You can enter the amount you actually PAID for 2018 on your 2018 tax return. If you paid some of it in 2019 then that amount can only be entered on your 2019 return. It is not important when you actually got the dental work done or completed; it is about when you PAID for it.
**Disclaimer: Every effort has been made to offer the most correct information possible. The poster disclaims any legal responsibility for the accuracy of the information that is contained in this post.**
