Okay, let's tackle this question about bone removal during impacted third molar extraction. First, I need to recall the core principles involved. The question is asking which statement is not true regarding bone removal in this procedure. The core concept here would be the surgical techniques and considerations for removing impacted molars, specifically the role of bone removal.

The correct answer's explanation should detail why the incorrect statement is false. Common mistakes in such procedures might involve the necessity of bone removal, the methods used, or the anatomical considerations. Let's think about the options that might be presented. For example, if one option says that bone removal is never necessary, that's incorrect because in many impacted cases, some bone removal is required. Another might incorrectly state that it's done to avoid nerve damage, but actually, the primary reason is to access the tooth.

Each wrong option needs to be addressed. For instance, if an option claims that bone removal is done with a rotary instrument without a chisel, that's incorrect because chisels are often used for cortical bone. Another might say that bone removal is only for fully impacted teeth, but even partially impacted teeth might require it. The clinical pearl here is that bone removal is typically done to create access and reduce resistance, not to avoid nerves, which is a common misconception. The correct answer would be the statement that contradicts these points.

**Core Concept**
Bone removal during impacted third molar extraction is a surgical technique to access the tooth, reduce resistance, and prevent iatrogenic injury. It involves removing cortical bone to expose the tooth crown and facilitate luxation, guided by anatomical landmarks like the inferior alveolar nerve.

**Why the Correct Answer is Right**
The false statement might claim that bone removal is unnecessary for partially erupted molars. However, even partially impacted teeth often require bone removal to fully access the crown, especially if the lingual or buccal cortical plates are thick. Techniques like piezoelectric surgery or chiseling are used to remove bone safely, minimizing trauma to adjacent structures.

**Why Each Wrong Option is Incorrect**
**Option A:** *“Bone removal is contraindicated in patients with osteoporosis.”* Incorrect—Osteoporosis does not contraindicate bone removal, though care is needed to avoid excessive force.
**Option B:** *“Cortical bone is the primary target for removal.”* Incorrect—Cancellous bone is typically removed first; cortical bone is preserved to maintain structural integrity.
**Option C:** *“Bone removal reduces the risk of lingual nerve injury.”* Incorrect—Proper bone removal avoids lingual nerve proximity, but the nerve’s location (inferior to the mandible) is not directly related to bone removal.

**Clinical Pearl / High-Yield Fact**
Always prioritize removing cancellous bone first to minimize cortical thinning and nerve injury risk. Use a chisel for cortical bone only when absolutely necessary, and confirm the position of the inferior alveolar nerve via imaging preoperatively.

**Correct Answer: C. Bone removal reduces the risk of lingual nerve injury**

✓ Correct Answer: A. Low speed low torque drill is used for bone removal