1. Related to access opening of the pulp space
    1. Treating the wrong tooth
      1. Arriving at a diagnosis and designing a treatment plan before beginning any procedure can definitely bring down the number of procedural mishaps that can occur during endodontic therapy.
    2. Incomplete removal of caries
      1. will prevent any chances of secondary caries being left behind when an endodontic procedure is completed.
    3. Access opening through full-coverage restoration
      1. best solution is to remove the crown and proceed with endodontic treatment
    4. Inability to locate extra canals (missed canal orifices)
      1. CAUSES
        1. Failure to externalize the internal anatomy while studying the preoperative radiograph
        2. Lack of knowledge pertaining to root canal anatomy, configuration, and its variations
        3. Improper access and not observing the basic cavity design features
        4. Incomplete deroofing of the pulp chamber
        5. Incomplete removal and shaping of the lateral walls of the pulp chamber
      2. prevention
        1. The access openings in both maxillary and mandibular molars are always on the mesial half of the occlusal surface rarely extending across midline
        2. Good periapical radiographs preoperatively and during root canal cleaning and shaping.
        3. Observe radiographs under magnification.
        4. Multiple radiographs in varying angulations help the clinician to better understand the morphology of the tooth and aid in tracing extra canals
        5. Use DG16 explorer or size 06/08/10 ISO K-file instruments to locate the orifices
    5. Iatrogenic perforations (cervical perforations)
      1. occur in the form of gouging which leads to crown perforation caused by directing the bur nonparallel to the long axis of the tooth.
      2. management
        1. MTA (mineral trioxide aggregate) is the material of choice for sealing perforations
        2. The patient should be informed that a procedural error has occurred and a guarded prognosis is communicated to the patient.
  2. Related to canal shaping and cleaning
    1. Canal blockage and ledge formation
      1. Blockage of canal is basically because of apical pushing of dentinal debris which has been removed during shaping and cleaning of the root canal.
        1. Always use the smaller sized instruments first.
        2. Use the instruments in a sequential order.
        3. Always precurve stainless steel hand instruments.
        4. Use reproducible reference points and stable silicon stoppers on instruments while cleaning and shaping.
        5. Use copious amounts of irrigants and always work in a wet canal.
        6. Recapitulate repeatedly. If there is a loss of working length at this step, take a radiograph and confirm.
      2. CAUSES OF LEDGING
        1. Not extending the access cavity sufficiently to allow adequate access to the apical part of the root canal
        2. Complete loss of control of the instrument if the endodontic treatment is attempted through a proximal surface cavity or through a proximal restoration
        3. Incorrect assessment of the root canal curvature
        4. Erroneous root canal length determination
        5. Forcing and driving the instrument into the canal
        6. Using a noncurved stainless steel instrument that is too large for a curved canal
        7. Failing to use the instruments in a sequential order
        8. Rotating the file at the working length (i.e., overuse of a reaming action)
        9. Inadequate irrigation and/or lubrication during instrumentation
      3. prevention
        1. preoperative radiograph is taken to assess and anticipate unusual root canal curvature
        2. Patency of the canal should be maintained throughout the cleaning and shaping procedure.
        3. Recapitulation with smaller instruments in between each change of instrument is the recommended method to prevent ledge formation
        4. Work passively without forcing the instruments into the canal.
        5. Never force an instrument apically. If resistance exists, confirm whether there is blockage due to other causes.
        6. Work sequentially by increasing the sizes of instruments without jumping to large numbers
    2. Deviation from normal canal anatomy
      1. zipping
        1. Zipping is defined as the apical transportation of a curved canal caused due to improper shaping technique.
      2. transportation
        1. instrument remains within the confines of the root canal
        2. the elliptic preparation will produce internal transportation of the foramen, and if the instrument is outside the confines of the root canal, it will produce external transportation of the foramen
      3. elbow
        1. Elbow is the narrowest portion of the zipped canal.
        2. A zipped canal is apical to elbow and usually obturation ends at the elbow.
      4. management
        1. Prevention is the best form of management of canal transportation.
        2. Adhering to the principles of root canal instrumentation and appreciation of canal anatomy and instrument dynamics would help in the prevention of this form of procedural error
        3. In cases of a zip or transportation, any type of obturation can be used but thermoplasticized obturation techniques are the preferred method of obturation
    3. Separation of instruments
      1. Instruments separate or break only when they are used incorrectly or overused.
      2. The best method to overcome this problem is to avoid instrument separation.
      3. treatment
        1. Instrument retrieval
          1. Endo Extractor and Mounce Extractor.
          2. The Masserann kit works on the principle of drilling a trepan around the separated instrument to loosen it and then pick up with an Endo Extractor.
          3. However, most endodontists prefer ultrasonic instrumentation for the retrieval of separated instrument
        2. 2. Bypassing the instrument and making it part of obturation
        3. Surgical intervention in the form of hemisection of the root or root resection of roots with apical third instrument separation
    4. Obstruction by previous obturating materials
      1. removing gutta-percha from the orifice and middle root canal is to use a solvent, which softens the gutta-percha and permits its removal through sequential instrumentation.
      2. Chloroform was the most popular solvent because of its efficiency.
      3. Gates-Glidden drills or rotary nickel titanium files.
      4. Thermostatically heated pluggers can also be employed
  3. Related to obturation
    1. Underfilling of gutta-percha
      1. happens mainly due to loss of working length as a result of packing dentinal mud into the pulp space without recapitulation or insufficient irrigation.
      2. The use of small-sized files to dislodge the packed dentinal mud and irrigation with sodium hypochlorite frequently is recommended.
      3. Obtain a radiograph after this procedure and reposition the master cone.
      4. Take a confirmatory radiograph and proceed with obturation after using a suitable sealer depending on the technique chosen.
    2. B. Overfilling of gutta-percha
      1. Instrumenting beyond constriction during root canal therapy should not routinely happen if the basic biological and mechanical principles are observed as cardinal rules.
      2. continuous tapered funnel preparation is a mandatory requirement for all canals receiving gutta-percha as obturating material by any technique.
      3. Accurate estimation of the working length.
  4. OTHER ERRORS
    1. Aspiration or Ingestion of Endodontic Instruments
      1. Aspiration of an endodontic hand instrument happens only when the rubber dam is not in place.
      2. if an instrument is swallowed by the patient, the dentist is likely to be confronted with a lawsuit.
      3. in the eyes of court, when an endodontic instrument escapes from the endodontist’s fingers and is ingested or aspirated, expert opinion is not necessary to justify the claims of negligence.