Root Canal Treatment Procedure

Root canal treatment is an endodontic procedure (treatment of the inside of the tooth) with the aim of removing the irreversibly (irreversibly) diseased pulp (tooth pulp) and, after disinfecting measures, sealing the resulting cavity with a root canal filling to make it bacteria-proof. Root canal treatment is indicated for devitalized (dead) or irreversibly inflamed pulp (tooth pulp).

Symptoms – Complaints

Painful pulpititis (inflammation of the pulp) and apical periodontitis (inflammation of the periodontium affecting the root apex) lead to the planning of root canal treatment. They are manifested by the following clinical symptoms, which may occur singly or in combination:

  • Cold pain and/or heat pain
  • Tooth feels elongated
  • Bite pain
  • Pain occurring independently of food intake
  • Feeling of pressure in the area of the apex (root tip).

Diagnostics

The diagnosis leading to the initiation of root canal treatment is made on the basis of clinical symptoms, supplemented if necessary by a positive radiographic finding:

  • Percussion test (checking the bite/knock sensitivity).
  • Thermal sensitivity testing:
  • Cold test – statement reliability 95% to 100%.
  • Heat test – no longer recommended because heat causes prolonged pain only from 80 °C and therefore heat damage to the pulp (tooth pulp) can not be ruled out.
  • Electrical sensitivity test: Statement reliability 90% to 95%; this test method is based on the conductivity ratios of the tooth hard tissues. It can not be used in principle in crowned teeth because of the shunt with metal and the insulator effect of ceramics.
  • Mechanical sensitivity test: exposed dentin (dentin; tooth hard tissue lying under the enamel) reacts sensitively to contact with the probe or drill.
  • X-ray examination of the root area with the question of apical periodontitis (inflammation of the periodontium affecting the root tip), which shows itself in the form of osteolysis (bone dissolution).

Indications (areas of application)

Thus, from the clinical findings and diagnostics, the following indications for root canal treatment:

  • Irreversible pulpitis (nonreversible pulp inflammation): whereas in a tooth that is only strongly sensitive to cold, one can still consider the possibility that the inflammation is of a temporary nature, if the sensitivity to heat and bite increases, the irreversibility (irreversibility) of the inflammatory process must be assumed.
  • Pulpanecrosis (dead pulp).
  • Pulpitis purulenta (synonym: gangrene) (purulent inflammation of the pulp).
  • Apical periodontitis (inflammation of the periodontium (periodontium) just below the tooth root; apical = “tooth rootward”).
  • Apical cyst formation

Contraindications

  • Reversible pulpitis (reversible pulp inflammation) must be observed first before a treatment decision is made, and possible triggering causes such as caries or occlusal trauma (incorrect loading during chewing) must be eliminated in advance.
  • Tooth structure is too far destroyed, so that the tooth after root canal treatment could no longer be adequately supplied: Indication for extraction (tooth removal).
  • The inflammatory process in the root tip area has progressed so far that it can no longer be preserved, even in combination with surgical measures (root tip resection): Indication for extraction
  • The tooth is periodontally (with respect to its periodontal bed) too severely pre-damaged: Indication for extraction (tooth removal).

The procedure

If the diagnosis reveals one of the above indications, root canal treatment is the therapy of choice. This aims to remove the bacterially damaged pulp as completely as possible using mechanical and chemical methods, to expand the cavity of the root canals, thereby removing bacterially contaminated canal walls, and to create the possibility of providing the root canals with a bacteria-tight root filling up to the narrowest point of the root canal, the apical constriction (synonyms: physiological apex, physiological root apex), after symptomlessness has been achieved.The treatment procedure is carried out in several sub-steps:

Preparation of the access cavity (opening of the tooth by drilling) – Here, particular attention must be paid to the axial direction of the drill and the complete removal of the pulp wax in order to have unhindered access to the root canal entrances in the following. Probing and uncovering the root canal entrances – Magnifying glasses with 6 to 8x magnification or a surgical microscope can be used to assist with this. Size 10 or 15 files are used to test whether the structure found is really a canal entrance. In case of doubt, an electrometric length gauge should be used to rule out perforation (piercing) of the pulp chamber floor. If no canal entrance is found, supportive ultrasonic reworking can be performed, followed by drying and staining to make the entrance visible. Determining the working length – The aim of preparation is to reach and widen the root canal to the apical constriction (physiological root apex, narrowest point of the root canal near the root apex). Precise determination of the working length is one of the most important steps in the entire root canal treatment. In this respect, electrical length measuring instruments are at least equal, if not superior, to measurement with the aid of an X-ray image. Ideally, both methods should complement each other. Preparation of the root canal – coronal-apical instrumentation: First, the coronal part of the canal (near the tooth crown) is widened, and then reamers and files (special instruments for canal preparation) are used to work towards the apical part (in the direction of the root tip). A wide variety of systems are available for this purpose. For apical expansion, instruments with standardized conicity (conical shape) and increasing diameter are used in succession. Irrigation (flushing of the root canal) – In the preparation phase, frequent intermediate irrigation must take place to flush out tissue residues and dentin chips filed off the canal walls so as not to obstruct the canal lumen (cavity of the root canal). In addition, the rinses chemically dissolve and disinfect tissue from the ramifications (ramifications of the dental pulp in the root apex area), which are not accessible to mechanical processing. The following rinsing solutions are usually used:

  • Sodium hypochlorite (NaOCl) 5%: has a bactericidal (bacteria-killing) and tissue-dissolving effect, and the dissolving effect is further improved by ultrasound.
  • Chelators (synonym: chelating agents): e.g. ethylenediaminetetraacetic acid (EDTA) or citric acid remove the smear layer from the canal walls and allow the root canal instruments to glide better.
  • Chlorhexidine 0.2% – 2%: must be used especially in the revision of a root canal, as it is effective against E. faecalis, whose colonization can be assumed in old root fillings in need of renewal.

Intermediate medical insertion – To continue antimicrobial therapy after the root canal preparation is completed, calcium hydroxide is placed in the root canal for a limited period of time as the first choice agent. Its highly alkaline environment renders 90% of the canals free of bacteria. However, calcium hydroxide is not effective against Enterococcus faecalis (also Streptococcus faecalis). In contrast, chlorhexidine and camphor-paramonochlorophenol are effective against contamination with E. faecalis, which is particularly likely to occur during root canal revision. Root canal filling – This is the final step in root canal treatment. The decisive aspects in the selection of the material are the impermeability of the margins to prevent recolonization with bacteria and the biocompatibility to prevent reactions of the periapical tissue (surrounding the root apex). Commonly used materials include gutta-percha in combination with sealers (root canal filling cement). Recently, bioactive root canal sealers with antimicrobial properties through the incorporation of additives such as quaternary ammonium compound and silver nanoparticles have been used. These new materials are expected to have the potential to improve the efficacy of endodontic (root canal) treatment while increasing the life of the tooth. Diverse methods of root canal filling are also being used, currently for example:

  • Single post method
  • Lateral condensation
  • Vertical condensation
  • thermoplastic gutta-percha injection

Possible complications

  • Instrument fracture (breakage of a preparation instrument): removal of the instrument is usually very difficult and, depending on the depth of the fracture, often unsuccessful. In the lower third of the root canal, surgical apicoectomy can be performed to remove the fracture.
  • Via falsa (“wrong way”): drilling through the root canal wall especially in the area of strong root curvatures.
  • Perforation (piercing) of the pulp chamber floor in the search for a root canal.
  • Overlooking or failure to find a root canal.
  • Preparation not possible up to the physiological apex (root tip)
  • Overcrowding of root filling material beyond the apex, especially in apical osteolysis (bone dissolution “tooth rootward”).