I would say both an artistic sense of what the completed project looks like (i.e. can you envision what you are doing and the area you're working in) and manual dexterity is needed. You will gain both in dental school.
A lot of people came into school thinking that because they played the guitar or played some video games that operative dentistry would come easy. That wasn't the case. The guitar just creates sound waves and video games just creates light on a TV. Dentistry is working in a small, 3D space + using your hands. It was new to most everyone. Don't worry about skill, it will be learned.