I wouldn't ordinarily post this but it may help in understanding the oversight of the tooth. There was a time that I had what I'll call an accident. My top teeth went into a very hard wall that was dry wall or whatever but it was very hard and my teeth left a pretty deep impression in the wall without me knocking out any teeth. Now keep in mind that there wasn't much force at all, like falling into a wall for instance, not pushed. Another important aspect of my experience is to let everyone know that there were no other injuries such as nose or face hitting the wall.
If Michelle's head was being slammed into the wall with as much force as she was hit with I have no doubt that a tooth could've been lodged into the wall. We know LE cut out dry wall. Although I don't know for a fact their evidence gathering procedures it's logical to conclude they took the drywall after they had completed the floor since that's where the body was found. That's how the tooth could've ended up where it was and also unnoticed by LE.