A patient arrives with his wife. Documentation states that the patient is ambulatory but legally incompetent and mute, and that the wife is his legal guardian and consents to a dental evaluation. Which of the following findings is MOST relevant to the wife's authority to consent on his behalf?

Correct answer: B. He sustained a brain injury

• A. Being mute is a communication impairment, not a cognitive one. A mute patient with intact capacity retains full decision-making authority and can consent by writing, sign language or an interpreter. Muteness alone never justifies guardianship.
• B. CORRECT. Guardianship is established on the basis of incapacity to make one's own decisions, and a brain injury is the finding that explains WHY this patient lacks decision-making capacity. That underlying cognitive impairment is the legal foundation for the guardianship and therefore for the wife's authority to give substitute consent.
• C. Denture identification is a good practice for institutionalised patients and is required in some jurisdictions, but it has nothing to do with who holds authority to consent.
• D. Providing daily oral care demonstrates caregiving and devotion but confers no legal authority. Caregiving and guardianship are entirely separate things.

Note: The distinction the item is drilling: capacity is about the ability to understand information, appreciate consequences, reason, and communicate a choice. Losing only the last of those — as in muteness, aphasia, or intubation — does NOT remove capacity. Cognitive impairment does.