Endodontic failures

ENDODONTIC FAILURES

ENDODONTIC FAILURESDeepthi P.R.

CONTENTSIntroductionTermsTreatment Outcome studiesPersistent Apical Periodontitis and its CausesMeasures to improve SuccessReferences

INTRODUCTIONNatural tooth with a good prognosis superior choice to loss & replacementFirst question by patients: Degree of anticipated SUCCESSSuccess enjoyed- much higher than other phases of reconstructive dentistry

Not all treatments result in optimum long- term healingVery small rate of unsuccessful outcomes: large numbers of patients requiring further treatment

TERMSUntil 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 implantFailure 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

Success 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 levelfor example, in terms of tissue function, elimination of pathology, comfort, or even survival

Communication with patients can be improved by replacing the value-laden terms success and failure with neutral expressions:chance of healingrisk of inflammation Avoid the terms success and failure in defining the outcome of endodontic treatment

Aim is to prevent or cure apical periodontitisThe 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:CompleteIncompleteUncertainUnsatisfactory

STRICT DEFINITION OF SUCCESSA successful outcome is strictly defined by complete absence of radiolucency & absence of clinical signs and symptomsComplete normalcy has been named successUnchanged radiolucencies represent failureA smaller radiolucency, in the presence of clinical normalcy, is usually considered as incomplete healingNot a successful outcome, but rather as an interim outcome requiring further observation

LENIENT DEFINITION OF SUCCESS Success is defined as the absence of clinical signs and symptomsClinical normalcy may be accompanied by a residual radiolucency, either decreased or unchanged in size, but not increasedUse 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 normalcyFriedman et al. reported 78% complete healing & 16% incomplete healing after NSRCT which would be 94% by the lenient criteria

STRICT vs LENIENTSpecific to teeth affected by preoperative apical periodontitis. Frequently asymptomatic, both before treatment & when persisting after treatment.But, universally considered a disease requiring therapyPersisting apical periodontitis after therapy cannot be regarded as success only because it is asymptomatic, & treatment is still indicated.

Healed Complete clinical and radiographic normalcyNo signs, symptoms, residual radiolucencyThe typical appearance of a scar after apical surgery

Healing (in progress)Decrease in size of a radiolucency & clinical normalcy after a follow-up period shorter than 4 years.

Disease (refractory/recurrent/emerged apical periodontitis)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

Aim-related terms, to define the outcome of treatment: improve communication with patientsPatients: encouraged to identify specific aims & define their expected outcome that can be considered a successIndividual patients may be satisfied with just elimination of clinical signs and symptoms: compromised prognosis cases

Asymptomatic functionClinical normalcy with or without a persistent radiolucency, decreased or unchangedPatient is still motivated to attempt treatment although healing is unlikely to occurThe aim of treatment is retention of the tooth in asymptomatic function

Outcome Definition as Uncertain,Questionable, Doubtful, or ImprovedOriginally introduced to imply uncertainty of the outcome & also to define improved outcomesStrictly: cases that could not be assessed because of insufficient radiographic information and thus were not included in either the successful or unsuccessful outcome categoriesSame 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 surgeryThis modified classification lowered the failure rate in comparison with the strict classification

TREATMENT OUTCOME STUDIESOutcome definitions & classification have been inconsistentConsiderable 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: InconsistencyOverstate the success rate by not noting teeth that could be radiographically normal but symptomatic

Radiographic treatment OutcomePeriapical 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 definitelynot presentPeriapical destruction of bone probablynot presentUnsure Periapical destruction of bone probablypresentPeriapical destruction of bone almost definitelypresent

No direct interpretation of the scores as success or failureScores 1 & 2: Healthy periapical tissuesScores 3 & above: DiseaseMere changes on a radiograph cannot determine the extent of the periradicular healing processENDODONTICS- Colleagues for Excellence. Fall/ Winter 2003

TREATMENT OUTCOME STUDIESIngle & Beveridge: undergraduate students at the University of Washington were capable of obtaining 95% successWhen a carefully followed course of therapy is instituted; little opportunity to deviate from predetermined patterns of therapy- results are strongly in favor of successStrindberg 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.

Washington Study- University of Washington School of Dentistry

Evaluate endodontically treated teeth to determine their rate of successRate of failure, causes of failure Analysis of the failures led to modifications in technique & treatmentImprovements 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 successfulThere was also a hidden agenda to the Washington studyto prove: root canal therapy could be successful if properly done

The modifications in treatment : instituted following a pilot study of endodontic success and failureEven 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

Patients were recalled for follow-up at 6 months, 1 year, 2 years, and 5 yearsRadiographs were carefully evaluated for improvement or lack of improvementSuccess group: Decided periradicular improvement & those with continuing periradicular healthFailures: Teeth that initially demonstrated periradicular damage and that had not improved, as well as those that had deteriorated since treatment

Decided periradicular improvement

Continuing periradicular health

The 2-year recall series was found to be ideal for this study because a statistically significant sample developed within this groupThe 5-year recall sample was also analyzed The study did not take into consideration any illnesses or systemic differences between patients

2- Year Recall Analysis1229/ 3678: recall rate of 33.41%Before improvements instituted: 91.10% success rate104 failures of 1,067 casesAfter these improvements were instituted, the success rate rose to 94.45%9 failures of 162 cases.

2- Year Recall Analysis by Age of Patient2.5 years -92 yearsFairly consistent rate of success & failure according to age as shown by statistical analysisOlder 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

Two-Year Recall Analysis by Individual ToothNo 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

Two-Year Recall Analysis by Individual ToothMandibular 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- 1944Pennsylvania study by Trope et al. in 1986 also confirmed: African American patients more frequently have two canals in lower premolars

Maxillary lateral incisor: Pucci & Reig showed extensive distal curvature of the maxillary lateral incisor root 49.2% of the timePoor judgment & preparation frequently prevent adequate instrumentation & obturation, with root perforation at the curvature a common occurrenceIncreased failure rate in the maxillary lateral incisor is also related to continuing root resorption following treatment, a finding peculiar to these teeth

Overall failure rate, mandible to maxilla, is striking but not statistically significantFailure in the mandibular arch was encountered 6.65% of the time & 9.03% of the time in the maxilla

Two-Year Recall Analysis: Nonsurgical versusSurgical InterventionAlthough NSRCT appears to be slightly more successful than surgical treatment, differences are not statistically significantFailure rate: three times higher if a periradicular lesion existed before treatment NelsonThe 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%) Sjgren et al. Teeth without periradicular lesions, reported a 96% success rate; 86% if periradicular lesions were present

Apical percolationPotential of microleakage under and around coronal restorationsBacteria penetrating from the crown to the periapex alongside poorly obturated canals

Operative errorsPenetrating through the side of a curved root ultimately leads to incomplete instrumentation and incomplete obturation

Operative errorsOpening wide the apical foramen during instrumentation: also a form of perforation & leads to gross overfilling or overextension

Operative errorsSurgical treatment is recommended: operable teeth if the instrument is broken off in the apical one-third of the canalif the canal is grossly overfilled with irretrievable gutta-perchaFailures associated with underfilled canals can usually be remedied by retreatment rather than surgeryoperative error is the simplest cause of failure to control and requires more patience, care, and understanding to overcome

Errors in Case SelectionExternal root resorption would continueApical cyst would develop following treatmentAdjacent tooth would become pulplessAssociated periodontal lesion would lead to failureWashington study: factors constituted 22.12% of the total failuresRoot resorption- maxillary lateral incisorsPeriodontal pockets: recognized before treatment

Causes of failure not revealedRetrofilling failuresRoot tip & foreign bodies left in surgical sitesRoot fenestration following surgery Cracked/ split rootsCarious destruction unrelated to the root canal treatment

one of the most frequent causes of failure of the treated pulpless tooth is fracture of the crownThe tooth must be carefully protected by an adequate restoration.

CRITICSMS AGAINST WASHINGTON STUDYOnly 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- WaltonSince histologic evaluation is impractical: comfort and function & the radiographic findings

43

Temple University 95.2% success rate at the end of 1 year with 458 canals filled by the gutta-percha-euchapercha methodVital 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%).

South African researchers Barbakow et al.Success rate -89% success at the end of 1 year92% of the time in teeth filled to the apex91% of the time if the canals were overfilledFilling short of the apex reduced their success rate to 82%

Study on 845 Dutch military servicemen by Meeuwissen et al.45% of the endodontically treated teeth had failed in nonaviators7% had failed in aviator patients Aviators- gutta-percha or silver point fillings & their teeth were more frequently crownedNonaviators: therapy with special chemical compounds. Furthermore, the aviators

Sjgren et al. from SwedenRemarkable study of 356 endodontic patients, re-examined 8 to 10 years later96% success rate if the teeth had vital pulps prior to treatment86% if the pulps were necrotic & the teeth had periradicular lesions62% if the teeth had been re-treatedDirect correlation between success & the point of termination of the root filling

Preoperative pulp necrosis & Apical periodontitis- Sjogren et al.

Retreatment of Apical periodontitis- Sjogren et al.

Generalizations from studies on prognosis1. 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 prognosisGood NSRCT has the best prognosisThe worst prognosis lies with teeth that have been retreated nonsurgically and then re-treated surgically once or twice more.

Past success- failure studies have erroneously included failures due to:periodontal diseaseroot fracturesInappropriate restorations presence of coronal leakage.These are not endodontic failuresENDODONTICS- Colleagues for Excellence. Fall/ Winter 2003

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 obturationCoronal leakage is negated through proper, sound restorations Patient practices preventive oral self careENDODONTICS- Colleagues for Excellence. Fall/ Winter 2003

Several comprehensive & narrative reviews: inconsistencies & contradictions among the reported outcomes of nonsurgical and surgical endodontic treatmentsAnswers to many questions concerning the outcome of endodontic treatment procedures: equivocal because of poorly standardized methodology of the many studiesRapid evolution of clinical procedures has rendered results of specific studies less relevant today than when they were published

PERSISTENT APICAL PERIODONTITISWhen root canal treatment of apical periodontitis has not adequately eliminated intraradicular infection.Problems include: inadequate aseptic controlpoor access cavity designmissed canalsinadequate instrumentation, debridement leaking temporary or permanent restorationsComplex anatomy uninstrumented even when the most careful clinical procedures are followedP.N.R. Nair. International Endodontic Journal, 39, 249281, 2006

Rhodes JS.Endodontic failure comprises: biological failings (infection) cysts root fracture incorrect diagnosis and primary treatment foreign body reactions healing with scar neuropathic problems economic constraints

BIOLOGICAL FAILINGSCommonest reason for failure: microbial infectionMicroorganisms & their byproducts- isolated from the RC system & the external surface of the root in failed casesPersisted following a previous attempt at RCT or gained access through coronal microleakageIntraradicular & Extraradicular Infection

CAUSES OF PERSISTENT APICAL PERIODONTITIS MICROBIAL CAUSESIntraradicular InfectionExtraradicular Infection NON MICROBIAL CAUSESCystic apical periodontitisCholesterol crystalsForeign bodiesGutta perchaOther plant materials/ foreign materialsP.N.R. Nair. International Endodontic Journal, 39, 249281, 2006

Intraradicular infectionTeeth with technically deficient root fillings: more likely to be associated with periapical radiolucenciesPoor quality root filling: the RC system may not have been effectively disinfected or could have become reinfected through coronal microleakage

Intraradicular infectionThe apical portion of the root canal system can contain bacteria & necrotic tissue substrate even following chemomechanical preparationIf the resultant microbial ecosystem is amenable to bacterial survival, a lesion may not heal

Intra radicular infectionMajority of root canal-treated teeth with asymptomatic apical periodontitis harboured persistent infection in the apical portion of the complex root canal systemMicroorganisms: 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, 249281, 2006

Intra radicular infectionOnly Gram positive bacteria were found

Intraradicular fungi: potential non-bacterial, microbial cause

The radiographic appearance of a RC filling does not give an indication of biological status A satisfactory radiographic result could be failing biologicallyIf the root canal filling fails to provide a complete seal, seepage of tissue fluids: provide a substrate for bacterial growthBacterial regulatory systems: automatically transcripted under adverse conditions: survive periods of starvation or nutrient depletion

MICROBESBacteria may not be completely eliminated after thorough cleaning, shaping & disinfectionMoreover, when obturation is postponed, bacteria may be able to recolonize in the canalNo preparation technique can totally eliminate the intracanal irritants, & a critical amount can sustain periradicular inflammationGutta-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.

Irritants: infected dentin chips, is packed at the apex or pushed through the apexPeriapical tissue could become colonized:periodontal contaminationthe virulence of the bacteriaExtrusion by overaggressive instrument action

Hosts 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

Organisms survive in periradicular lesions:ActinomycesPeptostreptococcusPropionibacteriumPrevotellaPorphyromonas- Staphylococcus- Pseudomonas aeruginosaBarnett, stated Pseudomonas refractory periradicular infection could be cured only by heavy doses of metronidazole (Flagyl) following the failure of re-treatment and apicoectomy

Bacterial infection: the major cause of persistent periapical inflammation following RCTTechnical 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.

Poor Aseptic TechniqueThe majority of RCT is carried out without a rubber damCould 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 ratesBENEFITS 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.

Incorrect irrigantsChemomechanical 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

Inability to Prepare to LengthFailure to achieve patency during preparation: inadequate penetrationPersistent infection & endodontic failureApical 3 mm of a RC- the highest percentage of lateral canals & deltasIf mechanical preparation & consequently irrigant penetration: 23 mm short of the constriction, the hypothetical length of canal that has not been disinfected could be as great as 67 mm

Outdated filing techniques: stepback method can be fraught with instrumentation errorsZips and elbows

Missed canalsAberrant or unusual anatomy: considered in retreatment casesIf a root-filled tooth appears satisfactory from a radiographic perspective but is still symptomatic, a missed canal could be suspectedThe clinician must be aware of normal root canal anatomy before re-entering a RCTreated tooth and be prepared for added complexity in retreatment cases

Procedural errorsInfected tooth: predispose the treatment to failure by making it more difficult to effectively disinfect the entire RC systemLedges: effectively an internal transportation of the canal & can be caused by a file working against compacted dentine chipsThis infected material may harbour bacteria: persistent inflammation

Procedural errorsApical transportation: Tend to be under-filledVoids between the filling material & the canal walls in which bacteria could persistPerforations: endodontic failure when they become infected or allow microleakage

Procedural errorsSuccess rate of RCT decreased in cases of over-fillingInfection is the most likely cause of failure when root canals are overfilledApical seal is inadequate in over-filled root canalsPercolation of tissue fluids could provide nutrients for residual microorganisms

Procedural errorsOverinstrumentation: teeth with infected necrotic pulps-displacement of infected dentine/debris into the periradicular tissues

Poor coronal restorationCoronal restoration: prevent ingress of bacteria into the internal environment & assists in providing a total sealGood RCT with good coronal restoration achieves the best outcomeleaking restorations & recurrent caries may compromise the effectiveness of cleaning and shaping: MicroleakageImportant to achieve an effective seal with a rubber dam to prevent salivary contamination & reinfection during root canal preparation

Resistant bacteriaThe microbiological flora in failing root-treated teeth: different from that of an untreated canalInfected untreated canals: mixed infection in which Gram-negative anaerobic rods predominateFailed root-treated canals may only have 12 species of generally Gram-positive bacteria

Microbial flora of RC Treated TeethPredominantly Gram-positive cocci, rods & filamentsSpecies belonging to the genera Actinomyces, Enterococcus & PropionibacteriumEnterococcus faecalis: it is rarely found in infected but untreated root canalsResistant to most of the intracanal medicaments & can tolerate a pH up to 11.5Grow as monoinfection in treated canals in the absence of synergistic support from other bacteriaBut its presence: not universalP.N.R. Nair. International Endodontic Journal, 39, 249281, 2006

E. faecalis Sundqvist et al: Enterococcus faecalis- 38% of failing canalsIncreased proportions of E. faecalis in teeth lacking adequate seal during treatmentE. 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

Characteristics E.FaecalisGram positive cocci: singly, in pairs or as short chainsFacultative anaerobes, possessing the ability to grow in the presence or absence of oxygenEnterococci 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 medicaments23 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

Virulence factorsThe factors most extensively studied are:Aggregation substanceSurface adhesionsSex pheromonesLipoteichoic acidExtracellular superoxideGelatinase,HyaluronidaseCytolysin (hemolysin).Bharadwaj. Int.J.Curr.Microbiol.App.Sci (2013) 2(8): 272-277

Survival of E. faecalisE. faecalis is less dependent upon virulence factorsAbility 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

Survival of E. faecalisAlkaline 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

Eradication of E. faecalisSodium 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

Resistant bacteriaMicroflora associated with failing endodontically treated teeth: extremely resistant and difficult to eradicate during retreatmentAlternative 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

Extraradicular infectionBacterial colonies: external root surface may be associated with failure- despite a high standard of primary endodontic treatmentActinomyces israelii, Propionibacterium propionicumBiofilm: A microbial population that is attached to an organic or inorganic substrate & surrounded by microbial extracellular products forming an intermicrobial matrixBacteria inside periapical granulomas: not responded to RCT

Extraradicular infection- ActinomycosisChronic, granulomatous, infectious disease in humans and animals caused by the genera Actinomyces & PropionibacteriumNonacid fast, non-motile, Gram-positive organisms revealing characteristic branching filaments that end in clubs or hyphaPeriapical actinomycosis: cervicofacial form of actinomycosisActinomyces israelii: commensal of the oral cavity


Because of the ability of the actinomycotic organisms to establish extraradicularly, they can perpetuate the inflammation at the periapex even after proper RCTActinomyces israelii and P. proprionicum are consistently isolated and characterized from the periapical tissue of teeth, which did not respond to proper NSRCTAbility to build cohesive colonies enables them to escape host defence systems: potential aetiological factor of persistent apical periodontitis


Other Extraradicular MicrobesLate 1980s: the concept of extraradicular microbes in apical periodontitis with the controversial suggestion: extraradicular infections are the cause of many failed endodontic treatmentsWould not be amenable to a non-surgical approachMost of the periapical samples isolated: contaminated by intracanal microbesTarget of treatment of persistent apical periodontitis: the microorganisms located within the complex apical root canal systemP.N.R. Nair. International Endodontic Journal, 39, 249281, 2006

Extra radicular virusesPresence of certain viruses in inflamed periapical tissues: etio-pathogenic relationship to apical periodontitisViruses are present in almost all humans in latent form from previous primary infectionsPeriapical inflammatory process activates the viruses, existing in latent formP.N.R. Nair. International Endodontic Journal, 39, 249281, 2006

CYSTIC APICAL PERIODONTITISThe 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 aloneReported incidence of periapical cysts is probably due to the difference in the interpretation of the sections52% of the lesions were found to be epithelialized but only 15% were actually periapical cystsP.N.R. Nair. International Endodontic Journal, 39, 249281, 2006

Cysts D/D: greater than 1 cm in diameter with well-defined marginsRadicular cysts are categorized as:

CystsPocket 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


EPITHELIUMResting cells of Malassez remain: they respond to the irritants and inflammation & proliferate into a cyst-like attempt to wall off the irritantslatent epithelial cell rests- activated by the EGF present in saliva that contaminates canals left open for drainage

Cracked teeth & FracturesCareful assessment of the tooth: operating microscope or loupes, an indicator dye- evaluate the degree of severity before embarking on RC retreatmentTreatment: Severity of the crackExposed to the oral cavity: a crack contains bacteria, reinfection of the root-filled canal/ inflammation alongside the fracture line in the PDLCracks across the pulpal floor: become infected with bacteria & are therefore more difficult for the clinician to manage

Cracked teeth & FracturesTeeth requiring endodontic treatment: may benefit from the placement of a band to prevent fractureFollowing RCT a full coverage crown or cusp coverage restoration is to protect the tooth from subsequent fracture

Cracked teeth & Fractures

Incorrect Diagnosis & treatmentDiagnosis: methodical & logical progressionSpecial tests : whether or not a pulp is necroticHaste in attaining a diagnosis can lead to treatment of the wrong tooth

Foreign body reactionsCholesterol crystals derived from disintegrating host cells: in failureINCIDENCE in apical periodontitis: 18% to 44% of such lesionsThese 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


Foreign body reactionsInsoluble substances: talc-contaminated gutta percha conesEvoke foreign body reactions when protruding into the periradicular tissues & cause failureCellulose component of paper points, cotton wool & some vegetables - persistent inflammationFragments of paper points: dislodged or pushed beyond the apexForeign-body giant cell reaction can occur without the presence of bacteria

Leaving a tooth open: RC can become packed with food debris, small particles of which can eventually be forced into the periapical tissuesComplications arising: often very difficult to treatIf a tooth is symptomatic following an orthograde approach- surgery

Healing with scarScar / fibrous healing is not normally failureCommon following surgical endodontics: buccal & lingual plates have been perforated by an existing lesionIrregular resolution of the previous radiolucent area.

Neuropathic problemsNeuropathic 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

Neuropathic problemsThe 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

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 suggestother sources of pain.

D/D & Treatment of PTPTrigeminal neuralgiaPostherpetic neuralgiaAcute herpes zosterMyofascial pain

Anticonvulsant gabapentin: phantom limb pain TCAsNerve block anaesthesiaTopical drugs such as capsaicin & clonidine

Economic constraintsPoor remuneration & the time constraints experienced by practitioners: reason for poor-quality RCTProviding high-quality endodontic treatment is time-consumingAttempting to achieve the desired goals too fast- biological treatment aims not met endodontic failure

PNR NairSix biological factors that contribute to the persistence of periapical radiolucency after RCTintraradicular infection persisting in the complex apical RC systemextraradicular infectionextruded root canal filling/ other exogenous materials accumulation of endogenous cholesterol crystals that irritate periapical tissuestrue cystic lesionsscar tissue healing of the periapexResidual 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

MEASURES TO BE EMPLOYED TO IMPROVE SUCCESSUse 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; maintainan 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 dbridementcleaning and shaping.

4. Determine the exact length of tooth to the foramenand 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 curvedcanals, and especially remember to clean and reshape the curved instrument each time it is used. This applies to stainless steel instruments.

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 forwhich surgery is definitely indicated

8. Always check the apical density of the completedroot 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 andretrofilled.

9. Properly restore each treated pulpless tooth to preventcoronal fracture and microleakage.

10. Practice endodontic techniques until the proceduresare 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%.

REFERENCESEndodontics. 6th ed. Ingle JI, Bakland LK, Baumgartner C.Endodontics. 5th ed. Ingle JI, Bakland LKAdvanced Endodontics. Clinical Retreatment and Surgery. Rhodes JSContemporary Endodontic Treatment. Endodontics. Colleagues for Excellence. Fall/ Winter 2003Nair. P.N.R. On the causes of persistent apical periodontitis: a review. International Endodontic Journal, 39, 249281, 20060rstavik 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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Endodontic failures