When the inside of the pulp chamber and root canal are clean and hollow, it's time to fill and seal the tooth. Depending on the type of tooth being repaired, there may be one or multiple canals to treat. For example, molars have three to four root canals but top and bottom front teeth have just one or two.
This step of the root canal procedure may take place during the same appointment as the measuring and cleaning of the tooth, or, if the tooth or surrounding tissue was infected before the root canal procedure, the dentist may choose to treat and clear the infection before permanently filling and sealing the tooth.
When infection is present, the patient may be prescribed antibiotics, and the tooth may be temporarily filled with an antibiotic solution and sealed with a temporary filling to protect it as it heals. When the infection is resolved, the temporary filling is removed and the pulp chamber and root canal are filled and sealed just as if no infection had ever been there.
The pulp chamber and root canal are filled with a substance called gutta-percha. Gutta-percha is a rubbery latex material that, when heated and cooled to room temperature, becomes a hard but flexible plastic. Over the years, gutta-percha has been used not only in dental treatments, but also as an ingredient in gum, golf balls and as insulation for underwater cables. In root canal procedures, the material is used to keep the inside of the tooth free from bacteria and to give the tooth a strong core. The amount of gutta-percha needed is determined using those diagnostic x-rays as well as x-rays taken throughout the procedure. If additional core support is needed to ensure a healthy and stable tooth, a metal or plastic rod may also be inserted inside the canal.
When completely filled, the access hole drilled earlier is filled with a sealant paste. It's time to crown the tooth, the final step in the root canal procedure.