arrange for a dental checkup for both of you. I repeat both of you, make it seem as if you need the dental check up more than him. private dental clinic should be like 100k for both of you, but places like Luth it's about 50 k for both of you.
they should perform teeth whitening amongst others for the both of you. thank me later

NB: you are paying. it's your idea and way to invest in your future.

He can remove the rotten tooth ot teeth and put artificial then take care of the smell