This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Dental
For generic root form implant, each .25mm increase in diameter corresponds to increase in surface area by 
Select and explain. 
A. 2%, B. 3%, C. 4%, D. 5%
D: 5%
Answer: D: 5% 
Explanation: With a greater surface area of implant-bone contact, less stress is transmitted to the bone, improving the implant prognosis. For a generic root-form implant design, each 0.25 mm increase in diameter corresponds to a surface area increase of 5% to 8%. Therefore, a cylinder root-form implant 1 mm greater in diameter will have a total surface area increase of 20% to 30%.