How do I say?!😟

My partner has horrible breath even after he brushes his teeth. Dont know if tonsill stones can be a reason as he has had them in the past/gets them from time to time. He is away on the road alot so doesn't have the best hygiene routine. Everytime I tell him he gets really offended and says he can't help it. I don't know how to encourage him to fix it. He refuses to go to the dentist(trauma as a kid).helppppp!