Ahsan Allahu ilaykum. Respected shaykhana, if someone naturally has off white teeth ( a bit yellowish) then in that case: would whitening the teeth be changing the creation of Allah? جزاكم الله خيرا

If the whitening removes yellowness and returns the teeth to their natural clean colour, it is not changing the creation of Allah. If it goes beyond the natural colour only to add beauty, then it falls under the added beautification the scholars forbade.