**Core Concept**
The modern approach to treating a discolored crown involves addressing the underlying cause and restoring the tooth to its natural appearance and function. This can include both non-invasive and invasive treatments, depending on the severity of the discoloration.

**Why the Correct Answer is Right**
The modern approach to treating a discolored crown often involves the use of bleaching agents to break down and remove the chromogens responsible for the discoloration. This can be done using in-office bleaching or at-home bleaching systems, which contain hydrogen peroxide or carbamide peroxide. The bleaching agent penetrates the tooth enamel and dentin, breaking down the chromogens and lightening the tooth. This approach is often preferred because it is minimally invasive and can be effective in treating mild to moderate discoloration.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not address the underlying cause of the discoloration and may not provide a long-term solution.
**Option B:** This option is incorrect because it is too invasive and may not be necessary for mild to moderate discoloration.
**Option C:** This option is incorrect because it is not a common or recommended treatment for discolored crowns.

**Clinical Pearl / High-Yield Fact**
A key consideration when treating a discolored crown is to determine the underlying cause of the discoloration, as this will guide the choice of treatment. Common causes of discoloration include extrinsic stains from food and drink, intrinsic stains from trauma or infection, and age-related changes in the tooth structure.

**Correct Answer:** C.