Revision of a Root Filling

Root canal treatment with a final root filling is used to preserve a tooth after removal of the diseased pulp (tooth pulp) – a treatment that, despite high success rates, does not always result in healing of the periapical inflammation (around the root tip). This may necessitate a revision of the root canal filling. In a revision, a previously placed root canal filling is removed and replaced with a new root canal filling after antimicrobial measures have been taken and the patient is free of symptoms.

Symptoms – Complaints

Radiographic findings:

  • A newly developed apical osteolysis (dissolution of the bone at the root apex).
  • A lightening existing at the time of placement of the first root filling does not diminish within the following four years (progress checks) or increases in size

Possible clinical findings:

  • Percussion dolence (sensitivity to tapping).
  • Bite sensitivity of the affected tooth
  • Pressure dolence (pressure pain) of the gum vestibular (in the front of the mouth) oral (inside the mouth).
  • Fistula or soft tissue swelling near the roots.
  • Clinical absence of symptoms with worsening radiographic findings.

Diagnostics

Diagnosis is made by clinical and radiographic findings.

Therapy

During revision, the old root canal filling is first removed as completely as possible. Subsequently, the root canals are mechanically widened to remove the infected dentin (tooth bone) near the canal wall. At the same time, thorough disinfection with rinsing solutions takes place. If additional canals are found during the revision, which may be the reason for the failure of the previous treatment, they are also prepared and, after the tooth is free of symptoms, a root canal filling is applied. The goal of the therapy is to create a germ-free, bacteria-tight seal of the root canal system and thus achieve permanent clinical and radiographic symptom freedom.

Indications (areas of application)

The indication for revision of a root canal filling may result from the clinical and radiographic findings listed above, but may also be due to the following prophylactic considerations:

  • Following bacterial contamination (contamination) prior to reprovisioning: If a root filling has been exposed to the microbial oral environment for a prolonged period of time, such as when a filling or crown has been lost, it must be assumed that the root canal has been recolonized bacterially along the borderline between the canal filling and the canal wall.
  • Before extensive therapy: If a root-filled tooth is included in an extensive planning for dental prosthesis, it is advisable to revise a root canal filling that has been in place for a long time and is free of complaints, but is radiographically deficient, in advance to create optimal conditions for the new elaborate dental prosthesis.
  • Before apicoectomy (WSR): If, due to the size of the apical osteolysis (dissolution of bone at the root tip), the WSR of a tooth that has been root-filled for some time is unavoidable, a preoperative revision improves the chances of success of the WSR.

Contraindications

  • The root-filled tooth is restored with dentures (post, crown, bridge) and the root filling is thus not accessible to orthograde preparation (preparation from the oral cavity via the root canal) without destroying the denture.
  • Due to the pre-treatment or the X-ray findings, an improvement of the root filling is not expected, e.g. due to a strong root curvature, restricted mouth opening or obliteration (adhesion by dentin-like hard substance) of the root canal.
  • A revision attempt has already been made.
  • The tooth is no longer worth preserving due to its periodontal condition.
  • The further care concept does not tolerate prognostically questionable teeth.
  • The condition of the tooth structure no longer allows a subsequent tooth-preserving restoration.

The procedure

Revisions are generally considered to be difficult. Revision can be complex depending on the root filling material used, the canal curvature, or the prepared diameter of the canal. While softer paste fillings and gutta-percha are usually removable, removing hard pastes or cements carries a high risk of perforating (piercing) the canal wall.Therefore, referral to an endodontically specialized practice is recommended for complicated revisions.

  • Create access to the root canal with rotary instruments.
  • Heating and removing a gutta-perch filling in the area near the crown with a hot probe
  • Removal of the following 5 mm of the filling, e.g., with Gates glidden drill.
  • Introduction of a solvent, e.g., eucalyptol, to soften the gutta-percha – but not in the case of poorly compacted gutta-percha filling or if the filling extends beyond the root tip
  • Removal of silver posts with the file-braiding technique: one or more Hedström files are placed around the post as deep as possible in the canal, then twisted against each other. This hooks the file edges in the softer silver and can be pulled out.
  • Introduction of ethylenediaminetetraacetic acid (EDTA) as a gel or rinse: removes the smear layer and improves the lubricity of the endodontic instruments.
  • Removal of the remaining filling with files (Hedström file, Pro-Taper Universal and others).
  • Approaching the apical constriction (physiological root apex; narrowed area at the root apex) to 2 mm.
  • Rinsing with sodium hypochlorite (2.5 – 5.25%) – Ultrasound-activated rinsing improves antibacterial and tissue dissolving effects.
  • Intermediate rinsing e.g. with saline or EDTA solution: hypochlorite and chlorhexidine react with each other, red-brown parachloroaniline is precipitated.
  • Rinse with chlorhexidine (0.2 – 2%): in revisions must be reckoned with colonization with Enterococcus faecalis, against which only chlorhexidine has an antibacterial effect.
  • Then complete reprocessing until apical constriction. The length determination during reprocessing must be done with radiographs and / or endometric length determination.
  • As a disinfectant insert in case of contamination (contamination) with E. faecalis, calcium hydroxide is less suitable, unlike in initial root canal treatment. Chlorhexidine 2% or camphor-paramonochlorophenol are effective, although chlorhexidine is preferable due to its better biocompatibility. The insert remains in place for one to about four weeks; meanwhile, the tooth must be sealed saliva-tight to prevent recontamination of the canal system.
  • Then, if necessary, repeat the disinfecting insert or final root canal filling with bacteria-proof further treatment.

Possible complications

  • Instrument fracture: fracture of a root canal instrument is the most common complication
  • Perforations: second most common problem, occurring, for example, when searching for root canal entrances, in highly curved roots, or when trying to make calcified (calcified) canals common
  • Root filling material can not be removed or only partially, so that the apical constriction (physiological root tip) is not reached
  • After revision, apical periodontitis (inflammation of the periodontium (periodontium) just below the tooth root; apical = “tooth rootward”) persists or develops new
  • Root canal system is partially inaccessible: branching, strong curvatures, obliterations (closure by hard substance formation).
  • Insufficient disinfection
  • Root fractures
  • Plugging of root filling material over the apex (root tip).
  • Overplugging of a fractured instrument piece over the apex.