Final answer:
The ethical principle that may be violated when a dental hygienist decides not to instrument sensitive teeth for pain control is nonmaleficence, as it could lead to greater harm due to untreated dental conditions.
Step-by-step explanation:
In the scenario where a dental hygienist tells a patient she will not instrument the sensitive teeth to assist with pain control, the ethical principle that may be violated is nonmaleficence. This principle is concerned with the obligation to not cause harm to others. While the intention of the dental hygienist might be to prevent pain, which aligns with nonmaleficence, if this decision leads to untreated dental issues that could cause harm in the long run, it could be construed as a violation of this principle. An avoidance of immediate discomfort at the expense of potentially greater future harm fails to meet this ethical directive. The principle of autonomy is also relevant, as it deals with a patient's right to make an informed decision about their healthcare. If the dental hygienist makes this decision without adequately informing the patient or obtaining their consent, it would undermine the patient's autonomy. However, in this case, the most salient concern is nonmaleficence, given the direct link to potential harm resulting from the decision to not address sensitive teeth.