Patient Resource
Endodontic Glossary
Plain-English definitions of the 49 terms you are most likely to hear in our office or read in your treatment plan. Each entry is written for patients, not specialists, and links to the relevant treatment or condition page when one exists.
Medically reviewed by Dr. Jason Kung, DDS, MS · Specialist Endodontist · UCLA DDS · OHSU MS ·
- Acute apical abscessalso called: AAA
- A rapidly developing infection at the tip of a tooth's root, marked by severe pain, swelling of the face or gum, and often a feeling that the tooth is sitting higher than the others. Patients may have a low-grade fever and feel generally unwell. This is an endodontic emergency — same-day treatment to relieve pressure and start root canal therapy or extraction is the standard of care. One of the six canonical AAE periapical diagnoses (Gutmann et al., J Endod 2009).Emergency root canal · Dental abscess condition guide
- Alternate benefitalso called: alternate benefit clause; LEAT
- A contract clause that lets an insurance company reimburse for the least expensive alternative treatment (sometimes abbreviated LEAT) that would treat the condition — even if your dentist recommends a more advanced option. Common example: a plan that pays for a tooth-colored crown only at the metal-crown rate. The dentist's actual fee still applies; you pay the difference.Insurance & billing guide
- Annual maximumalso called: yearly benefit maximum; annual cap
- The total dollar amount your dental insurance will pay toward your care in a single benefit year. Most PPO plans cap this at $1,000–$2,500 per person per year. Once you hit your annual maximum, you pay 100% of further treatment until the plan year resets. Splitting expensive treatment plans across two benefit years is a common strategy to make the most of this cap.Insurance & billing guide
- Apex locatoralso called: electronic apex locator; EAL
- A small electronic device that measures the length of a root canal during treatment by detecting changes in electrical impedance at the canal terminus. Modern apex locators are accurate to within half a millimeter and have largely replaced film-based working-length determination — fewer X-rays for the patient and a more precise endpoint for the endodontist.How we diagnose endodontic problems
- Apexification
- A procedure used on a permanent tooth whose root tip never finished forming — usually because the pulp died from decay or trauma during childhood. The endodontist places a biocompatible cement (most often MTA) at the open end of the root to create an artificial barrier, allowing the canal to be sealed normally. Distinct from apexogenesis, which encourages the root to keep growing on its own.
- Apexogenesis
- A vital pulp procedure performed on a young permanent tooth with an injured but still-living pulp, intended to keep enough of the pulp alive so the root can finish developing naturally. Success depends on early intervention and a tooth that has not yet become fully infected.
- Apical periodontitis
- Inflammation of the bone and ligament surrounding the tip of a tooth's root, almost always caused by bacteria leaking from inside the root canal system. Visible on X-ray as a dark area around the root tip.
- Apicoectomyalso called: root-end surgery; endodontic microsurgery
- A microsurgical procedure in which the very tip of a tooth's root (a few millimeters) is removed and the root canal is sealed from the end. Used when a previous root canal has not healed and a non-surgical retreatment is not the best option.Apicoectomy (root-end surgery)
- Asymptomatic apical periodontitisalso called: AAP
- Inflammation around the root tip that is visible on X-ray as a dark area but produces no pain, no swelling, and no tenderness — the patient typically does not know it is there. It is the classic incidental finding on routine films. Despite the absence of symptoms, the underlying infection is real and root canal therapy or retreatment is still indicated. One of the six canonical AAE periapical diagnoses (Gutmann et al., J Endod 2009).Pulp necrosis condition guide · Painless tooth infection
- Bioceramic sealeralso called: calcium silicate sealer
- A modern category of root canal sealer based on calcium silicate chemistry. Bioceramic sealers bond chemically to dentin, set in the presence of moisture, are dimensionally stable, and are highly biocompatible — they have largely supplanted older zinc-oxide-eugenol and resin sealers in contemporary endodontic practice.
- CBCT (Cone-beam CT)also called: 3D dental CT
- A low-dose three-dimensional X-ray that lets endodontists see the tooth, its roots, and surrounding bone from any angle. Particularly useful for finding cracks, hidden canals, and accurately diagnosing failed root canals. Our office scans on the J. Morita Veraview X800 — widely regarded as the leading dental CBCT for endodontics — in its high-resolution Endo Mode (80 µm voxel size, 40 × 40 mm limited field of view focused on a single tooth or sextant), the small-volume protocol the AAE/AAOMR Joint Position Statement on the Use of CBCT in Endodontics (2015) and the European Society of Endodontology Position Statement (Patel et al., IEJ 2019) both recommend.Technology we use · How we diagnose endodontic problems
- CDT codealso called: dental procedure code; D-code
- A short alphanumeric code (always starting with the letter D) from the American Dental Association's Current Dental Terminology that identifies a specific dental procedure on a claim. Examples include D3310 (root canal on a front tooth), D3330 (root canal on a molar), and D0367 (cone-beam CT). The CDT code set is updated annually and is the universal billing language between dental offices and insurance companies.Root canal procedure codes explained · Insurance & billing guide
- Chronic apical abscessalso called: CAA
- A long-standing low-grade infection at the tip of a tooth's root that has found a way to drain — usually through a small pimple-like opening on the gum (a sinus tract) that comes and goes. Because the infection drains, severe pain is unusual; many patients only notice an intermittent bad taste or a recurring gum bump. The condition is still an active infection and requires root canal therapy or extraction. One of the six canonical AAE periapical diagnoses (Gutmann et al., J Endod 2009).Dental abscess condition guide
- Condensing osteitis
- A localized increase in bone density (visible on X-ray as a brighter, denser area) around the root tip of a tooth with long-standing low-grade pulp inflammation. It represents the body's chronic immune response rather than an acute infection. One of the six canonical AAE periapical diagnoses (Gutmann et al., J Endod 2009); often resolves slowly after successful root canal treatment.
- Cracked tooth syndrome
- Pain caused by a crack that runs through the chewing surface of a tooth and into the dentin or pulp. Hallmark symptom is a sharp, brief pain on biting or releasing pressure, often without anything visible on a regular X-ray.Cracked tooth treatment · Cracked tooth condition guide
- Dentin
- The hard, yellowish tissue under the enamel that makes up most of a tooth. It contains microscopic tubules that conduct sensation to the pulp inside.
- Downcoding
- When an insurance company changes the procedure code your dentist submitted to a lower-paying code before processing the claim. For example, an insurer might downcode a posterior composite filling (white) to an amalgam (silver) and only pay the amalgam rate. Downcoding decisions can sometimes be appealed with a clinical narrative, photos, or CBCT imaging.Insurance & billing guide
- Endodontist
- A dentist who has completed two to three additional years of accredited residency training focused exclusively on the dental pulp, root canals, dental trauma, and microsurgery. In the United States, only graduates of CODA-accredited endodontic programs may use the title.What is an endodontist?
- Explanation of Benefits (EOB)also called: EOB
- A statement your dental insurance sends after processing a claim. The EOB shows the date of service, each CDT procedure code billed, the dentist's submitted fee, the amount the plan allowed, the percentage the plan paid, and your remaining patient portion. An EOB is not a bill — it explains how the insurer applied your benefits.Root canal procedure codes explained · Insurance & billing guide
- Gutta-percha
- A natural rubber-like material derived from the latex of the gutta tree. Heated and packed into the cleaned canal at the end of a root canal, it forms the inert filling that prevents bacteria from re-entering the root.
- In-network dentistalso called: participating provider; PPO contracted dentist
- A dentist who has signed a contract with a specific insurance carrier agreeing to accept that carrier's fee schedule as payment in full. Your out-of-pocket cost is typically lower with in-network providers because the contracted fees are pre-negotiated. Endodontists are often out-of-network because specialist fees on most PPO schedules don't cover the cost of microscope-based and CBCT-supported care.Insurance & billing guide
- Internal resorption
- A condition in which cells inside the root canal begin to dissolve the surrounding dentin, hollowing out the tooth from within. Often discovered incidentally on X-ray and usually treated with prompt root canal therapy.Tooth resorption overview · Root resorption condition guide
- Irreversible pulpitis
- A stage of inflammation inside the dental pulp that the tissue cannot recover from on its own. The hallmark symptom is severe, lingering pain to cold that lasts thirty seconds or longer. Treated by root canal therapy or extraction.Irreversible pulpitis condition guide · Will my root canal hurt?
- Isthmusalso called: anastomosis
- A narrow ribbon-shaped connection between two root canals in the same root, often invisible on standard X-rays and a notorious harbor for bacteria. Reliably cleaning an isthmus requires ultrasonic irrigation activation under high magnification — one of the main reasons specialist treatment outperforms conventional approaches on multi-canalled teeth.Complex root canal anatomy
- Microscope (surgical operating microscope)also called: dental operating microscope; DOM
- A free-standing operating microscope that magnifies the surgical field up to 25 times with coaxial illumination. Considered the standard of care in modern endodontics; absence of one in retreatment and surgical cases is associated with significantly lower success rates.Technology we use
- MTA (mineral trioxide aggregate)
- A calcium-silicate-based cement introduced to endodontics in the 1990s that seals against moisture, encourages hard-tissue formation, and is exceptionally biocompatible. Standard material for perforation repair, root-end fillings in apicoectomy, apexification, and pulp capping. Newer bioceramic variants share its core chemistry with improved handling.Apicoectomy (root-end surgery)
- Necrotic pulpalso called: dead nerve; non-vital tooth
- A dental pulp that has lost all blood supply and nerve function, almost always because of bacterial infection or trauma. The tooth no longer responds to cold testing and typically requires root canal therapy to remove the dead tissue.Pulp necrosis condition guide
- Non-endodontic painalso called: non-odontogenic pain
- Pain that feels like a toothache but originates outside of any tooth — for example from the trigeminal nerve, the sinuses, or jaw muscles. Recognizing it prevents unnecessary root canals or extractions.Non-endodontic (non-tooth) pain
- Normal apical tissues
- The formal diagnostic term for a tooth whose surrounding bone and ligament are healthy on examination: no tenderness to percussion or palpation and no widening of the periodontal ligament space on X-ray. One of the six canonical periapical diagnoses recognized by the American Association of Endodontists and the American Board of Endodontics (Gutmann et al., J Endod 2009).
- Out-of-network dentistalso called: non-participating provider
- A dentist who has not signed a contract with your insurance carrier. PPO plans generally still pay a percentage of treatment with out-of-network providers but reimburse at a lower allowed amount, leaving more for the patient. For endodontic treatment (D3310/D3320/D3330), the out-of-network gap is often modest — typically a $100–$300 difference depending on plan.Insurance & billing guide
- Perforation repair
- A specialized procedure to seal a hole accidentally created through the wall of a tooth or root — most often the result of an aggressively prepared post space or a misdirected search for a hidden canal. Outcomes are best when the perforation is sealed promptly with a calcium-silicate material such as MTA or a bioceramic under microscope visualization.
- Periapical abscessalso called: dental abscess
- A localized collection of pus at the tip of a tooth's root, formed when bacteria from inside the root canal trigger the immune system. Usually requires drainage plus root canal treatment or extraction.Dental abscess condition guide · Emergency root canal
- Periradicular surgery
- Surgical procedures performed on the tissues around a tooth's root tip, including apicoectomy, root resection, and intentional replantation.Apicoectomy (root-end surgery)
- Predeterminationalso called: pre-authorization; pre-treatment estimate
- A written estimate from your insurance company of what they expect to pay (and what you'll owe) for a planned procedure before treatment begins. Predeterminations are not guarantees of payment but are useful for any treatment over a few hundred dollars. Our office submits these on request for any treatment plan over $500.Insurance & billing guide
- Pulpalso called: dental pulp; the nerve
- The soft connective tissue at the center of every tooth that contains nerves, blood vessels, and immune cells. It nourishes the developing tooth and senses temperature, pressure, and pain in the adult tooth.
- Pulp testingalso called: vitality testing
- Diagnostic tests — most commonly cold and electric — that tell the endodontist whether the nerve inside a tooth is alive, inflamed, or dead. Multiple tests on multiple teeth are needed because no single test is perfect.How we diagnose endodontic problems
- Pulpitis
- Inflammation of the dental pulp. Reversible pulpitis resolves once the irritant (a deep filling, a leaking crown) is removed; irreversible pulpitis does not.Irreversible pulpitis condition guide
- Pulpotomy
- A partial pulp procedure that removes only the inflamed coronal portion of the pulp and preserves the healthy radicular pulp, sealed with a biocompatible material such as MTA. Indicated in carefully selected adult teeth with reversible-pulpitis-like symptoms and in pediatric primary teeth — an increasingly evidence-supported alternative to full root canal therapy in the right cases.
- Regenerative endodontics
- A set of biologically based procedures designed to replace damaged pulp tissue in young teeth with newly formed tissue, allowing the root to continue developing. Reserved for select immature, traumatized teeth.Regenerative endodontics
- Retreatmentalso called: non-surgical retreatment; redo root canal
- A procedure that reopens a tooth that has had a previous root canal, removes the existing filling material, disinfects the canal system again, and refills it. Performed when the original root canal has not healed.Root canal retreatment
- Root canal therapyalso called: root canal treatment; endodontic therapy
- A procedure in which the inflamed or infected pulp is removed from inside a tooth, the canal system is shaped and disinfected, and the empty space is filled and sealed. Modern root canals are typically painless and have a documented success rate above 90 percent.Root canal treatment overview · Will my root canal hurt?
- Root resorption
- The progressive loss of root structure caused by specialized cells (odontoclasts). Can be internal (starting inside the canal) or external (starting from the outside surface of the root). Often traumatic in origin.Tooth resorption overview · Root resorption condition guide
- Rubber damalso called: dental dam
- A thin sheet of latex or non-latex material clipped over the tooth being treated to isolate it from saliva and bacteria. Considered standard of care for root canal therapy; outcomes are documented to be significantly better when one is used.
- Sodium hypochloritealso called: bleach irrigant
- A diluted bleach solution used to dissolve organic debris and kill bacteria inside the root canal system during treatment. The single most important irrigant in endodontics.
- Symptomatic apical periodontitisalso called: SAP
- Inflammation of the bone and ligament around the tip of a tooth's root that is producing symptoms — most often pain on biting or percussion, sometimes spontaneous discomfort. The tooth may or may not show a visible dark area at the root tip on X-ray. The diagnosis is clinical (it is made by examination, not by imaging alone) and is one of the six canonical AAE periapical diagnoses standardized by Gutmann et al. (J Endod 2009).How we diagnose endodontic problems · Tooth pain when biting down
- Trauma (dental)
- Any injury that displaces, fractures, or knocks out a tooth. Time-critical: avulsed permanent teeth should be replanted within thirty minutes for the best outcome.Dental trauma overview · Dental trauma first aid
- Usual, customary, and reasonable (UCR) feealso called: UCR; allowed amount; reasonable and customary
- The fee an insurance company considers "usual" for a procedure in your geographic area, used as the cap for out-of-network reimbursement. UCR rates are set by each insurer using their own data and are often well below actual specialist fees in high-cost regions like the Bay Area, which is why out-of-network claims may reimburse a smaller percentage than expected.Insurance & billing guide
- Vital pulp therapyalso called: pulp cap; pulpotomy
- Treatments that preserve some or all of the dental pulp when it is inflamed but still healthy enough to recover, using biocompatible materials such as MTA or bioceramics. An alternative to full root canal therapy in carefully selected teeth.Regenerative endodontics
- Waiting period
- A length of time after enrolling in a dental insurance plan during which certain types of treatment (usually major services like crowns, endodontics, and oral surgery) are not yet covered. Waiting periods are typically 6–12 months for major services and are designed to prevent people from signing up only for expensive treatment. Emergency RCT may still be covered during a waiting period under some plans — always verify.Insurance & billing guide