Endodontics · single question
Which of the following is LEAST helpful in diagnosing a cracked tooth?
Show answer and explanation
Correct answer: C. Periapical radiography
Radiography is the least helpful tool for diagnosing cracks in teeth because cracks are typically hairline fractures that are too small to be detected on standard two-dimensional radiographs — unless the crack is wide enough or runs in the exact plane of the X-ray beam. In contrast, transillumination (passing a fiber-optic light through the tooth) can reveal cracks as areas of darkness, dye penetration with methylene blue or disclosing dye highlights the crack line, and visual examination under magnification with appropriate lighting can identify crack lines. CBCT may be more helpful for crack detection than conventional radiographs.
- A. Incorrect. Dye staining after removing a restoration is a classic method for delineating a crack.
- B. Incorrect. Pain on release of biting pressure is the single most characteristic finding in cracked tooth syndrome.
- C. Correct. Most cracks propagate in a mesiodistal plane, which is parallel to the x-ray beam. Radiographs therefore rarely reveal them until the crack has separated significantly.
- D. Incorrect. Transillumination is highly useful — light is blocked at the crack line, causing the segment beyond it to appear dark.
Note: CBCT is more sensitive than a PA for cracks but is still unreliable, especially with restorative scatter. Direct visualisation under magnification after restoration removal remains the definitive method.