent Apical Periodontitis and its Causes • Measures to improve Success • References
  3. 3. • Natural tooth with a good prognosis – superior choice to loss & replacement • First question by patients: Degree of anticipated SUCCESS • Success enjoyed- much higher than other phases of reconstructive dentistry • Not all treatments result in optimum long- term healing • Very small rate of unsuccessful outcomes: large numbers of patients requiring further treatment
  4. 4. • Until the 1990s, the terms “success” and “failure” were in vogue with endodontic treatment. • “healed,” “tendency to heal,” “not healed” and “regression” * • The very high ‘‘success’’ rates reported for single-tooth implants may mislead patients who are weighing endodontic treatment against replacement of the tooth with an implant • “Failure” does not imply the necessity to pursue any course of action, and in addition, it has a negative connotation *ENDODONTICS- Colleagues for Excellence. Fall/ Winter 2003
  5. 5. • ‘‘The accomplishment of an aim or purpose’’ (Oxford Dictionary), • Success of a given therapy in medicine or dentistry may be defined as the result obtained which achieved the initial treatment goal • The term "failure" consequently may be defined as a treatment that did not reach the objective or fell short of the acceptance level—for example, in terms of tissue function, elimination of pathology, comfort, or even survival
  6. 6. • Communication with patients can be improved by replacing the value-laden terms ‘‘success’’ and ‘‘failure’’ with neutral expressions: • ‘‘chance of healing’’ • ‘‘risk of inflammation’’ • Avoid the terms ‘‘success’’ and ‘‘failure’’ in defining the outcome of endodontic treatment
  7. 7. • Aim is to prevent or cure apical periodontitis • The outcome of endodontic treatment should be related to ‘‘healing.’ • Rud et al. introduced a classification for outcome assessment after apical surgery that referred to healing: - Complete - Incomplete - Uncertain - Unsatisfactory
  8. 8. • A successful outcome is strictly defined by complete absence of radiolucency & absence of clinical signs and symptoms • Complete normalcy has been named ‘‘success’’ • Unchanged radiolucencies represent ‘‘failure’’ • A smaller radiolucency, in the presence of clinical normalcy, is usually considered as ‘‘incomplete healing’’ • Not a successful outcome, but rather as an interim outcome requiring further observation
  9. 9. • ‘‘Success’’ is defined as the absence of clinical signs and symptoms • Clinical normalcy may be accompanied by a residual radiolucency, either decreased or unchanged in size, but not increased • Use of ‘‘lenient’’ outcome criteria that do not require radiographic normalcy increases the ‘‘success’’ rate in comparison with use of ‘‘strict’’ criteria that do require radiographic normalcy • Friedman et al. reported 78% complete healing & 16% incomplete healing after NSRCT which would be 94% by the ‘‘lenient’’ criteria
  10. 10. • Specific to teeth affected by preoperative apical periodontitis. • Frequently asymptomatic, both before treatment & when persisting after treatment. • But, universally considered a disease requiring therapy • Persisting apical periodontitis after therapy cannot be regarded as ‘‘success’’ only because it is asymptomatic, & treatment is still indicated.
  11. 11. • Complete clinical and radiographic normalcy • No signs, symptoms, residual radiolucency The typical appearance of a scar after apical surgery
  12. 12. • Decrease in size of a radiolucency & clinical normalcy after a follow-up period shorter than 4 years.
  13. 13. • Presence of radiolucency (new, increased, unchanged, or reduced after observation exceeding 4 years) regardless of clinical presentation • Presence of symptoms regardless of radiographic appearance Immediate Postop Emerged disease- 3 years Further expansion- 6 years
  14. 14. • Aim-related terms, to define the outcome of treatment: improve communication with patients • Patients: encouraged to identify specific aims & define their expected outcome that can be considered a success • Individual patients may be satisfied with just elimination of clinical signs and symptoms: compromised prognosis cases
  15. 15. • Clinical normalcy with or without a persistent radiolucency, decreased or unchanged • Patient is still motivated to attempt treatment although healing is unlikely to occur • The aim of treatment is retention of the tooth in ‘‘asymptomatic function”
  16. 16. • Originally introduced to imply uncertainty of the outcome & also to define improved outcomes • Strictly: cases that could not be assessed because of insufficient radiographic information and thus were not included in either the successful or unsuccessful outcome categories • Same terms describe cases with a decrease in size of the radiolucencies & considered either as a successful or as an uncertain outcome for nonsurgical treatment & apical surgery • This modified classification lowered the failure rate in comparison with the strict classification
  17. 17. • Outcome definitions & classification have been inconsistent • Considerable variability of the reported ‘‘success’’ rates • The definition of outcomes using nonspecific ambiguous terms, such as ‘‘success’’ and ‘‘failure.’’ • Lack of calibration in outcome assessment, particularly for recording of radiographic findings: Inconsistency • Overstate the ‘‘success’’ rate by not noting teeth that could be radiographically normal but symptomatic
  18. 18. • Periapical Index (PAI) by Orstavik et al. 1986 The periapical index: A scoring system for radiographic assessment of apical periodontitis. Endod Dent Traumatol 1986; 2: 20-34 Periapical destruction of bone almost definitely not present Periapical destruction of bone probably not present Unsur e Periapical destruction of bone probably present Periapical destruction of bone almost definitely present
  19. 19. • No direct interpretation of the scores as “ success” or “ failure” • Scores 1 & 2: “ Healthy” periapical tissues • Scores 3 & above: “Disease” • Mere changes on a radiograph cannot determine the extent of the periradicular healing process ENDODONTICS- Colleagues for Excellence. Fall/ Winter 2003
  20. 20. • Ingle & Beveridge: undergraduate students at the University of Washington were capable of obtaining 95% success • When a carefully followed course of therapy is instituted; little opportunity to deviate from predetermined patterns of therapy- results are strongly in favor of success • Strindberg reported on degree of success, criteria: the point to which the canal was filled whether past the radiographic apex, exactly to it, or short of it. • All types, responded with success more than 90% of the time, teeth filled slightly short of the apex had the highest ratio of success.
  21. 21. • Evaluate endodontically treated teeth to determine their rate of success • Rate of failure, causes of failure • Analysis of the failures led to modifications in technique & treatment • Improvements in treatment are reflected in the improvement in success, which increased to 94.45% from a former success rate of 91.10% • 95% of all endodontically treated teeth were successful • There was also a hidden agenda to the Washington study—to prove: root canal therapy could be successful if properly done
  22. 22. • The modifications in treatment : instituted following a pilot study of endodontic success and failure • Even with the limited number of patients in the pilot study, the causes of failure became apparent. • Clinical techniques were then changed in an effort to overcome failure
  23. 23. • Patients were recalled for follow-up at 6 months, 1 year, 2 years, and 5 years • Radiographs were carefully evaluated for improvement or lack of improvement • Success group: Decided periradicular improvement & those with continuing periradicular health • Failures: Teeth that initially demonstrated periradicular damage and that had not improved, as well as those that had deteriorated since treatment
  24. 24. • The 2-year recall series was found to be ideal for this study because a statistically significant sample developed within this group • The 5-year recall sample was also analyzed • The study did not take into consideration any illnesses or systemic differences between patients 2- Year Recall Analysis • 1229/ 3678: recall rate of 33.41% • Before improvements instituted: 91.10% success rate— 104 failures of 1,067 cases • After these improvements were instituted, the success rate rose to 94.45%—9 failures of 162 cases.
  25. 25. • 2.5 years -92 years • Fairly consistent rate of success & failure according to age as shown by statistical analysis • Older teeth: More restricted canals, were more successfully obturated than very “young” teeth with large- diameter canals. • Size and shape of the lumen of the canal, direction of root curvature, play an important part in the successful completion of a root canal filling
  26. 26. • No significant difference in failure existed between any of the teeth in either arch • No particular tooth can be considered a higher endodontic risk • A wide discrepancy between the mandibular second premolar with a failure rate of 4.54% and the mandibular first premolar with a failure rate of 11.45% • Canal anatomy might account for the greater increase in failure in the first premolar
  27. 27. • Mandibular 2nd Pm has 2 canals & 2 foramina 11.5% of the time, the mandibular 1st Pm has branching canals, apical bifurcation, and trifurcation 26.5% of the time- Pucci & Reig- 1944 • Pennsylvania study by Trope et al. in 1986 also confirmed: African American patients more frequently have two canals in lower premolars
  28. 28. • Maxillary lateral incisor: Pucci & Reig showed extensive distal curvature of the maxillary lateral incisor root 49.2% of the time • Poor judgment & preparation frequently prevent adequate instrumentation & obturation, with root perforation at the curvature a common occurrence • Increased failure rate in the maxillary lateral incisor is also related to continuing root resorption following treatment, a finding peculiar to these teeth
  29. 29. • Overall failure rate, mandible to maxilla, is striking but not statistically significant • Failure in the mandibular arch was encountered 6.65% of the time & 9.03% of the time in the maxilla
  30. 30. • Although NSRCT appears to be slightly more successful than surgical treatment, differences are not statistically significant • Failure rate: three times higher if a periradicular lesion existed before treatment Nelson • The Dutch study: “teeth with periradicular granulomas tend to heal less successfully than teeth showing cysts.” • Japanese researchers: Wide discrepancy in success between treated teeth that had no periradicular rarefaction (88%) & those with a 5.0 mm or greater rarefaction (38.5%) • Sjögren et al. Teeth without periradicular lesions, reported a 96% success rate; 86% if periradicular lesions
  31. 31. • Potential of microleakage under and around coronal restorations • Bacteria penetrating from the crown to the periapex alongside poorly obturated canals
  32. 32. • Penetrating through the side of a curved root ultimately leads to incomplete instrumentation and incomplete obturation
  33. 33. • Opening wide the apical foramen during instrumentation: also a form of perforation & leads to gross overfilling or overextension
  34. 34. Surgical treatment is recommended: • operable teeth if the instrument is broken off in the apical one-third of the canal • if the canal is grossly overfilled with irretrievable gutta- percha • Failures associated with underfilled canals can usually be remedied by retreatment rather than surgery • operative error is the simplest cause of failure to control and requires more patience, care, and understanding to overcome
  35. 35. • External root resorption would continue • Apical cyst would develop following treatment • Adjacent tooth would become pulpless • Associated periodontal lesion would lead to failure • Washington study: factors constituted 22.12% of the total failures • Root resorption- maxillary lateral incisors • Periodontal pockets: recognized before treatment
  36. 36. • Retrofilling failures • Root tip & foreign bodies left in surgical sites • Root fenestration following surgery • Cracked/ split roots • Carious destruction unrelated to the root canal treatment
  37. 37. • one of the most frequent causes of failure of the treated pulpless tooth is fracture of the crown • The tooth must be carefully protected by an adequate restoration.
  38. 38. • Only a radiographic study. • histologic evaluation is a much more accurate method of determining if inflammation remains at the apex than is radiologic evidence. • BUT , biopsy: impractical in live humans • 26% of the teeth with no radiolucencies showed chronic inflammation histologically- Walton • Since histologic evaluation is impractical: comfort and function & the radiographic findings
  39. 39. 95.2% success rate at the end of 1 year with 458 canals filled by the gutta-percha-euchapercha method • Vital inflamed pulps: more success (98.2%) than teeth with nonvital pulps (93.1%) • less successful with short-filled canals (71.1%) than with flush-filled or overfilled canals (100%).
  40. 40. • Success rate -89% success at the end of 1 year • 92% of the time in teeth filled to the apex • 91% of the time if the canals were overfilled • Filling short of the apex reduced their success rate to 82%
  41. 41. • 45% of the endodontically treated teeth had failed in nonaviators • 7% had failed in aviator patients • Aviators- gutta-percha or silver point fillings & their teeth were more frequently crowned • Nonaviators: “therapy with special chemical compounds.” Furthermore, the aviators’
  42. 42. • Remarkable study of 356 endodontic patients, re- examined 8 to 10 years later • 96% success rate if the teeth had vital pulps prior to treatment • 86% if the pulps were necrotic & the teeth had periradicular lesions • 62% if the teeth had been re-treated • Direct correlation between success & the point of termination of the root filling
  43. 43. 1. The more extensive and severe the endodontic pathosis, the poorer the prognosis. • Highest percentage of success is with teeth with vital pulps • Worst prognosis is for those with large, long-standing periradicular lesions. 2. The more dental treatment that is done, the poorer the prognosis • Good NSRCT has the best prognosis • The worst prognosis lies with teeth that have been retreated nonsurgically and then re-treated surgically once or twice more.
  44. 44. • Past “ success- failure” studies have erroneously included failures due to: - periodontal disease - root fractures - Inappropriate restorations - presence of coronal leakage. • These are not endodontic failures ENDODONTICS- Colleagues for Excellence. Fall/ Winter 2003
  45. 45. • When the studies are considered “en masse,” endodontic treatment results in more than a 90 percent success rate when: • Microbial challenges are eliminated through thorough canal cleaning, shaping & three-dimensional obturation • Coronal leakage is negated through proper, sound restorations • Patient practices preventive oral self care ENDODONTICS- Colleagues for Excellence. Fall/ Winter 2003
  46. 46. • Several comprehensive & narrative reviews: inconsistencies & contradictions among the reported outcomes of nonsurgical and surgical endodontic treatments • Answers to many questions concerning the outcome of endodontic treatment procedures: equivocal because of poorly standardized methodology of the many studies • Rapid evolution of clinical procedures has rendered results of specific studies less relevant today than when they were published
  47. 47. • When root canal treatment of apical periodontitis has not adequately eliminated intraradicular infection. • Problems include: - inadequate aseptic control - poor access cavity design - missed canals - inadequate instrumentation, debridement - leaking temporary or permanent restorations - Complex anatomy uninstrumented even when the most careful clinical procedures are followed P.N.R. Nair. International Endodontic Journal, 39, 249–281, 2006
  48. 48. Endodontic failure comprises: ● biological failings (infection) ● cysts ● root fracture ● incorrect diagnosis and primary treatment ● foreign body reactions ● healing with scar ● neuropathic problems ● economic constraints
  49. 49. • Commonest reason for failure: microbial infection • Microorganisms & their byproducts- isolated from the RC system & the external surface of the root in failed cases • Persisted following a previous attempt at RCT or gained access through coronal microleakage • Intraradicular & Extraradicular Infection
  50. 50. MICROBIAL CAUSES • Intraradicular Infection • Extraradicular Infection NON MICROBIAL CAUSES • Cystic apical periodontitis • Cholesterol crystals • Foreign bodies • Gutta percha • Other plant materials/ foreign materials P.N.R. Nair. International Endodontic Journal, 39, 249–281, 2006
  51. 51. • Teeth with technically deficient root fillings: more likely to be associated with periapical radiolucencies • Poor quality root filling: the RC system may not have been effectively disinfected or could have become reinfected through coronal microleakage
  52. 52. • The apical portion of the root canal system can contain bacteria & necrotic tissue substrate even following chemomechanical preparation • If the resultant microbial ecosystem is amenable to bacterial survival, a lesion may not heal
  53. 53. • Majority of root canal-treated teeth with asymptomatic apical periodontitis harboured persistent infection in the apical portion of the complex root canal system • Microorganisms: biofilm located within the small canals of apical ramifications in the root canal or in the space between the root fillings and canal wall. P.N.R. Nair. International Endodontic Journal, 39, 249–281, 2006
  54. 54. • Only Gram positive bacteria were found • Intraradicular fungi: potential non- bacterial, microbial cause
  55. 55. • The radiographic appearance of a RC filling does not give an indication of biological status • A satisfactory radiographic result could be failing biologically • If the root canal filling fails to provide a complete seal, seepage of tissue fluids: provide a substrate for bacterial growth • Bacterial regulatory systems: automatically transcripted under adverse conditions: survive periods of starvation or nutrient depletion
  56. 56. • Bacteria may not be completely eliminated after thorough cleaning, shaping & disinfection • Moreover, when obturation is postponed, bacteria may be able to recolonize in the canal • No preparation technique can totally eliminate the intracanal irritants, & a “critical amount” can sustain periradicular inflammation • Gutta-percha root canal fillings do not resist salivary contamination-“long term prognosis of treatment seems to correlate directly with the quality of the coronal seal.”
  57. 57. • Irritants: infected dentin chips, is packed at the apex or pushed through the apex • Periapical tissue could become colonized: - periodontal contamination - the virulence of the bacteria - Extrusion by overaggressive instrument action
  58. 58. • Host’s immune system can overcome these antigens • Some bacteria possess mechanisms to resist phagocytosis: encapsulation/ production of proteases aimed against the immune system • Bury themselves in a thick matrix that acts as a sort of apical plaque
  59. 59. • Organisms survive in periradicular lesions: - Actinomyces - Peptostreptococcus - Propionibacterium - Prevotella - Porphyromonas - Staphylococcus - Pseudomonas aeruginosa • Barnett, stated ‘Pseudomonas refractory periradicular infection could be “cured” only by heavy doses of metronidazole (Flagyl) following the failure of re- treatment and apicoectomy
  60. 60. • Bacterial infection: the major cause of persistent periapical inflammation following RCT • Technical failings that may predispose RC system to inadequate disinfection: - poor aseptic technique - incorrect irrigant - inability to prepare the canal to length - missed canals - procedural errors - poor obturation - poor restoration and coronal microleakage - resistant bacteria.
  61. 61. • The majority of RCT is carried out without a rubber dam • Could have a significant bearing on the likelihood of success, but to date there are no published data proving that the use of a rubber dam increases success rates BENEFITS ● prevention of microbial contamination ● the safe use of sodium hypochlorite ● airway protection ● retraction of the soft tissues ● unimpeded vision, which is useful with magnification ● quicker & more pleasant treatment ● reduction of microbial aerosol ● allows the operative field to be dried.
  62. 62. • Chemomechanical approach: Bacteria removed mechanically with instruments but also killed using irrigants which penetrate the complex internal anatomy • Irrigant choice: minimal effect on RCT outcome when analysed statistically
  63. 63. • Failure to achieve patency during preparation: inadequate penetration • Persistent infection & endodontic failure • Apical 3 mm of a RC- the highest percentage of lateral canals & deltas • If mechanical preparation & consequently irrigant penetration: 2–3 mm short of the constriction, the hypothetical length of canal that has not been disinfected could be as great as 6–7 mm
  64. 64. • Outdated filing techniques: stepback method can be fraught with instrumentation errors • Zips and elbows
  65. 65. • Aberrant or unusual anatomy: considered in retreatment cases • If a root-filled tooth appears satisfactory from a radiographic perspective but is still symptomatic, a missed canal could be suspected • The clinician must be aware of normal root canal anatomy before re-entering a RCTreated tooth and be prepared for added complexity in retreatment cases
  66. 66. • Infected tooth: predispose the treatment to failure by making it more difficult to effectively disinfect the entire RC system • Ledges: effectively an internal transportation of the canal & can be caused by a file working against compacted dentine chips • This infected material may harbour bacteria: persistent inflammation
  67. 67. • Apical transportation: Tend to be under-filled • Voids between the filling material & the canal walls in which bacteria could persist • Perforations: endodontic failure when they become infected or allow microleakage
  68. 68. • Success rate of RCT decreased in cases of over-filling • Infection is the most likely cause of failure when root canals are overfilled • Apical seal is inadequate in over-filled root canals • Percolation of tissue fluids could provide nutrients for residual microorganisms
  69. 69. • Overinstrumentation: teeth with infected necrotic pulps- displacement of infected dentine/debris into the periradicular tissues
  70. 70. • Coronal restoration: prevent ingress of bacteria into the internal environment & assists in providing a total seal • Good RCT with good coronal restoration achieves the best outcome • leaking restorations & recurrent caries may compromise the effectiveness of cleaning and shaping: Microleakage • Important to achieve an effective seal with a rubber dam to prevent salivary contamination & reinfection during root canal preparation
  71. 71. • The microbiological flora in failing root-treated teeth: different from that of an untreated canal • Infected untreated canals: mixed infection in which Gram-negative anaerobic rods predominate • Failed root-treated canals may only have 1–2 species of generally Gram-positive bacteria
  72. 72. • Predominantly Gram-positive cocci, rods & filaments • Species belonging to the genera Actinomyces, Enterococcus & Propionibacterium • Enterococcus faecalis: it is rarely found in infected but untreated root canals • Resistant to most of the intracanal medicaments & can tolerate a pH up to 11.5 • Grow as monoinfection in treated canals in the absence of synergistic support from other bacteria • But its presence: not universal P.N.R. Nair. International Endodontic Journal, 39, 249–281, 2006
  73. 73. • Sundqvist et al: Enterococcus faecalis- 38% of failing canals • Increased proportions of E. faecalis in teeth lacking adequate seal during treatment • E. faecalis enters the canal during treatment. • Strains of E. faecalis have shown resistance: Ca(OH)2 Yeast-like : Candida species- resistant to the most commonly deployed ICM
  74. 74. • Gram positive cocci: singly, in pairs or as short chains • Facultative anaerobes, possessing the ability to grow in the presence or absence of oxygen • Enterococci can grow at 100 C and 450 C at pH 9.6 in 6.5% NaCl broth and survive at 600C for 30 minutes (Sherman, 1937) • Survival in root canal infections, where nutrients are scarce & there are limited means of escape from root canal medicaments • 23 enterococci species & they are divided into 5 groups based on their interaction with mannitol, sorbose & arginine Bharadwaj. Int.J.Curr.Microbiol.App.Sci (2013) 2(8): 272-277
  75. 75. The factors most extensively studied are: • Aggregation substance • Surface adhesions • Sex pheromones • Lipoteichoic acid • Extracellular superoxide • Gelatinase, • Hyaluronidase • Cytolysin (hemolysin). Bharadwaj. Int.J.Curr.Microbiol.App.Sci (2013) 2(8): 272-277
  76. 76. • E. faecalis is less dependent upon virulence factors • Ability to survive & persist as a pathogen in root canals of teeth (Rocas et al.,2000) • Antibiotic resistance genes from other microbes or by spontaneous mutation (Mundy et al., 2000) • Presence of serine protease & collagen binding protein help in the invasion of E.faecalis into the dentinal tubules (Hubble et al., 2003). Bharadwaj. Int.J.Curr.Microbiol.App.Sci (2013) 2(8): 272-277
  77. 77. • Alkaline tolerance due to cell wall associated proton pump: resistant to the antimicrobial effect of Ca(OH)2 (Fabricus et al., 1982; Tansiverdi et al., 1997) • Forms biofilm that helps it resist destruction: 1000 times more resistance to phagocytosis, antibodies & antimicrobials than (Chavez De Paz Le et al., 2003) Bharadwaj. Int.J.Curr.Microbiol.App.Sci (2013) 2(8): 272-277
  78. 78. • Sodium hypochlorite effective against existence as a biofilm (Distel et al., 2002). • MTAD ( Abdullah M et al,2005). • Erythromycin mixed with Ca OH against monoinfections of enterococci (Shabahang and Torabinejab, 2003) • Chlorhexidine better antimicrobial action against E. faecalis (Basrani et al., 2002). • Activity of sealers:Roth 811 greatest antimicrobial activity against E. faecalis • Nanometric bioactive glass 45s5, the killing efficacy was higher (Waltimo et al., 2007). Bharadwaj. Int.J.Curr.Microbiol.App.Sci (2013) 2(8): 272-277
  79. 79. • Microflora associated with failing endodontically treated teeth: extremely resistant and difficult to eradicate during retreatment • Alternative ICM & irrigants may be required to enhance the elimination of resistant bacteria in previously root- treated canals. • Inadequate primary treatment may therefore have a negative effect on the prognosis of retreatment
  80. 80. • Bacterial colonies: external root surface may be associated with failure- despite a high standard of primary endodontic treatment • Actinomyces israelii, Propionibacterium propionicum • Biofilm: ‘A microbial population that is attached to an organic or inorganic substrate & surrounded by microbial extracellular products forming an intermicrobial matrix’ • Bacteria inside periapical granulomas: not responded to RCT
  81. 81. • Chronic, granulomatous, infectious disease in humans and animals caused by the genera Actinomyces & Propionibacterium • Nonacid fast, non-motile, Gram-positive organisms revealing characteristic branching filaments that end in clubs or hypha • Periapical actinomycosis: cervicofacial form of actinomycosis • Actinomyces israelii: commensal of the oral cavity P.N.R. Nair. International Endodontic Journal, 39, 249–281, 2006
  82. 82. • Because of the ability of the actinomycotic organisms to establish extraradicularly, they can perpetuate the inflammation at the periapex even after proper RCT • Actinomyces israelii and P. proprionicum are consistently isolated and characterized from the periapical tissue of teeth, which did not respond to proper NSRCT • Ability to build cohesive colonies enables them to escape host defence systems: potential aetiological factor of persistent apical periodontitis P.N.R. Nair. International Endodontic Journal, 39, 249–281, 2006
  83. 83. • Late 1980s: the concept of extraradicular microbes in apical periodontitis with the controversial suggestion: extraradicular infections are the cause of many failed endodontic treatments • Would not be amenable to a non-surgical approach • Most of the periapical samples isolated: contaminated by intracanal microbes • Target of treatment of persistent apical periodontitis: the microorganisms located within the complex apical root canal system P.N.R. Nair. International Endodontic Journal, 39, 249–281, 2006
  84. 84. • Presence of certain viruses in inflamed periapical tissues: ‘etio-pathogenic relationship’ to apical periodontitis • Viruses are present in almost all humans in latent form from previous primary infections • Periapical inflammatory process activates the viruses, existing in latent form P.N.R. Nair. International Endodontic Journal, 39, 249–281, 2006
  85. 85. • The recorded incidence of cysts among apical periodontitis lesions varies from 6% to 55% • Apical periodontitis cannot be differentially diagnosed into cystic and non-cystic lesions based on radiographs alone • Reported incidence of periapical cysts is probably due to the difference in the interpretation of the sections • 52% of the lesions were found to be epithelialized but only 15% were actually periapical cysts P.N.R. Nair. International Endodontic Journal, 39, 249–281, 2006
  86. 86. • D/D: greater than 1 cm in diameter with well-defined margins Radicular cysts are categorized as: Apical true cysts: lesion is completely enclosed by the epithelial lining & has no communication with the RC system of the tooth Apical pocket cysts: epithelial lined sac is in communication with the RC system of the tooth
  87. 87. • Pocket cyst: in communication with the root canal, healing should occur in most cases: NSRCT(Simon 1980, Nair et al. 1993, 1996). • A true cyst: self-sustaining unlikely to resolve(Simon 1980, Nair et al. 1993). • Conventional disinfection & surgical approach P.N.R. Nair. International Endodontic Journal, 39, 249–281, 2006
  88. 88. • Resting cells of Malassez remain: they respond to the irritants and inflammation & proliferate into a cyst-like attempt to wall off the irritants • latent epithelial cell rests- activated by the EGF present in saliva that contaminates canals left open for drainage
  89. 89. • Careful assessment of the tooth: operating microscope or loupes, an indicator dye- evaluate the degree of severity before embarking on RC retreatment • Treatment: Severity of the crack • Exposed to the oral cavity: a crack contains bacteria, reinfection of the root-filled canal/ inflammation alongside the fracture line in the PDL • Cracks across the pulpal floor: become infected with bacteria & are therefore more difficult for the clinician to manage
  90. 90. • Teeth requiring endodontic treatment: may benefit from the placement of a band to prevent fracture • Following RCT a full coverage crown or cusp coverage restoration is to protect the tooth from subsequent fracture
  91. 91. • Diagnosis: methodical & logical progression • Special tests : whether or not a pulp is necrotic • Haste in attaining a diagnosis can lead to treatment of the ‘wrong tooth’
  92. 92. • Cholesterol crystals derived from disintegrating host cells: in failure • INCIDENCE in apical periodontitis: 18% to 44% of such lesions • These are formed by: (i) disintegrating erythrocytes of stagnant blood vessels within the lesion (ii) lymphocytes, plasma cells and macrophages which die in great numbers & disintegrate in chronic periapical lesions (iii) the circulating plasma lipids P.N.R. Nair. International Endodontic Journal, 39, 249–281, 2006
  93. 93. • Insoluble substances: talc-contaminated gutta percha cones • Evoke foreign body reactions when protruding into the periradicular tissues & cause failure • Cellulose component of paper points, cotton wool & some vegetables - persistent inflammation • Fragments of paper points: dislodged or pushed beyond the apex • “Foreign-body giant cell reaction” can occur without the presence of bacteria
  94. 94. • Leaving a tooth open: RC can become packed with food debris, small particles of which can eventually be forced into the periapical tissues • Complications arising: often very difficult to treat • If a tooth is symptomatic following an orthograde approach- surgery
  95. 95. • Scar / fibrous healing is not normally failure • Common following surgical endodontics: buccal & lingual plates have been perforated by an existing lesion • Irregular resolution of the previous radiolucent area.
  96. 96. Neuropathic pain: ‘pain initiated or caused by a primary lesion or dysfunction in the nervous system’ - IASP • Phantom tooth pain (PTP): dental or surgical procedures such as RCT, root end surgery or exodontias. • Tooth pain prior to RCT: risk factor for PTP
  97. 97. The diagnostic criteria for PTP are as follows: ● the pain is in the face or described as toothache ● the pain is described as a constant deep, dull ache (some patients have a sharp pain that overlays the ache) ● a brief pain-free period is reported upon waking and there are no refractory periods ● pain develops (or continues) within 1 month of endodontic treatment, tooth extraction, trauma or medical procedure on the face
  98. 98. ● There is an area of hyperalgesia overlying the area of treatment either on the face or intraorally ● sleep is undisturbed ● no radiographic or laboratory tests suggest other sources of pain.
  99. 99. • Trigeminal neuralgia • Postherpetic neuralgia • Acute herpes zoster • Myofascial pain • Anticonvulsant gabapentin: phantom limb pain • TCAs • Nerve block anaesthesia • Topical drugs such as capsaicin & clonidine
  100. 100. • Poor remuneration & the time constraints experienced by practitioners: reason for poor-quality RCT • Providing high-quality endodontic treatment is time- consuming • Attempting to achieve the desired goals too fast- biological treatment aims not met  endodontic failure
  101. 101. • Six biological factors that contribute to the persistence of periapical radiolucency after RCT (i) intraradicular infection persisting in the complex apical RC system (ii) extraradicular infection (iii) extruded root canal filling/ other exogenous materials (iv) accumulation of endogenous cholesterol crystals that irritate periapical tissues (v) true cystic lesions (vi) scar tissue healing of the periapex Residual microbes in the apical portion of the root canal system is the major cause of apical periodontitis persisting post treatment in both poorly and properly treated cases
  102. 102. 1. Use great care in case selection. Be wary of the case that will be an obvious failure, but, at the same time, be daring within the limits of capability. 2. Use greater care in treatment. Do not hurry; maintain an organized approach. Be certain of instrument position and procedure before progressing. 3. Establish adequate cavity preparation of both the access cavity, which can be improved by modifications of the coronal preparation, and the radicular preparation, which can be improved by more thorough canal débridement—cleaning and shaping.
  103. 103. 4. Determine the exact length of tooth to the foramen and be certain to operate only to the apical stop, about 0.5 to 1.0 mm from the external orifice of the foramen. 5. Always use curved, sharp instruments in curved canals, and especially remember to clean and reshape the curved instrument each time it is used. This applies to stainless steel instruments.
  104. 104. 6. Use great care in fitting the primary filling point. One must be certain to obliterate the apical portion of the canal. Be more exacting in the total obturation of the entire root canal. Always use a root canal sealer cement. 7. Use periradicular surgery only in those cases for which surgery is definitely indicated
  105. 105. 8. Always check the apical density of the completed root canal filling of the patient undergoing periradicular surgical treatment, and this should be done by using a sharp right-angled explorer. If found wanting, the apical foramen is prepared and retrofilled. 9. Properly restore each treated pulpless tooth to prevent coronal fracture and microleakage.
  106. 106. 10. Practice endodontic techniques until the procedures are as routine as the placement of an amalgam restoration or the extraction of a central incisor. Practice on extracted teeth mounted in acrylic blocks is especially recommended Careful attention to details in following the Ten Commandments of Endodontics will ensure a degree of success approaching 100%.
  107. 107. • Endodontics. 6th ed. Ingle JI, Bakland LK, Baumgartner C. • Endodontics. 5th ed. Ingle JI, Bakland LK • Advanced Endodontics. Clinical Retreatment and Surgery. Rhodes JS • Contemporary Endodontic Treatment. Endodontics. Colleagues for Excellence. Fall/ Winter 2003 • Nair. P.N.R. On the causes of persistent apical periodontitis: a review. International Endodontic Journal, 39, 249–281, 2006 • 0rstavik D, Kerekes K, Eriksen HM. The periapical index: A scoring system for radiographic assessment of apical periodontitis. Endod Dent Traumatol 1986; 2: 20-34.

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