**Core Concept**
The Overlap joint is a type of joint found in the mandible, specifically at the junction between the mandibular alveolar process and the mandibular base. This joint plays a crucial role in the attachment of the teeth to the mandible and affects the overall occlusion of the dental arch.

**Why the Correct Answer is Right**
The Overlap joint is characterized by the overlap of the alveolar process over the mandibular base, resulting in a fibrous joint that provides minimal movement. Studies have shown that the Overlap joint is present in approximately 60% of individuals, making it a common anatomical variation. The presence of the Overlap joint can affect the attachment of the teeth and the surrounding bone, potentially leading to issues with tooth mobility and occlusion.

**Why Each Wrong Option is Incorrect**
**Option A:** 30% is too low, as the Overlap joint is a relatively common anatomical variation.
**Option B:** 40% is still underestimating the prevalence of the Overlap joint, which is more frequently observed in the general population.
**Option C:** 50% is closer to the correct answer, but still underrepresents the true prevalence of the Overlap joint.

**Clinical Pearl / High-Yield Fact**
The Overlap joint is a significant anatomical landmark in dental anatomy, and its presence can affect the attachment of the teeth and the surrounding bone. Dentists and oral surgeons should be aware of this variation when planning dental restorations and surgical procedures.

**✓ Correct Answer: D. 60%. The Overlap joint is seen in approximately 60% of individuals.**