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
A major difference between total-etch and selfetching primer dentin bonding systems include all of the following except _____. 
Select and explain. 
A. The time necessary to apply the material(s)., B. The amount of smear layer removed., C. The bond strengths to enamel., D. The need for wet bonding.
A: The time necessary to apply the material(s).
Answer: A: The time necessary to apply the material(s). 
Explanation: Self-etch dentin bonding systems differ from total-etch dentin bonding systems by removing less of the smear layer (they use a less potent acid), creating a weaker bond to enamel (especially nonprepared enamel), and not requiring wet bonding that may be necessary for some of the total-etch systems. Even though fewer actual materials may be needed with some of the self-etch systems, they need to be applied in multiple coats and thus the time necessary to apply the materials is similar for both systems.