He says he is so busy at work that he cannot find time to go to the dentist's. And I know for psychotherapy, just showing up is far from being enough, a real involvement is necessary. I can't watch him keep lying all the time either. I think that I am going crazy, I do not know what to do anymore. First we have the issue of the lying and second we have the issue of getting someone to seek help.
Some people are pathological liars.
Unless there is a clear gain from the lie, such as covering up something or conning someone, very often the need to lie stems from low self-esteem and insecurity. Liars may feel the need to protect themselves from imagined rebuke or to gain status they crave. In some ways chronic liars are similar to alcoholics. Let me ask two questions. If he does not, then you know he can control his lying but does not feel strongly enough to in some situations.