What are the contraindications for dental implant placement?

Contraindications for dental implant placement are critical considerations that ensure the safety and success of the procedure. The correct answer highlights three significant factors: uncontrolled diabetes, smoking, and a history of radiation therapy to the head and neck.

Uncontrolled diabetes can lead to poor wound healing, increased risk of infection, and compromised integration of the implant with the bone due to fluctuating glucose levels affecting blood flow and healing processes. Smoking is known to hinder healing and can cause implant failure due to reduced blood circulation and increased risk of peri-implantitis. A history of radiation therapy to the head and neck poses a risk due to potential damage to bone and soft tissue, which can impair healing and increase the likelihood of complications.

In contrast, the other options present situations that either include conditions that are not as detrimental to implant success or suggest scenarios that are not accurate regarding their impact on implant placement. For instance, having controlled diabetes or normal glucose levels would suggest a lower risk for implant failure, while obesity alone does not automatically contraindicate the procedure. Therefore, the detailing of these contraindications in the correct answer underscores the importance of evaluating a patient's overall health status before proceeding with dental implants.