Caries, pulp and periodontal disease: laser fluorescence caries detection: practice question

A Dentistry question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Dentistry · Caries, pulp and periodontal disease: laser fluorescence caries detection

Sample item

A laser fluorescence device is used to examine pits and fissures for hidden occlusal caries. How does it detect caries?

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

B. Bacterial metabolites in carious tissue fluoresce more intensely

Laser fluorescence devices such as DIAGNOdent emit red light and measure the fluorescence of bacterial porphyrins in carious tissue. Higher readings suggest caries, though stain and plaque can give false positives. It supports, and does not replace, clinical and radiographic examination.

Option by option

  • A. Carious tissue absorbs more X-rays

    X-ray absorption is the basis of radiography, not fluorescence.

  • B. Bacterial metabolites in carious tissue fluoresce more intensely (correct)

    Correct. Porphyrins from bacteria increase fluorescence.

  • C. Carious tissue reflects more visible light

    Reflected visible light is not the measured signal.

  • D. Carious tissue conducts more electric current

    Electrical conductance is the basis of electronic caries monitors.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

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Questions about this Dentistry question

What is the answer to this Dentistry question?

The best answer is B, Bacterial metabolites in carious tissue fluoresce more intensely. Laser fluorescence devices such as DIAGNOdent emit red light and measure the fluorescence of bacterial porphyrins in carious tissue.

Why is "Carious tissue absorbs more X-rays" not the answer?

X-ray absorption is the basis of radiography, not fluorescence.

Why is "Carious tissue reflects more visible light" not the answer?

Reflected visible light is not the measured signal.

Why is "Carious tissue conducts more electric current" not the answer?

Electrical conductance is the basis of electronic caries monitors.

What concept does this question test?

It tests Caries, pulp and periodontal disease: laser fluorescence caries detection in Dentistry. Higher readings suggest caries, though stain and plaque can give false positives. It supports, and does not replace, clinical and radiographic examination.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Caries, pulp and periodontal disease: laser fluorescence caries detection?

Learn the dental formula, eruption ages and tooth structure once, as tables. Then use the flashcards and the other Dentistry questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.