It is fewer not less teeth, isn't it?

[winkywinkola]

Because you can count teeth?

[monsterowl]

Correct: fewer for count nouns, less for mass nouns.

[Hadmeathello]

I'm not an expert but that's how I understand it too.

[Middleagedmotheroftwo]

Yes.

[badtime]

Fewer things, less stuff.

[minniebar]

Less custard, fewer prunes