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Root canal treatment (also known as endodontic therapy, endodontic treatment, or root canal therapy) is a treatment sequence for the infected pulp of a
tooth A tooth ( : teeth) is a hard, calcified structure found in the jaws (or mouths) of many vertebrates and used to break down food. Some animals, particularly carnivores and omnivores, also use teeth to help with capturing or wounding prey, tear ...
which is intended to result in the elimination of infection and the protection of the decontaminated tooth from future
microbial A microorganism, or microbe,, ''mikros'', "small") and '' organism'' from the el, ὀργανισμός, ''organismós'', "organism"). It is usually written as a single word but is sometimes hyphenated (''micro-organism''), especially in old ...
invasion.
Root canal A root canal is the naturally occurring anatomic space within the root of a tooth. It consists of the pulp chamber (within the coronal part of the tooth), the main canal(s), and more intricate anatomical branches that may connect the root ...
s, and their associated
pulp chamber The pulp is the connective tissue, nerves, blood vessels, and odontoblasts that comprise the innermost layer of a tooth. The pulp's activity and signalling processes regulate its behaviour. Anatomy The pulp is the neurovascular bundle cen ...
, are the physical hollows within a tooth that are naturally inhabited by
nerve tissue Nervous tissue, also called neural tissue, is the main tissue component of the nervous system. The nervous system regulates and controls body functions and activity. It consists of two parts: the central nervous system (CNS) comprising the brain ...
,
blood vessel The blood vessels are the components of the circulatory system that transport blood throughout the human body. These vessels transport blood cells, nutrients, and oxygen to the tissues of the body. They also take waste and carbon dioxide awa ...
s and other cellular entities. Together, these items constitute the dental pulp. Endodontic therapy involves the ''removal'' of these structures, disinfection and the subsequent shaping, cleaning, and decontamination of the hollows with small files and irrigating solutions, and the ''obturation'' (filling) of the decontaminated canals. Filling of the cleaned and decontaminated canals is done with an inert filling such as
gutta-percha Gutta-percha is a tree of the genus '' Palaquium'' in the family Sapotaceae. The name also refers to the rigid, naturally biologically inert, resilient, electrically nonconductive, thermoplastic latex derived from the tree, particularly fro ...
and typically a
zinc oxide eugenol Zinc oxide eugenol (ZOE) is a material created by the combination of zinc oxide and eugenol contained in oil of cloves. An acid-base reaction takes place with the formation of zinc eugenolate chelate. The reaction is catalysed by water and is acc ...
-based cement.
Epoxy Epoxy is the family of basic components or cured end products of epoxy resins. Epoxy resins, also known as polyepoxides, are a class of reactive prepolymers and polymers which contain epoxide groups. The epoxide functional group is also c ...
resin is employed to bind gutta-percha in some root canal procedures. Another option is to use an antiseptic filling material containing paraformaldehyde like N2. Endodontics includes both primary and secondary endodontic treatments as well as
periradicular surgery In the dental specialty of endodontics, periradicular surgery is surgery to the external root surface. Examples of periradicular surgery include apicoectomy, root resection, repair of root perforation or resorption defects, removal of broken fr ...
which is generally used for teeth that still have potential for salvage.


Treatment procedure

The procedure is often complicated, depending on circumstances, and may involve multiple visits over a period of weeks.


Diagnostic and preparation

Before endodontic therapy is carried out, a correct diagnosis of the dental pulp and the surrounding periapical tissues is required. This allows the endodontist to choose the most appropriate treatment option, allowing preservation and longevity of the tooth and surrounding tissues. Treatment options for an irreversibly inflamed pulp (irreversible pulpitis) include either extraction of the tooth or removal of the pulp. Removing the infected/inflamed pulpal tissue enables the
endodontist Endodontics (from the Greek roots ''endo-'' "inside" and ''odont-'' "tooth") is the dental specialty concerned with the study and treatment of the dental pulp. Overview Endodontics encompasses the study (practice) of the basic and clinical ...
to help preserve the longevity and function of the tooth. The treatment option chosen involves taking into account the expected prognosis of the tooth, as well as the patient's wishes. A full history is required (which includes the patient's symptoms and medical history), along with a clinical examination (both inside and outside the mouth), and the use of diagnostic tests. There are several diagnostic tests that can aid in the diagnosis of the dental pulp and the surrounding tissues. These include: * Palpation (this is where the tip of the root is felt from the overlying tissues to see if there is any swelling or tenderness present) * Mobility (this is assessing if there is more than normal movement of the tooth in the socket) * Percussion (TTP, tender to percussion; the tooth is tapped to see if there is any tenderness) * Transillumination (shining a light through the tooth to see if there are any noticeable fractures) * Tooth Slooth (this is where the patient is asked to bite down upon a plastic instrument; useful if the patient complains of pain on biting as this can be used to localise the tooth) * Radiographs *
Dental pulp test Dental pulpal testing is a clinical and diagnostic aid used in dentistry to help establish the health of the dental pulp within the pulp chamber and root canals of a tooth. Such investigations are important in aiding dentists in devising a treatment ...
s If a tooth is considered so threatened (because of decay, cracking, etc.) that future infection is considered very 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 and/or below the tooth. To cure the infection and save the tooth, the dentist drills into the pulp chamber and removes the infected pulp. To eliminate bacteria from the pulp chamber and root canals, the use of efficient antiseptics and disinfectants is necessary. The soft tissues are either drilled out of the root canal(s) with engine driven rotary files, or with long needle-shaped hand instruments known as hand files ( H files and K files).


Opening in the crown

The dentist makes an opening through the enamel and
dentin Dentin () (American English) or dentine ( or ) (British English) ( la, substantia eburnea) is a calcified tissue of the body and, along with enamel, cementum, and pulp, is one of the four major components of teeth. It is usually covered by en ...
tissues of the tooth, usually using a
dental drill A dental drill or handpiece is a hand-held, mechanical instrument used to perform a variety of common dental procedures, including removing decay, polishing fillings, performing cosmetic dentistry, and altering prostheses. The handpiece itsel ...
fitted with a
dental burr A dental drill or handpiece is a hand-held, mechanical instrument used to perform a variety of common dental procedures, including removing decay, polishing fillings, performing cosmetic dentistry, and altering prostheses. The handpiece itsel ...
. Isolating the tooth The use of a rubber dam for tooth isolation is mandatory in endodontic treatment for several reasons: # It provides an aseptic operating field, isolating the tooth from oral and salivary contamination. Root canal contamination with saliva introduces new microorganisms to the root canal which compromise the prognosis. # It facilitates the use of the strong medicaments necessary to clean the root canal system. # It protects the patient from the inhalation or ingestion of endodontic instruments.


Removal of pulp tissue


Procedures for shaping

There have been a number of progressive iterations to the mechanical preparation of the root canal for endodontic therapy. The first, referred to as the ''standardized technique'', was developed by Ingle in 1961, and had disadvantages such as the potential for loss of working length and inadvertent ledging, zipping or perforation. Subsequent refinements have been numerous, and are usually described as ''techniques''. These include the step-back, circumferential filing, incremental, anticurvature filing, step-down, double flare, crown-down-pressureless, balanced force, canal master, apical box, progressive enlargement, modified double flare, passive stepback, alternated rotary motions, and apical patency techniques. The step back technique, also known as telescopic or serial root canal preparation, is divided in two phases: in the first, the working length is established and then the apical part of the canal is delicately shaped since a size 25 K-file reaches the working length; in the second, the remaining canal is prepared with manual or rotating instrumentation. This procedure, however, has some disadvantages, such as the potential for inadvertent apical transportation. Incorrect instrumentation length can occur, which can be addressed by the modified step back. Obstructing debris can be dealt with by the passive step back technique. The crown down is a procedure in which the dentist prepares the canal beginning from the coronal part after exploring the patency of the whole canal with the master apical file. There is a hybrid procedure combining step back and crown down: after the canal's patency check, the coronal third is prepared with hand or Gates Glidden drills, then the working length is determined and finally the apical portion is shaped using step back techniques. The double flare is a procedure introduced by Fava where the canal is explored using a small file. Then canal is prepared in crown down manner using K-files then follows a "step back" preparation with 1 mm increments with increasing file sizes. With early coronal enlargement, also described as "three times technique", apical canals are prepared after a working length assessment using an apex locator; then progressively enlarged with Gates Glidden drills (only coronal and middle third). For the eponymic third time the dentist "arrives at the
apex The apex is the highest point of something. The word may also refer to: Arts and media Fictional entities * Apex (comics), a teenaged super villainess in the Marvel Universe * Ape-X, a super-intelligent ape in the Squadron Supreme universe *Apex ...
" and, if necessary, prepares the foramen with a size 25 K-file; the last phase is divided in two refining passages: the first with a 1-mm staggered instrument, the second with 0.5-mm staggering. From the early nineties engine-driven instrumentation were gradually introduced including the ProFile system, the Greater Taper files, the ProTaper files, and other systems like Light Speed, Quantec, K-3 rotary, Real World Endo, and the Hero 642. All of these procedures involve frequent irrigation and recapitulation with the master apical file, a small file that reaches the
apical foramen In dental anatomy, the apical foramen, literally translated "small opening of the apex," is the tooth's natural opening, found at the root's very tip—that is, the root's apex—whereby an artery, vein, and nerve enter the tooth and commingle w ...
. High frequency
ultrasound Ultrasound is sound waves with frequencies higher than the upper audible limit of human hearing. Ultrasound is not different from "normal" (audible) sound in its physical properties, except that humans cannot hear it. This limit varies ...
based techniques have also been described. These can be useful in particular for cases with complex anatomy, or for retained
foreign body A foreign body (FB) is any object originating outside the body of an organism. In machinery, it can mean any unwanted intruding object. Most references to foreign bodies involve propulsion through natural orifices into hollow organs. Foreign b ...
retrieval from a failed prior endodontic procedure. File:Step back.png, An example of step back technique File:Passive step back.png, An example of passive step back technique File:Crown down.png, An example of crown down technique


Operative techniques for instruments

There are two slightly different anti-curvature techniques. In the balanced forces technique, the dentist inserts a file into the canal and rotates clockwise a quarter of a turn, engaging dentin, then rotates counter-clockwise half/ three-quarter of a revolution, applying pressure in an apical direction, shearing off tissue previously meshed. From the balanced forces stem two other techniques: the reverse balanced force (where GT instruments are rotated first anti-clockwise and then clockwise) and the gentler "feed and pull" where the instrument is rotated only a quarter of a revolution and moved coronally after an engagement, but not drawn out.


Use of anesthetics

As of 2018,
novocaine Procaine is a local anesthetic drug of the amino ester group. It is most commonly used in dental procedures to numb the area around a tooth and is also used to reduce the pain of intramuscular injection of penicillin. Owing to the ubiquity ...
is most commonly used in dental procedures to numb the area around a tooth. More novocaine is required for a root canal treatment than for a simple filling.


Irrigation

The root canal is flushed with an irrigant. Some common ones are listed below: *
Sodium hypochlorite Sodium hypochlorite (commonly known in a dilute solution as bleach) is an inorganic chemical compound with the formula NaOCl (or NaClO), comprising a sodium cation () and a hypochlorite anion (or ). It may also be viewed as the sodium salt of h ...
(NaClO) in concentrations ranging between 0.5% and 5.25% * 6% sodium hypochlorite with surface modifiers for better flow into nooks and crannies * 2%
chlorhexidine gluconate Chlorhexidine (CHX) (commonly known by the salt forms chlorhexidine gluconate and chlorhexidine digluconate (CHG) or chlorhexidine acetate) is a disinfectant and antiseptic that is used for skin disinfection before surgery and to sterilize sur ...
* 0.2%
chlorhexidine gluconate Chlorhexidine (CHX) (commonly known by the salt forms chlorhexidine gluconate and chlorhexidine digluconate (CHG) or chlorhexidine acetate) is a disinfectant and antiseptic that is used for skin disinfection before surgery and to sterilize sur ...
plus 0.2% cetrimonium chloride * 17%
ethylenediaminetetraacetic acid Ethylenediaminetetraacetic acid (EDTA) is an aminopolycarboxylic acid with the formula H2N(CH2CO2H)2sub>2. This white, water-soluble solid is widely used to bind to iron (Fe2+/Fe3+) and calcium ions (Ca2+), forming water-soluble complexes ev ...
(
EDTA Ethylenediaminetetraacetic acid (EDTA) is an aminopolycarboxylic acid with the formula H2N(CH2CO2H)2sub>2. This white, water-soluble solid is widely used to bind to iron (Fe2+/Fe3+) and calcium ions (Ca2+), forming water-soluble complexes ev ...
) * Framycetin sulfate * Mixture of
citric acid Citric acid is an organic compound with the chemical formula HOC(CO2H)(CH2CO2H)2. It is a colorless weak organic acid. It occurs naturally in citrus fruits. In biochemistry, it is an intermediate in the citric acid cycle, which occurs in t ...
,
doxycycline Doxycycline is a broad-spectrum tetracycline class antibiotic used in the treatment of infections caused by bacteria and certain parasites. It is used to treat bacterial pneumonia, acne, chlamydia infections, Lyme disease, cholera, typhus, and ...
, and
polysorbate 80 Polysorbate 80 is a nonionic surfactant and emulsifier often used in pharmaceuticals, foods, and cosmetics. This synthetic compound is a viscous, water-soluble yellow liquid. Chemistry Polysorbate 80 is derived from polyethoxylated sorbitan an ...
(detergent) (MTAD) * Saline *Near anhydrous
ethanol Ethanol (abbr. EtOH; also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound. It is an alcohol with the chemical formula . Its formula can be also written as or (an ethyl group linked to a ...
The primary aim of chemical irrigation is to kill microbes and dissolve pulpal tissue. Certain irrigants, such as sodium hypochlorite and chlorhexidine, have proved to be effective antimicrobials in vitro and are widely used during root canal therapy worldwide. According to a systematic review, however, there is a lack of good quality evidence to support the use of one irrigant over another in terms of both short and long term prognosis of therapy. Root canal irrigation systems are divided into two categories: manual agitation techniques and machine-assisted agitation techniques. Manual irrigation includes positive-pressure irrigation, which is commonly performed with a syringe and a side vented needle. Machine-assisted irrigation techniques include sonics and ultrasonics, as well as newer systems which deliver apical negative-pressure irrigation.


Filling the root canal

The standard filling material is
gutta-percha Gutta-percha is a tree of the genus '' Palaquium'' in the family Sapotaceae. The name also refers to the rigid, naturally biologically inert, resilient, electrically nonconductive, thermoplastic latex derived from the tree, particularly fro ...
, a natural polymer prepared from latex from the percha tree (''
Palaquium gutta ''Palaquium gutta'' is a tree in the family Sapotaceae. The specific epithet ' is from the Malay word ''getah'' meaning "sap or latex". It is known in Indonesia as ''karet oblong''. Description ''Palaquium gutta'' grows up to tall. The bark i ...
''). The standard endodontic technique involves inserting a gutta-percha cone (a "point") into the cleaned-out root canal along with a sealing cement. Another technique uses melted or heat-softened gutta-percha which is then injected or pressed into the root canal passage(s). However, since gutta-percha shrinks as it cools, thermal techniques can be unreliable and sometimes a combination of techniques is used. Gutta-percha is
radiopaque Radiodensity (or radiopacity) is opacity to the radio wave and X-ray portion of the electromagnetic spectrum: that is, the relative inability of those kinds of electromagnetic radiation to pass through a particular material. Radiolucency or hypod ...
, allowing verification afterwards that the root canal passages have been completely filled and are without voids. Pain control can be difficult to achieve at times because of anesthetic inactivation by the acidity of the abscess around the tooth apex. Sometimes the abscess can be drained, antibiotics prescribed, and the procedure reattempted when inflammation has been mitigated. The tooth can also be unroofed to allow drainage and help relieve pressure. A root treated tooth may be eased from the occlusion as a measure to prevent tooth fracture prior to the cementation of a crown or similar restoration. 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 Pulpotomy is a minimally invasive procedure performed in children on a primary tooth with extensive caries but without evidence of root pathology. The minimally invasive endodontic techniques of vital pulp therapy (VPT) are based on improved unders ...
may be a relatively definitive treatment for infected primary teeth. The pulpectomy and pulpotomy procedures aim to eliminate pain until the follow-up visit for finishing the root canal procedure. Further occurrences of pain could indicate the presence of continuing infection or retention of vital nerve tissue. Some dentists may decide to temporarily fill the canal with
calcium hydroxide Calcium hydroxide (traditionally called slaked lime) is an inorganic compound with the chemical formula Ca( OH)2. It is a colorless crystal or white powder and is produced when quicklime ( calcium oxide) is mixed or slaked with water. It has m ...
paste in order to thoroughly sterilize the site. This strong base is left in place for a week or more to disinfect and reduce inflammation in surrounding tissue, requiring the patient to return for a second or third visit to complete the procedure. There appears to be no benefit from this multi-visit option, however, and single-visit procedures actually show better (though not statistically significant) patient outcomes than multi-visit ones.


Temporary filling

A temporary filling material is applied between the visits. Leaky temporary filling will allow the root canals to become reinfected by bacteria in the saliva (coronal microleakage). Khayat et al. showed that all root canals obturated with gutta-percha and root canal sealer using either lateral or vertical condensation were recontaminated in less than 30 days when exposed to saliva. Therefore, maintaining a coronal seal throughout root canal therapy is very important for the success of the treatment.


Final restoration

Molars and premolars that have had root canal therapy should be protected with a crown that covers the cusps of the tooth. This is because the access made into the root canal system removes a significant amount of tooth structure. Molars and premolars are the primary teeth used in chewing and will almost certainly fracture in the future without cuspal coverage. Anterior teeth typically do not require full coverage restorations after a root canal procedure, unless there is extensive tooth loss from decay or for esthetics or unusual occlusion. Placement of a crown or cusp-protecting cast gold covering is recommended also because these have the best ability to seal the treated tooth. There is insufficient evidence to assess the effects of crowns compared to conventional fillings for the restoration of root-filled teeth, decision of restoration should rely on the clinical experience of the practitioner and the preference of the patients. If the tooth is not perfectly sealed, the canal may leak, causing eventual failure. A tooth with a root canal treatment still has the ability to decay, and without proper home care and an adequate
fluoride Fluoride (). According to this source, is a possible pronunciation in British English. is an inorganic, monatomic anion of fluorine, with the chemical formula (also written ), whose salts are typically white or colorless. Fluoride salts ty ...
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 Pain is a distressing feeling often caused by intense or damaging stimuli. The International Association for the Study of Pain defines pain as "an unpleasant sensory and emotional experience associated with, or resembling that associated with, ...
perception). Thus, non-restorable carious destruction is the main reason for extraction of teeth after root canal therapy, accounting for up to two-thirds of these extractions. Therefore, it is very important to have regular
X-rays An X-ray, or, much less commonly, X-radiation, is a penetrating form of high-energy electromagnetic radiation. Most X-rays have a wavelength ranging from 10  picometers to 10 nanometers, corresponding to frequencies in the range 30  ...
taken of the root canal to ensure that the tooth is not having any problems that the patient would not be aware of.


Endodontic retreatment

Endodontic treatment may fail for many reasons: one common reason for failure is inadequate chemomechanical
debridement Debridement is the medical removal of dead, damaged, or infected tissue to improve the healing potential of the remaining healthy tissue. Removal may be surgical, mechanical, chemical, autolytic (self-digestion), and by maggot therapy. I ...
of the root canal. This may be due to poor endodontic access, missed anatomy or inadequate shaping of the canal, particularly in the apical third of the root canal, also due to the difficulty of reaching the accessory canals which are minute canals that extend in from the pulp to the periodontium in a random direction. They are mostly found in the apical third of the root. Exposure of the obturation material to the oral environment may mean the gutta-percha is contaminated with oral bacteria. If complex and expensive restorative dentistry is contemplated then ideally the contaminated gutta percha would be replaced in a retreatment procedure to minimise the risk of failure. The type of bacteria found within a failed canal may differ from the normal infected tooth.
Enterococcus faecalis ''Enterococcus faecalis'' – formerly classified as part of the group D ''Streptococcus'' system – is a Gram-positive, commensal bacterium inhabiting the gastrointestinal tracts of humans. Like other species in the genus ''Enterococcus'', ''E ...
and/or other facultative enteric bacteria or
Pseudomonas ''Pseudomonas'' is a genus of Gram-negative, Gammaproteobacteria, belonging to the family Pseudomonadaceae and containing 191 described species. The members of the genus demonstrate a great deal of metabolic diversity and consequently are able to ...
sp. are found in this situation. Endodontic retreatment is technically demanding; it can be a time-consuming procedure, as meticulous care is required by the
dentist A dentist, also known as a dental surgeon, is a health care professional who specializes in dentistry (the diagnosis, prevention, management, and treatment of diseases and conditions of the oral cavity and other aspects of the craniofacial com ...
. Retreatment cases are typically referred to a specialist
endodontist Endodontics (from the Greek roots ''endo-'' "inside" and ''odont-'' "tooth") is the dental specialty concerned with the study and treatment of the dental pulp. Overview Endodontics encompasses the study (practice) of the basic and clinical ...
. Use of an operating microscope or other magnification may improve outcomes. Currently, there is no strong evidence favoring surgical or non-surgical retreatment of periapical lesions. However, studies have reported that patients experience more pain and swelling after surgical retreatment compared to non-surgical. When comparing surgical techniques, the use of ultrasonic devices may improve healing after retreatment. Application of
nanomotor A nanomotor is a molecular or nanoscale device capable of converting energy into movement. It can typically generate forces on the order of piconewtons. While nanoparticles have been utilized by artists for centuries, such as in the famous Lycurg ...
implants have been proposed to achieve thorough disinfection of the dentine. There is no evidence that the use of antibiotics after endodontic retreatment prevents post-operative infection.


Instruments and equipment used

Since 2000 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 procedure. Root canal therapy has become more automated and can be performed faster thanks in part to machine-driven rotary technology and more advanced root canal filling methods. Many root canal procedures are done in one dental visit which may last for around 1–2 hours. Newer technologies are available (e.g. cone-beam CT scanning) that allow more efficient, scientific measurements to be taken of the dimensions of the root canal, however, the use of CT scanning in endodontics has to be justified. Many dentists use dental
loupe A loupe ( ) is a simple, small magnification device used to see small details more closely. They generally have higher magnification than a magnifying glass, and are designed to be held or worn close to the eye. A loupe does not have an attached ...
s to perform root canal therapy, and the consensus is that procedures performed using loupes or other forms of magnification (e.g. a surgical microscope) 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 root canal specialist (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 to the tooth.


Postoperative pain

Several randomized clinical trials concluded that the use of rotary instruments is associated with a lower incidence of pain following the endodontic procedure when compared to the use of manual hand instruments.
Corticosteroid Corticosteroids are a class of steroid hormones that are produced in the adrenal cortex of vertebrates, as well as the synthetic analogues of these hormones. Two main classes of corticosteroids, glucocorticoids and mineralocorticoids, are invo ...
intra-oral injections were found to alleviate pain in the first 24 hours in patients with symptomatic irreversible pulp inflammation.


Complications


Instrument fractures

Instruments may separate (break) during root canal treatment, meaning a portion of the metal file used during the procedure remains inside the tooth. The file segment may be left behind if an acceptable level of cleaning and shaping has already been completed and attempting to remove the segment would risk damage to the tooth. While potentially disconcerting to the patient, having metal inside of a tooth is relatively common, such as with metal posts, amalgam fillings, gold crowns, and porcelain fused to metal crowns. The occurrence of file separation depends on the narrowness, curvature, length, calcification and number of roots on the tooth being treated. Complications resulting from incompletely cleaned canals, due to blockage from the separated file, can be addressed with surgical root canal treatment. To minimise the risk of endodontic files fracturing: * Ensure access cavity allows straight-line introduction of files into canals * Create a glide path before use of larger taper NiTi files * Use rotary instruments at the manufacturer's recommended speed and torque setting * Adopt a single-use file policy to prevent overuse of files *Inspecting the file thoroughly every time before inserting it inside the canal *Using ample amounts of irrigation solutions * Avoid use of rotary files in severely curved or dilacerated canals


Sodium hypochlorite accident

A
sodium hypochlorite Sodium hypochlorite (commonly known in a dilute solution as bleach) is an inorganic chemical compound with the formula NaOCl (or NaClO), comprising a sodium cation () and a hypochlorite anion (or ). It may also be viewed as the sodium salt of h ...
incident is an immediate reaction of severe pain, followed by
edema Edema, also spelled oedema, and also known as fluid retention, dropsy, hydropsy and swelling, is the build-up of fluid in the body's tissue. Most commonly, the legs or arms are affected. Symptoms may include skin which feels tight, the area ma ...
,
haematoma A hematoma, also spelled haematoma, or blood suffusion is a localized bleeding outside of blood vessels, due to either disease or trauma including injury or surgery and may involve blood continuing to seep from broken capillaries. A hematoma is ...
and
ecchymosis A bruise, also known as a contusion, is a type of hematoma of tissue, the most common cause being capillaries damaged by trauma, causing localized bleeding that extravasates into the surrounding interstitial tissues. Most bruises occur clos ...
, as a consequence of the solution escaping the confines of the tooth and entering the periapical space. This may be caused
iatrogenic Iatrogenesis is the causation of a disease, a harmful complication, or other ill effect by any medical activity, including diagnosis, intervention, error, or negligence. "Iatrogenic", ''Merriam-Webster.com'', Merriam-Webster, Inc., accessed 27 ...
ally by binding or excessive pressure on the irrigant syringe or it may occur if the tooth has an unusually large apical
foramen In anatomy and osteology, a foramen (;Entry "foramen"
in
. It is usually self-resolving and may take two to five weeks to fully resolve.


Tooth discoloration

Tooth discoloration Tooth discoloration is abnormal tooth color, hue or translucency. External discoloration is accumulation of stains on the tooth surface. Internal discoloration is due to absorption of pigment particles into tooth structure. Sometimes there are s ...
is common following root canal treatment; however, the exact causes for this are not completely understood. Failure to completely clean out the necrotic soft tissue of the pulp system may cause staining, and certain root canal materials (e.g.
gutta percha Gutta-percha is a tree of the genus ''Palaquium'' in the family Sapotaceae. The name also refers to the rigid, naturally biologically inert, resilient, electrically nonconductive, thermoplastic latex derived from the tree, particularly from ' ...
and root canal sealer cements) can also cause staining. Another possible factor is that the lack of pulp pressure in dentinal tubules once the pulp is removed leads to incorporation of dietary stains in dentin.


Poor-quality root filling

Another common complication of root canal therapy is when the entire length of the root canal is not completely cleaned out and filled (obturated) with root canal filling material (usually gutta percha). On the other hand, the root canal filling material may be extruded from the apex leading to other complications. The X-ray in the right margin shows two adjacent teeth that had received bad root canal therapy. The root canal filling material (3, 4, and 10) does not extend to the end of the tooth roots (5, 6 and 11). The dark circles at the bottom of the tooth roots (7 and 8) indicated infection in the surrounding bone. Recommended treatment is either to redo the root canal therapy or extract the tooth and place dental implants. Poor quality filling material or sealant may also cause root canal treatment to fail.


Outcome and prognosis

Root-canal-treated teeth may fail to heal—for example, if the dentist does not find, clean and fill all of the root canals within a tooth. On a maxillary molar, there is more than a 50% chance that the tooth has four canals instead of just three, but the fourth canal, often called a "mesio-buccal 2", tends to be very difficult to see and often requires special instruments and magnification in order to see it (most commonly found in first maxillary molars; studies have shown an average of 76% up to 96% of such teeth with the presence of an MB2 canal). This infected canal may cause a continued infection or "flare-up" of the tooth. Any tooth may have more canals than expected, and these canals may be missed when the root canal procedure is performed. Sometimes canals may be unusually shaped, making them impossible to clean and fill completely; some infected material may remain in the canal. Sometimes the canal filling does not fully extend to the apex of the tooth, or it does not fill the canal as densely as it should. Sometimes a tooth root may be perforated while the root canal is being treated, making it difficult to fill the tooth. The perforation may be filled with a root repair material, such as one derived from natural cement called
mineral trioxide aggregate Mineral trioxide aggregate (MTA) was developed for use as a dental root repair material by Mahmoud Torabinejad. It is formulated from commercial Portland cement, combined with bismuth oxide powder for radio-opacity. MTA is used for creating apical ...
(MTA). A specialist can often re-treat failing root canals, and these teeth will then heal, often years after the initial root canal procedure. However, the survival or functionality of the endodontically treated tooth is often the most important aspect of endodontic treatment outcomes, rather than apical healing alone. Recent studies indicate that substances commonly used to clean the root canal space incompletely sterilize the canal. A properly restored tooth following root canal therapy yields long-term success rates near 97%. In a large-scale study of over 1.6 million patients who had root canal therapy, 97% had retained their teeth 8 years following the procedure, with most untoward events, such as re-treatment, apical surgery or extraction, occurring during the first 3 years after the initial endodontic treatment. Endodontically treated teeth are prone to extraction mainly due to non-restorable carious destruction, other times due to the improper fit of the
crown A crown is a traditional form of head adornment, or hat, worn by monarchs as a symbol of their power and dignity. A crown is often, by extension, a symbol of the monarch's government or items endorsed by it. The word itself is used, partic ...
margins that encircles the tooth which lead to the ingress of bacteria, and to a lesser extent to endodontic-related reasons such as endodontic failure, vertical root fracture, or perforation (procedural error).


Systemic issues

An infected tooth may endanger other parts of the body. People with special vulnerabilities, such as a recent prosthetic
joint replacement Replacement arthroplasty (from Greek ''arthron'', joint, limb, articulate, + ''plassein'', to form, mould, forge, feign, make an image of), or joint replacement surgery, is a procedure of orthopedic surgery in which an arthritic or dysfunctional j ...
, an unrepaired congenital heart defect, or immunocompromisation, may need to take antibiotics to protect from infection spreading during dental procedures. The
American Dental Association The American Dental Association (ADA) is an American professional association established in 1859 which has more than 161,000 members. Based in the American Dental Association Building in the Near North Side of Chicago, the ADA is the world's ...
(ADA) asserts that any risks can be adequately controlled. A properly performed root canal treatment effectively removes the infected part of the pulp from the tooth. In the early 1900s, several researchers theorized that bacteria from teeth which had
necrotic Necrosis () is a form of cell injury which results in the premature death of cells in living tissue by autolysis. Necrosis is caused by factors external to the cell or tissue, such as infection, or trauma which result in the unregulated dige ...
pulps or which had received endodontic treatment could cause chronic or local infection in areas distant from the tooth through the transfer of bacteria through the bloodstream. This was called the "
focal infection theory Focal infection theory is the historical concept that many chronic diseases, including systemic and common ones, are caused by focal infections. In present medical consensus, a focal infection is a localized infection, often asymptomatic, that c ...
", and it led some dentists to advocate
dental extraction A dental extraction (also referred to as tooth extraction, exodontia, exodontics, or informally, tooth pulling) is the removal of teeth from the dental alveolus (socket) in the alveolar bone. Extractions are performed for a wide variety of reaso ...
. In the 1930s, this theory was discredited.
Bacteremia Bloodstream infections (BSIs), which include bacteremias when the infections are bacterial and fungemias when the infections are fungal, are infections present in the blood. Blood is normally a sterile environment, so the detection of micro ...
(bacteria in the bloodstream) can be caused by many everyday activities, e.g. brushing teeth, but may also occur after any dental procedure which involves bleeding. It is particularly likely after dental extractions due to the movement of the tooth and force needed to dislodge it, but endodontically treated teeth alone do not cause bacteremia or systemic disease.


Alternatives

The alternatives to root canal therapy include no treatment or tooth extraction. Following tooth extraction, options for prosthetic replacement may include
dental implant A dental implant (also known as an endosseous implant or fixture) is a prosthesis that interfaces with the bone of the jaw or skull to support a dental prosthesis such as a crown, bridge, denture, or facial prosthesis or to act as an orthodon ...
s, a fixed partial denture (commonly referred to as a 'bridge'), or a removable denture. There are risks to forgoing treatment, including pain, infection and the possibility of worsening dental infection such that the tooth will become irreparable (root canal treatment will not be successful, often due to excessive loss of tooth structure). If extensive loss of tooth structure occurs, extraction may be the only option.


Implant therapy versus endodontic therapy

Research comparing endodontic therapy with implant therapy is considerable, both as an initial treatment and in retreatment for failed initial endodontic approaches. Endodontic therapy allows avoidance of disruption of the
periodontal fiber The periodontal ligament, commonly abbreviated as the PDL, is a group of specialized connective tissue fibers that essentially attach a tooth to the alveolar bone within which it sits. It inserts into root cementum one side and onto alveolar bo ...
, which helps with
proprioception Proprioception ( ), also referred to as kinaesthesia (or kinesthesia), is the sense of self-movement, force, and body position. It is sometimes described as the "sixth sense". Proprioception is mediated by proprioceptors, mechanosensory neuron ...
for ''occlusal feedback'', a reflex important in preventing patients from chewing improperly and damaging the
temporomandibular joint In anatomy, the temporomandibular joints (TMJ) are the two joints connecting the jawbone to the skull. It is a bilateral synovial articulation between the temporal bone of the skull above and the mandible below; it is from these bones that it ...
. In a comparison of initial nonsurgical endodontic treatment and single-tooth implants, both were found to have similar success rates. While the procedures are similar in terms of pain and discomfort, a notable difference is that patients who have implants have reported "the worst pain of their life" during the extraction, with the implantation itself being relatively painless. The worst pain of endodontic therapy was reported with the initial
anesthetic An anesthetic (American English) or anaesthetic (British English; see spelling differences) is a drug used to induce anesthesia ⁠— ⁠in other words, to result in a temporary loss of sensation or awareness. They may be divided into two ...
injection. Some patients receiving implants also describe a dull nagging pain after the procedure, while those with endodontic therapy describe "sensation" or "sensitivity" in the area. Other studies have found that endodontic therapy patients report the maximum pain the day following treatment, while extraction and implantation patients reported maximum pain the end of the week after the operation. Implants also take longer, with a typically 3- to 6-month gap between the tooth implantation and receiving the crown, depending on the severity of infection. With regard to gender, women tend to report higher psychological disability after endodontic therapy, and a higher rate of physical disability after tooth implantation, while men do not show a statistically significant difference in response.
Mastication Chewing or mastication is the process by which food is crushed and ground by teeth. It is the first step of digestion, and it increases the surface area of foods to allow a more efficient break down by enzymes. During the mastication process, ...
is significantly stronger in endodontically treated teeth as compared to implants. Initial success rates after single tooth implants and endodontic microsurgery are similar the first 2 to 4 years following surgery, though after this the success rate of endodontic microsurgery is decreased as compared to implantation. To an extent, the criteria for success due to the inherent differences in the procedure have historically limited comparisons, with success of endodontic therapy defined as the absence of periapical lucency on
radiograph Radiography is an imaging technique using X-rays, gamma rays, or similar ionizing radiation and non-ionizing radiation to view the internal form of an object. Applications of radiography include medical radiography ("diagnostic" and "therapeut ...
s, or the absence of visible cavity at the root of the tooth on imaging. Implant success, on the other hand, is defined by osseointegration, or fusion of the implant to the adjacent
maxilla The maxilla (plural: ''maxillae'' ) in vertebrates is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. The ...
or
mandible In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower tooth, teeth in place. The mandible sits beneath the maxilla. It is the only movabl ...
. Endodontically treated teeth have significantly less requirement for follow up treatment after final restoration, while implants need more appointments to finish treatment and more maintenance. Socioeconomically, Americans of European descent and affluent patients tend to choose implant therapy, while African American and less affluent patients prefer endodontic therapy.


See also

* American Association of Endodontists *
Dental implant A dental implant (also known as an endosseous implant or fixture) is a prosthesis that interfaces with the bone of the jaw or skull to support a dental prosthesis such as a crown, bridge, denture, or facial prosthesis or to act as an orthodon ...
*
Dental pulp The pulp is the connective tissue, nerves, blood vessels, and odontoblasts that comprise the innermost layer of a tooth. The pulp's activity and signalling processes regulate its behaviour. Anatomy The pulp is the neurovascular bundle cen ...
*
Dentistry Dentistry, also known as dental medicine and oral medicine, is the branch of medicine focused on the teeth, gums, and mouth. It consists of the study, diagnosis, prevention, management, and treatment of diseases, disorders, and conditions o ...
* Gum inflammation * Nickel titanium rotary file * Oral and maxillofacial surgery *
Periodontitis Periodontal disease, also known as gum disease, is a set of inflammatory conditions affecting the tissues surrounding the teeth. In its early stage, called gingivitis, the gums become swollen and red and may bleed. It is considered the main caus ...
*
Dental braces Dental braces (also known as braces, orthodontic cases, or cases) are devices used in orthodontics that align and straighten teeth and help position them with regard to a person's bite, while also aiming to improve dental health. They are ofte ...
*
Regenerative endodontics Regenerative endodontic procedures is defined as biologically based procedures designed to replace damaged structures such as dentin, root structures, and cells of the pulp-dentin complex. This new treatment modality aims to promote normal function ...
*
Smear layer In dentistry, the smear layer is a layer found on root canal walls after root canal instrumentation. It consists of microcrystalline and organic particle debris. It was first described in 1975 and research has been performed since then to evaluate ...
*
Tooth extraction A dental extraction (also referred to as tooth extraction, exodontia, exodontics, or informally, tooth pulling) is the removal of teeth from the dental alveolus (socket) in the alveolar bone. Extractions are performed for a wide variety of reaso ...
*
Toothache Toothache, also known as dental pain,Segen JC. (2002). ''McGraw-Hill Concise Dictionary of Modern Medicine''. The McGraw-Hill Companies. is pain in the teeth or their supporting structures, caused by dental diseases or pain referred to the te ...


References


External links


Primary tooth pulpectomy overfilling by different placement techniques: A systematic review and meta-analysis
{{Authority control Endodontics