How do I glide the pink over the white without ruining the white?

Smile lines are a tricky business. You must build a “wall” of white to achieve a crisp smile line. You need to create some height at the smile line so it looks sort of like a pie wedge from the side — thicker and angled at the smile line and thinner at the free edge. I prefer to carve the “wall” at a reverse angle instead of having a straight wall. This can be achieved with a brush if sculpting and a drill bit if doing a backfill. I like the diamond bit that looks like a flying saucer. This allows the pink to flood under the white instead of over it. When pulling your pink down the nail, it shouldn’t flood over the white; it should stop at the white to avoid shadowing. -- Maeling Parrish