Safe? I can't say definitively.
I do know you're not risking much by smoking after dental anesthesia and fillings. I'd think as soon as the fillings were dry/set it'd be okay to inhale some burning plant matter... The big issue with smoking after dental work revolves around having teeth pulled.
If I were in your shoes, GGooDD, I seriously wouldn't worry about it. Burn one or two or three or twenty, I doubt it'll have any significant effect on a cavity filling.