Endodontics Practice Questions
Endodontics is one of the most heavily tested clinical branches on dental board exams, and one of the easiest places to lose marks through imprecise diagnosis. These questions cover pulp biology and pathology, periapical pathology, access, instrumentation, irrigation and disinfection, obturation, vital pulp therapy and regenerative endodontics, trauma and resorption, emergencies, complications and retreatment, and the endodontic-restorative interface. On the AFK, INBDE, ORE and ADC, expect vignettes built on sensibility test results, radiographic findings and symptoms, where the task is to name the correct pulpal and periapical diagnosis and the treatment that follows.
10 questions · answers and explanations revealed as you go · no sign-up
Questions
Question 1 of 10
Root Canal Treatment, Access & Instrumentation
When an electronic apex locator is used to determine working length, the reading corresponds most closely to the
The answer is C.
An electronic apex locator reading corresponds most closely to the apical constriction, the narrowest point of the canal and the ideal endpoint for canal preparation and obturation.
Question 2 of 10
Periapical Pathology
A radiograph taken for an asymptomatic mandibular first molar with a deep restoration shows a well-defined radiopaque area surrounding the mesial root apex, with the periodontal ligament space still visible. What does this finding most likely represent?
The answer is A.
Condensing osteitis is a focal radiopaque reaction of bone to a low-grade, long-standing pulpal inflammatory stimulus, classically seen apical to a tooth with a deep carious lesion or restoration while the periodontal ligament space remains intact, distinguishing it from cystic or dysplastic radiopaque entities.
Question 3 of 10
Obturation
What is the significance of the 'apical foramen' in relation to obturation termination point?
The answer is B.
The apical foramen is the exit point of the root canal at the root surface. Obturation should terminate at the apical constriction, approximately 0.5–1 mm short of the foramen, to prevent extrusion of materials into periapical tissues.
Question 4 of 10
Endodontic-Related Pain & Emergencies
A patient reports facial pain but no tooth responds abnormally to percussion, palpation, or pulp sensibility testing, and no dental radiographic abnormality is found. Which feature would most support a non-odontogenic rather than odontogenic source for the pain?
The answer is C.
Odontogenic pain typically localizes to a tooth and is reproducible with thermal, percussion, or biting stimuli because it arises from pulpal or periapical nociceptors; pain that fails to localize and is unaffected by these tests points toward a non-odontogenic source such as myofascial, neuropathic, or sinus-related pain requiring a broader differential.
Question 5 of 10
Endodontic-Restorative Interface
Which of the following complications is most likely to occur as a direct result of choosing an excessively wide post for a narrow root canal?
The answer is A.
Excessive post width requires removal of valuable radicular dentin, which weakens the root and significantly increases the risk of vertical root fracture.
Question 6 of 10
Complications & Retreatment
A tooth has persistent periapical radiolucency despite adequate non-surgical root canal retreatment, and the canal system cannot be further improved through an orthograde approach due to a well-fitted post that cannot safely be removed. Which procedure is most appropriate?
The answer is A.
When persistent apical disease remains after adequate orthograde retreatment and the coronal restoration precludes safe canal re-access, apical surgery with root-end resection, preparation, and a retrograde filling material such as MTA or a bioceramic directly addresses the apical pathology without disturbing the existing coronal restoration.
Question 7 of 10
Trauma & Resorption
A periapical radiograph shows a round radiolucent area that appears to expand the canal outline symmetrically and remains centered within the root regardless of the horizontal angle at which the film is exposed. Which type of resorption does this finding most likely represent?
The answer is B.
Internal resorption originates from the canal wall and therefore stays concentric with and moves in unison with the canal outline on radiographs taken at different horizontal angles, a key differentiator from external resorption defects, which appear to shift position relative to the canal as the projection angle changes.
Question 8 of 10
Vital Pulp Therapy & Regenerative Endodontics
A 12-year-old has a necrotic tooth 21 with an open apex and a periapical radiolucency following trauma. Regeneration is not feasible. After disinfection, which material is used to create the apical barrier?
The answer is D.
Mineral trioxide aggregate is used to create an apical barrier in a necrotic immature tooth with an open apex when regenerative treatment is not feasible, allowing conventional obturation.
Question 9 of 10
Pulp Biology & Pathology
A patient complains of sharp pain on cold water on tooth 2.5. The pain resolves immediately within 1-2 seconds after the cold stimulus is removed. What is the most likely pulpal diagnosis and appropriate management?
The answer is D.
Reversible pulpitis is characterized by sharp, transient pain to thermal stimuli that ceases immediately after the stimulus is removed. It is managed by conservative restorative treatment.
Question 10 of 10
Irrigation & Disinfection
Which of the following is NOT an objective of root canal irrigation?
The answer is B.
Obturation (sealing the canal) is a separate, subsequent step from irrigation and is not an objective of irrigants. The goals of irrigation include: debris removal, antimicrobial action, dissolution of organic/inorganic tissue, smear layer management, lubrication, and cooling.
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