Remember: teeth are curved so there is depth involved, which means shading should come into play (appropriately).
Your colors are much better, but the sideways shading doesn't do much but make everything look cluttered and messy. Remember that colors compliment the image in this case, and don't conflict it. Keep it simple
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I'm going for the more top-down shade with a hint of horizontal-shading, but if your game does need horizontal-shading, you still should try to avoid using every color of the palette and instead polish the outlines with darker colors.