I've read this sentence in some novel.
He stayed standing in the doorway, not bending down eager and wet toothed like some grown- ups did with kids.
I don't know 'wet toothed' mean.
Could you let me know it?
Since this question has been out a while with no answer, I will combine some of the thoughts from the comments into an answer.
The phrase wet-toothed isn't common. The author made it up to create a picture of an adult who patronizes, or treats in a condescending way, kids. These adults bend over and smile big smiles and are eager to get the kids to like them, where the "he" in the sentence just stands in the doorway like he might if he had been introduced to another grown-up.
Wet-toothed is a good description because it tells us they have a big smile on their face, but it's not a smile that the kid thinks is nice or sincere. It's a smile full of spit and teeth and is kind of yucky. If the kid had liked the smile, the author might have written something like "an easy grin" or "a smile and a twinkle in his eye" or something more flattering than "wet-toothed".