Endodontics · single question
A cracked tooth is examined with a transillumination light. What is typically observed?
Show answer and explanation
Correct answer: B. Light illuminates one side, but is interrupted/blocked at the crack line so the far side appears darker
A crack interrupts the normal transmission of light through tooth structure — light entering from one side will illuminate that portion of the tooth, but is blocked/scattered at the fracture line, so the light does not continue uniformly through to the other side. This interruption (rather than uniform illumination of the whole tooth) is the classic transillumination finding used to help identify a crack.