It looks like you'll have to trim apart the teeth and insert them individually into the mask mouth. The most secure way to do that is to cut holes just a little smaller than the individual teeth. That way, the latex will grip them securely until you can add some glue.
The lower mandibles would likely need to be flush against the for an "invisible" seam. But the little bits of resin on the connecting end might be a good thing. Cut a smaller hole for those protruding bits and insert them into the mask jaw until the lower mandibles meet up against the jaw bone.
Hope this helps!
If anyone else has some good ideas, let's hear 'em!!
You have two different sets of teeth there. The large ones are for the matt P1 mask and the 4 smaller teeth are for a db P2. The large manibles you need to sand down the pour in nipples and with the smaller ones your going to have to sand down alot to get them into your mask if its a matt P1 you have.