ABE Endodontics common mistakes
ABE Endodontics · Understand the traps and how to avoid them.
Concludes a tooth is nonvital after a single negative cold test and moves straight to a diagnosis of necrotic pulp, without repeating the test or adding a second modality and controls.
Heavily restored or calcified canals, immature apices, recent trauma, and poor thermal contact can all produce a false-negative cold response; candidates memorize 'cold test = vitality' and stop at one data point.
What to do instead
Always test the contralateral and adjacent teeth, repeat the cold test, and add EPT plus percussion, palpation, and radiographic findings; report sensibility (nerve response), not vascularity, and state how the combined results support the diagnosis.
Differentiates a periapical granuloma from a radicular cyst by lesion size, border definition, or radiolucency, and answers that a lesion larger than 1 cm is a cyst.
Textbook heuristics and the fact that both appear as apical radiolucencies encourage a radiographic diagnosis; candidates forget that only histopathology can distinguish them.
What to do instead
State explicitly that radiographs cannot separate granuloma, cyst, and abscess, that cysts account for only a minority (roughly 10-20%) of periapical lesions, and that the treatment decision rests on the diagnosis of apical periodontitis, with biopsy reserved for persistent or atypical lesions.
Names Enterococcus faecalis as the dominant or most common organism in primary endodontic infections.
Retreatment and post-treatment disease literature is overlearned and then applied to untreated teeth.
What to do instead
Describe primary infections as polymicrobial with a predominance of gram-negative obligate anaerobes (Prevotella, Porphyromonas, Fusobacterium, Treponema), and reserve E. faecalis for secondary or persistent infections and failed cases; mention biofilm and extraradicular infection as persistence mechanisms.
Obturates a canal without confirming master cone tug-back and length, accepting a cone that is visibly short or overextended.
Candidates trust the shaped canal and want to finish; fear of extrusion leads to accepting a short cone, or a lack of tug-back is ignored.
What to do instead
Verify the master cone radiographically 0.5-1 mm from working length with tug-back at the apical seat before sealer; if there is no tug-back, re-shape or choose a cone of different taper or size, and document the fit.
Sets working length at the radiographic apex for every canal rather than at the apical constriction, and does not confirm with an electronic apex locator.
A simple memorized 'apex' rule persists; the radiographic apex and minor foramen differ, and anatomy is distorted by angulation.
What to do instead
Determine working length with an apex locator, confirm 0.5-1.0 mm short of the radiographic apex at the minor constriction, and verify radiographically; be explicit about limitations in resorption, immature apices, and metallic restorations.
Relies on sodium hypochlorite alone as the entire irrigation protocol and then states that the smear layer has been removed.
NaOCl is emphasized for its antimicrobial and tissue-dissolving action, so candidates assume it does everything; it cannot dissolve the inorganic smear layer.
What to do instead
Alternate NaOCl with a chelator (17% EDTA or 10% citric acid), use side-vented needles short of working length with activation, and describe the separate roles: NaOCl for organics and microbes, EDTA for inorganic debris and smear layer.
In retreatment, removes only the coronal gutta-percha, does not re-establish apical patency, and does not verify the apical terminus before re-obturation.
Retreatment files are easier to use coronally; the apical third is harder and carries extrusion and perforation risk, so the canal is 'retreated' only partially.
What to do instead
Remove filling material to the orifice level first, use rotary retreatment files and solvent as needed, then a small hand file to patency confirmed with an apex locator and radiograph; verify canal cleanliness and the full working length before re-obturation.
Describes a 45-degree bevel with amalgam retrofill as the standard for periradicular surgery.
Outdated textbook technique persists; candidates describe the surgical step they memorized rather than current microsurgical principles.
What to do instead
Describe microsurgical principles: magnification and hemostasis, minimal osteotomy, 3 mm root-end resection perpendicular to the long axis, ultrasonic retropreparation about 3 mm deep, and a bioceramic root-end filling, with the isthmus and root-end anatomy addressed.
Recommends immediate replantation of an avulsed tooth without establishing extraoral dry time and storage medium, and states a splinting duration without justification.
The rule 'replant immediately' is memorized in isolation; prognosis depends on periodontal ligament cell viability, which is determined by dry time and storage.
What to do instead
State dry time and storage (HBSS, milk, saline, saliva) first, then decide: replant within minutes when possible; if dry time exceeds 60 minutes, recognize poor prognosis and consider delayed replantation after appropriate soaking; use a flexible splint for about 2 weeks, check tetanus status, and consider antibiotics.
Prescribes systemic antibiotics for symptomatic irreversible pulpitis or a localized fluctuant abscess without systemic signs.
Patient expectation and the intuition that infection requires antibiotics; candidates conflate pulpal infection with spreading infection.
What to do instead
Reserve antibiotics for systemic involvement (fever, malaise, lymphadenopathy, spreading cellulitis), immunocompromise, or progressive infection; otherwise provide pulpectomy or incision and drainage; if indicated, state the drug, dose, and duration (e.g., amoxicillin 500 mg every 8 hours for 5-7 days).