**Core Concept**
The distance between an implant and an adjacent tooth, also known as the interproximal distance or interimplant distance, is crucial for maintaining optimal oral health and preventing complications such as bone loss, tooth mobility, and prosthetic failure. This distance is determined by the type of prosthesis, the size and shape of the implant, and the surrounding bone density.

**Why the Correct Answer is Right**
The American Academy of Implant Dentistry recommends a minimum interimplant distance of 3 mm to 5 mm to ensure proper bone regeneration, prevent bone loss, and maintain the health of the adjacent teeth. This distance allows for adequate bone formation around each implant, reducing the risk of implant failure and promoting a stable, long-lasting prosthetic outcome. The interimplant distance is also critical in preventing the overloading of the implants, which can lead to implant fracture or loosening.

**Why Each Wrong Option is Incorrect**
**Option A:** A distance of less than 2 mm may lead to inadequate bone formation, overloading of the implants, and an increased risk of complications such as implant failure, bone loss, and tooth mobility.
**Option B:** A distance of 2 mm to 3 mm may be insufficient for proper bone regeneration, increasing the risk of implant failure and prosthetic complications.
**Option C:** A distance of 6 mm or more may be excessive, leading to unnecessary bone loss and potentially compromising the stability of the prosthesis.

**Clinical Pearl / High-Yield Fact**
A minimum interimplant distance of 3 mm to 5 mm is recommended to ensure optimal bone regeneration, prevent complications, and maintain a stable, long-lasting prosthetic outcome.

**Correct Answer: C. 6 mm**