So today I was watching Grown-up again and saw the tooth of Lennys daughter fell and we can see she had no tooth. Similarly I remembered no tooth scene in the Hangover part 1. So I thought how do they do toothless shots? Are the actors really toothless and they wore any prop tooth for the previous scenes? So I searched for the hangover toothless scene and found an interesting interview with the actor Ed Helms:

The missing tooth, how did they do that?

Ed Helms: "When I was 15 I lost a tooth and had an implant put in. Cut to 20 years later, I'm doing this part and the script calls for my character to lose a tooth. We did some camera tests blacking it out, we made a prosthetic with a gap in it, but that made me look like a donkey, so I vetoed that right away. And then I just finally called my dentist and said, 'You know, I've had this implant for 20 years. What's it involve in taking it out?' And he said, 'It’s actually not that big a deal. We can do that.' So we took it out and I was toothless for three months, for the run of the movie."

But my question is it always possible to higher such an actor who has lost his/her tooth in past. Each director/producer may not get that lucky. But there are a lot of movies there where tooth picking or losing is shown. Like the girl in Grown Ups or the guy in The Tommyknockers (Reference). So what do they do then? How are they able to show tooth less mouth?