In the situation that a tooth is considered so threatened (because of decay, cracking, etc.) that future infection is considered likely or inevitable, a pulpectomy, removal of the pulp tissue, is advisable to prevent such infection. Usually, some inflammation and/or infection is already present within or below the tooth. To cure the infection and save the tooth, the dentist drills into the pulp chamber and removes the infected pulp by scraping it out of the root canals. Once this is done, the dentist fills the cavity with an inert material and seals up the opening. This procedure is known as root canal therapy. If enough of the tooth has been damaged, or removed as a result of the treatment, a crown may be required.
The standard filling material is gutta-percha, a natural thermoplastic polymer of isoprene, which is melted and injected to fill the root canal passages. Barium is added to the isoprene so the material will be opaque to X-rays, allowing verification afterwards that the passages have been properly completely filled in, without voids.
For patients, root canal therapy is one of the most feared procedures in all of dentistry; however, dental professionals assert that modern root canal treatment is relatively painless because the pain can be controlled. Lidocaine is a commonly used local anaesthetic. Pain control medication may be used either before or after treatment. However, in some cases it may be very difficult to achieve pain control before performing a root canal. For example, if a patient has an abscessed tooth, with a swollen area or "fluid-filled gum blister" next to the tooth, the pus in the abscess may contain acids that inactivate any anaesthetic injected around the tooth. In this case, it is best for the dentist to drain the abscess by cutting it to let the pus drain out. Releasing the pus releases pressure built up around the tooth; this pressure causes much pain. The dentist then prescribes a week of antibiotics such as penicillin, which will reduce the infection and pus, making it easier to anaesthetise the tooth when the patient returns one week later. The dentist could also open up the tooth and let the pus drain through the tooth, and could leave the tooth open for a few days to help relieve pressure.
At this first visit, the dentist must ensure that the patient is not biting into the tooth, which could also trigger pain. Sometimes the dentist performs preliminary treatment of the tooth by removing all of the infected pulp of the tooth and applying a dressing and temporary filling to the tooth. This is called a "pulpectomy". The dentist may also remove just the coronal portion of the dental pulp, which contains 90% of the nerve tissue, and leave intact the pulp in the canals. This procedure, called a "pulpotomy", tends to essentially eliminate all the pain. A "pulpotomy" may be a relatively definitive treatment for infected primary teeth. The pulpectomy and pulpotomy procedures eliminate almost all pain until the follow-up visit for finishing the root canal. But if the pain returns, it means any of three things: the patient is biting into the tooth, there is still a significant amount of sensitive nerve material left in the tooth, or there is still more pus building up inside and around the infected tooth; all of these cause pain.
After removing as much of the internal pulp as possible, the root canals can be temporarily filled with calcium hydroxide paste. This strong alkaline base is left in for a week or more to disinfect and reduce inflammation in surrounding tissue. Ibuprofen taken orally is commonly used before and/or after these procedures to reduce inflammation. The following substances are used as root canal irrigants during the root canal procedure:
5.25% sodium hypochlorite (NaOCl)
6% sodium hypochlorite (NaOCl) with Surface modifiers for better flow into nooks and crannies
2% chlorhexidine gluconate
0.2% chlorhexidine gluconate plus 0.2% cetrimide (Cetrexidin)
17% ethylenediaminetetraacetic acid (EDTA)
Framycetin sulfate (Septomixine)
After receiving a root canal, the tooth should be protected with a crown that covers the cusps of the tooth. Otherwise, over the years the tooth will almost certainly fracture, since root canals remove tooth structure from the tooth and undermine the tooth's structural integrity. Also, root canal teeth tend to be more brittle than teeth not treated with a root canal. This is commonly due to the fact that the blood supply to the tooth, which nourishes and hydrates the tooth structure, is removed during the root canal procedure, leaving the tooth without a source of moisture replenishment. Placement of a crown or cusp-protecting cast gold covering is recommended also because these have the best ability to seal the root canaled tooth. If the tooth is not perfectly sealed, the root canal may leak, causing eventual failure of the root canal. Also, many people believe once a tooth has had a root canal treatment it cannot get decay. This is not true. A tooth with a root canal treatement still has the ability to decay, and without proper home care and an adequate fluoride source the tooth structure can become severely decayed (– often without the patient's knowledge since the nerve has been removed, leaving the tooth without any pain perception). Thus, non-restorable carious destruction is the main reason for extraction of teeth after root canal therapy, with up to two-thirds of these extractions. Therefore it is very important to have regular X-rays taken of the root canal to ensure that the tooth is not having any problems that the patient would not be aware of.
The procedure is often complicated, depending on circumstances, and may involve multiple visits over a period of weeks. The cost is high, by local standards. In the United States, it would typically cost US$400-1,000—though exceeded by the even more expensive related crown procedure, typically around US$500-2000 with usually only 50% being covered by the dental insurer (DMO or DPO). In India , the root canal procedure would typically cost INR 1,500-4,500 (US$35-110), when performed by an endodontist — and the crown procedure, for a ceramic crown, would cost around INR 2,000-5,000 (US$50-125). In Argentina mostly all medical insurance services offer full coverage for the endodontic therapy. Without dental insurance, the average cost for an endodontic therapy, done by a qualified endodontist, is around ARP 140 or USD 44 (March, 2008). This procedure does not include the ceramic crown which, without dental insurance, is around ARP 540 or USD 170 (March, 2008)
In the last ten to twenty years, there have been great innovations in the art and science of root canal therapy. Dentists now must be educated on the current concepts in order to optimally perform a root canal. Root canal therapy has become more automated and can be performed faster, thanks to advances in automated mechanical instrumentation of teeth and more advanced root canal filling methods. Dentists also possess newer technologies that allow more efficient, scientific measurements to be taken of the dimensions of the root canal that must be filled. Many dentists use microscopes to perform root canals, and the consensus is that root canals performed using microscopes or other forms of magnification are more likely to succeed than those performed without them. Although general dentists are becoming versed in these advanced technologies, they are still more likely to be used by specialist root canal doctors (known as endodontists).
Laser root canal procedures are a controversial innovation. Lasers may be fast but have not been shown to thoroughly disinfect the whole tooth, and may cause damage.
All text of this article available under the terms of the GNU Free Documentation License (see Copyrights for details).