Obturation

The function of a root canal filling is to obturate the canal and eliminate all portals of entry between the periodontium and the root canal. The better the seal, the better the prognosis of the tooth. Achieving the ideal seal, however, is as complex as the anatomy of the root canal system itself. Because all root canal fillings must seal all foramina leading into the periodontium, an ideal filling must be well condensed, must conform and adhere to the instrumented canal walls, and must end at the juncture of the root canal and the periodontium.

Purpose of Obturation

1. To achieve total obliteration of the root canal space so as to prevent ingress of bacteria and body fluids into root canal space as well as regress of bacteria which are left in canal.
2. To attain fluid tight seal so as to prevent bacterial microleakage.
3. To replace the empty root canal space with an inert filling material so as to prevent recurrent infection.
4. To seal the root canal space as well as to have coronal seal for long term success of root canal therapy.

Timing of Obturation

Patient Symptoms

• If patient presents with sensitivity on percussion, it indicates inflammation in periodontal ligament space, canal should not be obturated before the inflammation has subsided.
• In case of irreversible pulpitis, obturation can be completed in single visit if the main source of pain, i.e. pulp has been removed.

Pulp and Periradicular Status

• Teeth with vital pulp can be obturated in same visit.
• Teeth with necrotic pulp may be completed in single visit if tooth is asymptomatic.
• Presence of even a slight purulent exudate may indicate possibility of exacerbation. If canal is sealed, pressure and subsequent tissue destruction may proceed rapidly.

Negative Culture

The reliance on negative cultures has decreased now since the researches have shown that false negative results can give inaccurate assessment on microbial flora, also the positive results do not indicate the potential pathogenicity of bacteria.

Extent of Obturation

Many studies have been conducted regarding the apical extent of obturation. It has been found that obturation should be done at the level of dentinocemental junction. Kutlur described DCJ as minor apical diameter which ends 0.5 mm short of apical foramen in young patients and 0.67 mm short in older patients. One should avoid overextension and overfilling of the root canal system.

• Overfilling is complete obturation of root canal system with excess material extruding beyond apical foramen.
• Overextension is extrusion of filling material beyond apical foramen but the canal may not have been filled completely.

Features of an ideal root canal obturation

• Three-dimensional obturation close to CDJ.
• Radiographically, filling should be seen 0.5-0.75 mm from radiographic apex.
• Minimal use of a root canal sealer which is confined to root canal.

Materials used for Obturation

After the pulp space has been prepared appropriately, it must be obturated with a material which is capable of completely preventing communication between oral cavity and periapical tissue. The prepared apical connective tissue wound area cannot heal with epithelium, thus root canal filling material placed against this wound serves as an alloplastic implant. There are expectations which make the selection of a good obturation material. These materials may be introduced into the canals in different forms and may be manipulated by different ways. Grossman grouped acceptable filling materials into plastics solids, cements and pastes. He also delineated ten requirements for an ideal root canal filling materials.

Characteristics of an ideal root canal filling material

1. Easily introduced in the canal.
2. Seal canal laterally and apically.
3. Dimensionally stable after being inserted.
4. Impervious to moisture.
5. Bacteriostatic or at least should not encourage bacterial growth.
6. Radiopaque.
7. Non staining to tooth structure.
8. Non irritating.
9. Sterile/easily sterilized.
10. Removed easily from canal if required.

Materials used for obturation

• Plastics: Gutta-percha, resilon
• Solids or metal cores: Silver points, Gold, stainless steel, titanium and irridio-platinum.
• Cements and pastes:

1. Hydron
2. MTA
3. Calcium phosphate
4. Gutta flow

Obturation Resources
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