How is the depth of curing and shade of the material related?
Optical modifiers affect light transmission through a composite. Thus, darker shades and greater opacities have a decreased depth of light-curing ability and require either an increased exposure time or a thinner layer when cured. Studies have shown that for optimal polymerization, resins with darker shades and opacifiers should be placed in thinner layers.
Phillip’s 12th edition page 291
Lighter shade requires more curing
Darker shade requires less curing
Lighter shade requires less curing
Both 1 and 2