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L1 NonSurgical Retreatment

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Non-Surgical Retreatment1

Etiology23

Causes of “Failure”

  • Poor access cavity design
  • Untreated canals
  • Canals that are poorly cleaned and obturated
  • Complications of instrumentation (ledges, perforations, or separated instruments)
  • overextensions of root-filling materials
  • Coronal leakage

Periradicular status for various combinations of treatment quality4

GroupEndoCoronalNo. teethPPIAPI%API
1Good (GE)Good (GR)330.528.5302.091.4
2Good (GE)Poor (PR)164.592.072.544.1
3Poor (PE)Good (GR)302.598.0204.567.6
4Poor (PE)Poor (PR)188.0154.034.018.1

PPI, presence of periradicular inflammation.
API, absence of periradicular inflammation.

  • Ray and Trope Int Endod J 1995; 28: 12-18

Additional Etiological Factors5

  1. Persistent or reintroduced intraradicular microorganisms
  2. Extraradicular infection
  3. Foreign body reaction
  4. True cysts

1. Persistent or reintroduced intraradicular microorganisms6

  • The major cause of posttreatment disease.
  • The major cause of posttreatment disease polymicrobial, predominantly anaerobic flora.

2. Extraradicular Infection7

  • Direct spread of infection from the root canal space via contaminated periodontal pockets that communicate with the apical area.
  • Extrusion of infected dentin chips
  • Contamination with overextended, infected endodontic instruments.
  • By producing an extracellular matrix or protective plaque.

3. Foreign Body Reaction8

  • Oral Pulse Granuloma
  • Cellulose Granuloma
  • Filling material extrusion leads to a lower incidence of healing

4. True Cyst9

  • The incidence of periapical cysts has been reported to be 15% to 42% of all periapical lesions.
  • There are two types of periapical cysts: the periapical true cyst and the periapical pocket cyst.

Microbiology10

  • Enterococcus faecalis, the root canal survivor and ‘star’ in posttreatment disease.
  • Candida albicans, are found frequently in persistent endodontic infections and may be responsible for the recalcitrant lesion.
  • Actinomyces israelii and Propionibacterium propionicum, are present in the periapical tissues and may prevent healing after root canal therapy

Diagnosis111213

The clinician must rule out non-odontogenic etiology, perform all of the appropriate tests, properly interpret the patient’s responses to these tests, derive at a definitive diagnosis, and decide on treatment options.

In cases of persistent disease, the diagnosis may not be as straightforward as the clinician may be dealing with

The diagnostic method requires collecting subjective information, developing objective findings, and using these to arrive at a diagnosis and plan of treatment.

The elements of diagnosis are as follows:

  1. Clinical Examination
  2. Radiographic Examination
  3. CBCT
  4. Comparative Testing

1. Clinical Examination1415

Visual examination (intra-oral and extra-oral)16

aided by magnification and illumination, which can allow the clinician to identify significant conditions invisible to the naked eye, such as fine fractures on root surfaces

  • Exposed dentin from recession and narrow based probing defects may be the result of an endodontic infection draining through the sulcus; however, they sometimes indicate vertical root fracture.

  • The presence of occlusal wear facets indicates the presence of occlusal trauma that may complicate diagnosis and treatment outcome by predisposing the tooth to fracture, and it has been associated with posttreatment disease.

2. Radiographic Examination171819

Bitewing radiographs are useful for determining periodontal bone height and looking for caries or fractures.

All sinus tracts should be traced with a cone of gutta-percha followed by a radiograph to localize their origin.

3. CBCT20

The CBCT allows the clinician to determine the true size, extent, and position of periapical and resorptive lesions and gives added information about tooth fractures, missed canals, root canal anatomy, and the nature of the alveolar bone topography around teeth.

4. Comparative Testing2122

Percussion, bite, and palpation to evaluate the status of the periradicular tissues.

Pulp vitality tests are often of little value when examining teeth with previous endodontic therapy. However, if the patient’s chief complaint reveals the need for these tests, they must be performed because it is possible that the pain may be referred from a nearby vital tooth and not from the root canal– treated tooth.

Treatment Planning2324

If the cause of the post-treatment condition remains unknown despite thorough diagnostic workup, then any decision results in an empirical “trial and error” type of treatment. This approach should be avoided if possible.

The patient is then allowed to make a decision based on his or her own perceptions of the options, not by the clinician’s opinion as to what is “best” for the patient.

Factors in the decision making process

  1. Identify the Cause of Failure: Is it correctable?
  2. Assess Restorability: After removing the existing restoration and filling, will there be enough tooth structure left for a new, durable restoration? Each treatment cycle removes tooth structure.
  3. Discuss Options with the Patient: o Non-surgical retreatment o Surgical retreatment (apicoectomy) o Extraction and replacement (e.g., implant)
  4. Referral: Consider referring complex cases or those beyond your skill and confidence level to an endodontist. Single-rooted teeth are generally considered more straightforward for retreatment by a general dentist.

Removal of Obturating Materials2526

Types of Obturation Materials

  • Gutta Percha
  • Solid core obturators.
  • Paste
  • Resilon
  • Silver points.

Types of gutta Percha Fills

  • Single Cone: Typically easier to remove as it’s one solid piece
  • Condensed GP: Can be more difficult to remove due to multiple, compacted Accessory cones
  • Aged GP: old GP becomes more brittle over time, making it harder to engage and remove in one piece

Methods for Gutta Percha Removal27

  • Removal of gutta percha manually
  • Removal of gutta percha using rotary system
  • Removal of gutta percha using LASER

Solvents

Solvents are used to soften the GP, making it easier to remove. · Chloroform: Historically used, but no longer indicated for intraoral use due to toxicity and carcinogenicity. · Eucalyptus Oil: Effectively softens GP, rendering it mushy. Caution: It can dissolve a rubber dam if it comes into contact with it.

Removal of Gutta Percha Steps**28293031323334353637383940

· Specialized Files: Retreatment rotary systems differ from standard shaping files. The first file in the sequence typically has a cutting tip to pierce the coronal GP, whereas shaping files have a non-cutting pilot tip. The files often have larger tapers for coronal removal and smaller tapers for apical removal. · Technique: a. Remove the coronal GP to the level of the orifice using a thermal cut bur or a large composite finishing bur (red stripe). b. Use the first (largest taper) retreatment file in a \

Rotary GP removal

D1 is used for coronal filling removal (16 mm long) D2 is used for mid-root filling removal (18 mm long) D3 is used for apical filling removal (22 mm long)

Canal negotiation & W.L. determination

This is the most challenging step after bulk GP removal. The previous treatment may have created ledges or blocks that prevent reaching the full working length. Careful manual negotiation with small hand files is required.

Finishing the preparation

Once working length is achieved, the canal is fully shaped and disinfected with copious irrigation, just as in a primary root canal treatment.

Just remember

· Irrigate ·

Removal of Solid Core Obturators4142434445

These consist of a central carrier (plastic or cross-linked GP) coated with gutta-percha. · Challenge: The central plastic carrier can be difficult to remove. · Techniques: a. Bypass: Attempt to slide a file alongside the carrier. Some carriers have vents designed to facilitate this. b. Engagement: Use a Hedstrom file rotated clockwise to engage the file

Heating Obturarors

Products like the Thermaprep2 overn allow for heating the obturator

Paste Removal46474849

NOTE

Pastes are considered historical filling materials but they will still be encountered in practice!

Removal of Non-setting or Soft paste

  • Solvent
  • Hand or rotary instrument (copious Naocl irrigation).
  • Ultrasonically activated and irrigated files

Hard Setting Paste505152

  • Resorcinol-formaldehyde resin “Russian Red”

  • Removal of Hard setting pastes:

    • Burs, Ultrasonic tips (accessible straight portion of the canal)
    • Precurved small hand files (apical area)
    • Use of Solvent (Endosolve – R, Septodent)

Removal of Silver Point5354

Silver points are a historical obturation material no longer in use. · Reason for Failure: a. Poor Adaptation: They are round and cannot conform to the irregular shape of a root canal, leaving large voids. b. Corrosion: When exposed to tissue fluids, silver points corrode, releasing cytotoxic byproducts (e.g., silver sulfide, silver amine) that are toxic to periapical tissues. ·

Principles of Silver Point Removal

  1. Visibility: The coronal end of the point must be fully exposed by carefully removing the surrounding restoration.
  2. Looseness: The point must be loosened in the canal. This is best achieved with ultrasonics , which vibrate the point and break the cement seal.
  3. Firm Grasp: A firm grip must be established before attempting removal to prevent the soft, ductile silver from breaking.

Techniques for Silver Point Removal

· Ultrasonics (Preferred Method): Use an ultrasonic tip around the circumference of the silver point with low power and high patience. The vibration will break the cement line and often cause the point to loosen

Footnotes

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