Oral and maxillofacial surgery: maximum dose of lignocaine: 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 · Oral and maxillofacial surgery: maximum dose of lignocaine

Sample item

A dentist uses 2 percent lignocaine with adrenaline in a 20 kg child. What is the usual maximum dose per kg?

ANo upper limitBAbout 7 mg/kg with adrenalineCAbout 1 mg/kgDAbout 20 mg/kg

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

The answer and the reasoning

B. About 7 mg/kg with adrenaline

The maximum safe dose of lignocaine with adrenaline is approximately 7 mg/kg, and about 4.5 mg/kg without adrenaline. One cartridge of 2 percent solution contains about 36 mg.

Option by option

A. No upper limit
Local anaesthetics have defined toxic limits.
B. About 7 mg/kg with adrenaline (correct)
Correct. Lignocaine with adrenaline has a ceiling of about 7 mg/kg.
C. About 1 mg/kg
1 mg/kg is too low to be useful for dentistry.
D. About 20 mg/kg
20 mg/kg would cause toxicity.

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.

Questions about this Dentistry question

What is the answer to this Dentistry question?

The best answer is B, About 7 mg/kg with adrenaline. The maximum safe dose of lignocaine with adrenaline is approximately 7 mg/kg, and about 4.

Why is "No upper limit" not the answer?

Local anaesthetics have defined toxic limits.

Why is "About 1 mg/kg" not the answer?

1 mg/kg is too low to be useful for dentistry.

Why is "About 20 mg/kg" not the answer?

20 mg/kg would cause toxicity.

What concept does this question test?

It tests Oral and maxillofacial surgery: maximum dose of lignocaine in Dentistry. 5 mg/kg without adrenaline. One cartridge of 2 percent solution contains about 36 mg.

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 Oral and maxillofacial surgery: maximum dose of lignocaine?

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.