Start practicing

Radiology: INBDE study notes and practice questions

Radiology covers how x-rays are produced and controlled, how to take good images safely, and how to recognize normal anatomy and common abnormalities. Several items test image errors: what you did wrong and how to fix it.

412 practice questions · 21 patient cases

Practice Radiology

Where it fits in the official INBDE blueprint

Diagnosis and Treatment Planning (selecting and interpreting diagnostic tools). Nearest foundation knowledge areas: FK 2, FK 3. See the content outline for the official weights. This mapping is approximate: real items combine a clinical area with a foundation area.

What this area tests

High-yield checklist

Common traps

These notes are original study aids, not official exam content. Confirm clinical details against current guidelines.

Sample questions

1. What distinguishes CONDENSING OSTEITIS from IDIOPATHIC OSTEOSCLEROSIS on X-ray?

  1. Condensing osteitis = vital teeth; idiopathic = nonvital
  2. Condensing osteitis always = NONVITAL tooth + apical inflammation; idiopathic = VITAL tooth, unknown cause
  3. Both always associated with nonvital teeth
  4. Both always require treatment
  5. They cannot be distinguished radiographically
Show answer and explanation

Correct answer: B. Condensing osteitis always = NONVITAL tooth + apical inflammation; idiopathic = VITAL tooth, unknown cause

✓ B) Key distinction: Condensing osteitis = NONVITAL tooth; Idiopathic osteosclerosis = VITAL tooth.
CONDENSING OSTEITIS: localized increased bone radiodensity at root apex due to low-grade chronic pulpal inflammation; associated tooth is ALWAYS NONVITAL; may have widened PDL space or periapical radiolucency; treatment = RCT or extraction. IDIOPATHIC OSTEOSCLEROSIS (bone scar, focal sclerosing osteomyelitis): area of increased bone density of UNKNOWN origin; associated tooth is VITAL; regular PDL space; no treatment needed. The PULP VITALITY TEST is the key diagnostic differentiator. Multiple idiopathic osteoscleroses → consider Gardner's syndrome.

Permanent page

2. On a panoramic radiograph, the hyoid bone is a normal structure that can be mistaken for pathology because it commonly projects:

  1. Over the inferior border/angle region of the mandible
  2. Within the maxillary sinus
  3. Over the orbit
  4. In the nasal cavity
Show answer and explanation

Correct answer: A. Over the inferior border/angle region of the mandible

The hyoid bone frequently projects over the inferior border and angle region of the mandible on panoramic films. Recognizing it as normal anatomy avoids misdiagnosis as a pathologic radiopacity.Other options: The hyoid lies in the anterior neck; it does not project into the sinus, orbit, or nasal cavity.Key exam takeaway: Know panoramic landmarks; the hyoid overlaps the lower mandible and is normal, not pathology.

Permanent page

3. Toothlike radiopaque mass without denticles blocking eruption of #22 u2014 most likely diagnosis:

  1. Compound odontoma
  2. Complex odontoma
  3. Supernumerary tooth
  4. Cementoblastoma
Show answer and explanation

Correct answer: B. Complex odontoma

Complex odontoma appears as an amorphous radiopaque mass of dental tissues WITHOUT recognizable tooth structures (no denticles). It commonly blocks eruption in the posterior jaws. Compound odontoma shows multiple distinct 'denticles' and occurs in the anterior maxilla.

Permanent page

4. A 30-year-old patient presents with proximal caries detected radiographically at the dentin-enamel junction (DEJ) with no frank cavitation visible clinically. What is the most minimally invasive treatment?

  1. Composite resin restoration (Class II cavity preparation)
  2. Silver diamine fluoride (SDF) application
  3. Resin infiltration (ICON)
  4. Amalgam restoration with retention grooves
Show answer and explanation

Correct answer: C. Resin infiltration (ICON)

For a 30-year-old with an early proximal carious lesion at the DEJ (radiographically visible, no clinical cavitation), the most minimally invasive approach is RESIN INFILTRATION (ICON — DMG). This technique: opens the proximal contact, etches with hydrochloric acid gel to open the enamel surface, then infiltrates low-viscosity resin into the porous carious enamel to arrest lesion progression. ICON is indicated for initial-to-moderate enamel caries (ICDAS 1-3) and early dentin lesions without cavitation — precisely this clinical scenario. It is more conservative than cavity preparation and more effective than fluoride alone for arrested DEJ caries. SDF is primarily used in older adults with root caries, pediatric patients, or patients unable to cooperate — and turns carious tissue black. Composite and amalgam require mechanical preparation, which is NOT indicated for a non-cavitated lesion. ICON represents the ideal 'least invasive first' approach for a young adult with early proximal caries.

Permanent page

5. A patient with sickle cell anemia presents for dental X-rays. What finding would you MOST expect on a panoramic radiograph?

  1. Step-ladder (staircase) pattern of trabecular bone
  2. Widened periodontal ligament space
  3. Hypercementosis
  4. Ground-glass opacity
Show answer and explanation

Correct answer: A. Step-ladder (staircase) pattern of trabecular bone

Sickle cell anemia causes vascular occlusion and bone infarcts, resulting in characteristic radiographic changes including: step-ladder (staircase) trabecular pattern of alveolar bone (coarse, perpendicular trabeculae), generalized osteoporosis, enlarged marrow spaces, and thinning of cortical bone. Other systemic findings include: hair-on-end pattern on skull X-ray. The 'step-ladder' pattern is the classic INBDE answer.
  • A. ✅ CORRECT – Sickle cell anemia creates a step-ladder (staircase) trabecular bone pattern on radiographs due to vascular compromise and bone infarction.
  • B. ❌ Widened PDL space is a sign of occlusal trauma or periodontal disease — not specific to sickle cell disease.
  • C. ❌ Hypercementosis is excessive cementum formation — associated with Paget's disease, not sickle cell disease.
  • D. ❌ Ground-glass opacity is characteristic of fibrous dysplasia — not sickle cell anemia.

Permanent page

6. On a panoramic radiograph, a patient with jewelry in both ears shows earrings appearing inside the maxillary sinuses. The left sinus contains one earring's image. Which earring is actually inside the left maxillary sinus image?

  1. The left earring (ipsilateral)
  2. The right earring (contralateral)
  3. Both earrings overlap in the left sinus
  4. Neither — the image is the uvula
Show answer and explanation

Correct answer: B. The right earring (contralateral)

Panoramic radiographs produce ghost images of objects on the opposite side — because the X-ray beam passes through an object on the RIGHT side and projects its ghost onto the LEFT side of the image (and vice versa). Therefore, an earring appearing in the LEFT maxillary sinus area is actually the ghost image of the RIGHT earring. The real (direct) image of the right earring would appear on the right side, and its ghost appears on the left.

Permanent page

7. A bitewing radiograph of tooth #15 is inconclusive for the periapical region. Which additional radiograph best provides a diagnosis of the apex?

  1. Periapical radiograph
  2. Another bitewing
  3. Panoramic only
  4. Occlusal film
Show answer and explanation

Correct answer: A. Periapical radiograph

A periapical radiograph captures the entire tooth including the apex and surrounding periradicular bone, which bitewings do not, making it the appropriate next image. (CBCT is reserved for complex cases.)Other options: A repeat bitewing still omits the apex; a panoramic lacks fine detail; an occlusal film does not image the posterior apex well.Key exam takeaway: To evaluate the apex, take a periapical radiograph (bitewings show crowns/crestal bone only).

Permanent page

8. Which radiographic finding is associated with dentigerous cyst?

  1. Radiolucency attaches to CEJ of an unerupted tooth
  2. Multilocular radiolucency with soap bubble appearance
  3. Radiopaque mass within a radiolucent border
  4. Periapical radiolucency at root apex
Show answer and explanation

Correct answer: A. Radiolucency attaches to CEJ of an unerupted tooth

A dentigerous (follicular) cyst characteristically presents as a well-defined radiolucency that cleanly attaches to the cementoenamel junction (CEJ) of an unerupted tooth, surrounding the crown. This attachment to the CEJ is nearly pathognomonic for dentigerous cyst.

Permanent page

Patient cases

All Radiology questions (412)