Haha, that’s a good question! Definitely something worthy of making people wake up at 3 AM.
This touches on a question that I’ve thought about ever since I first watched Toy Story: how do toys who were made with closed mouths have teeth, or even open their mouths, when they come to life?
The main answer is, of course, plot reasons. Because it would be too unsettling to have eternally smiling toys as your main characters.
Basically, a lot of toys in Chrisville don’t have teeth until Chris brings them to life in his mind. Even Leo doesn’t originally have teeth!
Leo’s teeth are more obvious because he’s a lion, and Chris wanted to show off those fangs of his. Softboy, however, would have “normal” human-like teeth, but Chris probably doesn’t even consider Softboy’s teeth unless he’s giving a toothy grin, or is biting something.
So to paraphrase Who Framed Roger Rabbit?, Softboy has teeth only when it’s funny necessary.