Radiology · patient case with 4 questions
Ossifying Fibroma and Anterior Maxillary Radiolucency
demo: 31-year-old female
chief: Asymptomatic lesion noted on routine imaging.
history: Non-contributory.
meds: None
findings: A well-circumscribed lesion of mixed density is present in the posterior mandible (images below). On a separate periapical film of the maxillary central incisors, a well-defined radiolucency is seen between the roots of #8 and #9.
Question 1
For the well-defined radiolucency between the roots of the maxillary central incisors, all of the following belong in the differential EXCEPT:
Show answer and explanation
Correct answer: B. Buccal bifurcation cyst
- A. An OKC can occur anywhere in the jaws and is a legitimate, if less likely, differential.
- B. Correct — this is the exception. A buccal bifurcation cyst is an inflammatory cyst on the buccal aspect of an erupting mandibular first or second molar in a child. It has no relationship to the anterior maxilla.
- C. A prominent incisive foramen is normal anatomy and is the first thing to exclude before treating.
- D. The nasopalatine duct cyst is the most common non-odontogenic cyst of the jaws and sits exactly here, classically heart-shaped.
Note: The practical rule: an incisive foramen wider than about 6 mm, or one that enlarges over time or is symptomatic, moves from normal variant toward nasopalatine duct cyst.
Question 2
The same patient reports tenderness between #8 and #9. The radiograph shows a balloon-like radiolucency arising from the root canal space with loss of the canal outline. What is the diagnosis and treatment?
Show answer and explanation
Correct answer: B. Internal resorption — treat with root canal therapy
- A. A lateral periodontal cyst sits in the bone lateral to a vital root, not within the canal space.
- B. Correct. Internal resorption is odontoclastic activity within the canal, driven by inflamed vital pulp tissue. The canal outline is lost within the lesion and the defect moves with the tooth on parallax. Removing the pulp arrests it — root canal therapy is the treatment.
- C. External resorption preserves the canal outline through the defect and the lesion shifts relative to the canal when the beam angle changes.
- D. Condensing osteitis is a sclerotic radiopacity, not a radiolucent balloon.
Question 3
On a full-mouth series, one endodontically treated tooth shows a radiolucent space between the apical extent of the post and the remaining gutta-percha. This finding indicates:
Show answer and explanation
Correct answer: A. Improper post space preparation or cementation technique, leaving a void
- A. Correct. A gap between the post and the gutta-percha is a void created during post space preparation or cementation. It is a potential pathway for coronal leakage and bacterial recontamination of the seal.
- B. Apexification concerns the formation of an apical barrier in an immature tooth, unrelated to post placement.
- C. Secondary dentin is a pulpal response and would not create a radiolucent void around a post.
- D. Periapical healing is judged at the apex, not within the canal.
Question 4
On the same full-mouth series, which radiographic finding would most strongly indicate that a root-treated tooth requires retreatment?
Show answer and explanation
Correct answer: A. A persistent or enlarging periapical radiolucency with poor obturation density
- A. Correct. Persistent or growing apical rarefaction combined with visible voids or an inadequate seal is the standard indication for retreatment — the disease has not resolved and the cause is identifiable.
- B. Sealer extrusion with healed bone represents a successful biological outcome despite the imperfect radiographic appearance.
- C. A short but well-condensed fill with healthy periapical bone is generally monitored, not retreated.
- D. A post alone is not an indication; many well-functioning teeth carry posts.