**Core Concept**
Precarving burnishing is a technique used in orthognathic surgery to shape and smooth the bone surfaces before fixation. This process involves using a specialized instrument to remove excess bone and create a smooth surface for optimal contact between the bone segments.

**Why the Correct Answer is Right**
The correct answer is related to the limitations of precarving burnishing in orthognathic surgery. Precarving burnishing can be helpful in certain situations, but it is not ideal when the bone segments have significant movement or instability. In such cases, the burnished surface may not provide sufficient stability, leading to complications like malunion or nonunion. The burnishing process can also lead to bone loss, making it difficult to achieve optimal bone contact.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because precarving burnishing is actually helpful in cases where the bone segments have minimal movement or instability, allowing for optimal bone contact and fixation.

**Option B:** This option is incorrect because precarving burnishing can be helpful in reducing the risk of complications like malunion or nonunion, especially in cases where the bone segments have significant movement or instability.

**Option C:** This option is incorrect because precarving burnishing is actually helpful in cases where the bone segments have a complex shape or anatomy, allowing for optimal bone contact and fixation.

**Option D:** This option is incorrect because precarving burnishing is actually helpful in reducing the risk of complications like malunion or nonunion, especially in cases where the bone segments have significant movement or instability.

**Clinical Pearl / High-Yield Fact**
A key consideration in orthognathic surgery is the balance between achieving optimal bone contact and avoiding complications like malunion or nonunion. Precarving burnishing can be a valuable technique in certain situations, but it is essential to carefully evaluate the individual case and consider the potential risks and benefits.

**Correct Answer: D.**