Iran Dental Specialty Board - Endodontics cheat sheet

Pulp healing capacity depends on blood supply through the apical foramen; a narrow apical diameter (<0.5 mm in mature teeth) limits revascularization and regenerative potential compared with immature open apices.

Reversible pulpitis: provoked pain of short duration that ceases after stimulus removal, no spontaneous pain, vital pulp, normal percussion and probing; histologically limited inflammation with intact odontoblast layer.

Irreversible pulpitis: spontaneous or prolonged pain, pain on lying down, referred pain; inflammation extends beyond the coronal pulp and healing without removal of the inflamed tissue is unpredictable.

Pulp necrosis is confirmed by absence of response to cold and EPT plus no bleeding on access; note that a multirooted tooth can have a necrotic canal alongside a vital canal, so test per canal.

Acute apical periodontitis: intense pain on biting, tooth tender to percussion, widened PDL on radiograph, typically no distinct periapical radiolucency yet (radiolucency requires mineral loss of roughly 30-50%).

Chronic apical periodontitis (apical granuloma) is the most common periapical lesion; histologically granulation tissue with lymphocytes, plasma cells, and macrophages, often with epithelial rests of Malassez.

Radicular cyst arises from epithelial rests stimulated by inflammation; diagnosis is histologic (epithelium-lined cavity), and radiographic appearance alone cannot distinguish cyst from granuloma.

Condensing osteitis is a reactive dense bone formation at the apex of a tooth with low-grade chronic pulpitis, most common in young patients and mandibular posterior teeth.

External cervical resorption is initiated in the cervical region below the epithelial attachment; it is often asymptomatic, misdiagnosed as caries or internal resorption, and CBCT is the imaging method of choice for mapping it.

Diagnostic sequence: chief complaint and history, extraoral and intraoral examination, pulp sensibility testing, percussion and palpation, periodontal probing, then radiographs (periapical plus CBCT when indicated).

Cold test (refrigerant spray) is the most reliable test for pulp vitality; EPT confirms vitality but gives false negatives in immature teeth, recently traumatized teeth, and teeth with calcific metamorphosis.

False-positive cold response can occur in multirooted teeth with one vital canal, in teeth with referred sensation, and when refrigerant contacts adjacent gingiva.

Test cavity (access without anesthesia) is reserved for teeth with calcific obliteration where sensibility tests are unreliable; a vital bleeding response indicates vital pulp.

Percussion tenderness indicates apical periodontitis; palpation of swelling or sinus tract indicates extension beyond the cortex; a sinus tract should be traced with gutta-percha to identify the source tooth.

Cracked tooth syndrome: sharp pain on release of biting, often not reproducible with percussion; transillumination, bite test with a bur or Tooth Slooth, and CBCT help localize the fracture.

Restorability assessment: ferrule of at least 1.5-2 mm of circumferential dentin, adequate remaining walls, no fracture below the alveolar crest, and periodontal support determine whether endodontic treatment is justified.

Teeth with a poor prognosis (vertical root fracture, perforation with uncontrolled infection, unrestorable crown-root fracture, severe periodontal involvement) should be planned for extraction rather than endodontic treatment.

Prophylactic (pre-emptive) endodontic treatment is not indicated for teeth with normal pulp to support a crown; the decision must be based on pulp diagnosis and restorability.

Primary endodontic infections are polymicrobial, dominated by obligate anaerobes: gram-negative rods (Porphyromonas, Prevotella, Fusobacterium, Tannerella) and gram-positive cocci/rods (Peptostreptococcus, Eubacterium, Actinomyces).

Enterococcus faecalis is the most frequently recovered species from failed root canal treatment, tolerates high pH, survives as a monoinfection, and can invade dentinal tubules.

Bacteria in dentinal tubules can penetrate up to roughly 200-500 micrometers; mechanical instrumentation alone leaves a substantial proportion of canal walls untouched, so irrigation is essential.

Sodium hypochlorite is the only irrigant that dissolves organic tissue and has broad antimicrobial action; concentration (0.5-5.25%) trades tissue-dissolving speed against cytotoxicity, and it must be replenished because it is consumed by tissue.

EDTA (17%) chelates smear layer and opens dentinal tubules; a final rinse of EDTA followed by NaOCl is a common regimen, and chlorhexidine can follow EDTA as a substantive antimicrobial but must not be mixed with NaOCl (brown precipitate, potentially carcinogenic).

Chlorhexidine 2% is substantive (binds to dentin, released over time) and effective against E. faecalis, but it does not dissolve tissue and is not a substitute for NaOCl.

Rubber dam isolation is mandatory for endodontic treatment; it protects the airway from instruments and irrigants, maintains a dry field, and reduces microbial contamination.

Sterilization: instruments must be autoclaved (134 degrees C, 3-4 minutes or equivalent cycle); NaOCl extrusion into the periapical tissues causes severe pain, tissue necrosis, and possible nerve injury, and should be managed with immediate cessation, irrigation with saline, and analgesia.

Aerosol and splash control requires high-volume evacuation, rubber dam, and eye protection; endodontic procedures generate aerosols containing oral microorganisms.

Access principles: remove all caries, achieve straight-line access to the apical third, preserve the pulp chamber floor anatomy, and do not sacrifice pericervical dentin unnecessarily.

Mandibular first molar typically has two roots (mesial and distal); the mesial root usually has two canals (mesiobuccal and mesiolingual) and the distal root one canal, but a distolingual canal (radix entomolaris) occurs in a significant minority, especially in East Asian populations.

Maxillary first molar typically has three roots and three or four canals; the second mesiobuccal canal (MB2) is present in roughly 50-70% of cases and should be actively sought.

Maxillary first premolar usually has two canals (buccal and palatal); mandibular first premolar is usually single-canal but can have a bifurcation or three canals in a small percentage of cases.

Mandibular incisors usually have one canal, but a second lingual canal is found in roughly 30-40% of cases; a buccolingual radiograph with slight angulation helps detect it.

C-shaped canal systems are most common in mandibular second molars, particularly in East Asian populations; they require careful troughing and continuous ultrasonic irrigation because walls connect through a thin isthmus.

The apical foramen is typically located 0.5-1.0 mm short of the anatomic apex and deviates from the root axis; working length should be determined with an apex locator and confirmed radiographically.

Dens invaginatus (dens in dente) most commonly affects maxillary lateral incisors; Type III invagination can communicate with the periodontal ligament and cause a periapical lesion in a tooth with a normal pulp.

Accessory and lateral canals occur most often in the apical third and at furcation areas; they are difficult to instrument and depend on irrigant penetration for disinfection.

Working length is established with an electronic apex locator (accuracy within about 0.5 mm) and confirmed with a periapical radiograph; instrumentation is generally terminated 0.5-1.0 mm short of the radiographic apex.

Crown-down technique removes coronal interference first, improves irrigant penetration, and reduces the risk of apical extrusion of debris compared with step-back preparation.

Rotary nickel-titanium instruments have superelasticity and shape-memory; they are used with a torque-controlled motor, and the risk of cyclic fatigue fracture increases with curvature, while torsional fracture occurs with excessive apical pressure.

A glide path (usually a size 10-15 hand file to length) should be established before rotary instrumentation to reduce instrument separation and ledging.

Apical preparation size: a common guideline is to enlarge the apical foramen to at least three sizes larger than the first file that binds at the apex (or approximately 0.25-0.30 mm in the apical region), balanced against dentin preservation.

Irrigation activation methods include sonic and ultrasonic activation, negative-pressure systems, and manual dynamic activation; they improve irrigant exchange in the apical third and into isthmuses compared with syringe irrigation alone.

Irrigant extrusion beyond the apex is the main safety concern in irrigation; the needle should be loose in the canal, placed short of the working length (about 1-2 mm), and never wedged.

Reciprocating single-file systems and continuous-rotation multi-file systems both achieve acceptable shaping; the choice should be based on canal anatomy, curvature, and operator experience rather than on a single superior system.

Patency filing with a small file through the apical foramen maintains the apical anatomy and reduces debris accumulation, but must be balanced against the risk of pushing infected debris into periapical tissues.

Obturation is indicated when the canal is cleaned, shaped, and dry, with a confirmed working length and no persistent exudate; the goal is a three-dimensional seal of the entire canal space.

Gutta-percha with a sealer is the most widely used technique; cold lateral compaction, warm vertical compaction, and carrier-based systems all rely on sealer to fill the interface between gutta-percha and dentin.

Sealer selection: resin-based sealers offer good adhesion but are technique-sensitive; bioceramic sealers are hydrophilic and dimensionally stable; zinc oxide-eugenol sealers have a long history but are more soluble.

The quality of the coronal restoration is strongly associated with periapical healing; a well-adapted coronal restoration significantly improves outcomes compared with an inadequate one, even when the root filling is adequate.

Immediate coronal sealing after obturation reduces coronal leakage and microleakage; when a post is planned, the post space should be prepared after the sealer has set, preserving at least 4-5 mm of apical gutta-percha.

Overextension of obturation material is associated with a higher risk of postoperative pain and persistent inflammation; overfill should be avoided, and extrusion is not a marker of a good seal.

The quality of the apical seal is assessed radiographically by density, adaptation to canal walls, and termination within 0.5-1.0 mm of the radiographic apex; a void or short fill is a risk factor for failure.

Post-endodontic restoration: cuspal coverage (onlay or crown) is recommended for posterior teeth with significant loss of tooth structure; a post is indicated only when retention cannot be achieved otherwise and should not be used to strengthen the root.

Failure is defined as persistence or development of apical periodontitis after treatment; the main causes are untreated canals, missed anatomy, coronal leakage, and persistent intraradicular infection.

Retreatment is indicated for teeth with persistent apical periodontitis, inadequate previous root filling, untreated canals, or a new coronal restoration that requires re-treatment; the decision should consider restorability and patient factors.

Nonsurgical retreatment is the first choice for most failures; periapical surgery is reserved for cases where retreatment is not feasible (blocked canal, separated instrument beyond the curve, persistent lesion after adequate retreatment).

Removal of gutta-percha can be done with rotary retreatment files, heat, or solvents (chloroform, eucalyptol); solvents soften gutta-percha but can push material apically and must be used sparingly.

Separated instrument management: bypass with a small file if possible, use ultrasonic retrieval under magnification, and consider surgery if the fragment cannot be removed and the tooth is otherwise restorable.

Perforation repair uses bioceramic or MTA-based materials; the prognosis depends on the level and size of the perforation, with coronal and mid-root perforations having a better prognosis than apical ones.

Post-treatment apical periodontitis with an adequate root filling and a persistent lesion may indicate a missed canal (often MB2 or a second distal canal) or a root fracture; CBCT is the imaging method of choice.

Retreatment outcomes are generally lower than primary treatment outcomes; the presence of a periapical lesion and the quality of the previous root filling are key prognostic factors.

Luxation injuries: concussion and subluxation usually need monitoring and soft diet; extrusive and lateral luxation require repositioning and splinting (flexible splint for 2-4 weeks); intrusive luxation management depends on apex maturity.

Avulsion: replant as soon as possible; if the tooth is dry for more than 60 minutes, the prognosis is poor. Store in milk, saline, or Hank's balanced salt solution; do not scrub the root; splint flexibly for 2 weeks and consider systemic antibiotics.

Root fracture: coronal and mid-root fractures are usually splinted; apical third fractures often require no treatment. Pulp sensibility may be temporarily negative after trauma and should be retested over months.

Replantation of an avulsed immature tooth may allow revascularization; the risk of inflammatory resorption is reduced by timely replantation and, in some protocols, by topical or systemic antibiotics.

Regenerative endodontic procedure (revascularization) is indicated for immature permanent teeth with necrotic pulp and open apices; it involves minimal instrumentation, disinfection with NaOCl (often 1.5-3%) and EDTA, and induction of a blood clot.

In regenerative procedures, avoid aggressive instrumentation and high-concentration NaOCl to preserve stem cells in the apical papilla; a blood clot is created by overinstrumentation beyond the apex, then covered with a bioceramic or MTA plug and a coronal seal.

Success of regenerative procedures is judged by resolution of symptoms and periapical lesion, increased root wall thickness, and continued root development; root length increase is less predictable than wall thickening.

Crown fracture with pulp exposure in an immature tooth may be treated with partial pulpotomy (Cvek pulpotomy) using calcium hydroxide or MTA, preserving pulp vitality and allowing continued root development.

Indications for periapical surgery: persistent periapical lesion after adequate nonsurgical treatment, blocked canal, separated instrument that cannot be bypassed, perforation not accessible nonsurgically, and biopsy of a suspected non-endodontic lesion.

Contraindications include uncontrolled systemic disease, severe periodontal involvement, unfavorable anatomy (proximity to the inferior alveolar nerve or maxillary sinus), and a tooth that is not restorable.

Modern microsurgery uses an operating microscope, ultrasonic retrotips, and bioceramic retrofilling materials; the success rate is higher than with traditional techniques.

Root-end resection should be performed with a bevel of about 0 degrees to 10 degrees (or a shallow bevel), removing about 3 mm of the root end to eliminate the apical delta and resect the uninstrumented apical portion.

Root-end preparation is done with ultrasonic tips to a depth of about 3 mm, following the canal axis; the preparation must be centered in the canal and not perforate the root wall.

Retrograde filling materials: MTA and bioceramic cements are preferred for their sealing ability and biocompatibility; amalgam and zinc oxide-eugenol are no longer recommended.

Hemostasis is essential for a dry field; agents include ferric sulfate, aluminum chloride, and local anesthetic with epinephrine; care must be taken to avoid bone staining and nerve injury.

Flap design: sulcular (crevicular) incision for access to the apical region, with vertical releasing incisions when needed; the papilla-base incision preserves the interdental papilla and reduces recession.

Postoperative instructions after surgery include ice, analgesia, chlorhexidine rinse, and avoidance of trauma to the surgical site; sutures are usually removed after 5-7 days.

A combined endodontic-periodontal lesion requires determining the primary cause; a sinus tract that traces to the sulcus suggests periodontal origin, while a tract that traces to the apex suggests endodontic origin.

Endodontic treatment is performed first when the primary cause is endodontic; periodontal treatment follows after the endodontic prognosis is established, and healing is reassessed over 3-6 months.

A true combined lesion has both pulpal and periodontal involvement and generally has a guarded prognosis; the presence of a deep narrow pocket to the apex with a vital pulp suggests a periodontal origin.

Vertical root fractures present with a deep narrow pocket, a J-shaped radiolucency, and pain on biting; the tooth is generally not restorable and should be extracted.

Ferrule effect: a circumferential band of at least 1.5-2 mm of dentin above the crown margin improves fracture resistance of endodontically treated teeth; lack of ferrule is a risk factor for failure.

Post space preparation should preserve at least 4-5 mm of apical gutta-percha; posts do not strengthen the root and are indicated only for retention of the core.

Teeth with a questionable prognosis should be evaluated with a multidisciplinary approach (endodontics, periodontics, prosthodontics); the decision should be based on restorability, periodontal support, and strategic value.

Occlusal adjustment and splinting may be considered for teeth with reduced periodontal support or after trauma; however, evidence for routine splinting of endodontically treated teeth is limited.

Articaine 4% with 1:100,000 epinephrine provides good bone penetration and is effective for mandibular infiltration; it is metabolized in plasma and has a short half-life.

Lidocaine 2% with 1:100,000 epinephrine is the standard inferior alveolar nerve block; the maximum recommended dose is about 4.4 mg/kg (or 7 mg/kg for articaine) and should be calculated per patient weight.

Inferior alveolar nerve block failure is common in mandibular molars with irreversible pulpitis; supplemental techniques include intraligamentary, intraosseous, and buccal infiltration with articaine.

Epinephrine-containing local anesthetics should be used with caution in patients with severe cardiovascular disease; the maximum dose of epinephrine is about 0.2 mg for healthy adults and lower in cardiac patients.

Nonsteroidal anti-inflammatory drugs (ibuprofen 400-600 mg every 6-8 hours) are first-line for endodontic postoperative pain; acetaminophen can be combined, and opioids are rarely indicated.

Antibiotics are not indicated for irreversible pulpitis or pulp necrosis without systemic involvement; they are indicated for systemic signs (fever, cellulitis, spreading infection) or immunocompromised patients.

Amoxicillin (500 mg every 8 hours) is a common first-line antibiotic; for penicillin-allergic patients, clindamycin or azithromycin is an alternative. Antibiotics are adjunctive to drainage and endodontic treatment.

Local anesthetic overdose presents with CNS excitation followed by depression, and cardiovascular effects; management includes stopping the injection, airway support, and benzodiazepines for seizures.

Pregnancy: lidocaine with epinephrine is considered safe; avoid articaine and mepivacaine in early pregnancy per some guidelines, and avoid metronidazole in the first trimester.

Levels of evidence: systematic reviews and meta-analyses of randomized controlled trials are highest, followed by RCTs, cohort studies, case-control studies, case series, and expert opinion.

Randomization, allocation concealment, and blinding reduce bias in clinical trials; intention-to-treat analysis preserves the benefit of randomization.

Sensitivity and specificity describe a diagnostic test: sensitivity is the proportion of diseased patients correctly identified, and specificity is the proportion of healthy patients correctly identified.

Positive predictive value depends on prevalence; a test with high sensitivity and specificity can have a low positive predictive value in a low-prevalence population.

Confidence intervals describe the precision of an estimate; a 95% CI that excludes the null value corresponds to a statistically significant result at the 0.05 level.

Consent for endodontic treatment must include the diagnosis, treatment options (including no treatment and extraction), risks (instrument separation, perforation, flare-up, failure), and the expected prognosis.

Record keeping: accurate documentation of diagnosis, treatment, materials, and follow-up is an ethical and legal obligation; alteration of records is unethical.

Conflict of interest disclosure and honest reporting of results are core ethical requirements in research; fabricated or falsified data constitute research misconduct.

Evidence-based endodontic practice integrates the best available evidence, clinical expertise, and patient values; guidelines should be adapted to the individual patient rather than applied rigidly.