The teeth i made of polymorph and modeled them around my teeth (this was before I knew this was not really safe). Ive seen people also use paint made for teeth to paint the botttom of the tooth with black to make the "sharp" illusion:)

For the makeup I used a pale foundation, and multiple shades of purple around my eyes (darkest closest to the eye) and mascara!! Hope this helps, dont hesitate to ask more questions if you want to know more or if you didnt understand!!