ENDODONTIC FAILURES

Presentation By: Garima Singh

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Content • Introduction• Historical and contemporary views on success and failure• Factors influencing success or failure• Evaluation of success / failure

Clinical evaluationRadiographic evaluationHistological evaluation

Influence of microbial factor in success/failure• Interpretation of evaluative factors in determination of success/ failure• Establishing a differential diagnosis of endodontic failure• conclusion

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Introduction•The concepts of success and failure in endodontics are often relegated to positions of secondary importance.

•This is evident in textbooks, in which chapters on these issues, if present, are situated deep into the written material, where as those chapters that deal with canal cleaning and shaping, obturation, surgery, and so forth are in forefront.

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•Many aspiring professionals are never faced with the concepts of success and failure in didactic courses, and certainly not in clinical training: In a requirement-driven curriculum, success is erroneously assumed once treatment is completed.

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•The dental professional is faced with a daily continuum of clinical situations requiring an integration of facts, experiences, interpretation, applications, and analyses.

•The ability to confront these situations in a systemic and successful manner characterizes the problem-solving approach to treatment and evaluation.

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Historical and contemporary views on success and failure•Historically the concept of success or failure of endodontic therapy has centered on the “sterilization” of root canal system, coupled with the perceived need to achieve a hermetic apical seal.

•Both research and clinical studies focused on these issues as the priorities in successful treatment.

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•A more through understanding of pulpal and periradicular disease processes indicates that the key to success in endo therapy is the debridement and neutralization of any tissue, bacteria, or inflammatory products within the root canal system .

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Factors that will influence success or failure in all cases•Radiographic interpretation,•Anatomy of the root canal system and external root,

•Thoroughness of debridement and apical level of instrumentation,

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•Degree of apical seal,•Degree of coronal seal and quality of coronal restoration,

•Operator skill and expertise

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Evaluation of success and failure

•Success or failures following endodontic therapy could be evaluated from combination of Clinical criteria,radiographical criteria and,Histopathological criteria.

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Clinical evaluation for success & failure

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•If retention of the tooth in symptom-free clinical function is the aim of endodontic therapy, then many cases can be classified as clinically acceptable using previous criteria.

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•The use of the term ‘ adequate clinical function’ may be more realistic, if retention of the tooth in function is the ultimate aim of treatment.

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•nevertheless, ultimate success or failure must identify a middle ground where the integration of all factors- clinical, radiographic, histologic and their ultimate effects can be recognised and accepted.

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Overfilling of gutta-perhca, n loss of root curvature

After 3 yrs: resolution of periapical pathosis and reformation of sound

lamina dura and pdl space

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•However, despite the assessment of all these factors, failure will at times occur, and a realistic perspective must be maintained.

•In all cases, neither the presence nor absence of clinical symptoms alone should determine the success or failure of a case without integrating other factors.

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Radiographic evaluation for success & failure•The radiographic evaluation of the periradicular tissue is highly dependent on subjective evaluation and interpretation.

•Objective criteria for treatment have been published by American Association of Endodontists (AAE) in their Quality Assurance Guidelines.

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“radiograph should show a dense, three-

dimentional filling that extends as close as

possible to the cementum- dentin junction.”

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•These criteria can be classified into three categories:Radiographically acceptableRadiographically questionableRadiographically unacceptable

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Radiographically acceptable•Normal or slightly thickened (<1 mm)periodontal ligament space

•Reduction or elimination of previous radiolucency

•No evidence of resorption•Normal lamina dura•A dense three dimensional obturation of canal space

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Premolar classified as unacceptable, fiest molar as acceptable, and 2nd molar as questionable

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Radiographically questionable•Increased pdl space ( <2mm)•Radiolucency of similar size or slight evidence of repair•Irregularly thickend lamina dura in relation to adjacent teeth.

•Progressive resorption•Voids in density of canal obturation, especially in apical third of canal

•Extension of filling material beyond the apex.23

Maxillary 2nd premolar: viewed as acceptable by one practitioner and

unacceptable by other

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Radiographically unacceptable•Increased width of pdl space (>2mm)•Lack of osseous repair within a periradicular rarefaction , or increase in size of radiolucency

•Presence of osseous radiolucency in perradicular areas where previously none existed, including lateral radiolucencies.

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•Visible patent canal space/ voids in canal obturaiton

•Excessive overextension of filling material with obvious voids in apical 3rd of canal

•Definitve evidence of progressive resorption26

Failure to clean and shape the canal system , poor obturation

and presence of broken instrument in middle of the canal

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•The determination of success or failure based solely on radiographic criteria is ill advised, because clinical findings must be included in the decision- making process.

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Histological evaluation for success/ failure•Histological assessment of success and failure is relatively meaningless in the clinical practice of endodontics.

•Several studies have supported the concept; apparently patients can exist in a state of chronic inflammation without measurable symptoms.

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•This state may be common in patients placed in the clinically or radiographically questionable categories in as much as vague symptoms may occur, coupled with a slightly increased periodontal ligament space or a lack of complete osseous repair as viewed on a radiograph.

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•As an aid to clinician, histologic criteria of assessment are listed to facilitate an understanding of the nature of periradicular tissues when treatment evaluation is questionable or unacceptable.

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•Acceptable criteria:Absence of inflammation Regeneration of periodontal ligament fibersPresence of osseous repairAbsence of resorptionRepair of previously resorbed areas

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Influence of Microbial factor in success / failure•In a study of monkey teeth, Möller et al. (1981) demonstrated that only devitalized pulps that were infected induced periradicular lesions, whereas devitalized and uninfected pulps showed absence of pathological changes in the periradicular tissues.

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•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.

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• 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).

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•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.

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•How high the risk of reinfection will be is dependent on the quality of the root filling and the coronal seal (Saunders & Saunders 1994)

•In most cases, failure of endodontic treatment is a result of microorganisms persisting in the apical portion of the root canal system, even in well-treated teeth.

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•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.

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• Studies have reported the occurrence of viable microbial cells in treated teeth with a persistent periradicular lesion indicates that microorganisms derive nutrition, presumably from tissue fluid which can seep into the root canal space (Sjögren

1996, Sundqvist et al. 1998, Molander et al. 1998).

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•Failure of endodontic treatment attributed to remaining microorganisms will only occur if they possess pathogenicity, reach sufficient numbers, and gain access to the periradicular tissues to induce or maintain periradicular disease.

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•Möller (1966), after examining failed cases, 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.

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•Sundqvist et al. (1998) observed a mean of 1.3 bacterial species per canal and 42% of the recovered strains were anaerobic bacteria. E. faecalis was detected in 38% of the infected root canals.

•E faaecalis is the pathogen of significance in most cases of failing endodontic treatment.

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Integration of evaluative factors in determination of success and failure:•The clinician is frequently required to assess the success of previously completed endodontics treatment to identify and manage teeth that exhibit signs and symptoms of pulpal and periradicular pathosis.

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The evaluation of previous endodontic treatment during routine examination•Research and successful clinical experience indicate that endodontic therapy is most successful when the root canal system has been thoroughly cleaned to the apical construction and sealed.

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21 month follow up radiograph

Angled view of the obturation showing

the entire canal system

Immediately following RCT

Mandibular incisor, bifurcation of canal at midroot level (arrow)

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•In case of root canal fillings that terminate 2mm or more from the radiographic apex, it is obvious that there may be uninstrumented and unfilled canal space, which are a potential cause of failure.

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Maxillary molar with RCT. Tooth was symptom free. All canal were filled far short of the ideal apical position. Long-term

prognosis is questionable.

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•Root canals filled with pastes, silver cones, or other materials have questionable success rates as compare with well condensed gutta-percha.

Multiple maxillary posterior teeth with a history of paste-filled root canals at least 5 yrs before this radiograph. All teeth are symptom free. 48

•The presence of these former materials in symptom free teeth represents a significant potential for failure because their removal in retreatment situations almost invariably show evidence of a poor seal.

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•Often a symptom free , grossly carious tooth exhibits apparently successful root canal treatment.

Maxillary premolar showing extensive coronal destruction

Radiograph of same tooth: shows RCT of acceptable quality, there is a periradicular

radiolucency50

•Although it might be assumed that the canal seal is adequate, numerous studies indicate that the seal is as vulnerable to failure from coronal leakage .

A demineralized and cleared tooth specimen of an extracted tooth showing leakage staining from the pulp chamber to the root apex. Note the apical sealing (arrow) that did not stop

the leakage pattern

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•It would be unwise to proceed to the restoration of any tooth which the endodontic filling has been exposed to saliva for an extended period of time.

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Establishing a differential diagnosis of endodontic failure: percussion tenderness•It is not unusual to receive a patient referral with a diagnosis of endodontic failure, only to find on examination that the endodontic treatment is satisfactory.

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•The signs and symptoms of endodontic failure usually originate in the periradicular tissues.

•Swelling , tenderness to palpation or percussion and development of or increase in a periradicular lesion are common.

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•There are only three potential causes for percussion tenderness:Recent traumaOcclusal traumaEndodontic failure

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•Recent trauma:Easy to diagnose, and percussion tenderness alone would be expected to resolve gradually without specific treatment, as long as the tooth is not on abnormal occlusion.

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•Occlusal traumaA tooth in occlusion in which there is tenderness to percussion and there has been no injury.

Occlusal abnormalities should be considered when there is evidence of bruxism or wear facets.

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Extreme occlusal wear consistent with bruxism

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Occlusal wear facets on a mandibular molar

•Failing root canal treatmentA root canal treated tooth remains percussion tender 2 weeks after elimination of occlusal contacts or presents initially without an opposing tooth.

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•Assuming that examination with the periodontal probe has ruled out fracture and the root canal treatment is not recent , the diagnosis of endodontic failure is probably in order.

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•Since it is not unusual to observe percussion tenderness in a recently completed endodontic case, diagnosis of failure would be premature.

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•Likewise, since the periradicular inflammation associated with failure is due to loss or lack of an apical seal, or remnants of tissue debris, symptoms of failure do not usually appear until months after completion of treatment.

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Establishing a differential diagnosis of endodontic failure- discomfort to thermal stimulus•Discomfort to a thermal stimulus without exception requires the presence of dental pulp tissue in the tooth that hurts.

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•In a clinical situation in which the patient complains of thermal sensitivity or discomfort originating from an endodontically treated tooth, only two possibilities exist:

Untreated canal in the endodontically treated tooth.Discomfort originates from another tooth.

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Establishing a differential diagnosis of endodontic failure: radiographic signs of endodontic failure•interpretation of minimally widened apical periodontal ligament space,

•Interpretation of a periradicular lesion on a tooth with prior endodontic treatment.

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Interpretation of minimally widened apical periodontal ligament space•There are three possibilities that may exist A normal PDL space superimposed over an anatomic void in the bone.

Other common examples are superimposed over the mandibular canal, the incisive canal foramen, or a cystic cavity caused by another tooth.

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Two endodontically treated maxillary posterior teeth with apices near or above the sinus floor.The molar appears to have a widened apical periodontal ligament space. This is

normal. The premolar has a periradicular lesion.

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•A periradicular lesion may be developing from failing root canal treatment.

Maxillary lateral incisor with poor quality RCT.The widened PDL space is evidence of pathosis

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•Scar tissue may be present after the healing of a periradicular radiolucency.

25month revaluation radiograph.

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Periradicular lesion is noted at the apex of a mandibular

incisor:

immediately following obturation ,

•In all three cases, without a history of symptoms and without clinical signs of pathosis , the best course is to wait and observe the area.

•If symptoms or clinical signs of pathosis reappear at any time, revaluation would be indicated.

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Interpretation of a periradicular lesion on a tooth with prior endodontic treatment•All three possibilities discussed previously exist as for the previous problem, superimposition over normal structures is found much less frequently, since only a large foramen would have the approximate shape of an apical lesion.

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•Healing lesions could also be ruled out as a possibility if the tooth is 2 yrs after treatment.

A large periradicular lesion on a mandibular central incisor. Root canal treatment was completed with a silver cone, 18yrs earlier

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•In the distinct majority of endodontically treated teeth, the presence of periradicular lesion represents failure for which surgical retreatment would be the treatment of choice.

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Interpretation of very large periradicular lesion associated with the apex of an endodontically treated tooth•Occasionally a normal sinus might be misinterpreted as a large periradicular lesion.

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•If a large lesion has no symptoms and no evidence of drainage , a biopsy might be indicated if normal anatomy cannot account for the radiographic presentation.

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•It is uncommon but not impossible for a large periradicular lesion to develop from an endodontic failure.

Large periradicular lesion associated with failing RCT on mandibular molar

Reevaluation 7 months after nonsurgical retreatment

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•Lesions of nonpulpal origin must always be suspected, and a biopsy to provide a differential diagnosis may be indicated.

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Interpretation of radiographic lesions enveloping an entire root•Lesions that appear to involve significant bone loss limited to a single root and extending to the crest of bone should be suspected of having a sever periodontal defect, a vertical root fracture of a failing RCT that would be capable of healing.

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A periradicular radiolucency enveloping the entire distal root of mandibular 2nd molar. Periodontal probing was consistent

with advanced periodontal disease

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•It is more difficult to reach a diagnosis of advanced periodontitis where such a lesion seems to be solitary.

•In term of prognosis, however, if the probing pattern confirms deep pocketing and loss of attachment over a wide area of the root circumferentially, the prognosis is nearly hopeless regardless of the cause.

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Establishing a differential diagnosis of endodontic failure: clinical signs of pathosis•Clinical signs of pathosis associated with endodontic problems generally result from infection.

•Other causes are a periodontal lesion, a vertical root fracture and a lesion arising from an adjacent tooth.

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•Most vertical root fractures occur on the buccal or lingual of the root; consequently, radiographic changes are often absent.

•When bone destruction associated with a vertical root fracture is sufficient to cause radiographic changes, the periodontal ligament will usually appear distinctly and uniformly widened around the entire root to the crest of bone.

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Bone loss around a mandibular premolar consistent with a vertical root fracture . This was confirmed with probing

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•If on the same endodontically treated root the clinician finds both a mucosal sinus tract and a narrow vertical probing pattern the diagnosis will always be vertical root fracture.

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Deep narrow probing defect over the buccal aspect of distal root, note the sinus opening on

the mucosa

Radiograph of same tooth, showing no apical lesion.

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Draining mucosal sinus tract associated with an endodontically treated tooth•Assuming the probing is normal, there are two radiographic possibilities:A radiographic lesion The absence of radiographic lesion

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•Only exploratory surgical tissue reflection will reveal the exact cause .

•Other possibilities arePost perforationRetentive pin perforationRoot fracture

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•If there is radiographic evidence of bone loss, the location of the radiolucency will give a clue to the cause.

•Apical lesions will most likely be the result of endodontic failure.

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•If a 2nd canal is likely and radiographs exposed from different angles are not helpful, the tooth should be reopened for retreatment.

•It is sometimes possible to treat only an untreated canal without retreating the filled canals.

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•A midroot radiolucency presents various possibilities. If the root is straight and the canal appearance does not suggest perforation, a lateral canal could be the cause.

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Surgical exposure reveals a lateral lesion.

Radiograph of same tooth:Apical PDL space is minimally widened

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Draining sinus tract over lateral incisor

•There is no effective treatment for a midroot perforation.

•Root resection or tooth extraction is often indicated.

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Summery : causes of endodontic failures

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Conclusion

•Determination of endodontic failure in absence of symptoms is difficult. In most cases where accurate diagnosis is not possible , a wait and watch approach is best.

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•The clinician who performs endodontic therapy must understand the level of diagnosis, treatment planning and treatment necessary to achieve success and to attain that level on a consistent basis.

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References • Siqueira JF.Aetiology of root canal treatment failure: why well-treated teeth can

fail. Int endo J. 2001; 34: 1–10.

• Gutmann JL , Dumsha TC, Lovdahl PE, Hovland EJ. Problem solving in

endodontics. In: Gutmann JL, Lovadahl PE, editors. Problems in the assessment

of success and failure, quality assurance and their integration into endodontic

treatment planning. 3rd ed. USA: Mosby Publications; 1997. p. 1-22.

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Thank you97