Another Complete Shot In The Dark...

Idea 1:
What if we thought of the question as:

Why The (CombOfNatashaOtomoski) Has 21 teeth?

My reason to focus on CombOfNatashaOtomoski is that it's 21 chars.

Likewise, we can choose to interpret the question in 2 more ways:
Why The Combination "OfNatashaOtomoski" Has 21 Teeth?
Why The Combination Of "NatashaOtomoski" Has 21 Teeth?


Idea 2:

Letters like m, n, h can look like teeth. Depending on what you interpret to look as a tooth (e.g m looks like 2 teeth):

      1            2                3,4                                       5                      6,7                    8                                        9
W   h   y   T   h   e   C   o   m   b   O   f   N   a   t   a   s   h   a   O   t   o   m   o   s   k   i   H   a   s   2   1   T   e   e   t   h      

9 "teeth" in this sentence, or more or less depending on what you interpret as "teeth".    


Just trying to think super "out of the box"...
                    

Edit: Included more interpretations of the question